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Tyrosinase inhibitory activity of proanthocyanidins from woody plants


Flavanol values, molecular weight distributions, polyphenolic patterns, and tyrosinase inhibitions of proanthocyanidins (PACs) from karamatsu (Larix sp.) bark, acacia Morishima (Acacia mearnsii) bark, and commercial quebracho (Schinopsis lorentzii) extracts were examined to investigate the relation between the structures of PACs from woody plants and tyrosinase inhibitory activities. Aqueous acetone (70%) extracts of acacia showed high flavanol contents and strong tyrosinase inhibition. On the other hand, the quebracho extracts inhibited tyrosinase activity slightly despite its high flavanol content. Phenyl nucleus analysis by the nucleus exchange reaction provided information that karamatsu, quebracho, and acacia extracts consist of procyanidin, profisetinidin, and prorobinetinidin, respectively. The relation between the phenolic hydroxylation pattern and tyrosinase inhibition suggested that the PACs with a 5,7-dihydroxyphenyl structure in the A-ring and a 3,4,5-trihydroxyphenyl structure in the B-ring have potent tyrosinase inhibitory activity.

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Correspondence to Keiji Takagi.

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Part of this paper was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999

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Takagi, K., Mitsunaga, T. Tyrosinase inhibitory activity of proanthocyanidins from woody plants. J Wood Sci 49, 461–465 (2003).

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Key words

  • Tyrosinase inhibition
  • Proanthocyanidin
  • Condensed tannin
  • Nucleus exchange reaction