The objectives of this research are to identify, isolate and determine the structure of cytotoxic and in vivo tumor inhibitory compounds from a variety of marine organisms. The primary sources for new compounds will be sponges, ascidians, and coelenterates. In addition, marine bacteria isolated from sponges and some other marine sources will be cultured and extracted to search for potential antitumor compounds. Isolation will be guided by activity testing provided by the National Cancer Institute using in vivo (PS) and/or in vitro (KB, P388, L1210) test systems. To the extent possible compounds will be isolated in sufficient quantities to conduct in vivo activity testing. Antitumor activity enhancement will be sought through structural modification of some of the active compounds isolated. A variety of established, modern separation techniques will be used to isolate compounds, and structures will be determined by single cystal x-ray analysis and/or conventional spectroscopic methods. The structures of chemically novel compounds obtained incidental to the primary objective will be investigated to the extent possible. The long term goal of this project is to discover clinically useful anticancer agents.