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A cyclic heptapeptide, c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yunnanensis Franch (M), was synthesized by solution method for the first time. Protected heptapeptide Z-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OBzl was synthesized with 3-(diethoxy-phosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT) as a coupling reagent. After deprotection of benzyl and benzyloxycarbonyl groups, a free linear heptapeptide H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH was cyclized in DMF (2×10 -3 mol/L) in the presence of nine different metal ions, i.e., Li +, Na +, K +, Cs +, Mg 2+, Ca 2+, Ba 2+, Ni 2+ and Cr 3+ respectively, using DEPBT as a coupling reagent. Univalent metal ion Cs + enhanced both the cyclization yield and cyclization rate of H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH, while some bivalent metal ions, such as Mg 2+, Ca 2+ and Ni 2+ decreased the yields of c(Gly-Ile-Pro-Tyr-Ile-Ala-Ala) drastically. Trivalent metal ion Cr 3+ even inhibited the cyclization reaction completely.
A cyclic heptapeptide, c (Gly-Ile-Pro-Tyr-Ile-Ala-Ala), which was isolated and identified from Stellaria yunnanensis Franch (M), was synthesized by solution method for the first time. Protected heptapeptide Z-Gly- Ile-Pro-Tyr-Ile-Ala-Ala-OBzl was synthesized with 3- (diethoxy-phosphoryloxy) -1,2,3-benzotriazin-4 (3H) -one (DEPBT) as a coupling reagent. and benzyloxycarbonyl groups, a free linear heptapeptide H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH was cyclized in DMF (2 × 10 -3 mol / L) Li +, Na +, K +, Cs +, Mg 2+, Ca 2+, Ba 2+, Ni 2+ and Cr 3+, using DEPBT as a coupling reagent. Univalent metal ion Cs + enhanced both the cyclization yield and cyclization rate of H-Gly-Ile-Pro-Tyr-Ile-Ala-Ala-OH, while some bivalent metal ions, such as Mg 2+, Ca 2+ and Ni 2+ decreased the yield of c -Pro-Tyr-Ile-Ala-Ala) drastically. Trivalent metal ion Cr 3+ even inhibited the cycl ization reaction completely.