Search Results (9)

Gracilaria species, a widely distributed genus of red macroalgae, have gathered significant attention for their diverse medical applications attributable to their bioactive sulphated polysaccharides (SPs). This review examines the global narrative of various Gracilaria SP applications in terms of their therapeutic potential and mechanistic insights into the use of these SPs against a range of medical conditions, including cancer, inflammation, neurodegenerative disorders, diabetes, and immune dysfunctions. SPs extracted from G. lemaneiformis and G. fisheri have demonstrated potent anti-tumour activities by inducing apoptosis through various mechanisms, including the upregulation of CD8⁺ T cells and IL-2, inhibition of EGFR/MAPK/ERK signalling pathways, and activation of the Fas/FasL pathway. Selenium nanoparticles (SeNPs) conjugated with SPs further enhanced the targeted delivery and efficacy of these SPs against glioblastoma by the downregulation of ROS followed by the activation of p53, MAPK, and AKT pathways. The anti-inflammatory properties of SPs are evidenced by key suppressive inflammatory markers like NO, TNF-α, IL-1β, and IL-6 in mutant rodent models. SPs from G. cornea and G. birdiae effectively reduce neutrophil migration and vascular permeability, offering potential treatments for acute inflammation and conditions such as colitis by modulating pathways involving COX-2 and NF-κB. Neuroprotective effects by SPs (from G. cornea and G. gracili) studied in 6-OHDA-induced rats, which mitigate oxidative stress and enhance neuronal cell viability, facilitate the management of neurodegenerative diseases like Parkinson’s and Alzheimer’s. Regarding the hypoglycaemic effect, SPs from G. lemaneiformis exhibit a glucose-modulating response by improving insulin regulation, inhibiting α-amylase activity, repairing pancreatic β-cells, and modulating lipid metabolism. Moreover, immunomodulatory activities of Gracilaria-derived SPs include the stimulation of macrophages, T-cell proliferation, and cytokine production, underscoring their potential as functional food and immunotherapeutic agents. Recently, Gracilaria-derived SPs have been found to modulate gut microbiota, promote SCFA production, and enhance gut microbials, suggesting their potential as prebiotic agents (G. rubra and G. lemaneiformis). This review highlights the multifaceted medical applications of Gracilaria sulphated polysaccharides, providing detailed mechanistic insights and suggesting avenues for future clinical translation and therapeutic innovations. Full article

Gracilaria fisheri (GF) is a red seaweed that is widely found in Southeast Asia and has gained attention for its potential bioactive compounds and versatile applications in food products. This study explored the potential of GF as a natural gelling agent in the development of sustainable strawberry-based drinking jelly. By utilizing GF at varying concentrations (0.2 (S1), 0.4 (S2), 0.6 (S3), 0.8 (S4), and 1.0% (S5)), the impact on the physicochemical, textural, phytochemical, and flavor profiles of the strawberry concentrate-based drinking jelly was examined. The results demonstrated that GF concentration significantly affected the color characteristics, structural development, and flavor profiles of the drinking jelly samples. Increasing GF levels progressively enhanced the lightness (L*) and redness (a*) values while reducing the yellowness (b*), with optimal visual appeal achieved in the S4 samples compared to others. Microscopical observations revealed that gel matrix development improved with GF concentrations up to 0.8% (S4), transitioning from a sparse, liquid-like structure at lower levels to a compact, over-gelated network at 1.0% (S5). Physicochemical parameters, including pH, total soluble solid (TSS), and TSS/titratable acidity (TA) ratios, increased with GF levels, contributing to a sweeter, less acidic product, while water activity (a_w) decreased, enhancing jelly stability. Viscosity and sulfate content increased significantly with GF concentration, indicating improved gel strength but reduced fluidity. Phytochemical analysis revealed that ascorbic acid (AsA) and total phenolic content (TPC) decreased progressively with higher GF levels, leading to a reduction in antioxidant activity (DPPH and ABTS). Volatile compound analysis identified alcohols, esters, and aldehydes as dominant contributors to the flavor profile. 1-Octanol (waxy, citrus-like) and methyl anthranilate (grape-like, sweet) increased substantially, while minor groups such as terpenoids and phenolic compounds contributed floral and woody notes. The findings suggest that S4 samples strike the optimal balance between texture, color, flavor, and antioxidant properties, achieving a cohesive, visually appealing, and flavorful drinking jelly suitable for commercial applications. Full article

Currently, the demand in the food market for oligosaccharides with biological activities is rapidly increasing. In this study, agar polysaccharides from Gracilaria fisheri were treated with β-agarases and hydrolyzed to agar oligosaccharides (AOSs). High-performance anion-exchange chromatography/pulsed amperometric detection (HPAEC-PAD), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC), were employed to analyze the chemical characteristics of AOSs. The FT-IR spectra revealed that the enzymatic hydrolysis had no effect on specific functional groups in the AOS molecule. To investigate the prebiotic and pathogen inhibitory effects of AOSs, the influence of AOSs on the growth of three probiotic and two pathogenic bacteria was examined. The gastrointestinal tolerance of probiotics in the presence of AOSs was also investigated. AOSs enhanced the growth of Lactobacillus plantarum by 254%, and inhibited the growth of Bacillus cereus by 32.80%, and Escherichia coli by 58.94%. The highest survival rates of L. plantarum and L. acidophilus were maintained by AOSs in the presence of α-amylase and HCl under simulated gastrointestinal conditions. This study demonstrates that AOSs from G. fisheri exhibit potential as a prebiotic additive in foods. Full article

Various seaweed sulfated polysaccharides have been explored for antimicrobial application. This study aimed to evaluate the antibacterial activity of the native Gracilaria fisheri sulfated galactans (NSG) and depolymerized fractions against the marine pathogenic bacteria Vibrio parahaemolyticus and Vibrio harveyi. NSG was hydrolyzed in different concentrations of H₂O₂ to generate sulfated galactans degraded fractions (SGF). The molecular weight, structural characteristics, and physicochemical parameters of both NSG and SGF were determined. The results revealed that the high molecular weight NSG (228.33 kDa) was significantly degraded to SGFs of 115.76, 3.79, and 3.19 kDa by hydrolysis with 0.4, 2, and 10% H₂O₂, respectively. The Fourier transformed spectroscopy (FTIR) and ¹H− and ¹³C−Nuclear magnetic resonance (NMR) analyses demonstrated that the polysaccharide chain structure of SGFs was not affected by H₂O₂ degradation, but alterations were detected at the peak positions of some functional groups. In vitro study showed that SGFs significantly exerted a stronger antibacterial activity against V. parahaemolyticus and V. harveyi than NSG, which might be due to the low molecular weight and higher sulfation properties of SGF. SGF disrupted the bacterial cell membrane, resulting in leakage of intracellular biological components, and subsequently, cell death. Taken together, this study provides a basis for the exploitation and utilization of low-molecular-weight sulfated galactans from G. fisheri to prevent and control the shrimp pathogens. Full article

Urolithiasis is a common urological disease characterized by the presence of a stone anywhere along the urinary tract. The major component of such stones is calcium oxalate, and reactive oxygen species act as an essential mediator of calcium oxalate crystallization. Previous studies have demonstrated the antioxidant and antiurolithiatic activities of sulfated polysaccharides. In this study, native sulfated galactans (N-SGs) with a molecular weight of 217.4 kDa from Gracilaria fisheri were modified to obtain lower molecular weight SG (L-SG) and also subjected to sulfation SG (S-SG). The in vitro antioxidant and antiurolithiatic activities of the modified substances and their ability to protect against sodium oxalate-induced renal tubular (HK-2) cell death were investigated. The results revealed that S-SG showed more pronounced antioxidant activities (DPPH and O₂⁻ scavenging activities) than those of other compounds. S-SG exhibited the highest antiurolithiatic activity in terms of nucleation and aggregation, as well as crystal morphology and size. Moreover, S-SG showed improved cell survival and increased anti-apoptotic BCL-2 protein in HK-2 cells treated with sodium oxalate. Our findings highlight the potential application of S-SG in the functional food and pharmaceutical industries. Full article

Currently, research on the accumulation of microplastics (MPs) in the marine food web is being highlighted. An accurate and reliable digestion method to extract and isolate MPs from complex food matrices has seldom been validated. This study aimed to compare the efficacy of MP isolation among enzymatic-, oxidative-, and the combination of two digestion methods on red seaweed, Gracilaria fisheri. The dried seaweed sample was digested using three different methods under various conditions using enzymes (cellulase and protease), 30% H₂O₂, and a combination of enzymes and 30% H₂O₂. The method possessing the best digestion efficiency and polymer recovery rate of MPs was selected, and its effect on spiked plastic polymer integrity was analyzed by Raman spectroscopy. As a result, the enzymatic method rendered moderate digestion efficiency (59.3–63.7%) and high polymer recovery rate (94.7–98.9%). The oxidative method using 30% H₂O₂ showed high digestion efficiency (93.0–96.3%) and high polymer recovery rate (>98%). The combination method was the most effective method in terms of digestion efficiency, polymer recovery rate, and expenditure of digestion time. The method also showed no chemical changes in the spiked plastic polymers (PE, PP, PS, PVC, and PET) after the digestion process. All the spiked plastic polymers were identifiable using Raman spectroscopy. Full article

Sulfated galactans (SG) isolated from red alga Gracilaria fisheri have been reported to inhibit the growth of cholangiocarcinoma (CCA) cells, which was similar to the epidermal growth factor receptor (EGFR)-targeted drug, cetuximab. Herein, we studied the anti-cancer potency of SG compared to cetuximab. Biological studies demonstrated SG and cetuximab had similar inhibition mechanisms in CCA cells by down-regulating EGFR/ERK pathway, and the combined treatment induced a greater inhibition effect. The molecular docking study revealed that SG binds to the dimerization domain of EGFR, and this was confirmed by dimerization assay, which showed that SG inhibited ligand-induced EGFR dimer formation. Synchrotron FTIR microspectroscopy was employed to examine alterations in cellular macromolecules after drug treatment. The SR-FTIR-MS elicited similar spectral signatures of SG and cetuximab, pointing towards the bands of RNA/DNA, lipids, and amide I vibrations, which were inconsistent with the changes of signaling proteins in CCA cells after drug treatment. Thus, this study demonstrates the underlined anti-cancer mechanism of SG by interfering with EGFR dimerization. In addition, we reveal that FTIR signature spectra offer a useful tool for screening anti-cancer drugs’ effect. Full article

Macroalgae are the primary source of non-animal sulphated polysaccharides (SPs) in the marine environment with fucoidans derived from brown algae (Phaeophyta) and carrageenans from red algae (Rhodophyta). Much research has been carried out on SP effects on Asian shrimp species (genera Penaeus and Metapenaeus) but their effect on commercially important bivalve mollusc species is limited and in Pacific oyster Crassostrea gigas is unknown. Knowledge of their impact on bivalve pathogens and Palaemon shrimp is unknown. The objectives of this study were to assess the effects of Fucus vesiculosus (Phaeophyta), Mastocarpus stellatus (Rhodophyta) and algal derivatives (fucoidan and κ-carrageenan) on C. gigas performance, and on ostreid herpesvirus-1 microvar (OsHV-1 μVar) and bacteria Vibrio spp. development. Both pathogens have been associated with significant oyster mortalities and economic losses globally. The effects of sulphated galactan from Gracilaria fisheri (Rhodophyta) on European common prawn Palaemon serratus, an important fishery species, was also assessed. Findings indicate a rapid and prolonged increase in total blood cell count, lysozyme (enzyme that destroys pathogens), and a difference in the ratio of blood cell types in treated individuals compared to their control counterparts. A significantly lower OsHV-1 μVar prevalence was observed in treated oysters and κ-carrageenan was found to suppress viral replication (loads), while OsHV-1 μVar was not detected in the fucoidan treated oysters from Day 8 of the 26-day trial. No antibacterial effect was observed however, the oysters did not succumb to vibriosis. These findings contribute further knowledge to macroalgae sulphated polysaccharide biotherapeutic properties, their twofold effect on animal health and viral suppression. Full article

Previously, we reported that the ethanol extract from red seaweed Gracilaria fisheri effectively decreased biofilm formation of Vibrio harveyi. In this study, the anti-biofilm active compounds in the ethanol extract were isolated and their structures identified. The anti-biofilm fractionation assay for minimum inhibitory concentration (MIC) produced two fractions which possessed maximal inhibitory activities toward the biofilm formation of V. harveyi strains 1114 and BAA 1116. Following chromatographic separation of the bioactive fractions, two pure compounds were isolated, and their structures were elucidated using FTIR, NMR, and HR-TOF-MS. The compounds were N-benzyl cinnamamide and α-resorcylic acid. The in vitro activity assay demonstrated that both compounds inhibited the biofilm formation of V. harveyi and possessed the anti-quorum sensing activity by interfering with the bioluminescence of the bacteria. However, the N-benzyl cinnamamide was more potent than α-resorcylic acid with a 10-fold lesser MIC. The present study reveals the beneficial property of the N-benzyl cinnamamide from the ethanol extract as a lead anti-microbial drug against V. harveyi. Full article