Antitrypanosomal sesquiterpene lactones from Saussurea costus.

Abstract In the course of a larger screen of 1800 plant and fungal extracts, the ethyl acetate extract of Saussurea costus roots potently inhibited the growth of Trypanosoma brucei rhodesiense . Subsequent HPLC based activity profiling led to the identification of the sesquiterpene lactones arbusculin B ( 1 ), α-cyclocostunolide ( 2 ), costunolide ( 3 ), and dehydrocostuslactone ( 4 ). They were tested for in vitro antitrypanosomal activities and cytotoxicity alongside the structurally related sesquiterpene lactones parthenolide ( 5 ), zaluzanin D ( 6 ), and eupatoriopicrin ( 7 ), and had IC 50 s between 0.8 and 22 μM. Cytotoxic IC 50 s were from 1.6 to 19 μM, and selectivity indices from 0.5 to 6.5.