Two new cyclic peptides from Psammosilene tunicoides

From Psammosilene tunicoides W. C. Wu et C. Y. Wu, two cyclic octapeptides (named psammosilenins A and B) were isolated. Their structures were determined as cyclo(-Pro(1)-Phe(1)-Pro(2)-Phe(2)-Phe(3)-Ala-Pro(3)-leu-) and cyclo(-Pro(1)-Gly-Phe(1)-Val-Pro(2)-Phe(2)-Thr-Ile-) by spectroscopic methods.