NATURALLY-OCCURRING SOMATOSTATIN AND VASOACTIVE-INTESTINAL-PEPTIDE INHIBITORS - ISOLATION OF ALKALOIDS FROM 2 MARINE SPONGES

The vasoactive intestinal peptide (VIP) and somatostatin (somatotropin release inhibiting factor, SRIF) are important neurotransmitters in a number of basic physiological events. Their disturbances have been re ported in many diseases such as cystic fibrosis, impotent man (VIP), A lzheimer's disease, and some tumours (SRIF). Xestospongine B (1), scep trine (2), and ageliferine (3), three alkaloids isolated from Xestospo ngia sp. and Agelas novaecaledoniae are reported as somatostatin and V IP inhibitors. The natural products 1, 2, and 3 exhibited a high affin ity for somatostatin (IC50 = 12 mu M, 0.27 mu M, and 2.2 mu M, respect ively), 2 and 3 showed an affinity for VIP (19.8 mu M and 19.2 mu M, r espectively). Due to the interaction between non-peptidic compounds an d somatostatin/VIP receptors, these three alkaloids could be promising agents in the research on natural non-peptidic compounds for therapeu tical interventions.