Antimycobacterial physalins from Physalis angulata L. (Solanaceae)

Crude extracts and fractions from aerial parts of Physalis angulata have been bioassayed for antimycobacterial activity. Fraction A1-29-12 containing physalins B, F and D exhibited a minimum inhibitory concentration value (MIC) against Mycobacterium tuberculosis H(37)Rv strain of 32 microg/mL. Purified physalin B and physalin D were also tested showing MIC values against Mycobacterium tuberculosis H(37)Rv strain of > 128 microg/mL and 32 microg/mL respectively, suggesting that physalin D plays a relevant role in the antimycobacterial activity displayed. Structural elucidation of both physalins D and B was based on detailed (13)C and (1)H NMR spectral analysis with the aid of 2D-correlation spectroscopy ((1)H-(1)H, COSY, HSQC and HMBC). The assignment of the (13)C chemical shift for physalin D is reported here for the first time.