6.1.4. Environment

Specific pigment fractions have been utilized to identify the algal types in the phytoplankton community. Fucoxanthin is a specific pigment in Bacillariophyceae and Chrysophyceae, whereas Pyrrophyta consists of peridinin as their unique pigment. Chlorophyll *b* and/or lutein are exclusive to Chlorophyta and Euglenophyta, while the specific pigment of Cyanophyta is myxoxanthophyll [143,144]. Pigment analysis using chromatographic methods provided reliable results of different major algal types in the phytoplankton community than microscopy enumeration [143]. Therefore, pigment analysis has been applied in the environmental study of algae. For example, Barlow (1995) [145] investigated the phytoplankton community in the western Alboran Sea based on pigment biomarkers. Recently, Wang et al. (2020) [146] reported the seasonal differences of the phytoneuston community structure in Daya Bay based on algal pigment analysis. The unique pigment of algae could also be employed to monitor the phytoplankton changes during the bloom of phytoplankton and determine the causative species for the bloom [147]. Moreover, the freshwater phytoplankton dynamics affected by seasonally variable freshwater inputs were investigated using pigment biomarkers [148]. Another study employed phytoplankton pigment profiling as a potential bioindicator of stratification conditions in lakes [149]. Apart from these, the significance of algal pigments was highlighted for paleolimnological research [150,151]. On the other hand, the algal pigment was also utilized to study the diet of zooplankton [152] and the impact of grazing by zooplankton on phytoplankton in the environment [153].

#### **7. Commercial Products and Potential Applications of Fucoxanthin**

Until now, only two algae extracts containing fucoxanthin as commercial products are available in the market (Figure 6). Xanthigen is an antiobesity commercial product, which combined 0.4% fucoxanthin from brown macroalgae *Undaria pinnativida* and 35% punicic acid from pomegranate seed oil (https://nektium.com/branded-ingredient/xanthigen/, accessed on 30 July 2021). The antiobesity activity of this product was examined in a clinical trial [154]. The findings indicated the reduction of body and liver fat content and improved liver function in the subjects after orally administered Xanthigen for 16 weeks. The suppression of adipocyte differentiation and lipid accumulation by Xanthigen was via multiple mechanisms [155]. In addition, Xanthigen was demonstrated to be safe for consumption [156]. The other commercial product is FucoVital (https://www.algatech.com/ algatech-product/fucovital/, accessed on 30 July 2021), which consists of 3% fucoxanthin, omega-3s, and other beneficial fatty acids (extracted from *P. tricornutum*). FucoVital is the first fucoxanthin food ingredient product to improve liver health that was approved by the United States Food and Drug Administration (NDI 1048, 2017).

**Figure 6.** Commercial products and potential applications of fucoxanthin.

Several studies demonstrated the potential in commercializing fucoxanthin. For renewable energy, brown macroalgae (*Sargassum wightii*) extract (contained fucoxanthin) was shown to be suitable as a sensitizer in a solar cell, as it is a low-cost and environmentally friendly alternative to the ruthenium metal complexes [157]. In addition, high open-circuit photovoltage was observed in the bio-photovoltaic devices fabricated with FCP complexes and titanium dioxide nanostructures [158]. These findings indicated the possibility of fucoxanthin to be exploited in solar cells at the commercial level.

On the other hand, the cosmetic properties of fucoxanthin have been illustrated in several studies. For instance, a topical formulation containing fucoxanthin has been developed that could prevent exacerbations related to skin inflammatory pathologies and protect skin against UV radiation [159]. In addition, solid lipid nanoparticle formulation loaded with fucoxanthin demonstrated the UV-blocking potential [160]. Furthermore, Kang et al. (2020) reported that fucoxanthin concentrate extracted from *P. tricornutum* could be utilized as an active ingredient in wrinkle care cosmetics [161].

The benefits of fucoxanthin as a feed to broiler chicken were highlighted in several studies. Sasaki et al. (2010) [162] demonstrated feeding fucoxanthin to the broiler chicken enhanced both the plasma antioxidative status and meat color of the chicken. Moreover, fucoxanthin also decreased the number of harmful microorganisms and regulated the antioxidant metabolism of the chicken meat [163]. The addition of 10–15% of brown macroalgae into the basal diet of laying hens augmented the carotenoid content of the yolks by 7.5–10-fold [164]. Apart from these, the incorporation of edible brown macroalgae (rich in fucoxanthin) into the semolina (wheat)-based pasta enhanced the nutritional value of the pasta [165]. Furthermore, Mok et al. (2016) developed whole milk and skimmed milk fortified with fucoxanthin [166]. These fucoxanthin incorporated products showed superior plasma absorption and organ tissue accumulation rates for fucoxanthin [167]. Overall, these studies revealed the possibility of fucoxanthin to be widely exploited at the commercial level in addition to the health supplements (Xanthigen and FucoVital).

#### **8. Challenges and Possible Solutions**

Recently, a broad spectrum of health benefits of fucoxanthin has been well illustrated. Thus, the demand for fucoxanthin is increasing rapidly. To fulfill the demand, the commercial production of fucoxanthin is a necessity. However, there are several challenges in fucoxanthin production. The amount of fucoxanthin produced using chemical synthesis is insufficient to meet the demand of the fucoxanthin market [168]. Hence, the fucoxanthin source has been shifted to natural sources such as brown macroalgae [40] and microalgae [111]. Microalgae are preferred as fucoxanthin sources due to their superior fucoxanthin content [111]. Commercial viability in fucoxanthin production was only examined in a few microalgae strains [169]. A comprehensive screening of high fucoxanthin-producing microalgae should be adopted globally via international collaboration. A further selection is needed to ensure the consistent production of biomass and fucoxanthin under variable conditions when cultivated in either the laboratory or outdoors [170]. Commercial fucoxanthin production relies on cultivation, extraction, and purification parameters. The optimization of these parameters is needed to enhance fucoxanthin production. With the optimized parameters, a standardized fucoxanthin production protocol could be developed to achieve a cost-effective production of fucoxanthin. Although biosynthesis pathways of fucoxanthin have been reviewed extensively [127–129], some pathways remain obscure due to the lack of experimental validation of these enzymes, intermediate products, and pathways [171]. Utilizing "omics" techniques could offer detailed insight into the ambiguous metabolic pathways and regulatory mechanisms in producing fucoxanthin [172].

Quality control is important in ensuring the safety, efficacy, and quality of a particular product. Heavy metal, pesticides, and other chemical contaminations might be present in the microalgae samples. Thus, monitoring the level of these contaminations according to the World Health Organization and the United States Food and Drug Administration is essential. The poor stability, low solubility, and weak bioaccessibility of fucoxanthin pose a challenge when incorporating fucoxanthin into food or supplements. The usage of nano/micro-encapsulation of fucoxanthin improved its stability and bioavailability [173,174]. Furthermore, most of the studies examined fucoxanthin effects only for a short duration [154]. Some bioactive compounds, such as alginates, have short period effects [175]. The effect of fucoxanthin might be overestimated regarding long-term effects. Thus, more intensive and longer studies, particularly human trials, are required to develop and verify fucoxanthin's "true" effects.
