Procyanidins from Acer komarovii bark

초록

The bark of Acer komarovii was collected, ground, and extracted with 70% aqueous acetone to obtain concentrates. The concentrates were suspended in H<inf>2</inf>O, and then successively partitioned with n-hexane, dichloromethane and ethylacetate to be freeze dried. A portion of ethylacetate fraction was chromatographed on a Sephadex LH-20 and a RP C-18 column with various aqueous MeOH-H<inf>2</inf>O (1:0, 1:1, 1:2, 1:5, 1:7, 1:9, 1:10, 3:1, and 4:1, v/v) eluents. Four compounds were isolated; (-)-epicatechin (9.6 g), procyanidin A2 (epicatechin-(4β→8, 2β→O→7)-epicatechin) (1.3 g), procyanidin B2 (epicatechin-(4β→8)-epicatechin) (40.0 mg), and cinnamtannin B1 (epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin) (690 mg). The analysis of the bark procyanidins showed that the basic unit constituting condensed tannins was only (-)-epicatechin. This study, for the first time, report the procyanidins of Acer komarovii bark.

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