REGIOSELECTIVE BIOCONVERSION OF COLCHICINE AND THIOCOLCHICINE INTO THEIR CORRESPONDING 3-DEMETHYL DERIVATIVES

A variety of plant cell cultures and microbial soil isolates were scre ened for their ability to specifically demethylate colchicine at the C -3 position. Among all plant cell cultures tested, the newly establish ed Colchicum variegatum culture was the only one able to demethylate c olchicine, however unspecifically, yielding a mixture of 3-demethylcol chicine and 2-demethylcolchicine. In contrast, two bacterial strains w ere found among more than 500 isolates tested which expressed highly r egio-specific demethylation activity exclusively at C-3 of colchicine, The bioconversion product of the microorganisms, 3-demethylcolchicine , was completely excreted into the medium. The specific C-3 bioconvers ion of colchicine as well as of thiocolchicine by one of these strains , Bacillus IND-B 375, was characterized in function of substrate conce ntration and incubation time.