The marine carotenoid fucoxanthin can be found in marine brown seaweeds, the macroalgae, and diatoms, the microalgae, and has remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable potential and promising applications in human health. In this article, we review the current available scientific literature regarding the metabolism, safety, and bioactivities of fucoxanthin, including its antioxidant, anti-inflammatory, anticancer, anti-obese, antidiabetic, antiangiogenic and antimalarial activities, and its protective effects on the liver, blood vessels of the brain, bones, skin, and eyes. Although some studies have shown the bioavailability of fucoxanthin in brown seaweeds to be low in humans, many studies have suggested that a dietary combination of fucoxanthin and edible oil or lipid could increase the absorption rate of fucoxanthin, and thus it might be a promising marine drug.

Background: Gas hydrate-bearing subseafloor sediments harbor a large number of microorganisms. Within these sediments, organic matter and upward-migrating methane are important carbon and energy sources fueling a light-independent biosphere. However, the type of metabolism that dominates the deep subseafloor of the gas hydrate zone is poorly constrained. Here we studied the microbial communities in gas hydrate-rich sediments up to 49 m below the seafloor recovered by drilling in the South China Sea. We focused on distinct geochemical conditions and performed metagenomic and metatranscriptomic analyses to characterize microbial communities and their role in carbon mineralization.Results: Comparative microbial community analysis revealed that samples above and in sulfate-methane interface (SMI) zones were clearly distinguished from those below the SMI. Chloroflexota were most abundant above the SMI, whereas Caldatribacteriota dominated below the SMI. Verrucomicrobiota, Bathyarchaeia, and Hadarchaeota were similarly present in both types of sediment. The genomic inventory and transcriptional activity suggest an important role in the fermentation of macromolecules. In contrast, sulfate reducers and methanogens that catalyze the consumption or production of commonly observed chemical compounds in sediments are rare. Methanotrophs and alkanotrophs that anaerobically grow on alkanes were also identified to be at low abundances. The ANME-1 group actively thrived in or slightly below the current SMI. Members from Heimdallarchaeia were found to encode the potential for anaerobic oxidation of short-chain hydrocarbons.Conclusions: These findings indicate that the fermentation of macromolecules is the predominant energy source for microorganisms in deep subseafloor sediments that are experiencing upward methane fluxes.