Gossypol inhibition of LDH-X

Reproductive toxicologic effects of gossypol on male rabbits: biochemical, enzymatic, and electrolytic properties of seminal plasma

“…Concerning LDH activity, gossypol may act as an uncoupler of mitochondrial oxidative phosphorylation (28) and inhibit LDH-X, an enzyme that is postulated to participate in a shuttle system transferring H þ from cytosol to mitochondria (29).…”

Effects of gossypol on the motility of mammalian sperm

“…In common with other aromatic phenols, gossypol is an antioxidant (Adams et al, 1960;Janero and Burghardt, 1988). Gossypol has been found to inhibit several kinetic enzymes (Maugh, 1981;Hoffer, 1985;Lee et al, 1985;Mohri, 1985;Rovan et al, 1985;Sadykov et al, 1985;Tso, 1985;Tso et al, 1985;Moore et al, 1988). In addition, it inhibits a number of oxidoreductases (Gerez DeBurgos et al, 1984) as well as arachidonate lipoxygenases (Hamasaki and Tai, 1985).…”

“…This can be attributed to the reaction of gossypol with membrane compounds and to inactivation of metabolic enzymes (Rovan et al, 1985). Several studies reported that essential kinetic enzymes, such as ATPase, lactate dehydrogenase, and lactate dehydrogenase isoenzyme X (a sperm-specific enzyme postulated to participate in a shuttle system transferring H' from the cytosol to the mitochondria) are partially inactivated by gossypol (Maugh, 1981;Hoffer, 1985;Lee et al, 1985;Mohri, 1985;Rovan et al, 1985;Sadykov et al, 1985;Tso, 1985;Tso et al, 1985;Moore et al, 1988). Gossypol inhibition of sperm acrosin (a hydrolytic enzyme of acrosomal origin important in oocyte penetration) has also been suggested as the mechanism leading to sperm immotility (Kennedy et al, 1982;Sadykov et al, 1985).…”