The focus of this research is the biosynthetic study of the cyanobacterial toxins anatoxin a-(s)n Anabaena flos-aquae NCR 525-17, microcystin-LR in Microcystis aeruginosa PCC-7820, the cytotoxins cryptophycin-1 in Nostoc sp. GSV 224, cylindrocyclophane D in Cylindrospermum lichenforme ATCC 29204 and fungal alkaloids from the Stigonemataceae. One of the ultimate goals of the project will be to study biosynthetic processes at the enzymatic level. Also several unnatural C-substituted aspartic acids and beta-alanines will be evaluated as substrates for the `aberrant` biosynthesis of cryptophycin analogs. With this renewal award, the Synthetic Organic Program is supporting the research of Drs. Richard E. Moore and Thomas K. Hemscheidt of the Department of Chemistry at the University of Hawaii, Manoa. Drs. Moore and Hemscheidt will focus their work on biosynthetic studies of cyanobacterial toxins produced by blue-green algae. It is important to learn exactly how potent cyanobacterial toxins are produced , since poisonous blooms of blue-green algae in eutrophic freshwater and brackish lakes present serious environmental and health problems , not only to domestic animals and wildlife that live on the surrounding shores, but to human populations that depend on the water for drinking.