Cyclic peptides from Oldenlandia affinis DC. Molecular and biological properties

A new isolation procedure for Kalata polypeptides from the tropical plant Oldenlandia affinis DC is described. Fractions were screened by thin-layer chromatography, and Van Urk positive fractions were tested for oxytocic activity in estrogenized rat uteri. By using this procedure, we were able to isolate and characterize three macrocyclic polypeptides with uterine activity. Their amino acid sequence and biological effects have been analyzed, and their NMR spectra were compared with those of the earlier ones. All three peptides showed hemolytic activity on human blood, and were tested for antibiotic effect against E. coli, Staphylococcus aureus, and Hemophilus influenzae.