PHENACEIN-AN ANGIOTENSIN-CONVERTING ENZYME INHIBITOR PRODUCED BY A STREPTOMYCETE

I.TAXONOMY, FERMENTATION AND BIOLOGICAL PROPERTIES

Abstract

Phenacein, 3, 6-dihydroxy-1-phenazinecarboxylic acid, was a specific angiotensin-converting enzyme (ACE) inhibitor isolated from a member of the Streptomyces tanashiensis-zaomyceticus group. Phenacein acted as a pure competitive inhibitor with a Ki of 0.58μM. ACE inhibition could be reversed by Zn⁺⁺, but not by Co⁺⁺, Ca⁺⁺, or Mg⁺⁺; therefore, phenacein may chelate the active site zinc of ACE. However, other zinc-containing enzymes were not inhibited at high phenacein concentrations. Phenacein exhibited weak activity against Gram-positive bacteria, but was not active against Candida sp. or Gram-negative organisms.