PRENYLATED FLAVANONES FROM MONOTES ENGLERI - ONLINE STRUCTURE ELUCIDATION BY LC UV/NMR/

The CH2Cl2 extract of Monotes engleri GILG. (Dipterocarpaceae) showed antifungal activity against the yeast Candida albicans in our bioautog raphic TLC assays. After a first fractionation of the crude extract, t he bioactivity was located in one of the fractions. To perform an effi cient targeted isolation of the active compounds. LC/UV/MS and LC/UV/N MR analyses of the crude extract and the active fraction were performe d. LC/UV.LC/MS, and LC/NMR data (1D and 2D) allowed the identification of 1 as ethylbut-2-enyl)oxy]phenyl}-4H-1-benzopyran-4-one, a new pren ylated flavanone, named monotesone A. Subsequent isolation of 1 has pe rmitted the determination of its absolute configuration on the basis o f CD measurements. Three other prenylated flavanones 2-4 were isolated from the same extract. Compound 3 was identified as 6,8-bis(3-methylb ut-2-enyl)-4H-t-benzopyran-4-one, another new natural product, named m onotesone B. The structures of 2 and 4 were established as selinone an d lonchocarpol A, respectively. The antifungal activity against Candid a albicans was determined for all compounds.