| Summary: | 碩士 === 國立臺南大學 === 生物科技學系碩士班 === 103 === The inhibition of melanogenesis by yeast extracts from cultiva¬tions of recombinant Pichia pastoris catalyzing ortho-hydroxylation of flavonoids was investigated. The recombinant yeast harbored a fu¬sion gene composed of the CYP57B3 gene from Aspergillus oryzae and a cytochrome reductase gene from Saccharomyces cerevisiae. Ten flavonoids belonging to flavones, flavonols, flavanones, fla¬vanols, and isoflavones were evaluated for biotransformation by the re¬combinant strain. The results showed that five flavonoids, includ¬ing the flavone apigenin, the flavanones naringenin and liquiritigenin, and the isoflavones daidzein and genistein, could be biotransformed. The yeast extracts from the five biotransformation fermentations were then evaluated for inhibitory activity on melanogenesis in cul¬tured mouse B16 melanoma cells. Three yeast extracts from biotransfor¬mation fermentation feeding with daidzein, genistein, or apigenin showed inhibitory activity on melanogenesis in the B16 cells, while the extract from genistein biotransformation exhibited the highest activity. The yeast extract from genistein biotransformation also showed inhibitory activity on cellular tyrosinase activity in the B16 cells. The present study shows a CYP with multiple flavonoid sub¬strates for the first time and highlights the usage of yeast extracts from cultivations of the recombinant yeast catalyzing flavonoids’ bio¬transformation in the development of skin-whitening agents.
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