Prenylated chalcones and flavones from the leaves of Dorstenia kameruniana

Two novel flavonoids: 6,7-(2,2-dimethylchromano)-5,4'-dihydroxyflavone and 3,4-,4',5'-bis-(2,2-dimethylchromano)-2'-hydroxychalcone together with the known 6-(3-methylbut-2-enyl)apigenin and two chalcones (E)-1-[2,4-dihydroxy-3-[3-methylbut-2-enyl]phenyl]-3-[4-hydroxyphenyl]-prop-2-en-1-one and (E)-1-[2,4-dihydroxy-5-[3-methylbut-2-enyl]phenyl]-3-[4-hydroxy-3-[3-methylbut-2-enyl]phenyl]-prop-2-en-1-one were characterised from leaf tissue of Dorstenia Kameruniana. The structures were established on the basis of spectroscopic data. (C) 1998 Elsevier Science Ltd. All rights reserved.