A new flavone and a newly synthesized alkaloid from Lippia rugosa A. Chev (Verbenaceae).

The chemical investigation of the leaf extract of a Cameroonian medicinal plant, Lippia rugosa A Chev (Verbenaceae) led to the isolation of a new flavonoid derivative flavolippia ( 1 ), alongside eleven known compounds: 2,4-dimethylpyridin-3,5-diol ( 2 ), 5-hydroxy-6,7,4'-trimethoxylflavone ( 3 ), 5-hydroxy-3,7,4'-trimethoxyflavone ( 4 ), 7-hydroxy-5,6,4'-trimethoxyflavone ( 5 ), 3 β -hydroxy-urs-12-en-3-ol ( α -amyrin) ( 6 ), lupeol acetate ( 7 ), lup-20(29)-en-3 β -ol (lupeol) ( 8 ), lup-20(29)-en-3β,28-diol (betulin) ( 9 ), fridelan-3-one (fridelan) ( 10 ), saccharose ( 11 ), cosanol ( 12 ). In addition, a new semi-synthetic alkaloid derivative named lippiamicin ( 13 ) was prepared from 2,4-dimethylpyridin-3,5-diol ( 2 ). Their structures were established on the basis of their spectroscopic data, as well as 1 D and 2 D NMR. Compounds 1-13 were evaluated for their antioxidant activities. The results obtained showed that compounds 2 and 12 were the most active with IC 50 values of 0.145 ± 0.011 and 0.195 ± 0.017 µM/mL respectively (for DPPH•) and 0.241 ± 0.027 and 0.223 ± 0.024 µM/mL respectively (for FRAP) compared to butylated hydroxyltoluene used as positive control.