Several novel spiro derivatives of parthenin (1) have been synthesized by the dipolar cycloaddition using
various dipoles viz; benzonitrile oxides, nitrones and azides with exocyclic double bond of C ring
(a-methylene-g-butyrolactone). Majority of the compounds exhibited improved anti-cancer activity
compared to the parthenin, when screened for their in vitro cytotoxicity against three human cancer cell
lines viz., SW-620, DU-145 and PC-3. In vivo screening of select analog revealed improved anti-cancer
activity with low mammalian toxicity as compared to parthenin. The results of the cytotoxicity pattern of
these derivatives reveals the SAR of these sesquiterpinoid lactones and possible role of a,b-unsaturated
ketone of parthenin in inhibiting NF-kB. A mechanistic correlation of anti-cancer activity along with
in vivo and western blotting experiments has been described.