Okunji C, Komarnytsky S, Fear G, Poulev A, Ribnicky DM, Awachie PI, Ito Y, Raskin I. Preparative isolation and identification of tyrosinase inhibitors from the seeds of Garcinia kola by high-speed counter-current chromatography.
J Chromatogr A 2007;
1151:45-50. [PMID:
17367799 DOI:
10.1016/j.chroma.2007.02.085]
[Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 02/16/2007] [Accepted: 02/23/2007] [Indexed: 11/25/2022]
Abstract
In continuation of our search for bioactive natural products that can be used for the treatment of dermatological disorders associated with melanin hyperpigmentation, 50 extracts/fractions from 21 families of medicinal plants from West and Central Africa were evaluated for inhibitory activity against tyrosinase (E:C:1.14.18.1), the rate-limiting enzyme in melanin synthesis. Four extracts including the methanol extract of Garcinia kola seeds at 100 microg/ml displayed >60% inhibition of tyrosinase activity. Preparative high-speed counter-current chromatography with solvent system composed of n-hexane-ethyl acetate-methanol-water (3:5:3:5) successfully separated the most active extract from G. kola seed. By stepwise increase of the flow-rate of the mobile phase, five major biflavanones including GB-I-glucoside (1) GB-1a (2), GB-1 (3), GB-2 (4), kolaflavonone (5) were successfully isolated in 6 h. Compound (4) was the most potent (IC(50) 582 microM) and compared favorably with a reference tyrosinase inhibitor (kojic acid, IC(50) 130 microM).
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