title: In vitro inhibition by gossypol of oxidoreductases from human tissues.
abstract: The effect of gossypol, a polyphenolic compound with antifertility action on human males, has been investigated on the following oxidoreductases purified from human tissues: lactate dehydrogenase (EC 1.1.1.27) isozymes 1 or B4 from heart, 5 or A4 from liver and X or C4 from spermatozoa; malate dehydrogenase (EC 1.1.1.37) mitochondrial and "soluble" isozymes from heart and NADP-glutamate dehydrogenase (EC 1.4.1.4) from liver. Gossypol proved to be a powerful inhibitor of the six enzymes studied. For all of them, inhibition was of the competitive type with respect to the coenzyme and non-competitive in relation to substrate. The lowest ki values were shown for lactate dehydrogenase isozyme 1 or B4 and for the two isozymes of malate dehydrogenase. Results did not show selectivity of gossypol for the sperm-specific isozyme X or C4 of lactate dehydrogenase.
mesh_terms: D005969:Glutamate Dehydrogenase / Q000037:antagonists & inhibitors*; D006072:Gossypol / Q000494:pharmacology*; D006801:Humans; D007248:Infertility, Male / Q000139:chemically induced; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors*; D008297:Male; D009206:Myocardium / Q000201:enzymology; D013094:Spermatozoa / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D005969:Glutamate Dehydrogenase; D006072:Gossypol