A new 5-dehydroxyflavan, namely Albiziaflavan B or (+)-(2R, 3S, 4R)-3′,4′, 7-trihydroxy-4-methoxy-2,3-trans-flavan-3,4-trans-diol (1) was isolated from the root bark of Albizia glaberrima, together with six known compounds including three flavans: (+)-mollisacacidin (2), (+)-fustin (3) and butin (4); two steroids: chondrillasterol (5) and chondrillasterone (6), and a triterpenoid: lupeol (7). The structure of 1 was established by detailed analysis of its spectroscopic data, especially 1D and 2D NMR spectra, HRESIMS and CD data. Compounds 1–6 were assayed for their antiproliferative effects on two human cancer cells, HeLa at 50 μM (n = 2) and HL60 at 20 μM (n = 2). Compound 3 and 4 were the most active on HL60 with IC50 of 8.1 and 8.3 μM, respectively. Compound 6 was the most active with an IC50 of 4.6 μM on HeLa.
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