Isolation and characterization of new secondary metabolites from Asphodelus microcarpus .

Phytochemical study of the ethanolic extract of Asphodelus microcarpus Salzm. et Viv. (Asphodelaceae) resulted in the isolation of two new compounds, methyl-1,4,5-trihydroxy-7-methyl-9,10-dioxo-9,10-dihydroanthracene-2-carboxylate ( 1 ), and (1 R ) 3,10-dimethoxy-5-methyl-1 H -1,4-epoxybenzo[ h ]isochromene ( 2 ) as well as three known compounds; 3,4-dihydroxy-methyl benzoate ( 3 ), 3,4-dihydroxybenzoic acid ( 4 ), and 6-methoxychrysophanol ( 5 ). Compound 1 showed a potent activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus with IC ₅₀ values of 1.5 and 1.2 µg/mL, respectively. Compound 3 showed antileishmanial activity with an IC ₅₀ value of 33.2 µg/mL. Compound 2 is the first isochromene possessing a highly strained 1,4-epoxy moiety. The structure elucidation of isolated metabolites was carried out using spectroscopic data, the absolute configuration of 2 based on optical rotation and electronic circular dichroism experiments and calculations.