Studies in the biochemistry of micro-organisms. 106. Metabolites of Alternaria tenuis auct.: the structure of tenuazonic acid

Abstract

On mild acid hydrolysis, tenuazonic acid yields acetic acid and a decacetyl compound. Hydrolysis with stronger acid produces acetic acid, CO2 and a basic ketone, shown to be 3-amino-4-methylhexan-2-one. Ozonolysis of tenuazonic acid, followed by acid hydrolysis, gives acetic acid, oxalic acid and L-isoleucine. It is concluded that tenuazonic acid is a-acetyl-gamma-sec-butyltetramic acid. The configuration about the 2 asymmetric centres corresponds to that in L-isoleucine. The crystalline isomer obtained from tenuazonic acid, and previoulsy called isotenuazonic acid, is shown to be a mixture of tenuazonic acid and a disastereoisomer. Tenuazonic acid is believed to be the 1st substituted tetramic acid isolated from natural sources.