POLYCITONE A AND POLYCITRIN-A AND POLYCITRIN-B - NEW ALKALOIDS FROM THE MARINE ASCIDIAN POLYCITOR SP

Three novel compounds polycitone A (1a) and polycitrins A and B (2 and 3) were isolated from the marine ascidian Polycitor sp. The structure s of compounds 1a, 2, and 3 were established mainly on the basis of NM R spectroscopic data and, in the case of 1a, also by single-crystal X- ray diffraction analysis. The crystallographic analysis was performed on 1b, the penta-O-methyl derivative of 1a, both compounds yielding po orly diffracting crystals of highly anisotropic shape. It required, in view of the dominating heavy-atom content of 1b; diffraction measurem ents with an intense rotating-anode X-ray source. Polycitone A and pol ycitrins A and B represent the first examples of two new classes of ma rine products which might biogenetically be close to the lamellarins. The penta-O-methyl derivative 1b, was found to inhibit the growth of S V40 transformed fibroblast cells in a concentration of 10 mu g/mL.