Inhibitory effects of whisky polyphenols on melanogenesis in mouse B16 melanoma cells.

Whisky exerts an inhibitory effect on melanogenesis in B16 cells, the anti-melanogenic activity being positively correlated with the aging period and anti-oxidative activity of whisky. We examined the correlation between the inhibition of melanogenesis and the concentration of each compound in various whiskies to evaluate the importance of 11 different whisky polyphenols, including ellagic acid, gallic acid and lyoniresinol, in the anti-melanogenic activity of whisky. The concentration of all the compounds was positively correlated with the anti-melanogenic activity of whisky. Ellagic acid, gallic acid and lyoniresinol were the predominant polyphenols in the whiskies measured by HPLC. These three compounds also significantly inhibited the melanogenesis and tyrosinase activity in B16 cells. Ellagic acid, gallic acid and lyoniresinol were confirmed as the major participants in the anti-melanogenic activity of whisky.

GADD34 induces p21 expression and cellular senescence.

We previously identified GADD34 (growth arrest and DNA damage protein 34) by screening for genes involved in oncogenic-transformation and/or cellular senescence in Ras-transformed rat F2408 fibroblasts (7EJ-Ras), which exhibit anchorage-independent growth and do not senesce. In the current study, we found that transduction of 7EJ-Ras cells with a retroviral vector expressing GADD34 suppressed their proliferation. Furthermore, we observed that fibroblasts derived from GADD34-knockout mice (GADD34-KO MEFs) did not undergo senescence. Whereas the expression of p21 was decreased in GADD34 KO MEFs, its expression was rescued in these cells by ectopic expression of GADD34 by retroviral transduction. These findings suggest that GADD34 contributes to the regulation of p21 expression, and that it suppresses cellular proliferation through the induction of cellular senescence.

Horseradish peroxidase degrades lipid hydroperoxides and suppresses lipid peroxidation of polyunsaturated fatty acids in the presence of phenolic antioxidants.

Linoleic acid hydroperoxide (LAOOH) was effectively degraded by horseradish peroxidase (HRP) in the presence of quercetin. Several natural phenolic antioxidants, such as quercetin, capsaicin, and alpha-tocopherol, acted as good hydrogen donors in the peroxidase reaction that occurs during lipid hydroperoxide degradation. However, glutathione, which is a non-phenolic antioxidant that acts as a hydrogen donor for glutathione peroxidase, could not suppress lipid peroxidation in the presence of HRP. Lipid hydroperoxides generated from eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also degraded with HRP in the presence of quercetin, and oxidative decomposition of DHA was suppressed by this reaction.

Molecular cloning of the gene encoding thermostable endo-1,5-alpha-L-arabinase of Bacillus thermodenitrificans TS-3 and its expression in Bacillus subtilis.

The gene that encodes a thermostable endo-arabinase (called ABN-TS) from Bacillus thermodenitrificans TS-3 was cloned, sequenced, and expressed in the mesophilic B. subtilis. The gene contained an open reading frame consists of 939 bp, which encodes 313 amino acids. The deduced amino acid sequence of the enzyme showed 50, 46, and 36% similarity with endo-arabinase from B. subtilis IFO 3134 (PPase-C), Pseudomonas fluorescens (ArbA), and Aspergillus niger (ABNA), respectively. The hydrophobic and acidic amino acids making up ABN-TS outnumbered those in PPase-C. The gene product expressed in B. subtilis, as the host, had substantially the same characteristics, and was stable up to 70 degrees C, and the reaction was optimal around 70 degrees C, as well as native ABN-TS.