• Archives of Pharmacal Research
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• v.27 no.11
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• pp.1132-1135
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• 2004

In order to find new tyrosinase inhibitors and the effects of prenyl residue on flavonoid molecules, eight prenylated and three synthetic vinylated flavonoids were examined on their inhibitory effect against tyrosinase activity. From the results, kuwanon C, papyriflavonol A, sanggenon D and sophoflavescenol were found to possess the considerable inhibitory activity. Especially, sanggenon D is revealed as a potent inhibitor ($IC_{50}$ =7.3$\mu$ M), compared to the reference compound, kojic acid ($IC_{50}$ =24.8 $\mu$M). However, the prenylation with isoprenyl group or the vinylation to flavonoid molecules did not enhance tyrosinase inhibitory activity.

• YAKHAK HOEJI
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• v.41 no.4
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• pp.439-443
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• 1997

From the root bark of Broussonetia kazinoki (Moraceae) two antioxidant components were identified. Their structures were determined as kazinol A (1) and kazinol E (2) (is oprenylated flavan and isoprenylated 1,3-diphenyl propan derivatives) by comparing NMR data with those of the reported compounds from relative plants. The antioxidant activity of 1 and 2 were monitored by the method of DPPH radical scavenging activity, whose $SC_{50}$ values were $41.4{\mu}M\;and\;33.4{\mu}M$, respectively. These compounds also exhibited inhibitory activity against tyrosinase, which is the sole key enzyme for the melanin biosynthesis and play a role in conversion of tyrosine to dopa, and dopa to dopaquinone. The antioxidant effect and the suppression of melanin biosynthesis are useful for anti-aging, increasing vitality in the incidence of major degenerative diseases, and cosmetic products in relation to hyperpigmentation.