New prenylated metabolites of Deguelia longeracemosa and evaluation of their antimicrobial potential.

The analysis of root extracts from Deguelia longeracemosa (Benth.) A.M.G. Azevedo yielded fifteen prenylated metabolites. Nine of them are novel, and their molecular structures were determined through spectral analyses (UV, IR, MS and NMR) as being five derivatives of 4-hydroxy-3-phenylcoumarin: 4-hydroxy-3-(4'-hydroxyphenyl)-5-methoxy-6-(8',9'-epoxy-9'-methylbutyl)-2'',2''-dimethylpyrano-(5'',6'':8,7)-coumarin; 4-hydroxy-3-(3',4'-methylenedioxyphenyl)-5-methoxy-6-(3,3-dimethylallyl)-2'',2''-dimethypyrano-(5'',6'':8,7)-coumarin; 4-hydroxy-3-(3'-hydroxy-4'-methoxyphenyl)-5-methoxy-6-(3,3-dimethylallyl)-2'',2''-dimethylpyrano-(5'',6'':8,7)-coumarin; 4-hydroxy-3-(3'-hydroxy-4'-methoxyphenyl)-5-methoxy-2'',2''-dimethylpyrano-(5'',6'':6,7)-coumarin and 4-hydroxy-3-[4'-O-(3,3-dimethylallyl)phenyl]-5-methoxy-2'',2''-dimethylpyrano-(5'',6'':6,7)-coumarin, three derivatives of 1,2-diphenyl-1,2-ethanodione (alpha-oxodeoxybenzoin derivatives): 1-[6-hydroxy-2-methoxy-3-(3,3-dimethylallyl)-2'',2''-dimethylpyrano-(5'',6'':5,4)- ]-2-(4'-hydroxyphenyl)-1,2-ethanedione; 1-[6-hydroxy-2-methoxy-2'',2''-dimethylpyrano-(5'',6'':3,4)]-2-(4'-methoxyphenyl)-1,2-ethanedione; 1-[6-hydroxy-2-methoxy-2'',2''-dimethylpyrano-(5'',6'':3,4)]-2-(3',4'-methylenedioxyphenyl)-1,2-ethanedione and one derivative of deoxybenzoin: 2,4'-dimethoxy-6-hydroxy-2'',2''-dimethylpyrano-(5'',6'':3,4)-deoxybenzoin. The antimicrobial activity of roots extracts and some isolated compounds was screened through bioautography against bacteria and fungi.