Inhibition of human and ovine acrosomal enzymes by tannic acid in vitro.
The effect of tannic acid, a common flavonoid, on the acrosin and plasminogen activator activity and plasmin activity of human and ram spermatozoa was evaluated. Acrosin and plasminogen activator activity were determined by spectrophotometry using the chromogenic substrates N-alpha-benzoyl-DL-arginine para-nitroanilide-HCl (BAPNA) and H-D-valyl-L-leucyl-L-lysine-p-nitroanilide-2HCl (S-2251), respectively. In extracts from both human and ovine acrosomes, the activities of acrosin and plasminogen activators were susceptible to tannic acid inhibition. The inhibitory effect of tannic acid was observed at concentrations > 50 micromol l(-1) in a dose-dependent manner. In additional experiments, low concentrations of tannic acid significantly inhibited tissue-type plasminogen activator, urokinase-type plasminogen activator and plasmin activity in a concentration-dependent manner over the range 0.25-200 micromol l(-1). Tannic acid reduced the motility of ram spermatozoa at a concentration of 1000 micromol l(-1) after 2 and 3 h co-incubation with spermatozoa. The motility of human spermatozoa remained unchanged over the range 0.1-1000 micromol tannic acid l(-1) during 3 h co-incubation. These results indicate that tannic acid inhibited the activity of both acrosin and plasminogen activator and indicates a possible mechanism by which flavonoids exert their antifertility effects.
Taitzoglou
I A
IA
Department of Physiology, Faculty of Veterinary Medicine, University of Thessaly, 431 00 Karditsa, Greece.
Tsantarliotou
M
M
Zervos
I
I
Kouretas
D
D
Kokolis
N A
NA
D000176:Acrosin / Q000037:antagonists & inhibitors / Q000378:metabolism; D000177:Acrosome / Q000187:drug effects* / Q000201:enzymology*; D000818:Animals; D001586:Benzoylarginine Nitroanilide / Q000378:metabolism; D002863:Chromogenic Compounds / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005341:Fibrinolysin / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D047348:Hydrolyzable Tannins / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009842:Oligopeptides / Q000378:metabolism; D010960:Plasminogen Activators / Q000037:antagonists & inhibitors / Q000378:metabolism; D012756:Sheep; D013045:Species Specificity; D013053:Spectrophotometry; D013081:Sperm Motility / Q000187:drug effects; D010959:Tissue Plasminogen Activator / Q000037:antagonists & inhibitors; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors
D002863:Chromogenic Compounds; D004791:Enzyme Inhibitors; D047348:Hydrolyzable Tannins; D009842:Oligopeptides; C018788:valyl-leucyl-lysine 4-nitroanilide; D001586:Benzoylarginine Nitroanilide; D010960:Plasminogen Activators; D000176:Acrosin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator