Quercetin-3-O-ß-d-glucopyranosyl-(1 → 6)-ß-d-glucopyranoside suppresses melanin synthesis by augmenting p38 MAPK and CREB signaling pathways and subsequent cAMP down-regulation in murine melanoma cells.

In this study, the effect of purified quercetin-3-O-ß-d-glucopyranosyl-(1 â†’ 6)-ß-d-glucopyranosid (QCGG) on melanogenesis was investigated. QCGG was isolated from the calyx of a traditional Korean medicinal herb, Persimmon (Diospyros kaki). The hypopigmentation effects of QCGG were determined by examination of cellular melanin contents, tyrosinase activity assay, cAMP assay, and Western blotting of α-MSH-stimulated B16F10 mouse melanoma cells. Our results showed that QCGG inhibited both melanin synthesis and tyrosinase activity in a concentration-dependent manner as well as significantly reduced the expression of melanogenic proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1, tyrosinase-related protein-2, and tyrosinase. Moreover, QCGG inhibited intracellular cAMP levels, cAMP response element-binding protein (CREB), and p38 MAPK expression in α-MSH-stimulated B16F10 cells. Taken together, the suppressive effects of QCGG on melanogenesis may involve down-regulation of MITF and its downstream signaling pathway via phosphorylation of p38 MAPK and CREB along with reduced cAMP levels. These results indicate that QCGG reduced melanin synthesis by reducing expression of tyrosine and tyrosine-related proteins via extracellular signal-related protein kinase (ERK) activation, followed by down-regulation of CREB, p38, and MITF.

Faecalibaculum rodentium gen. nov., sp. nov., isolated from the faeces of a laboratory mouse.

A novel strictly anaerobic strain, ALO17(T), was isolated from mouse faeces and found to produce lactic acid as a major metabolic end product. The isolate was observed to be Gram-stain positive, non-motile, non-spore forming small rods, oxidase and catalase negative, and to form cream-coloured colonies on DSM 104 agar plates. The NaCl range for growth was determined to be 0-2 % (w/v). The isolate was found to grow optimally at 37 °C, with 0.5 % (w/v) NaCl and at pH 7. The cell wall hydrolysates were found to contain ribose as a major sugar. The genomic DNA G+C content was determined to be 52.3 mol%. A phylogenetic analysis of the 16S rRNA gene sequence revealed that Holdemanella biformis DSM 3989(T), Faecalicoccus pleomorphus ATCC 29734(T), Faecalitalea cylindroides ATCC 27803(T), and Allobaculum stercoricanis DSM 13633(T) are closely related to the isolate (87.4, 87.3, 86.9 and 86.9 % sequence similarity), respectively. The major cellular fatty acids (>10 %) of the isolate were identified as C18:1 cis 9 FAME (36.9 %), C16:0 FAME (33.7 %) and C18:0 FAME (13.2 %). In contrast to the tested reference strains, C20:0 FAME (4.0 %) was detected only in strain ALO17(T) whilst C16:0 DMA was absent. The isolate also differed in its substrate oxidation profiles from the reference strains by being positive for D-melibiose and stachyose but negative for N-acetyl-D-galactosamine and 3-methyl-D-glucose. On the basis of polyphasic taxonomic evidence from this study, the isolate is concluded to belong to a novel genus within the family Erysipelothricaceae. We propose the name Faecalibaculum rodentium gen. nov., sp. nov. to accommodate strain ALO17(T) (=KCTC 15484(T) = JCM 30274(T)) as the type strain.

Erysipelothrix larvae sp. nov., isolated from the larval gut of the rhinoceros beetle, Trypoxylus dichotomus (Coleoptera: Scarabaeidae).

A novel, Gram-stain positive, facultative anaerobic, non-motile and straight to curve rod shaped bacterium, strain LV19(T) was isolated from the larval gut of the rhinoceros beetle, Trypoxylus dichotomus, which was collected from Yeong-dong, Chuncheongbuk-do, South Korea. The colonies of the new isolate were convex, circular, cream white in color and 1-2 mm in diameter after 3 days incubation on Tryptic Soy Agar at 37 °C. Based on the 16S rRNA gene sequence similarity, the new isolate was most closely related to Erysipelothrix inopinata MF-EP02(T), E. rhusiopathiae ATCC 19414 (T) and E. tonsillarum T-305(T) (94.8, 93.8 and 93.7 % similarity, respectively). Strain LV19(T) grew optimally at 37 °C, at pH 8.0 and in the presence of 0.5 % (w/v) NaCl. Oxidase activity and catalase activity were negative. The major cellular fatty acids (>10 %) were C18:2 cis-9,12 (28.9 %), C18:1 cis-9 (22.3 %), C16:0 (22.2 %) and C18:0 (18.5 %). The cell-wall hydrolysates contained ribose as a major sugar. Major polar lipids were phosphatidylglycerol and three unidentified glycolipids. No quinone was detected. The G+C content of the genomic DNA was 36.3 mol%. The levels of DNA-DNA relatedness between strain LV19(T) and all the reference strains were less than 20 %. On the basis of polyphasic evidence from this study, the isolate is considered to represent a novel species of the genus Erysipelothrix, for which the name Erysipelothrix larvae sp. nov. is proposed; the type strain is LV19(T) (=KCTC 33523(T) = DSM 28480(T)).

Aequorivita capsosiphonis sp. nov., isolated from the green alga Capsosiphon fulvescens, and emended description of the genus Aequorivita.

A marine bacterial strain, designated A71(T), was isolated from marine algae collected from the South Sea, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain A71(T) belonged to the family Flavobacteriaceae and was closely related to Aequorivita antarctica SW49(T) (96.5 % sequence similarity). Cells of strain A71(T) were Gram-negative, aerobic, oxidase-negative, catalase-positive, yellow/orange-pigmented and non-motile. The major fatty acids were iso-C(15 : 0) (20.6 %), iso-C(17 : 1)omega9c (13.3 %), anteiso-C(15 : 0) (13.1 %), iso-C(17 : 0) 3-OH (12.7 %) and summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c; 6.6 %). The DNA G+C content was 36.9 mol%. Several phenotypic characteristics served to differentiate the isolate from recognized members of the genus Aequorivita. Data from this polyphasic study clearly demonstrated that strain A71(T) represents a novel species of the genus Aequorivita. The name Aequorivita capsosiphonis sp. nov. is proposed, with strain A71(T) (=KCTC 22183(T) =JCM 15070(T)) as the type strain. In addition, an emended description of the genus Aequorivita is presented.