Twelve pseudotetrapeptides, Boc-NHCH(CH2Ph)CH(OH)CH2CH(CH2Ph) CO-Xaa-Phe-NH2 9-11, were prepared by [(benzotriazol-1-yl)oxy]tris(dimethylamino)phosphonium hexafluorophosphate-mediated couplings of diastereoisomeric O-silylated (2R or 2S,4R or 4S,5S)-2-benzyl-5-(tert-butoxycarbonyl)amino-4-hydroxy-6-phenylhexanoic acids 1 with dipeptides H-Xaa-Phe-NH2 (Xaa = Gln, Glu(OBzl) or Ile) 3-5, followed by O-deprotection. Pseudotetrapeptides 9-11 were tested for inhibition of aspartic proteinases secreted by Candida albicans and C. tropicalis. The level of inhibition of both yeast proteinases was very low, contrasting with the nanomolar IC50 values obtained for inhibition of HIV-1 proteinase.
十二种伪四肽Boc-NHCH(CH2Ph)CH(OH)CH2CH(CH2Ph)CO-Xaa-Phe-NH2(9-11)通过[(苯并三唑-1-基氧基)三(二甲基氨基)磷酸六氟磷酸盐]介导的偶联反应制备,反应物为对映异构的O-硅烷基化(2R或2S,4R或4S,5S)-2-苄基-5-(tert-丁氧羰基)氨基-4-羟基-6-苯基己酸1与二肽H-Xaa-Phe-NH2(Xaa = 谷氨酰谷氨酸、谷氨酸(OBzl)或异亮氨酸)(3-5),然后进行O-去保护。伪四肽9-11被用于抑制由白念珠菌和热带白念珠菌分泌的天冬氨酸蛋白酶。两种酵母蛋白酶的抑制水平非常低,与抑制HIV-1蛋白酶所获得的纳摩尔IC50值形成对比。