New 4 '-substituted flavones from the fruit peels of Citrus limon (L.) Burm.f.

Two new 4'-substituted flavones isolated from the fruit peels of Citrus limon (L.) Burm.f. (Rutaceae) have been characterized as 4'-(9'-ethylene-16'-methylnon-9',15'-dien-7',11'-oate)-5,7-dimethoxyflavone (limonflavonyl lactone A, 1) and 4'-(9'-ethylene-16'-methylnon-9',15'-dien-7',11'-oate)-5,7,3'-trimethoxyflavone (limonflavonyl lactone B, 2) on the basis of spectral data and chemical analyses. Both the flavones are reported for the first time from a plant source.