Isolation and cytotoxicity of two new flavonoids from Chrysosplenium grayanum and related flavonols.

In view of the observation that a CHCl3-soluble fraction of the MeOH extract of Chrysosplenium grayanum has shown cytotoxic activity in the KB cell in vitro system, the fraction has been further fractionated to furnish five known flavonoids (chrysosplenols B, D, and E, retusin, and brickellin), 3,5-dihydroxy-4-methoxybenzoic acid methyl ester, and two new flavonoids named chrysosplenols F [1] and G [2]. The structures of the new flavonoids have been elucidated to be 5,4',5'-trihydroxy-3,7,2'-trimethoxyflavone [1] and 5,5'-dihydroxy-3,7,2',4'-tetramethoxyflavone [2] on the basis of spectral data. Certain of the isolated compounds and related flavonol aglycones showed marginal activities against KB cells in vitro.