Cryptocin, a potent tetramic acid antimycotic from the endophytic fungus Cryptosporiopsis cf. quercina.

[formula: see text] The endophytic fungus Cryptosporiopsis cf. quercina produces cryptocin in culture. Among other fungi, this unique tetramic acid displays antimycotic activity against Pyricularia oryzae, the causal agent of rice blast disease. Cryptocin also possesses activity against a wide variety of plant pathogenic but not human pathogenic fungi. The fine rhomboid-like crystals of cryptocin allowed structural elucidation by X-ray crystallography. The importance of cryptocin to the symbiotic relationship of C. quercina to its hosts is briefly discussed.