Selected biological activities of saraines.

1. The Mediterranean sponge Reniera sarai, Pulitzeri-Finali, 1969 (Demospongiae: Haploscleridae: Renieridae) possesses in large amounts a series of unprecedented polycyclic alkaloids, saraines 1-3 and saraines A-C. 2. The structural peculiarities of saraines, their chemical-physical characteristics, along with their relevant abundance in the sponge, prompted a study aimed at investigating their biological properties. 3. Saraines were assayed for their cytotoxic, antibacterial, insecticidal and potential antitumoral activities. These results, along with the growth inhibition of fertilized sea urchin eggs, are reported.

Conformational analysis of morphiceptin by NMR spectroscopy.

Three exorphins, beta-casomorphin-5, morphiceptin and its D-Pro4 analog, were studied in DMSO by means of 1H and 13C NMR spectroscopy, with the aim of detecting conformational features of potential biological significance for the mu opioid activity since the presence of two Pro residues restricts the accessible conformational space more than in all other peptides. It is found that the conformational mixtures present in solution contain relevant fractions of folded conformers, a feature that assures the observation of four different Tyr OH signals in the 500 MHz spectrum of morphiceptin. The conformer distribution of (very active) (D-Pro4)-morphiceptin is different from those of its (less active) congeners.