Toxins, anticancer agents, and tumor promoters from marine prokaryotes
Marine prokaryotic organisms, in particular blue-green algae belonging to the Oscillatoriaceae, are potentially good sources of new antineoplastic agents. The dermatitis-producing substances in the bluegreen alga Lyngbya majuscula, however, which exhibit marginal anticancer activities, are powerfultumor promoters. The potencies and modes of action of two of these tumor promoters, aplysiatoxin and lyngbyatoxin A, are essentially identical with the potency and mode of action of the well known tumor promoter from Croton oil, 12-O-tetradecanoylphorbol 13-acetate (TPA). Structure-activity relationships are presented for aplysiatoxin, lyngbyatoxin A, TPA, and related compounds. The absolute stereochemistries of the aplysiatoxin and lyngbyatoxin A are discussed.