Antimutagenic activities of 24 synthetic flavones with the Salmonella microsomal assay

Twenty-four flavones were synthesized with various hydroxyl and/or methoxyl groups on A and B rings. Their antimutagenic properties were evaluated against benzo(a)pyrene (BaP) and a pool of mutagenic urine concentrate (U) using a modified liquid incubation method of Ames test. The tester strain was Salmonella typhimurium TA98+S9 Mix. The antimutagenic activities were calculated by non linear regression analysis and the doses of flavones (in nmoles) required for a 50% reduction of induced revertants with BaP and U were defined as the inhibition doses (ID50B and ID50U respectively). Seventeen flavones possessed significant antimutagenic activity against BaP. ID50B ranged from 15.1 nmoles (F22) to 1000.6 nmoles (F13). Eighteen flavones showed significant antimutagenic activity against U. ID50U ranged from 23.5 nmoles (F22) to 354.6 nmoles (F3). The 2',3',4'-trihydroxyflavone (F22, ID50B=15.1 nmoles, ID50U=23.5 nmoles) and the 2',3',4',7-tetrahydroxyflavone (F20, ID50B=37.8 nmoles; ID50U=62.3 nmoles) had antimutagenic activities similar to those of chlorophyllin (ID50B=19.6 nmoles and ID50U=44.2 nmoles) and were evaluated against B(a)P 7,8-dihydrodiol-9,10-epoxide. Against this last mutagen, the flavones which included three OH in B ring showed the highest activity and this property seemed independent of the substituent groups on A ring.