β-Glucans are a class of polysaccharides consisting of D-glucose units that are polymerized primarily via the β-1,3 glycosidic bonds, in addition to the β-1,4 and/or β-1,6 bonds. They are present in various food products such as cereals, mushrooms, and seaweeds and are known for their numerous effects on the human body, depending on their structures, which are diverse. The major physicochemical properties of β-glucans include their antioxidant property, which is responsible for the scavenging of reactive oxygen species, and their role as dietary fiber for preventing the absorption of cholesterol, for promoting egestion, and for producing short-chain fatty acids in the intestine. Dietary β-glucans also exert immunostimulatory and antitumor effects by activation of cells of the mucosal immune system via β-glucan receptors, such as dectin-1. In this review, we elaborate upon the diversity of the structures and functions of β-glucans present in food, along with discussing their proposed mechanisms of action. In addition to the traditional β-glucan-containing foods, recent progress in the commercial mass cultivation and supply of an algal species, Euglena gracilis, as a food material is briefly described. Mass production has enabled consumption of paramylon, a Euglena-specific novel β-glucan source. The biological effects of paramylon are discussed and compared with those of other β-glucans.

Euglena gracilis, a microalgal species of unicellular flagellate protists, has attracted much attention in both the industrial and academic sectors due to recent advances in the mass cultivation of E. gracilis that have enabled the cost-effective production of nutritional food and cosmetic commodities. In addition, it is known to produce paramylon (β-1,3-glucan in a crystalline form) as reserve polysaccharide and convert it to wax ester in hypoxic and anaerobic conditions–a promising feedstock for biodiesel and aviation biofuel. However, there remain a number of technical challenges to be solved before it can be deployed in the competitive fuel market. Here we present a method for efficient selective breeding of live oil-rich E. gracilis with fluorescence-activated cell sorting (FACS). Specifically, the selective breeding method is a repetitive procedure for one-week heterotrophic cultivation, staining intracellular lipids with BODIPY505/515, and FACS-based isolation of top 0.5% lipid-rich E. gracilis cells with high viability, after inducing mutation with Fe-ion irradiation to the wild type (WT). Consequently, we acquire a live, stable, lipid-rich E. gracilis mutant strain, named B1ZFeL, with 40% more lipid content on average than the WT. Our method paves the way for rapid, cost-effective, energy-efficient production of biofuel.

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The degree and type of melanogenesis, i.e., either eumelanin of pheomelanin, has been shown to be a reliable marker for the differentiation of the melanocyte. If exposed to UV light, these two melanins were reported to behave differently; eumelanin was photoprotective whereas pheomelanin was phototoxic to cultured tumor cells. Our previous study indicated that dysplastic melanocytic nevus (DMN) undergoes altered melanogenesis, forming pheomelanosome-like granules. The present study examined chemically the type and degree of melanin synthesized in 31 melanocytic nevi excised from 27 patients as compared with that occurring in the surrounding normal skin. The tissue content of eumelanin and pheomelanin was expressed by the amounts of pyrrole-2,3,5-tricarboxylic acid (PTCA) and aminohydroxyphenylalanine (AHP), respectively. We found that DMN lesions contain significantly higher amounts of pheomelanin than either common melanocytic nevus (CMN) or normal skin. Differences in pheomelanin content between DMN and CMN could not be accounted for by inherently higher levels of pheomelanin within the skin in general from DMN patients. Our present finding substantiates our previous claim that epidermal melanocytes in DMN undergo deranged melanogenesis.

Human malignant melanoma represents a difficult therapeutic challenge to both medical scientists and practicing physicians. However, the biologic uniqueness of the tumor may provide opportunities for exploitation in therapeutics. This study proposed to undertake a systemic approach to the chemotherapy of malignant melanoma based upon the uniqueness of pigment-cell metabolic pathway pertaining to conversion of tyrosine and dopa with subsequent formation of melanin by tyrosinase and its related enzymes. The sulphur homologue of tyrosine, cysteinylphenol (CP), its amine derivative, cysteaminylphenol (CAP), and their N-acetyl and alpha-methyl derivatives have been synthesized and tested in in vivo and in vitro melanocytotoxicity and antimelanoma effects. These phenolic thioethers (PTEs) and phenolic thioether amine (amides) (PTEAs), which are substrates of tyrosinase, showed significant cytotoxicity that is selective to melanocytes and melanoma cells. Most previous attempts to impair the melanin pathway as a therapeutic strategy have been of limited success because they have been directed to catecholic compounds that are unstable and insufficient in lethality at physiologically tolerable doses. By contrast, our approach relies on phenolic compounds, PTEs and PTEAs, which are more stable than catechols and become toxic only after oxidation by tyrosinase. We found PTEA as the most promising agent for the future development of chemotherapeutic agents. The possible biologic, chemical, and pharmacologic reactions of these synthetic compounds within the melanoma cells are studied and discussed.