Tetronic Acid Biosynthesis in Molds

Abstract

The tetronic acid structure not only appears in the vitamin, n-ascorbic acid, but in addition is frequently found in natural products.A group of related tetronic acids was identified by Raistrick and his colleagues (1, 2) in Penicillium charlesii and some other molds.The interrelationships among the structures of these acids are indicated in Fig. 1.It was of interest to determine the pathway for the biosynthesis of the tetronic acid structure in molds, particularly in view of the known mechanisms for n-ascorbic acid synthesis in mammals and of the apparently different pathway in plants.Carolic (I, R = -COCH2CH2CH20H) and carlosic (II, R = -COCH#H&H,) acids could be isolated in adequate amounts from single flask cultures of Penicillium churlesii NRRL 778, and these acids were chosen for this study.A further tetronic acid from other molds, penicillic acid, has a markedly different structure from the carlosic and carolic acid types.A study of the biosynthesis of this compound is the subject of the following paper (3).