Theasinensin A (TSA) is a major group of catechin dimers mainly found in oolong tea and black tea. This compound is also manufactured with epigallocatechin gallate (EGCG) as a substrate and is refined after the enzyme reaction. In previous studies, TSA has been reported to be effective against inflammation. However, the effect of these substances on skin melanin formation remains unknown. In this study, we unraveled the role of TSA in melanogenesis using mouse melanoma B16F10 cells and normal human epidermal melanocytes (NHEMs) through reverse transcription polymerase chain reaction (RT-PCR), Western blotting analysis, luciferase reporter assay, and enzyme-linked immunosorbent assay analysis. TSA inhibited melanin formation and secretion in α-melanocyte stimulating hormone (α-MSH)-induced B16F10 cells and NHEMs. TSA down-regulated the mRNA expression of tyrosinase (Tyr), tyrosinase-related protein 1 (Tyrp1), and Tyrp2, which are all related to melanin formation in these cells. TSA was able to suppress the activities of certain proteins in the melanocortin 1 receptor (MC1R) signaling pathway associated with melanin synthesis in B16F10 cells: cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), protein kinase A (PKA), tyrosinase, and microphthalmia-associated transcription factor (MITF). We also confirmed α-MSH-mediated CREB activities through a luciferase reporter assay, and that the quantities of cAMP were reduced by TSA in the enzyme linked immunosorbent assay (ELISA) results. Based on these findings, TSA should be considered an effective inhibitor of hyperpigmentation.
A gram-positive, white-pigmented, aerobic, rod-shaped bacterium, designated strain NIBRBAC000506063T, was isolated from a sludge sample from Yeosu, Korea. Optimal growth of strain NIBRBAC000506063T was observed at 25 °C and pH 8.0, in the absence of NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain NIBRBAC000506063T belongs to the genus Microbacterium and is closely related to Microbacterium invictum DC-200T (98.3 % sequence similarity). Next-generation sequencing (NGS) analysis indicated that the strain NIBRBAC000506063T genome was comprised of one circular chromosome (2,576,190 bp, G+C content: 69.14 mol%) and one plasmid (465,341 bp, G+C content: 68.45 mol%) with 4,046 coding sequences, 47 tRNAs, and 4 rRNAs. The major respiratory isoprenoid quinone was MK12, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, aminophospholipids, and glycolipids. The major fatty acids of strain NIBRBAC000506063T were C16:0 iso and C15:0 anteiso, and the G+C content of the genomic DNA was 69.5 mol%. Based on the polyphasic taxonomic data obtained in this study, it is proposed that strain NIBRBAC000506063T represents a novel species of the genus Microbacterium. The type strain is NIBRBAC000506063T (=KCTC49453T =DSM111108T).
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