Synthesis and Antinociceptive Activity of Orally Active Opioid Peptides: Improvement of Oral Bioavailability by Esterification
作者:Tadashi Ogawa、Mamoru Araki、Tetsuhisa Miyamae、Toru Okayama、Masaki Hagiwara、Shinobu Sakurada、Tadanori Morikawa
DOI:10.1248/cpb.51.759
日期:——
To improve the oral bioavailability of a dermorphin tetrapeptide analog, Nα-1-iminoethyl-Tyr-D-MetO-Phe-MeβAla-OH (III),1) which has a potent analgesic activity after oral administration, various derivatives were synthesized to increase lipophilicity by esterification of the C-terminal carboxyl group and/or acylation of the phenolic hydroxyl group on Tyr1. Antinociceptive activity was evaluated after subcutaneous or oral administration using the mouse tail pressure test. As a result, increased antinociceptive activity after oral administration as well as an improved ED50(p.o.)/ED50(s.c.) ratio, which is an indicator of oral bioavailability, were found for some compounds. With regard to the improvement of bioavailability, derivatives with acylation of the phenolic hydroxyl group on Tyr1 showed better results than derivatives with esterification of the C-terminal carboxyl group. In particular, an ED50(p.o.)/ED50(s.c.) ratio equivalent to that of morphine was found for an acetylated derivative, Nα-1-iminoethyl-Tyr(COMe)-D-MetO-Phe-MeβAla-OH (7a), as well as for a methoxycarbonylated derivative, Nα-1-iminoethyl-Tyr(CO2Me)-D-MetO-Phe-MeβAla-OH (7l).
为了提高地莫芬四肽类似物Nα-1-亚氨乙基-酪氨酸-D-甲氧基甲硫氨酸-苯丙氨酸-甲基β丙氨酸-OH(III)的口服生物利用度,该化合物在口服后具有强大的镇痛活性,通过对其C端羧基和/或酪氨酸1上的酚羟基进行酯化或酰化,合成了多种衍生物以增加其脂溶性。利用小鼠尾部压力测试,通过皮下或口服途径给药后评估其镇痛活性。结果发现,部分化合物在口服给药后显示出增强的镇痛活性,并且ED50(p.o.)/ED50(s.c.)比值有所改善,这一比值是口服生物利用度的指标。在改善生物利用度方面,酪氨酸1上的酚羟基被酰化的衍生物比C端羧基被酯化的衍生物效果更好。特别是,乙酰化衍生物Nα-1-亚氨乙基-酪氨酸(COMe)-D-甲氧基甲硫氨酸-苯丙氨酸-甲基β丙氨酸-OH(7a)和甲氧基羰基化衍生物Nα-1-亚氨乙基-酪氨酸(CO2Me)-D-甲氧基甲硫氨酸-苯丙氨酸-甲基β丙氨酸-OH(7l)的ED50(p.o.)/ED50(s.c.)比值与吗啡相当。