Antitubercular constituents of Valeriana laxiflora.

Antitubercular bioassay-guided fractionation of the n-hexane- and CH (2)Cl (2)-soluble extracts of the above-ground biomass and roots of Valeriana laxiflora led to the isolation of a new iridolactone, (4R,5R,7S,8S,9S)-7-hydroxy-8-hydroxymethyl-4-methyl-perhydrocyclopenta[ c]pyran-1-one ( 1), and a new lignan, (+)-1-hydroxy-2,6-bis- epi-pinoresinol ( 2), along with eleven known compounds, betulin ( 3), betulinic acid ( 4), 5,7-dihydroxy-3,6,4'-trimethoxyflavone ( 5), 23-hydroxyursolic acid ( 6), oleanolic acid ( 7), tricin ( 8), ursolic acid ( 9), ferulic acid, (+)-1-hydroxypinoresinol, prinsepiol, and 5,7,3'-trihydroxy-4'-methoxyflavone. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic evidence. The absolute stereochemistry of 1 was determined by chemical transformations and Mosher ester procedures. In a microplate alamar blue assay against Mycobacterium tuberculosis, compounds 2 - 9 exhibited minimum inhibitory concentrations (MIC) of 15.5 - 127 microg/mL, while the other isolates were regarded as inactive (MIC > 128 microg/mL). In addition, all the isolates were tested for cytotoxicity against African green monkey Vero cells in order to evaluate their selectivity potential.