Change of Mechanical Activity to Contraction from the Relaxation Induced by the Intracellular Ca2+ Antagonist KT-362; Effects of Alkylation of Side Chain, and Substitution of 2,3,4,5-Tetrahydro-1,5-Benzothiazepine Derivatives.
作者:Naoto UEYAMA、Shyuichi WAKABAYASHI、Tsuyoshi TOMIYAMA
DOI:10.1248/cpb.45.1761
日期:——
KT-362 (5-[3-[2-(3, 4-Dimethoxyphenyl)ethyl]aminopropionyl]-2, 3, 4, 5-tetrahydro-1, 5-benzothiazepine fumarate) is an intracellular Ca2+ antagonist. The compound obtained by introducing methyl groups onto the nitrogen (R2) of the side chain of KT-362 showed vasoconstrictive activity. Therefore we synthesized various derivatives, and examined their activities. Substitution at position R2 of the side chain resulted in potent contractile activity, and the optimal alkyl length was to or three carbons. The potency was further increased by the introduction of a chloro group at the R1 position of 2, 3, 4, 5-tetrahydro-1, 5-benzothiazepines. One of the synthesized compounds, 8-chloro-5-N-ethyl-N-[2-(3, 4-dimethyoxyphenyl)ethyl]aminopropionyl}-2, 3, 4, 5-tetrahydro-1, 5-benzothiazepine fumarate (9b), showed an EC50 value of 3.47×10-8 M for contraction of rabbit iliac artery. The action of compound 9b was antagonized competitively by an H1-histamine receptor antagonist, diphenhydramine, and the pA2 value was 7.82. The maximum constriction was inhibited by a Ca2+ entry blocker, nicardipine, but not by an α1-adrenoreceptor antagonist, prazosin. In a Ca2+-free medium, tonic constriction induced by 9b disappeared, and only a phasic constriction was oberved. Though this phasic constriction was inhibited by diphenhydramine, it was not inhibited by prazosin or nicardipine.
KT-362 (5-[3-[2-(3, 4-二甲氧基苯基)乙基]氨基丙酰基]-2, 3, 4, 5-四氢-1, 5-苯并硫氮杂卓富马酸盐)是一种细胞内 Ca2+ 拮抗剂。在 KT-362 侧链的氮(R2)上引入甲基后得到的化合物具有收缩血管的活性。因此,我们合成了多种衍生物,并研究了它们的活性。侧链 R2 位置的取代可产生强效收缩活性,最佳烷基长度为一到三个碳原子。在 2, 3, 4, 5-四氢-1, 5-苯并硫氮杂卓的 R1 位引入一个氯基,可进一步提高药效。合成的化合物之一,8-氯-5-N-乙基-N-[2-(3,4-二甲氧基苯基)乙基]氨基丙酰基}-2,3,4,5-四氢-1,5-苯并硫氮杂卓富马酸盐(9b)对兔髂动脉收缩的 EC50 值为 3.47×10-8 M。化合物 9b 的作用被 H1-组胺受体拮抗剂苯海拉明竞争性拮抗,pA2 值为 7.82。Ca2+ 进入阻断剂尼卡地平能抑制最大收缩,但α1-肾上腺素受体拮抗剂哌唑嗪不能抑制收缩。在不含 Ca2+ 的介质中,9b 诱导的强直性收缩消失了,只有阶段性收缩。虽然苯海拉明能抑制这种阶段性收缩,但哌唑嗪或尼卡地平却不能抑制这种收缩。