(Rel)-1 beta,2 alpha-di-(2,4-dihydroxy-6-methoxybenzoyl)-3 beta,4 alpha-di-(4-methoxyphenyl)-cyclobutane and other flavonoids from the aerial parts of Goniothalamus gardneri and Goniothalamus thwaitesii

The aerial parts of Goniothalamus gardneri (Annonaceae) has yielded the kno wn flavonoids 2'-hydroxy-4,4',6'-trimethoxychalcone (flavokawain A), 2',4'- dihydroxy-4,6'-dimethoxydihydrochalcone, 4:2',4'-trihydroxy-6'-methoxydihyd rochalcone, 5,7,4'-trimethoxyflavanone (naringenin trimethyl ether) and 7-h ydroxy-5,4'-dimethoxyflavanone (tsugafolin) together with three novel compo unds, the dimer characterised as (rel)-1 beta ,2 alpha -di-(2,4-dihydroxy-6 -methoxybenzoyl)-3 beta ,4 alpha -di-(4-methoxyphenyl)-cyclobutane, 2',4'-d ihydroxy-4,6'-dimethoxychalcone and 2'-hydroxy-4,4',6'-trimethoxydihydrocha lcone. The last two have previously been synthesised but appear to be new n atural products. A similar study of the aerial parts of G. thwaitesii led o nly to the isolation of the known flavonoids myricetin 4'-O-methyl ether-3- O-alpha -L-rhamnopyranoside (mearnsitrin) and myricetin-3-O-methyl ether (a nnulatin), together with the triterpenes friedelinol, friedelin and betulin ic acid. All compounds were identified by spectroscopic analysis and, for k nown compounds, by comparison with published data. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.