Abstract

The authors report the synthesis of some bioactive organic compounds which could be of pharmacological interest using Dioscorea praehensilis tyrosinase immobilized on calcium-alginate beads. The enzymatic synthesis of these compounds involved pyruvic acid as a source of carbonyl groups, ammonia and catechol. Catechol was used as substrate and a parent compound that supplied aromatic ring carbons for the reactions. The structures of novel compounds synthesized were deduced using UV, IR and NMR spectroscopic techniques. Structural elucidation revealed that a novel lactone (3-hydroxyl-3-methylbenzo[b][1,4]-lactone) was synthesized in the presence of pyruvic acid and catechol only. When ammonia solution was introduced into the reaction system, there was conversion of the blue-colored lactone compound into a red-colored product. The structure was elucidated as 2-(2-hydroxyphenoxy)-2-aminopropanoic acid. Whereas, in the presence of ammonia and catechol only, a novel secondary amine (1,6-dihydroxy-7-aza,bicyclo[4.1.0]-2,4-heptadiene) was synthesized. Though the synthesized compounds possess functional groups, the specific pharmacological or biotechnological applications are yet to be investigated and established.

Key words: Yam Tyrosinase, catechol, novel lactone, novel amino acid, novel secondary amine.