An analysis of the uterotonic potencies of all analogs having substituted L- or D-tyrosine or -phenylalanine in position 2 and L-arginine, D-arginine or D-homoarginine in position 8 was made. The series of analogs already published was completed by the solid phase synthesis of ten new analogs having L- or D-Phe, L- or D-Phe(2-Et), L- or D-Phe(2,4,6-triMe) or D-Tyr(Me) in position 2 and either L- or D-arginine in position 8. All newly synthesized analogs were found to be uterotonic inhibitors. Deamination increases both the agonistic and antagonistic potency. In the case of phenylalanine analogs the change of configuration from L to D in position 2 enhances the uterotonic inhibition for more than 1 order of magnitude. The L to D change in position 8 enhances the inhibitory potency negligibly. Prolongation of the side chain of the D-basic amino acid in position 8 seems to decrease slightly the inhibitory potency if there is L-substituted amino acid in position 2. On the other hand there is a tendency to the increase of the inhibitory potency if there is D-substituted amino acid in position 2.
对于所有具有取代L-或D-酪氨酸或苯丙氨酸在第2位以及L-精氨酸,D-精氨酸或D-同型精氨酸在第8位的类似物的子宫收缩药效进行了分析。已经发表的类似物系列通过合成具有L-或D-Phe,L-或D-Phe(2-Et),L-或D-Phe(2,4,6-triMe)或D-Tyr(Me)在第2位以及L-或D-精氨酸在第8位的十个新类似物的固相合成而得到完善。所有新合成的类似物均被发现是子宫收缩抑制剂。脱氨增加了激动和拮抗效力。在苯丙氨酸类似物的情况下,从第2位的L到D的构型变化使子宫收缩抑制剂的效力提高了超过一个数量级。在第8位的L到D的变化几乎不会增强抑制效力。如果第2位存在L-取代氨基酸,则D-基本氨基酸侧链的延长似乎会略微降低抑制效力。另一方面,如果第2位存在D-取代氨基酸,则有增加抑制效力的趋势。