NEW ANALOGS OF LULIBERIN WHICH INHIBIT OVULATION IN THE RAT

Fifteen analogs of luliberin (<Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2, LRH) were synthesized by the solid phase method and examined for their ability to block ovulation in the rat. Two analogs, [Ac-DAla1,DPhe2,DTrp3,6]-LRH and [Ac-DPhe1,DPhe2,DTrp3,6]-LRH, each blocked ovulation at a single injection dose of 250 μg administered at noon on the day of proestrus; three peptides, [Ac-DPro1,DPhe2,DTrp3,6]-LRH, [Ac-DThi1,DPhe2,DTrp3,6]-LRH and [Ac-DTrp1,DPhe2,DTrp3,6]-LRH, were effective at doses of 500 μg each; and four others, [Ac-DTrp1,DPhe2,DTrp3,DTrp(Nps)6]-LRH, [Chlorambucil-DPhe1, DPhe2, DTrp3,6]-LRH, [<DGlu1,DThi2,DTrp3,6]-LRH and [(<DGlu-DThi-DTrp-Ser-Tyr)2-DLys6]-LRH, gave partial inhibition at doses tested. © 1979.