Gossypol effect

Since feeds contain other substances than those required by the animals of interest, studies have also been conducted on antinutritional factors in feedstuffs and on the use of additives. Certain feed ingredients contain chemicals that retard growth or may actually be toxic. Examples are gossypol in cottonseed meal and trypsin inhibitor in soybean meal. Restriction on the amount of the feedstuffs used is one way to avoid problems. In some cases, as is tme of trypsin inhibitor, proper processing can destroy the antinutritional factor. In this case, heating of soybean meal is effective. 

Raw defatted cottonseed flours contain 1.2—2.0% gossypol [303-45-7] (7) (19). When cottonseed is treated with moist heat, the S-amino group of lysine and gossypol forms a derivative that is biologically unavailable thereby inactivating gossypol but further lowering the effective content of lysine. 

Use of some oilseed proteins in foods is limited by flavor, color, and flatus effects. Raw soybeans, for example, taste grassy, beany, and bitter. Even after processing, residues of these flavors may limit the amounts of soybean proteins that can be added to a given food (87). The use of cottonseed and sunflower seed flours is restricted by the color imparted by gossypol and phenoHc acids, respectively. Flatus production by defatted soy flours has been attributed to raffinose and stachyose, which are removed by processing the flours into concentrates and isolates (88). 

T. Deuterium isotope effects on 13 C chemical shifts In the studies of proton transfer equilibrium of Schiff bases, the most informative are deuterium isotope effects measured for carbons bonded with proton donor groups (C-2 or C-7 for gossypol derivatives). For imines in which... 

Hansen et al.52 measured the deuterium isotope effects for the Schiff base being a derivative of racemic gossypol [7]. The high negative value of deuterium isotope effect observed at carbon C-7 linked with proton donor group (—190 — 240 ppb), solvent and temperature independent, clearly indicated the existence of this compound as enamine-enamine tautomer. 

The concept of torsional asymmetry is not jnst an interesting abstract idea. Some years ago, fertility in some Chinese rnral commnnities was found to be below normal levels, and this was traced back to the presence of gossypol in dietary cottonseed oil. Gossypol acts as a male contraceptive, altering sperm matnration, spermatozoid motility, and inactivation of sperm enzymes necessary for fertilization. Extensive trials in China have shown the antifertility effect is reversible after stopping the treatment, and it has potential, therefore, as a contraceptive for men. 

Only a few efforts have been made to evaluate the effects of TA structural variations on toxicity. Methylation decreases toxicity of hemigossypol to Verticillium dahliae (25), of gossypol to rat mast cells (23), and of various TA to HelionTis sod. (22). In contrast, methylaTTon increases the toxicity of various TA"To nematodes (26) and the toxicity of heliocides to rat mast cells ( ). The order of toxicity of different TA to rat mast cells is quinones > heliocides > naphthols > binaphthols (23). Gossypol generally is somewhat more toxic to insects than heliocides, and quinones are least toxic (29,22). 

Alkaloids are active bioagents in animal tissues. There is clear scientific evidence of this. Crawford and Kocan" " have tested the toxicity of steroidal alkaloids from the potato Solanum tuberosum), such as a-chaconine, a-solanine, solanidine and solasodine, and Veratrum alkaloid, jervine on fish. The results of Crawford and Kocan s research proved that rainbow trout exhibited a toxic response to chaconine, solasidine and solanine, while medaka only did so to chaconine and solanine. Embryo mortality was observed as an effect of toxicity in both species. Many other alkaloids are known to disturb or cause disorder in animal reproductive systems. For example, gossypol from cotton-seed oil is known as a clear reducer of spermatogenesis and premature abortion of the embryo. 

The one product obtained from cottonseed oil, Gossypol which is categorized as non-hormonal selective spermatogenesis suppressant, is effective in producing azoospermia or severe oligospermia but it is not widely used as male contraceptive. Mechanism of action is not known. Adverse effects are edema, diarrhoea, hypokalemia, neuritis. 

The effect of gossypol on three consecutive generations of llttoralls has been studied by El-Sebae, et al. (280). 

At a concentration of 0.50% gossypol In the diet, the effect was even more dramatic, with the hatchablllty dropping below 1% In the third generation. 

As opposed to the results indicated above, the effect of gossypol on the boll weevil is quite different. Gossypol is a feeding stimulant to the boll weevil (260). Boll weevils feeding on an artificial diet were healthier and had In jroved egg hatch when the gossypol fraction from cotton seed was used as the principle protein source. 

Plants that produce "specific toxins may be plagued by Insects that develop a tolerance to these toxins in much the same way as Insects develop tolerance to synthetic insecticides. Two examples from this chapter are the tobacco hornworm and the boll weevil which have developed a high tolerance to nicotine and gossypol, respectively. Some occurrence in the distant past may have placed sufficiently high selection pressure on these Insects that they developed tolerance to these compounds. Alternatively, the same effect could have occurred by a low selection pressure applied over a very long period time. Other plants protect themselves by employing general" toxins. 

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