Oxyresveratrol inhibits cellular tyrosinase-related oxidative stress-induced melanogenesis in B16 melanoma cells

Cellular oxidative stress is caused by an imbalance in the redox status and manifests as hyperpigmentation disorders.Reactive oxygen species, particularly hydrogen peroxide (H2O2) as the highly reactive hydroxyl radicals, promotethe melanin production through the induction of tyrosinase enzyme activity. In this study, the antioxidant activity ofoxyresveratrol was investigated by 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. In addition, melanin biosynthesis, tyrosinase activity, and cellular oxidants due to thebioactive component, oxyresveratrol, were determined in B16 cells by melanin content assay, cellular tyrosinase activityassay, and the dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay, respectively. Hydrogen peroxide induced themelanogenesis through tyrosinase activity-related cellular oxidants, whereas oxyresveratrol showed a potent antioxidantactivity by DPPH and ABTS assays. At the concentrations of 10 and 12.5 µg/ml, oxyresveratrol significantly inhibitedmelanogenesis in B16 melanoma cells and also suppressed tyrosinase activity and cellular oxidants. Effective doses ofoxyresveratrol inhibit melanogenesis through bioactivity of cellular tyrosinase-related oxidative stress

Screening and characterization of β-glucosidase production by Saccharomyces cerevisiae.

Beta-Glucosidases (BGS) are the group of hydrolase enzymes, involved in the degradation processes and many biological processes. Due to demand, intensive screening of BGS is required to explore the natural microbial source of BGS. The current study deals with isolation and identification of BGS producing S. cerevisiae from Thai fruits & beverages and assessment of impact of pH, temperature, and salt concentration on BGS production. About 34 samples were collected. Yeast cells were isolated by plate method and characterized. About ten different strains were isolated and identified. The strain has been confirmed as S. cerevisiae through ribosomal sequencing. The optimization of BGS production was achieved by Box-Behnken design and Response Surface Methodology and confirmed that pH 4.0, temperature at 40 C, and 0.5% of NaCl are optimum conditions. The kinetic analysis suggested that 24 h of incubation achieve the maximum yield. The reported S. cerevisiae strain could be the safer source for BGS. Further studies on enzyme recovery and purification will unbolt the way to attain high-quality microbial enzyme.