A Review of Marine Algae as a Sustainable Source of Antiviral and Anticancer Compounds

Abstract

Biopolymers, such as polysaccharides, polyphenols, alkaloids, and terpenoids, found in marine algae exhibit antiviral and anticancer properties. These compounds can inhibit viral replication, induce apoptosis in cancer cells, and enhance the immune response. Their diverse bioactive properties make marine algae a promising source for the development of sustainable antiviral and anticancer therapies. A major advantage of marine algae is that they do not require freshwater or arable land and can be cultivated in seawater, thus making them sustainable substitutes for conventional resources. Additionally, their ability to sequester carbon and recycle nutrients enhances their environmental sustainability. Despite their promising biomedical potential, challenges, such as compound extraction, large-scale production, and clinical validation, must be addressed for effective drug development. The vast biological diversity of marine algae across different ocean ecosystems is a largely unexplored source of distinct chemical structures, which may be the basis for new therapeutic schemes. Despite their therapeutic potential, the translation of marine algae-derived compounds into clinical applications faces significant hurdles, including challenges in large-scale extraction, bioavailability enhancement, and regulatory approval. The need to extract particular compounds to make them available for large-scale production and to overcome issues such as bioavailability and regulatory policies are formidable challenges. Marine algae represent innovative advances in antiviral and anticancer drug development, but only when combined with ecologically sound cultivation methods, interdisciplinary approaches, and understanding. The integration of advanced biotechnological approaches, innovative gene editing techniques, and environmentally sustainable aquaculture practices is pivotal for harnessing the full potential of marine algae for the development of next-generation antiviral and anticancer therapeutics.

1. Introduction

Marine algae have emerged as an important focus in biomedical research, owing to their rich content of bioactive compounds with potential antiviral and anticancer properties [1]. These compounds (polysaccharides, phenolics, terpenoids, alkaloids, and sulfated carbohydrates) have yielded remarkable pharmacological activities. The growing resistance to synthetic drugs and the demand for new, naturally derived therapeutics make marine algae a potential resource for drug discovery and an increasingly important subject [1,2]. Marine algae, microalgae (diatoms, dinoflagellates, and cyanobacteria), and macroalgae (green, brown, and red seaweeds) can withstand extreme oceanic conditions and, as defensive mechanisms, have evolved specialized secondary metabolites. These metabolites have attracted attention owing to their antiviral, anticancer, anti-inflammatory, and immunomodulatory activities. Antigenic polysaccharides from red algae (carrageenans and fucoidans) have shown antiviral activities against human herpes simplex virus (HSV), human immunodeficiency virus (HIV), and influenza virus. Similarly, brown algae metabolites such as phlorotannins and sulfated polysaccharides have also been reported to induce apoptosis and restrain cancer cell proliferation [3,4]. Antiviral activity of marine algae mainly relies on sulfated polysaccharides including carrageenans, fucoidans, and ulvans, which exert this effect by blocking viral binding and replication. Carrageenans isolated from Chondrus crispus and Kappaphycus alvarezii have shown suppressive activity against HIV, HSV, human papillomavirus (HPV), and dengue virus, inhibiting viral entry into the host cells [5,6]. Likewise, fucoidans from brown seaweeds like Fucus vesiculosus and Undaria pinnatifida can block the replication of viruses by binding to viral surface proteins, thereby blocking infection processes [6]. Research on ulvans from green algae has also shown potential activity against respiratory viruses, such as influenza A and coronaviruses [7]. However, there are some challenges in the standardization of extraction procedures, bioavailability optimization, and clinical trials to support the therapeutic activity of these compounds in human therapeutics. Further research should aim to increase the structural characterization of antiviral polysaccharides and optimize their formulation for therapeutic purposes [8]. Marine algae are also known to have anticancer activity, and reports on their tumor growth-inhibiting, apoptosis-inducing, and tumor metastasis-suppressing abilities have been presented. Cytotoxic properties of compounds (phlorotannins, bromophenols, and terpenoids) have been demonstrated in several cancers (including breast, lung, colon, and liver) [9]. Fucoidan, a sulfated polysaccharide isolated from brown algae, has received considerable attention because of its apoptosis activity in cancer cells via caspase activation and the inhibition of angiogenesis [8,9]. In addition, algae-derived alkaloids and flavonoids have demonstrated selective inhibitory effects on essential cellular activities such as cell cycle, migration, and invasion. Extracts from Ulva lactuca, Sargassum dentifolium, and Cystoseira myrica have exhibited potent antitumor activity, with studies indicating their ability to suppress tumor progression in vitro and in vivo [10,11]. Although promising results have been obtained, low bioavailability, structural complexity, and a lack of clinical trials limit the direct utilization of these compounds for cancer treatment [11]. Filling these gaps that have been achieved by biotechnological advances, nano-formulation tactics, as well as mechanistic studies of these gaps, are likely to play a critical role in incorporating marine algae bioactives into future oncology treatments. Marine algae contain a phenomenal library of bioactive compounds; however, the potential biomedical applications of these algae are poorly explored because of limitations in large-scale production, extraction efficacy, and clinical evidence (Figure 1) [9,10,11]. The requirements for sustainable extraction, upgraded techniques of purification, and extensive molecular characterization point to the need for further research. The need to understand structure–activity relationships (SARs) and optimize bioactive compound delivery systems will be a crucial factor in moving marine algae metabolite-based solutions for antiviral and anticancer therapeutics from the lab bench to patient use [8,9]. Marine algae are promising sources of modern medicine, offering a natural and sustainable source of antiviral and anticancer drugs. Future research at the frontier of this area would necessitate interdisciplinary teamwork between marine biology, pharmacology, and clinical sciences to explore the vast potential of these marine-derived compounds in human medicine [10,11].

Marine macroalgae and microalgae are eco-friendly and can be acquired as rich sources of bioactive molecules, which have promising biomedical and industrial applications for restoring properties of microorganisms, tissues, or cells. These bioactive compounds are carbohydrates, proteins, minerals, fatty acids, antioxidants, and pigments, depending on the content of these substances, which are under the control of biotic (plant and microorganism) and abiotic (temperature, pH, salinity, light intensity) factors [11,12]. Marine algae are promising anticancer and antiviral agents because of the vast amount of bioactive metabolites accumulated therein. Compounds including brominated metabolites, polysaccharides, terpenes, polyphenols, and phlorotannins have anticancer effects in vitro and in vivo by activating apoptosis, suppressing angiogenesis, and activating the immune system [13,14,15]. In addition, the anticancer effects of microalgae-derived pigments, lipids, and carotenoids have been demonstrated in many cell lines by targeting the anticancer-related molecular targets involved in cancer progression [15,16]. The specific antiviral activity of sulfated polysaccharides (SPs), fucoidans, carrageenans, and ulvans, is strong, and these offer potential for leading antiviral drugs. These SPs, along with other secondary metabolites, suppress viral replication and could be candidate therapeutic agents against viral infections [7,17]. In general, brown seaweeds are equipped with potent anti-biofilm compounds, including sulfated polysaccharides (fucoidan), carotenoids (zeaxanthin and lutein), lipids and fatty acids (γ-linolenic acid and linoleic acid), and phlorotannins. These species are used to inhibit bacterial adhesion, suppress proliferation, and denature extracellular polymeric substances, and are therefore important in preventing the development of biofilm. This is especially relevant for preventing the corrosion of metal components which can lead to substantial economic losses in many industries [17,18]. They are recognized in the food industry as a high-protein, nutrient-rich meal with vitamin and mineral components that can prevent chronic diseases such as obesity and cardiovascular disorders. Due to the presence of abundant n-3 fatty acids, essential amino acids, and dietary fibers that most of the usual algae-based food products contain, algae-based food items are helpful for human health and nutrition [16,17,18,19]. However, given the high diversity of bioactive compounds in marine algae, there are still many challenges in their extraction and practical applications.

Traditional solvent extraction procedures typically have poor efficiency, require high processing, and are extensive. To address these deficiencies, several high-tech extraction methods have been proposed, including enzyme-assisted, microwave-assisted, ultrasound-assisted, supercritical fluid, and pressurized liquid extractions. These novel methods enhance the efficiency, sustainability, and purity of compounds that are produced from algae-derived products, thereby enabling algae-derived products to be of use in production [18,19,20]. Brown, red, and green algae possess a wide variety of unique bioactive molecules such as sulfogalactofucans, fucoidans, carrageenans, and ulvans (

Table 1. Different types of marine algae and their representative species.

Algae	Phylum	Family	Scientific Name
Green algae	Chlorophyta	Ulvaceae	Ulva lactuca
Red algae	Rhodophyta	Gigartinaceae	Chondrus crispus
Brown algae	Ochrophyta	Laminariaceae	Laminaria digitata
Blue–green algae	Cyanobacteria	Nostocaceae	Nostoc commune
Dinoflagellates	Dinoflagellata	Gonyaulacaceae	Gonyaulax polyedra
Diatoms	Bacillariophyta	Thalassiosiraceae	Thalassiosira pseudonana

); therefore, they have great potential in biomedical research and industry [21].

Data Analysis

Keywords were used to search for articles in the following four databases: Google Scholar, SCOPUS, PubMed, and Web of Science. The domains were title, abstract, and keywords, which included “Marine algae, Antiviral compounds, Anticancer compounds, Bioactive compounds, Pharmaceutical applications, Algal secondary metabolites, Sustainable resources”. The duration for the search was limited to the years 2000–2024; however, two citations were taken from 1997 and four citations were taken from 1999, 1987, 1975, and 1981, respectively. A total of 70 citations were retrieved from SCOPUS, 70 from Google Scholar, 25 from PubMed, and 5 from Web of Science.

Publications were checked for duplication, and the publications whose scope was limited to applications of marine algae other than antiviral and anticancer compounds were excluded from the review. After screening, 62 publications from SCOPUS, 47 publications from Google Scholar, and 29 publications from PubMed, and 5 from Web of Science were retained for the review.

2. Classification and Distribution of Marine Algae

Marine algae are autotrophs that live in the ocean and can be either micro- or macro-sized (Figure 2). Microalgae, including diatoms, dinoflagellates, and cyanobacteria (blue–green algae), are single-celled organisms, whereas macroalgae, also known as seaweeds, are multicellular and comprise green, brown, and red algae, respectively. Cyanobacteria, diatoms, and dinoflagellates are examples of microalgae because they are unicellular. They are also essential components of and hold substantial importance in underwater biodiversity and oxygen production, and have a variety of industrial applications as basic living beings of underwater systems. They live in marine settings, and are classified into the following two main types: microalgae and macroalgae. In addition to their ecological importance, marine algae are used efficiently in the food, pharmaceutical, and biofuel sectors. However, they are also important reservoirs of blue carbon sequestration, which plays a role in mitigating climate change. Classification, bioactive compounds, and environmental and geographical distribution need to be understood to be sustainably utilized and conserved [22,23].

2.1. Classification of Marine Algae

Microalgae are unicellular, nearly microscopic organisms, including cyanobacteria, diatoms, and dinoflagellates. These algae are the primary producers in the marine food chain in terms of organic synthesis via photosynthesis. Some of the most important microalgae species include Chlorella, Spirulina (Arthrospira platensis), Dunaliella salina, and Haematococcus pluvialis, some of which are beneficial for their nutritional and pharmacological properties [22,23,24]. In contrast, macroalgae and seaweeds are multicellular and are known to grow on macroscopic scales. Seaweeds also produce vast underwater forest habitats that provide both food and habitat for marine organisms. Examples include kelps (Laminaria, Macrocystis), Sargassum, and Gracilaria [24,25]. Macroalgae are commercially exploited in food and medicine because of the high content of polysaccharides and bioactive compounds in these taxa.

2.2. Bioactive Compounds and Industrial Applications

Marine algae are rich in bioactive compounds with significant applications in various fields. Microalgal lipids are abundant, and, as such, their potential use as biomass in biodiesel production is promising. The high lipid contents of species such as Nannochloropsis and Botryococcus braunii enables the extraction and conversion of the lipids into biofuels [24,25]. In addition, microalgae-derived antioxidants such as beta-carotene (Dunaliella salina) and astaxanthin (Haematococcus pluvialis) have been extensively utilized in the pharmaceutical and cosmetic fields due to their strong antioxidant activity [26]. However, macroalgae are also of interest for their high polysaccharide content (e.g., agar, carrageenan, and alginate), collectively known as phycolloids, which serve as gelling, thickening, and stabilizing agents in food, pharmaceuticals, and cosmetics. The natural origin compounds for Gracilaria, Gelidium, and Macrocystis, which might be present in dairy foods, cosmetics, and biomedical applications, are elaborated on in [27,28,29]. Furthermore, macroalgae are rich in bioactive compounds, including phlorotannins, bromophenols, and flavonoids with antioxidant, antimicrobial, and anticancer activities. Brown seaweeds such as Turbinaria ornata and Hormopysa triquetra have extremely high contents of antioxidant activity and are beneficial for nutraceutical and pharmaceutical applications [30,31]. Marine algae also play an important role in aquaculture. Microalgae constitute a significant food source for larval fish, prawns, and bivalves, which have major importance in the sustainable development of the aquaculture industry. Species of Isochrysis galbana and Tetraselmis suecica are employed to enhance larval feeding, thereby enhancing the survival rate of larvae at hatcheries [26]. Additionally, algae-derived food supplements (e.g., Spirulina and Chlorella) are very commonly consumed due to their high protein, β-carotene, and vitamin contents, which are known to enhance the immune system and reduce neurodegeneration and cholesterol content [24,32].

2.3. Ecological Importance and Environmental Factors

Marine algae are fundamental to oceanic ecosystems, and serve as primary producers of organic matter and oxygen. They are responsible for over 90% of photochemical activity at the Earth’s surface and, accordingly, play an important role in carbon fixation and oxygen production. Macroalgal forests (e.g., kelp forests) provide a source of food, a refuge, and a breeding environment for a wide range of animal species [5,33]. Marine algae also function as regulators of natural climate. Macroalgal ecosystems, by providing blue carbon sequestration, absorb and store atmospheric CO₂ to help limit global warming. As brown algae (e.g., Sargassum and Laminaria) are efficient at carbon storage, they play a key role in mitigation strategies for climate change [33]. However, not all algae have positive ecological impacts. Harmful algae blooms (HABs) resulting from toxic algae, such as Alexandrium, Karenia brevis and Pseudo-nitzschia, produce toxins and contaminate seafood through the pollution of shellfish and marine ecosystems, leading to ecosystem destabilization [34]. These blooms are highly indicative of excess nutrients in, warming of, and alterations in the oceanographic environment. Information on how algal growth is regulated in relation to environmental factors such as nutrients, temperature, light intensity, and wave action is helpful for algal growth inhibition and ecological balance [35].

2.4. Geographical Distribution and Environmental Impact

The distribution of marine algae is affected by a wide range of environmental factors such as temperature, salinity, and ocean currents. Microalgae such as Alexandrium are predominantly found in cold to temperate coastal waters, including the Northwest Pacific and the Mediterranean, where specific sea surface temperatures and oxygen levels favor their growth. These areas are especially susceptible to the rising frequency of HABs; therefore, surveillance and countermeasure actions are required [36]. By contrast, macroalgae, including kelps and fucoid seaweeds, are the key grazers of temperate coastal communities, especially in the Northeast Pacific and Southeast Australia. These macroalgal species can grow in areas with adequate light penetration and stable temperature. Their presence also plays a major role in marine biodiversity and coastal protection, decreases erosion, and provides important habitats for fish and invertebrates [37]. Recent reports indicate that up to 20.8 million km² of ocean area can be farmed with marine algae, highlighting the scale at which the farming of macroalgae can occur and how the industry can be commercialized. The increased production of seaweed for farming can contribute to food security, carbon sequestration, and sustainable biofuel creation, extending marine algae’s involvement in the global economy [38]. Marine algae also engage with microorganisms to create holobionts composed of microbial communities that flourish with algae and play a role in nutrient cycling and ecological stability. Nevertheless, climate change, as well as its impacts on air quality and pollutant loss in habitats, interfere with these symbiotic relationships and disturbing dynamics of marine ecosystems [39].

Marine algae play an indispensable role in marine ecosystems as habitat providers and key contributors to global oxygen production. The bioactive compounds in marine algae have fueled innovations in pharmaceuticals, nutraceuticals, and renewable energy. Moreover, their role in blue carbon sequestration positions them as vital components in climate change mitigation efforts [38,39]. Despite their benefits, harmful algae blooms pose ecological and economic threats, highlighting the importance of effective environmental management [33]. Additionally, geographical factors influence algal distribution, shaping biodiversity hotspots across different marine regions. The continued exploration of marine algae’s potential in food, medicine, and energy sectors, coupled with conservation efforts, is crucial for harnessing their benefits sustainably. Understanding marine algae’s functional diversity, environmental significance, and economic applications will ensure their effective utilization while maintaining ecological balance. Future research should focus on optimizing cultivation methods, exploring novel bioactive compounds, and mitigating the adverse effects of harmful blooms to maximize the potential of these marine organisms in a sustainable manner [5,33,40].

3. Bioactive Compounds in Marine Algae

Marine algae are potential sources of bioactive compounds that can be harnessed for therapeutic interventions, especially as anti-inflammatory agents, antioxidants and antimicrobials (

Table 2. Biopolymers and bioactive compounds derived from marine algae and their biological activities.

Category	Compound	Source Algae Type	Biological Activity	Potential Applications	References
Polysaccharides	Fucoidan	Brown algae	Antiviral, anticoagulant, anticancer	Pharmaceuticals, nutraceuticals	[1,49]
	Carrageenan	Red algae	Antiviral, anti-inflammatory	Food industry, drug formulations	[50]
	Alginate	Brown algae	Wound healing, antibacterial	Biomedicine, food Additives	[51,52]
Proteins and Peptides	Phycobiliproteins	Red algae	Antioxidant, immunomodulatory	Nutraceuticals, cosmetics	[1,53]
	Lectins	Red and green algae	Antiviral, antitumor	Drug development	[49,52]
Lipids	Omega-3 fatty acids	Microalgae	Cardioprotective, anti-inflammatory	Dietary supplements	[50,51]
Phenolic Compounds	Phlorotannins	Brown algae	Antioxidant, antidiabetic	Cosmetics, pharmaceuticals	[1]
Pigments	Chlorophyll	Green algae	Antioxidant, antimicrobial	Health supplements, dyes	[52,53]
	Fucoxanthin	Brown algae	Anticancer, anti-obesity	Nutraceuticals, cosmetics	[49,51]
Terpenes	Halimedatetraacetate	Green algae	Antimicrobial, cytotoxic	Drug development	[52]
Sterols	Fucosterol	Brown algae	Antioxidant, antidiabetic	Pharmaceuticals, nutraceuticals	[50,53]

). Secondary metabolites that are synthesized by both micro- and macroalgae, such as polyphenols, carotenoids, phlorotannins, and bromophenols, exhibit biological activities, including antioxidant, anticancer, and antibacterial properties. Marine algae are also potential sources for the manufacture of pharmaceutical drugs, biomedical products, nutraceuticals, and cosmeceuticals. Such compounds are polyunsaturated fatty acids (PUFAs), pigments, antioxidants, terpenoids, carotenoids, tocopherol, phenolic compounds, polysaccharides, and mycosporine-like amino acids [41,42,43]. For example, phlorotannins derived from brown algae and carotenoids obtained from different algae types have been reported to alter inflammatory pathways as well as oxidative stress. Sulfated polysaccharides (SPs), particularly carrageenans, fucoidans, and ulvans, which are extracted from marine algae, are abundant and have significant health benefits, including antioxidant, anti-allergic, antiviral, anticancer, and anticoagulant activities [21,30]. Microalgae have been shown in recent studies to possess anticancer activity, with extracts having a considerable anti-proliferative impact on various cancer cell lineages. Fucoidans from brown seaweeds, such as Ecklonia cava, Sargassum horneri, and Costaria costata, inhibit colony formation in human melanoma and colon cancer cells by modulating key signaling pathways. They suppress the PI3K/Akt (Phosphoinositide 3-Kinase/Protein Kinase B) pathway, which leads to reduced cell survival and promotes apoptosis. Fucoidans also inhibit NF-κB (Nuclear Factor-KappaB) activation, thereby downregulating the expression of inflammatory and pro-survival genes. Furthermore, fucoidans interfere with the MAPK (Mitogen-Activated Protein Kinase) signaling cascade (comprising ERK(Extracellular Signal-Regulated Kinase), JNK,(c-Jun N-terminal Kinase) and p38), which further limits cancer cell proliferation and enhances apoptosis induction [44,45]. Additionally, research on Hawaiian algae revealed that the extract of Turbinaria ornata exhibited the highest antioxidant activity, with fucoxanthin identified as the primary bioactive antioxidant compound [43,46,47]. More specifically, some bioactive metabolites, such as halogenated mono- and sesquiterpenoids from red algae, have cytotoxic effects on tumor cells and exhibit antifeeding effects on marine animals [13]. Through the generation of cell toxicity, red algae produce brominated metabolites, including terpenoids and phenols, that possess anticancer activity. Furthermore, macromolecules, such as polysaccharides from green algae, are still being researched rather than existing as established treatments. While studies suggest they can block angiogenesis, stimulate immune responses, and trigger apoptosis, further preclinical and clinical trials are required to confirm their effectiveness and safety [48].

Studies have shown that polysaccharides extracted from the green seaweed Enteromorpha (Ulva) prolifera have hypoglycemic activity; they have also been shown to modulate gut microbiota, boost the immune response, and possess antioxidant properties, as well as antidiabetic, antimicrobial, and hypolipidemic activities. These polysaccharides can be utilized to foster even more therapeutic potential through the degradation, carboxymethylation, or sulfonation of the polysaccharides, as indicated by recent work on molecular modification techniques. There is a growing trend of employing modern extraction techniques over those old trends because of the lack of suitable tools and techniques. Modern extraction methods, such as supercritical fluid extraction, subcritical water extraction, ultrasound-assisted extraction, and microwave-assisted extraction, are being used to isolate these compounds, as they present more benefits than the conventional methods. Marine algae bioactive compounds vary significantly based on species, environmental conditions, and growth parameters. These permissive conditions mean that algae grow under their most favorable conditions. Different species produce various compounds; some are specific to those types of algae and other compounds are common in all algae [54]. The following are general compounds found in marine algae.

3.1. Polysaccharides

Marine algae contain several important biopolymers, as follows:

• Fucoidan: Sulphated polysaccharides found in brown algae, with structural variations including U-fucoidan (contains glucuronic acid), F-fucoidan (sulfated fucose), and G-fucoidan (contains galactose). They have been shown to have anticoagulant, antiviral, and anticancer activities [55].
• Carrageenan: A sulfated polysaccharide classified into kappa, iota, and lambda types. It is extracted from red algae (Rhodophyceae) and is used as a gelling and thickening agent in the food industry [56].
• Porphyran: A sulfated polysaccharide from Rhodophyta, with a linear backbone of alternating β-D-galactose and α-L-galactose-6-sulfate units [56].

3.2. Proteins and Amino Acids:

Marine algae are rich in the following unique protein structures:

• Glycoproteins: Found in various marine algae, these are bound to carbohydrates, with approximately 36.24% composed of rhamnose, galactose, glucose, and mannose [12].
• Phycobiliproteins: Found in red algae and cyanobacteria, these are water-soluble proteins linked to chromophores like phycocyanin (PC) and phycoerythrin (PE), which demonstrate antioxidant and potential anticancer properties [12].

3.3. Lipids

Marine algae contain various bioactive lipids, including polyunsaturated fatty acids (PUFAs) and sterols, as follows:

• Omega-3 fatty acids: Found in microalgae and some macroalgae, omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have well-documented health benefits, including cardiovascular protection and anti-inflammatory effects [57].
• Fucosterol: Found in brown algae, fucosterol is a sterol with potential antioxidant, anti-inflammatory, and anticancer activities [58].

3.4. Secondary Metabolites

Marine algae produce a diverse array of secondary metabolites with various bioactivities, as follows:

• Phlorotannins: Found in brown algae, phlorotannins are polyphenolic compounds with antioxidant, anti-inflammatory, and anticancer properties [59].
• Fucoxanthin: A carotenoid found in brown algae, fucoxanthin has been studied for its antioxidant, anti-inflammatory, and anti-obesity effects [60].

4. Antiviral Compounds from Marine Algae

Algae, over the centuries, have become a powerhouse of bioactive compounds, specifically those with the scope of antagonizing viruses (

Table 3. Antiviral compounds derived from different marine algal species.

Algae Species	Compound	Target Virus	Action	References
Gracilaria corticata	Sulfated polysaccharide	HIV, HSV-1	Inhibits viral entry and replication	[73]
Gigartina skottsbergii	Carrageenan	Influenza A, HPV	Blocks viral attachment	[74]
Codium fragile	Lectin	Dengue, Hepatitis C	Prevents adsorption and replication	[75]
Sargassum spp.	Fucoidan	HIV, Hepatitis B	Inhibits reverse transcriptase	[76]
Kappaphycus alvarezii	Carrageenan	SARS-CoV-2	Prevents viral attachment	[56]
Ulva lactuca	Sulfated galactan	Herpes simplex virus (HSV-2)	Disrupts viral envelope	[71]

). In vitro research has shown that algae extracts exhibit antiviral activity against SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) by inhibiting viral replication. Similarly, alginate-based materials have demonstrated the in vitro inhibition of structurally similar RNA (Ribonucleic Acid) viruses, including HIV-1, RV (Rotavirus), HCV(Hepatitis C Virus), and SINV (Sindbis Virus). These findings suggest that algae-derived compounds and materials could be promising for SARS-CoV-2 treatment and prevention, though further research on this is needed [61]. The antiviral activities of algal extracts are directed by diverse compounds, with significant contributions made by sulfated polysaccharides like fucoidan, carrageenan, and alginate [62,63]. For example, according to one research study, extracts from Tetraselmis sp. exerted substantial antiviral effects against the Zika virus, and chlorophylls, as the main active components, were proven to modulate the immune response without cytotoxic effects on cells in culture [64]. Another example is the macroalga Sargassum aquifolium, which has been shown to inhibit the propagation of influenza A viruses and other viruses in models. In addition, tetradecanoic acid exhibited strong antiviral activity against influenza A virus, strongly binding to viral enzymes [65]. The antiviral effects of marine macroalgae are not limited to human pathogens. One study on thirty species of marine algae showed that extracts from six species had strong inhibitory effects against potato virus X; this reached more than 90% for alginate from Fucus gardneri [66]. Terpenes from brown seaweeds showed anti-HSV-2 effects and could serve as an adjunct to normal treatment [67]. Algal lectins also offer a distinct pathway in antiviral therapies since they are effective against a wide range of viruses and appear to be promising in terms of drug development [68]. A good example would be the sulfated polysaccharides extracted from marine red algae (Rhodophyta). These polysaccharides have a category of gene molecules known as carrageenans that render it a strong antiviral compound. Various carrageenans are capable of blocking the viral replication of cells that are infected with herpes simplex virus (HSV) and human papillomavirus (HPV) virus [69]. On the other hand, brown algae (Phaeophyceae) are also useful, as they produce fucoidans. Fucoidans are polysaccharides that have been sulfated, which were found to be effective in combating influenza viruses [70]. Marine algae-derived tannins, especially phlorotannins, show noteworthy levels of anti-infective activity and offer possibilities for the formulation of nutraceuticals. These compounds may work by boosting the host’s defense mechanisms or suppressing viral reproduction [71,72].

Marine seaweeds have revealed adequate antiviral activity through several means that present opportunities for the innovation of new drug molecules against viruses. Several algal extracts, especially from the subclasses of Heterokontophyta, have been reported to have strong activity against viral infectivity. For example, the polysaccharide composed of alginate extracted from Fucus gardneri reduced potato virus X (PVX) infectivity by nearly 95%, likely by causing an aggregation of the virus particles [66]. Microalgae aquatic species such as Arthrospira platensis are reported to possess antiviral components and provide favorable immune responses that can be applied as nutraceuticals against many viruses [77]. Certain metabolites extracted from marine brown seaweeds, such as atomaric acid and dolastane, have been shown to be active against herpes simplex virus type 2 by neutralizing virions and preventing their attachment [67]. Also, polysaccharides derived from microalgae, like exopolysaccharides, have been shown to possess antiviral activity against different targets which are important for anti-inflammatory and immunological functions [78]. In addition, recent studies on seaweeds have identified antiviral drug candidates that prevent virus entry and act by inhibiting major capsid proteins as a novel target for antiviral drug development [79]. Drugs and cytotoxins derived from marine algae have the ability to inhibit viruses using a variety of mechanisms, including the following: the aggregation of viral particles, the suppression of virus replication, restraining viral entry, and the stimulation of cellular immunity [43]. Research conducted both in vitro and in vivo has revealed the antiviral properties of compounds sourced from marine algae, demonstrating their effectiveness against a variety of viruses. Fucoidans extracted from brown algae, like Saccharina cichorioides, have shown notable anti-HIV-1 activity by preventing the virus from attaching and entering cells, achieving a selectivity index (SI) greater than 160 [80]. In vitro experiments indicate that extracts from different marine algae species possess antiviral effects against multiple viruses. For example, methanolic extracts from six algal species, including F. gardneri and Codium fragile, were able to reduce potato virus X infectivity by more than 80% in local lesion assays [66]. The polysaccharide alginate was recognized as an antiviral agent in F. gardneri, which likely functions by clumping virus particles together. Furthermore, sulfated polysaccharides derived from marine algae have shown strong anti-HIV activity in vitro, with their effectiveness increasing alongside the level of sulfation. While the majority of studies have concentrated on in vitro research, there have also been some in vivo investigations utilizing compounds isolated from algae or their synthetic counterparts [81].

Marine algae have emerged as a potential source of antiviral compounds that may be useful in drug discovery/development. Sulfated polysaccharides (SPs) from marine algae, such as fucoidans, carrageenans, and ulvans, have shown strong antiviral effects. These compounds have also demonstrated activity against several viruses, including SARS-CoV-2, thereby suggesting their potential future therapeutic roles in applied biology and drug discovery [73]. The antiviral activity of marine algae extends beyond polysaccharides [7,82]; other bioactive compounds such as polyphenols also display antiviral activity, and thereby have broad potential applications in pharmaceutical and nutraceutical fields [7,82]. In fact, compounds that are produced from Arthrospira platensis exhibit antiviral and anti-inflammatory effects, suggesting their use as nutraceuticals for different kinds of viral infection. Furthermore, algal lectins have been shown to be active against a variety of viruses, indicating their suitability for novel antiviral therapies [68,77]. However, these compounds have regulatory and safety issues, creating many challenges. One of the challenges is the complex task of isolating and identifying the active substances contained in marine algae. Extraction and purification methods have to be very efficient and affordable to allow the process to be also commercially economically feasible [83]. The selectivity of marine algal compounds is an important issue because some may only be effective against certain microbes and not work against others. Additionally, their safety needs to be carefully studied. Although research suggests potential benefits, detailed toxicology tests are required to confirm that these compounds are safe for clinical use [84]. From a regulatory perspective, the approval process for marine algal compounds as antiviral agents can be lengthy and complex. Regulatory challenges in seaweed-based pharmaceuticals and food products include the standardization of bioactive compounds, ensuring batch-to-batch consistency, and addressing contaminant risks such as heavy metals and marine toxins. Compliance with food safety regulations (e.g., EU (European Union) Novel Foods, FDA (Food and Drug Administration) GRAS (Generally Recognized as Safe) status) and the clinical validation of therapeutic claims further complicate approval processes. Additionally, scalability and sustainable cultivation must meet environmental and economic standards [85,86].

5. Anticancer Compounds from Marine Algae

Marine algae are also a rich source of bioactive compounds displaying significant anticancer activities. These molecules have pleiotropic pharmacological effects (e.g., antiproliferative, antioxidant, anti-inflammatory, and immunomodulatory effects) (

Table 4. Anticancer compounds derived from marine algae and their mechanisms of action.

Algae Species	Compound	Target Cancer Types	Mechanism of Action	References
Turbinaria spp.	Fucoidan	Various cancers	Induces apoptosis and inhibits tumor growth	[94]
Eisenia bicyclis	Phlorotannins	Colon cancer	Antioxidant activity and inhibition of cell proliferation	[94]
Gracilaria spp.	Sulfated polysaccharides	Breast cancer	Modulation of immune response and apoptosis induction	[95]
Laminaria japonica	Laminarin	Leukemia	Induces apoptosis and cell cycle arrest	[96]
Sargassum muticum	Fucoxanthin	Prostate cancer	Inhibits cell proliferation and induces apoptosis	[97]

). Sulfated polysaccharides (SPs), such as carrageenan, fucoidan, and laminarin, have demonstrated anticancer and antimetastatic activities [87]. Marine algae are receiving increased attention for their anticancer metabolites—for instance, red algae yield elatol from Callophycus serratus, which has cytotoxic effects, while brown algae provide pachydictyol A, bifurcarenone, and meroditerpenoids (e.g., stypolactone and atomaric acid), which are active against various cancer cell lines [88]. Microalgae, i.e., Acutodesmus obliquus and Desmodesmus perforates, have been previously reported to possess high antiproliferative activity against breast cancer cell line models with methanolic extracts, characterized by cell inhibition rates up to 87%. In addition, algal polysaccharides (fucoidan and alginate) have also been proposed for controlling tumor growth and enhancing the efficacy of current cancer therapies [14,89]. Over 60% of commercially available anticancer agents have been developed based on natural biomimetics, thereby underscoring the value of marine natural products for anticancer therapy. The anticancer effects of marine algae are not limited to direct cytotoxic activity; marine algae-derived bioactive substances can also exert inhibitory activities on major cellular events, for example, angiogenesis, migration, and invasion in vitro and vivo. In addition, the green alga Sphaerococcus coronopifolius is known to synthesize cytotoxic compounds and has possible anticancer applications. The multiple secondary metabolites in marine algae, such as phenolic compounds and polysaccharides, exert anticancer activity through activating the programmed cell death and immune response [8,13]. For example, Cladophora glomerata, harvested from the Hare Island–Tuticorin area, has shown potent anticancer activity on HT-29 colon cancer cell cultures, provided by the methanol extract. Its IC50 (half maximal inhibitory concentration), which represents the concentration needed to inhibit cell proliferation by 50%, was measured at 28.46 ± 0.65 µg/mL, demonstrating strong anticancer effects [90]. Extracts of polysaccharides and sulfated polysaccharides from Ulva lactuca, Sargassum dentifolium, and Cystoseiara myrica have demonstrated antitumor and antiviral activities with good activity profiles and without cytotoxicity [10]. These results indicate the possibility of using these natural substances for therapeutic uses. In particular, red algae are also recognized for the formation of brominated metabolites, including terpenoids and phenols components, which cause cell destruction. Non-toxic biological macromolecules, such as polysaccharides, produced by green algae, which can suppress tumor angiogenesis (the new blood vessel sprout-like supply for tumors), elicit an immune response, and elicit apoptosis. The marine-derived anticancer drug pipeline is one of the strongest in the industry, with four approved drugs and eighteen agents in late-stage development [13,14]. Many algal metabolites, including polysaccharides, terpenes, and phenols, exhibit anticancer activity by targeting key molecular pathways involved in cancer progression. They induce apoptosis, inhibit angiogenesis, and stimulate the immune system, thereby exerting proapoptotic, antiangiogenic, anti-invasive, and antimetastatic effects [13,91]. Macroalgal extracts and compounds also show potential as cancer chemopreventive agents due to their antioxidant, anti-inflammatory, and antimutagenic properties [91]. These kinds of compounds are also known to have a broad range of pharmacological activities including antioxidant, anti-inflammatory, antimicrobial, antiviral and anticancer properties. Marine algal peptides demonstrate anticancer properties, including, for example, apoptosis induction, cell cycle arrest inhibition, and angiogenesis inhibition [56,92]. In addition to showing great promise for cancer research, marine algae also show promising potential as drugs for the treatment of chronic diseases and neurodegenerative diseases. Additionally, marine algae carbohydrates have been shown to be useful in providing skin health benefits; therefore, they have appealing potential for cosmetics applications [56,93].

The clinical translation of marine algae-derived bioactive compounds faces several challenges, including complex extraction and purification, unclear mechanisms of action, and scalability issues. Marine algae are chemically diverse, requiring advanced extraction technologies to isolate specific bioactive molecules effectively [94]. Furthermore, many compounds exhibit promising anticancer properties in vitro, but their precise molecular targets and mechanisms remain poorly understood [1]. Another major barrier is the scalability of production, as sustainable harvesting and biotechnological synthesis are necessary to ensure a stable supply without overexploiting marine ecosystems [45]. Additionally, regulatory challenges related to toxicity, bioavailability, and clinical validation hinder the transition of these compounds into approved pharmaceuticals [8,56].

6. Sustainability and Environmental Considerations

The cultivation of marine algae presents great promise for sustainable development and ecological safeguards. Research has indicated that about 20.8 million km² of ocean area is potentially available for the aquaculture of marine algae species, with the majority of potential sites lying within coastal zones. This agronomic potential relates to many United Nations Sustainable Development Goals (SDGs)—food security and energy independence, carbon neutrality, and ecosystem restoration [38,98]. Seaweed cultivation demonstrates promising environmental benefits. It has the potential to contribute to carbon sequestration; a previous study found a net carbon emission of −1.11 kgCO₂eq/kg for the production of agar using seaweed. Furthermore, seaweed cultivation can play a role in the removal of nitrogen, phosphorus, and heavy metals from sea areas [99]. Nevertheless, its negative effects should be considered, especially in terms of the impact of aquaculture on marine ecosystems without effective management [100]. Marine algae present great promise in terms of environmental sustainability and for tackling global issues. They can be applied to the fight against water contamination, ocean acidification, and global warming. Among others, microalgae in particular have potential as the feedstock for biofuels and fine chemicals [101,102]. Nevertheless, the economic viability of large-scale algae production represents one important challenge. To improve the viability, recent studies have focused on increasing productivity, multi-product situations, and developing the cultivation of algae within current industrial infrastructure [103]. The sustainable harvesting of marine algae integrates methods like offshore cultivation, rotational harvesting, and integrated multi-trophic aquaculture (IMTA) to minimize environmental impact. Offshore cultivation reduces coastal ecosystem degradation, while rotational harvesting allows regrowth before re-harvesting, maintaining biodiversity [104]. IMTA enhances sustainability by integrating algae with fish and shellfish farming, thereby recycling nutrients and reducing waste accumulation [105]. Additionally, spore-based seaweed propagation ensures long-term sustainability by reducing wild harvesting pressure [106]. These innovations help preserve marine ecosystems while ensuring a steady algae supply. Current progress in microalgae harvesting methods include bioflocculation, electrolytic coagulation, and ultrasonic aggregation, all of which have significantly lowered the energy consumption required for production and have the potential to exclude harmful chemicals, thereby making them sustainable engineering tools for food-grade microalgae production [107]. Furthermore, the environmental impacts of microalgae production have been critically evaluated via life cycle analysis and it has been concluded that the sustainability of microalgae production should not be taken for granted, particularly in the way inputs and emissions are managed in order to reduce environmental pollution [108]. In the context of wild seaweed harvesting, ecosystem-based management strategies are essential to maintain biodiversity and ecosystem functions; advocating for selective harvesting methods and the establishment of harvest-exclusion zones to protect habitats are important [109]. Technology for cultivating marine algae is being continuously refined, with different approaches introduced to achieve the best growth and yields. Standardized, routine, and economical large-scale seaweed cultivation has emerged as a result of progress in environmental regulation, due to studies on life histories and the asexual reproduction of the thalli. There are several taxa for which unique agronomy methods are necessary, and only a few dozen species are currently commercially farmed. The five family names Laminaria, Undaria, Porphyra, Eucheuma/Kappaphycus, and Gracilaria account for ~98% of global seaweed production [110]. Conventional approaches include bamboo raft, tube mesh, and stone techniques, whereas more sophisticated strategies include bio-refinery treatment [111]. New methods of planting have been devised to deal with environmental and economic issues. Land-based cultivation (e.g., segmental and ring-like channels) and tumble cultivation (circular tanks) have been contrasted. These systems offer benefits like a reduced cultivation medium volume, increased process control, and the separation of CO₂ and nutrient supply from temperature control and agitation [112].

Marine algae play a crucial role in environmental sustainability by contributing to carbon sequestration, improving marine water quality through nutrient removal, and serving as a valuable source of bioactive compounds with applications in food, agriculture, and bioenergy. The cultivation of macroalgae, such as Gracilaria lemaneiformis, not only mitigates pollution and resource depletion but also supports carbon neutrality, with an overall negative carbon emission of −1.11 kgCO₂eq/kg associated with agar production [99,113]. However, large-scale seaweed farming poses challenges, including the accumulation of litter that can lead to pollution if not properly managed. Implementing sound management practices like early sward harvesting and litter removal is essential to maximize ecological benefits while minimizing environmental risks [114]. Additionally, marine algae populations are under increasing threat due to over-exploitation, pollution, climate change, and unsustainable fishing practices, leading to biodiversity loss and the disappearance of certain algal species, challenging the notion that “everything is everywhere” in microalgae distribution [115]. Climate change, particularly ocean warming and marine heatwaves, has already had negative effects on key species such as canopy-forming brown algae, giant kelp, and bull kelp in regions like New Zealand, while also driving poleward range shifts in various seaweed species [116]. Future research should focus on improving sustainable cultivation techniques, developing policies for responsible exploitation, and understanding the impacts of climate change on algal biodiversity to enhance the ecological contributions of these technologies while minimizing risks to marine ecosystems.

7. Economic and Commercial Aspects

The global seaweed industry is projected to reach approximately USD 25.4 billion by 2025, growing at a CAGR (Compound Annual Growth Rate) of 11% [117]. This surpasses earlier estimates of USD 11.7 billion, indicating rapid market expansion. For comparison, the global aquaculture industry is valued at approximately USD 376 billion, while the pharmaceutical algae market stands at USD 5 billion, and the functional food sector, which includes algae-based products, exceeds USD 300 billion [118]. Key drivers of the seaweed industry’s growth include a rising demand for plant-based foods and functional ingredients, expanded applications in pharmaceuticals and cosmetics, and the increasing use of seaweed for biofuel, bioplastics, and fertilizers, contributing to sustainability goals [98]. Commercial cultivation primarily involves species such as Gracilaria, Kappaphycus, and Porphyra, which are essential for producing agar, carrageenan, and nori [119]. In India, the total marine algae dry standing crop is estimated to be over 301,646 tons; it is a basic ingredient for food, fertilizers, and bioactive compounds.

Seaweeds include nutritive and polysaccharide components (agar and carrageenan), which are particularly important in several industries [120,121]. However, despite the potential of this product, large-scale algae cultivation is primarily restricted to Asian waters. Other continents demonstrate increasing interest, but there remains a considerable gap in the amount of relevant knowledge about the appropriate environmental conditions for further development. Moreover, agricultural developments are likely to play an important role in alleviating the increasing global demand and creating a reduction in production costs; this means that we are due to enter a new phase in which seaweed cultivation will become economically usable in areas such as the North Sea [38,122]. The industry has grown exponentially, with an 8.13% annual industry growth between 2003 and 2012 [123]. Bioactive compounds extracted from microalgae are being applied to nutraceuticals and pharmaceuticals, but there are still some challenges related to their large-scale production and commercialization. Seaweed aquaculture has the potential to be sustainable and efficient, with additional potential for biofuel production [124]. The rapidly expanding demand for algae-based biofuels and the lucrative market for cosmetics and pharmaceuticals based on algal natural products has fueled interest in the genetic toolset of marine algae [125]. Marine algae are now considered a potential feedstock for renewable fuels, such as biogas, in the energy sector. Their capacity to capture carbon dioxide, their increased rates of biomass production compared to terrestrial plant crops, and the absence of water and land resource competition make them very appealing as a source for producing industrial feedstocks. The food industry also considers marine algae a valuable nutrient source, with applications in food, beverages, fertilizers, and animal feed [82,126]. There has been a great deal of interest in marine algae-derived bioactive compounds from the cosmetic and pharmaceutical industries. The antibacterial, antiviral, and antifungal properties of polysaccharides and polyphenols derived from seaweeds have already been substantiated, and thus they are of great interest for cosmeceuticals, nutraceuticals, and pharmacology. Rising environmental consumerism has further driven the need for eco-friendly products and, thereby, marine algae-derived nanocellulose has been employed for packaging, environmental, and biomedical purposes [42,127]. Marine algae-based aquaculture is expected to make a substantial contribution to the global demand for animal protein, which is estimated to rise from 263.8 Mt/yr to 286.5 Mt/yr by 2050 [128]. Nevertheless, it is imperative to deal with the problems of overexploitation and environmental factors in order to ensure the sustainable development of this industry [129]. These organisms are, to a certain extent, now known to be valuable to the pharmaceutical, cosmeceutical, nutraceutical, and energy industries and are providers of antioxidant, anti-inflammatory, and antimicrobial compounds. Moreover, marine algae are also being used as foodstuff, animal feed, and as a nutrient fertilizer that can boost agricultural production through their nutrient contents. The increasing interest in marine biotechnology has opened up new potential applications, particularly in biofuels and phycoremediation, which offer sustainable environmental solutions [130,131].

8. Future Perspectives

The biorefinery and market development of products derived from marine algae are attractive areas in which there is an increasing demand for economically feasible production schemes capable of outputting high-added value nutraceuticals products while using alternative nutrient sources (e.g., wastewater and flue gases) [132,133]. However, the large-scale metabolic engineering and industrial production of anti-fouling agents remain relatively unstudied. Climate change poses a significant threat to seaweeds, seaweed communities, and ecosystem services; thus, there is a need to carry out research on resistant strains and sustainable culture processes. Compared with terrestrial plants, damage to marine algae habitats is less pronounced due to the unique ecological characteristics of these algae. However, expanding the global algae farming industry depends on more research being performed on the selection of optimal cultivation grounds, as well as on the evaluation of the suitability of the nutrient supply, temporal fluctuations in temperature, and hydrodynamic conditions [134,135]. Advancements in state-of-the-art technology, including CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) -based bioengineering, synthetic biology, and nanomaterials, are currently transforming the field of algae research and commercialization. CRISPR-Cas9 genes are used in precise genetic manipulation, which can be expanded to algae to enhance their biomass yield, biofuel lipid contents, and high-potential value-added compound contents, including antioxidants and pharmaceuticals [21].

Synthetic biology contributes in this way by redesigning metabolic pathways for efficient nutraceutical, bioactive peptide, and industrial enzyme production, enhancing algae to act as bioreactors for pharmaceuticals and biofuels. Another significant innovation is the incorporation of algae in CO₂ capture/sequestration applications; marine algae can effectively remove CO₂ from industrial outgasses by acting as a biofilter of the treatment flue gas and enabling the development of biomass [21]. Through this approach, climate change impacts are mitigated and a circular economy is supported. In particular, bioplastics extracted from algae, for example, polysaccharide-based biopolyesters like carrageenan and alginate, can also be considered a green bioplastic alternative to plastics derived from fossil fuels, which contributes to reductions in plastic pollution and reductions in fossil fuel use. Nanotechnological applications are also being implemented in the study of algae, in the application of algae-derived nanomaterials to directed drug delivery, in biosensing, and in the decontamination of polluted water. The combination of nanotechnology and algae bioproducts improves the stability and bioavailability of pharmaceutical active substances and thus enables new medication uses. Metabolic engineering developments also enable the high-yield synthesis of antifouling compounds and environmentally friendly, toxic-free alternatives for anti-fouling coatings for the maritime sector [136]. In addition to industrial applications, marine algae play an important role in sustainable aquaculture development. Hence, proposing algae-based aquaculture as a green substitute for both the conventional and freshwater modes of production, one that does not require arable land and minimizes the pollution of the environment, is deemed suitable [111,137]. Some companies are leading the way in commercializing algae technologies for circular economy strategies and a variety of uses in food, pharmaceuticals and energy. Despite these advancements, research gaps persist. To achieve the most efficient large-scale production of commercially relevant macroalgae, their genome organization and metabolic pathways should be explored. High-throughput screening methods, e.g., Gas Chromatography-Mass Spectrometry (GC-MS) profiling, have revealed a number of antioxidative/anti-proliferative bioactive compounds; however, macroalgae pharmacological activity still needs to be studied [119]. Additionally, little research has been conducted regarding marine epiphytes, particularly macroalgae, within regions like Mexico and the Central American Pacific coast, indicating a need for further floristic and ecological studies [138,139]. To date, though bioactive compounds from marine algae, particularly as neuroprotective and anticancer agents [138,139,140], have already proven their therapeutic value, there is still a need for clinical studies that demonstrate the molecular mechanisms and therapeutic activity of these compounds in patients [141,142,143]. Closing these knowledge gaps is essential for the development of the sustainable exploitation of marine algae, biotechnologies, aquaculture, and drug discovery [74,140].

9. Conclusions

Marine algae offer an attractive, environmentally friendly, and valid platform for the production of biopolymers that contain antiviral and anticancer compounds with the potential to solve major global health issues. Their bioactive molecules, such as polysaccharides, polyphenols, alkaloids, and terpenoids, possess various mechanisms of action, including antiviral activity, the induction of cancer cell apoptosis, and immune modulation. However, the ecological benefits of algae farming, including the ability to grow them in uncultivated land and use seawater, contribute to making them a sustainable resource. Nevertheless, challenges remain, such as the difficulty in separating specific bioactive compounds, production scalability, and concerns regarding toxicity and bioavailability. Developments in biotechnology, including genetic manipulation and bioreactor systems, together with further understanding of the unique marine ecosystem, will be essential for the exploitation of the full pharmaceutical value of marine algae. Through the integration of interdisciplinary methods, marine algae may become the cornerstone of novel, potent, and environmentally friendly therapies for viral infections and cancer.