Anti-implantation activity of S(-)- and R(+)-camphor-yuehchukene in rats

(+/-)-Yuehchukene is a dimeric indole alkaloid with potent anti-implantation activity in rats. Since (+/-)-yuehchukene occurs in nature as a racemate, it would be desirable to find out which enantiometer is the bio-active form. To this end, S(-)-camphor-yuehchukene and R(+)-camphor-yuehchukene were synthesised and tested in three bioassay models. It was found that the R(+) enantiomer was the active form. It was equipotent with (+/-)-yuehchukene in both anti-implantation and estrogenic activity tests. It seems fair to conclude that both activities reside in the same molecule.