Investigation of Pharmacologically Active Substances from Marine Flora and Fauna

Abstract

Until recently, the only source of active natural molecules were secondary metabolites for micro-organisms and higher plants. Todays, the number of biologically active products being discovered is supplemented by a new range of substances from marine sources. The seas and oceans that cover almost two-third of the earth’s surface contain nearly 500,000 species which are virtually untapped sources of natural products, many of which are biologically active and potentially useful. Since marine organisms live in significantly different environment from those terrestrial organisms, it is reasonable to suppose that their secondary metabolites will differ considerably. Surprisingly, however, scientists engaged in research on natural products have focused their attention entirely on land sources, to the exclusion, at least until about fifteen years ago, of marine natural products. The rapid growth in the chemistry of marine organisms over the last fifteen years has led to the discovery of a surprisingly large number of new structures, many of which has no precedence among structures of terrestrial origin and possess previously unknown pharmacological and toxicological properties. The marine environment contains many poisonous species, and research carried out has resulted in the identification of various toxic substances, many of which have unexpected structures and remarkable physiological properties. These could serve the crucial needs of modern medicine. It is therefore reasonable to say that systematic research into marine products, algae and invertebrates, including micro-organisms, should be pursual vigorously. Only time will tell whether medicine from the sea was a dream of the 1970s or if the efforts made so far produced really useful results. The aim of this project were: - a) Evaluation of anti-microbial activities of alcoholic extracts of marine organisms. b) Isolation of hitherto unknown products from biologically interesting marine organisms. c) Determination of their structure by chemical and spectroscopic means. d) Evaluation of pharmacological activity. Under the project the following ten marine organisms/plant were collected for the above investigation such as antibacterial and toxicological screening. 1. Zoanthid sp. 2. Aplysia Juliana 3. Onchidium peronii 4. Bursatella leachi leachi 5. Broyzone sp. 6. Sponge sp. 7. Laurencia pinnatifida (red algae) 8. Cystoseira indica (brown algae) 9. Sargassum borinium 10. Sargassum terrinum Out of the initially selected above mentioned 10 marine organisms the following three showed promising activity in anti-bacterial and brine-shrimp lethality screening. The rest were inactive, as shown in table 1. 1. Zoanthid sp. 2. Aplysia Juliana 3. Laurencia pinnatifida Photochemical investigation on these marine organisms have resulted in the isolation of several exciting new compounds with novel structures and the following three top-class scientific publications in leading international journals. Several dozen reprint requests have been received for the following published articles. 1. Zoanthaminone, A new Triterpenoidal Alkalloid from Marine, Atta-ur-Rehman, K.A. Alvi, S.A. Abbas, K.A. Alvi, S.A Abbas, M.I Choudhary and J. Clardy, Tetrahedron Letters, 30, 6825 (1989). 2. Pinnatazane, A bridged Cyclic Ether Sesquiterpene from Laurencia pinnatifida, Atta-ur-Rehman, V.U. Ahmad, S. Bano, S.A. Abbas, K.A. Alvi, M.S. Ali, H.M.S. Lu and J. Clardy, Phytochemistry, 27, (12), 3879 (1988). 3. A New Diterpenoidal Lactone from Aplysia Juliana, Atta-ur-Rehman, S.A. Abbas, K.A. Alvi, T. Sultana, M.I. Choudhary and J. Clardy, J.Nat.Prod., (in press). During the report period (third and final year) several known compounds have been isolated from sea hare Aplysia Juliana, along with a new diterpenoidal lactone, anagasiol acetate the structure of which was established by using modern X-rays crystallographic and spectroscopic techniques. Heavy atom method has been used to determine the absolute configuration of angasiol acetate by X-ray diffraction techniques.