Isolation and biological activities of termilignan B and arjunic acid from Terminalia sericea roots.

Bioassay-guided fractionation of ethyl acetate root extracts of Terminalia sericea yielded a new compound, termilignan B, and the known arjunic acid. Both compounds showed activity against Gram-positive and Gram-negative bacteria with MIC values ranging between 1.9 and 15.6 microg/mL. The lowest MIC value (1.9 microg/mL) was observed with termilignan B against Bacillus subtilis. Neither of the compounds showed significant activity against Mycobacterium aurum A+. In the cyclooxygenase assays, the compounds showed weak inhibitory activity with IC (50) values of 78 microM (COX-1) and 156 microM (COX-2) (termilignan B) and 36 microM (COX-1) and 253 microM (COX-2) (arjunic acid). No potential mutagenic effects were observed with the two compounds in the Salmonella microsome assay (TA 98).