New Minor Cyclic Peptides from Brachystemma calycinum (in English) CHENG

From the ethanol extract of the roots of Brachystemma calycinum D.Don, a Chinese folk herb, four new minor cyclic peptides namely brachystemin A, B, C and D (1-4) have been isolated. Their structures were established as cyclo (Pro¹-Phe-Leu-Ala¹-Thr-Pro²-Ala²-Gly)(1)、cyclo(Pro¹-Ala-Phe-Trp-Asp-Pro²-Leu-Gly)(2)、cyclo (Pro¹-Ile-Gly-Pro²-Val-Ala¹-Ala²-Tyr) (3) and cyclo (Pro-OMet-Trp-Ile-Gly-Ala-Leu-Asp) (T4) respectively by means of extensive spectral methods.