Geranylated and prenylated flavonoids from the twigs of Dorstenia mannii

The twigs of Dorstenia mannii yielded three prenylated and one geranylated flavonoids: 3',4'-(2,2-dimethylchromano)-2' ,4-dihydroxychalcone, 3',4'-6,7-bis-(2,2-dimethylchromano)-flavanone,7,8-(2,2- dimethylchromeno)-6-geranyl-3,5,3',4'-tetrahydroxyflavonol and 6,8-bis-(3,3-dimethylallyl)-3,5,7,4'-tetrahydroxy-3'-methoxyflavonol for which the names dorsmanin A-D, respectively, are proposed. Also identified were the known flavonoids: 3',4'-(2,2-dimethylchromeno)-2',4-dihydroxychalcone,6-(3,3-dimethylallyl)-5,7,4'-trihydroxy-3'-methoxyflavone and 6,8-bis-(3,3-dimethylallyl)-5,7,3',4'-tetrahydroxyflavanone. (C) 1998 Elsevier Science Ltd. All rights reserved.