Stereoselective interaction between gossypol and rat plasma

Effects of sublethal doses of gossypol on haematological properties and biochemical metabolites of male rabbit

The purpose of this study was to investigate the effects of two sublethal doses of gossypol (GOS) (4 and 20 mg/kg of body weight), administered every other day, on some haematological, biochemical, enzymatic and electrolytic properties and amino and fatty acids in male rabbit blood plasma. The experiment lasted for 16 wk and included two phases: 1) administration period; rabbits were given the experimental doses of GOS for 8 wk; and 2) recovery period; rabbits were allowed 8 wk for complete withdrawal of drugs from the plasma. Results showed that low levels of gossypol increased (<em>P</em>&lt;0.01) haemoglobin, mean corpuscular haemoglobin and white blood cells compared to control. Plasma total protein was increased (<em>P</em>&lt;0.01) by the low GOS dose in both experimental phases. Likewise, glucose concentration was increased (<em>P</em>&lt;0.01) by the high GOS dose during the recovery period. Aspartate aminotransferase and alanine aminotransferase enzymes were increased (<em>P</em>&lt;0.01) by the high dose of GOS treatment only. Low GOS dose increased (<em>P</em>&lt;0.01) blood plasma Na+ concentration in the recovery period only. Results revealed that total essential amino acids (EAA), and EAA/non-EAA ratio were not affected in a dose-dependent manner during the treatment phase expect for plasma proline, which was increased along with non-EAA (<em>P</em>&lt;0.01) by high GOS dose. Additionally, GOS administration did not affect total unsaturated fatty acids (USFA), total saturated fatty acids (SFA) and SFA/USFA ratio in a dose-dependent manner. In conclusion, Gossypol treatment affected rabbit haematological parameters and biochemical properties of blood plasma in a dose-dependent manner.

Long-term effects of gossypol and vitamin E in the diets of dairy bulls

Long-term effects of the inclusion of cottonseed meal in the diet on hematological and tissue parameters of Holstein bulls were investigated. Twenty-four Holstein bulls that were approximately 6 mo of age received the following treatments for 10 mo: 1) soybean meal plus 30 IU of vitamin E/kg, 2) cottonseed meal plus 30 IU of vitamin E/kg, and 3) cottonseed meal plus 4000 IU of vitamin E/d per bull. Treatments 2 and 3 were formulated to supply 14 mg of free gossypol/kg of body weight per d. Average daily gain, total gain, and final body weights were not affected by treatment. The osmotic fragility of erythrocytes was greater during all collection periods for bulls on treatments 2 and 3 than for bulls on treatment 1. The inclusion of 4000 IU of vitamin E/d per bull did not reduce the increase in the osmotic fragility of erythrocytes that was caused by gossypol. Bulls on treatment 3 had higher plasma alpha-tocopherol concentrations than did bulls on treatments 1 and 2. Vitamin E supplementation did not affect gossypol concentrations in plasma or tissue. The highest gossypol concentrations were found in the liver followed by the heart and testis. In vitro lipid peroxidation of tissue indicated that gossypol acts as an antioxidant in lipid peroxidation systems, and its role as an antioxidant may be dependent on dose or tissue. Cottonseed meal in the diets of bulls did not affect growth or vitamin E status.

Effect of gossypol on cultured TM3 Leydig and TM4 Sertoli cells: 31P and 23Na NMR study

The effects of gossypol on glucose metabolism, ATP levels and intracellular sodium levels in murine TM3 Leydig and TM4 Sertoli cell lines were investigated, and their response compared. Relative ATP levels and sodium ion levels in the two cell lines were determined by 31P and 23Na NMR spectroscopy. Short-term effect of gossypol on phosphate metabolism in immobilized and perfused cells was apparent in 31P NMR spectra only with relatively high concentrations of gossypol, corresponding to about 40 times IC50. However, incubation with low gossypol concentrations markedly affected the energetic status of the cells, especially of the TM3 cells. Although inhibition of proliferation by gossypol was stronger with the TM4 cells, the decrease of intracellular ATP level and increase of sodium ion concentration were more pronounced in the TM3 cells. The growth-inhibitory effect of (-)-gossypol was stronger than that of (+)-gossypol, with the eudesmic ratio of 2-2.5. The enantioselectivity of the effect of gossypol on the energy metabolism of TM3 and TM4 cells was low, in contrast to the in vivo antispermatogenic effect, which was reported to be solely associated with (-)-gossypol. Inhibition of energy production in somatic testicular tissue is thus unlikely to be major cause of the antispermatogenic effect of gossypol.

Genetic toxicity studies of gossypol

Gossypol, a polyphenolic compound extracted from cotton plants, shows promise for use as a male contraceptive, as well as a treatment for gynecological disorders, cancer, and certain microbial diseases. Before gossypol can be considered safe for widespread human use, particularly by healthy people of childbearing age, its effect on normal genetic processes should be understood. Characterization of gossypol's genotoxic potential has not been approached systematically, although numerous clinical and laboratory studies have addressed issues relating to genetic effects of gossypol. This review summarizes results of relevant studies and offers recommendations for the emphasis of future efforts to understand gossypol's genotoxicity potential. Evidence suggesting that gossypol has any genotoxic effects in mammals under normal physiologic conditions so far is weak, at best. However, several unresolved issues that are important for establishing long-term genetic safety of gossypol were uncovered by this analysis. These include the need for a better understanding of the significance of weak increases in SCE frequency seen in a number of laboratory exposure studies, and more definitive, comprehensive animal tumor bioassay data.