Accumulation of gossypol enantiomers in ovine tissues

Effect of increasing dietary fat by feeding 15% whole cottonseed on milk production, total-tract digestibility, and methane emission in dairy cows

Whole cottonseed (WCS) is fed as a source of fat, protein, and fiber. Cottonseed is high in unsaturated fatty acids (FA) but is considered lower risk for biohydrogenation-induced milk fat depression because it is slowly released in the rumen. Unsaturated FA have been reported to decrease methane emissions in some experiments, but the effect of FA source is unclear. The objective of the current experiment was to investigate the effect of FA from WCS on milk and methane production and total-tract nutrient digestibility. Sixteen multiparous cows were arranged in a crossover design with 21-d periods. Treatments were 15% WCS substituted for a mixture of cottonseed hulls and soybean meal. Cottonseed had no effect on DMI and milk yield (MY) but increased milk fat concentration (0.2 percentage units) and yield (110 g/d). Cottonseed also decreased the concentration of FA <16 C and 16 C in milk fat and increased FA >16 C and trans-10 18:1 and trans-11 18:1. Increasing dietary fat had no effect on the efficiency of transfer of 18 C FA to milk. There was no effect on milk protein concentration and yield. Whole cottonseed decreased apparent total-tract digestibility of OM and DM due to a decline in NDF digestibility, but less than 3% of seeds consumed were recovered intact in the feces. Whole cottonseed increased digestibility of 16 C FA, but the digestibility of total and 18 C FA were not changed. The production (g/d), yield (g/kg of DMI), and intensity (g/kg of MY or ECM) of H2, CH4, and CO2 were not changed with WCS. Plasma total gossypol and the positive and negative isomers increased with WCS but were below toxic levels. In conclusion, increasing dietary UFA by feeding 15% WCS increased milk fat yield through an increased supply of preformed FA and did not affect methane production under these dietary conditions.

Evaluation of ozone technology as an alternative for degradation of free gossypol in cottonseed meal: a prospective study

Free gossypol is a toxic compound which naturally occurs in cottonseed and its derivates, affecting animal and possibly human health. Consequently, alternatives for gossypol destruction must be evaluated. This work evaluated the emerging technology of ozone processing for free gossypol destruction in cottonseed meal. Ozonation was carried out in the actual cottonseed meal and also a model system, designed to describe the involved mode of action. The model system consisted of glass pearls beads covered with free gossypol. Ozonation was performed in two ways: as a static process, i.e., without homogenising the sample after placing them in the reactor, and also homogenising it. Ozone degraded free gossypol in all the systems, but reaching different levels. Free gossypol reduction was higher in the model system than the cottonseed meal, and higher in the homogenised processing than the static one: cottonseed meal in homogenised (56%) and static (25%); model system homogenised (98%) and static (80%). The obtained differences suggest a problem of gas penetration in the solid particles, the effect of unexposed surfaces due to contact areas, and the reaction with other organic molecules further than the target. Ozonation is a promising technique for gossypol degradation in cottonseed meal, but additional strategies are needed to optimise the ozonation process and evaluate toxicological aspects.

Gossypol Induces Disruption of Spermatogenesis and Steroidogenesis in Male Mice

Gossypol, commonly found in cotton seeds, is hazardous to male reproductive physiology. Although several studies have indicated the toxicity of gossypol in human and animal reproduction, the mechanism of gossypol action in testes has not yet been elucidated. In the present study, we investigated the effects of gossypol in normal mouse testis cells, TM3 and TM4 cells, and in gossypol-treated C57BL/6 mice. We confirmed the antiproliferative effects of gossypol using cell viability assays, with PCNA as a proliferation marker, and cell cycle analysis. We also verified mitochondrial dysfunction and Ca²⁺ dysregulation in the cytosol of TM3 and TM4 cells, using JC-1 and Fluo-4 dyes. To confirm the cellular signaling mechanisms in testis cell lines, we performed Western blot analysis to assess the changes in MAPK and PI3K/Akt signal transduction, using their pharmacological inhibitors. Moreover, we screened the mRNA expression of genes involved in spermatogenesis and steroidogenesis in TM3 and TM4 cells. We also confirmed the mRNA expression and localization of genes regulating testis function in gossypol-treated and untreated mice testes. Collectively, we suggest that gossypol induces negative effects on testis function by reducing cell viability, mitochondrial membrane potential, and testis development-related genes in vitro and in vivo as well as by modulating the MAPK and PI3K signaling pathways.

Physicochemical, technological and sensory properties of hamburger made with meat from lambs fed on whole cottonseed

The physicochemical composition and the technological and sensory properties of hamburgers made with meat from Ile de France lambs fed on different levels (0, 10, 20, 30 and 40%) of whole cottonseed were studied. The addition of whole cottonseed to the lambs' diets decreased the thiobarbituric acid reactive substances in the lamb meat and altered the physicochemical characteristics of the hamburgers, which were characterised by low lipid ( y^=4.27 ), cholesterol ( y^=75.15 ) and caloric content ( y^=122.04 ). The results regarding cooking characteristics were directly related to the microscopic observations regarding the hamburgers; the more cohesive structures exhibited better performance after cooking, with increased cooking yield and moisture retention, and decreased cooking loss. The levels of whole cottonseed did not influence the texture profile, but they negatively affected the acceptability of the hamburgers, since as the levels of cotton seedlings increased, the scores for the sensorial attributes decreased. Thus, a maximum inclusion of 16.7% of whole cottonseed in the dry matter of the diet of lambs is recommended.

Dietary gossypol suppressed postprandial TOR signaling and elevated ER stress pathways in turbot (Scophthalmus maximus L.)

Gossypol is known to be a polyphenolic compound toxic to animals. However, its molecular targets are far from fully characterized. To evaluate the physiological and molecular effects of gossypol, we chose turbot (Scophthalmus maximus L.), a carnivorous fish, as our model species. Juvenile turbots (7.83 ± 0.02 g) were fed diets containing gradient levels of gossypol at 0 (G0), 600 (G1), and 1,200 (G2) mg/kg diets for 11 wk. After the feeding trial, fish growth, body protein, and fat contents were significantly reduced in the G2 group compared with those of the G0 group (P < 0.05). Gossypol had little impact on digestive enzyme activities and intestine morphology. However, gossypol caused liver fibrosis and stimulated chemokine and proinflammatory cytokine secretions. More importantly, gossypol suppressed target of rapamycin (TOR) signaling and induced endoplasmic reticulum (ER) stress pathway in both the feeding experiment and cell cultures. Our results demonstrated that gossypol inhibited TOR signaling and elevated ER stress pathways both in vivo and in vitro, thus providing new mechanism of action of gossypol in nutritional physiology.

Gossypol toxicity from cottonseed products

Gossypol is a phenolic compound produced by pigment glands in cotton stems, leaves, seeds, and flower buds (Gossypium spp.). Cottonseed meal is a by-product of cotton that is used for animal feeding because it is rich in oil and proteins. However, gossypol toxicity limits cottonseed use in animal feed. High concentrations of free gossypol may be responsible for acute clinical signs of gossypol poisoning which include respiratory distress, impaired body weight gain, anorexia, weakness, apathy, and death after several days. However, the most common toxic effects is the impairment of male and female reproduction. Another important toxic effect of gossypol is its interference with immune function, reducing an animal's resistance to infections and impairing the efficiency of vaccines. Preventive procedures to limit gossypol toxicity involve treatment of the cottonseed product to reduce the concentration of free gossypol with the most common treatment being exposure to heat. However, free gossypol can be released from the bound form during digestion. Agronomic selection has produced cotton varieties devoid of glands producing gossypol, but these varieties are not normally grown because they are less productive and are more vulnerable to attacks by insects.

Stereoselective coupling of hemigossypol to form (+)-gossypol in moco cotton is mediated by a dirigent protein

The terpenoid gossypol, a secondary metabolite found in the cotton plant, is synthesized by a free radical dimerization of hemigossypol. Gossypol exists as an atropisomeric mixture because of restricted rotation around the central binaphthyl bond. The dimerization of hemigossypol is regiospecific in cotton. In the case of some moco cotton, the dimerization also exhibits a high level of stereoselectivity. The mechanism that controls this stereoselective dimerization is poorly understood. In this paper, we demonstrate that a dirigent protein controls this stereoselective dimerization process. A partially purified protein preparation from cotton flower petals, which by itself is unable to convert hemigossypol to gossypol, converts hemigossypol with a 30% atropisomeric excess into (+)-gossypol when combined with an exogenous laccase, which by itself produces racemic gossypol.

Determining Larval Host Plant Use by a Polyphagous Lepidopteran Through Analysis of Adult Moths for Plant Secondary Metabolites

Many polyphagous insect species are important economic pests on one or more of their crop hosts. For most important insect pests, the common crop hosts are well-known, but knowledge of weedy and unmanaged hosts is limited. Furthermore, the relative contribution of different hosts to local and regional populations has rarely been ascertained because this requires having some way to determine which plant hosts are the source of the adult moths observed ovipositing in a crop field at a given place and time. One way of determining the larval host of polyphagous pest species is to analyze for several plant-derived chemicals that are each specific to a different small set of related plant species and are preserved in detectable amounts in adult moths. In this paper, we describe novel methods for analyzing adults of the polyphagous lepidopteran, the tobacco budworm (TBW) Heliothis virescens (F.), for plant secondary metabolites, specifically cotinine and gossypol, which are diagnostic for larval feeding on tobacco and cotton, respectively. Cotinine was extracted from individual TBW moths with acetic acid and methanol, then concentrated and analyzed directly by gas chromatography/mass spectrometry (GC/MS). The same moths then were analyzed for bound gossypol by creating a Schiff's base that used aniline, and the resulting dianilino-gossypol complex was quantified using high pressure chromatography coupled with a triple quadrupole mass spectrometer (MS) as the detector. Based on analysis of standards, the detection limit for the cotinine was less than 1.5 ppb by dry weight. Comparable standards were not available for the gossypol derivative so a quantitative limit of detection could not be calculated. When TBW moths reared on known hosts were analyzed for gossypol and/or cotinine, all of the moths reared on tobacco or cotton were correctly identified, although some false positives were recorded with the gossypol method. Analysis of TBW moths of various ages and at various lengths of time after death determined that a significant gossypol signal was detectable in all moths reared on cotton. TBW moths collected from the vicinity of cotton fields in July and August in North Carolina also were analyzed. A much larger portion of the moths were derived from tobacco (6.7-46.4%) than from cotton (0-3.6%) in both months. Thus, these methods can be reliably used to estimate the proportion of TBW derived from noncotton host plants in populations trapped around Bt cotton fields, thereby providing insight into the risk of TBW evolving resistance to Bt cotton.

Gossypol inhibits calcineurin phosphatase activity at multiple sites

Calcineurin, the Ca2+/calmodulin-dependant serine/threonine phosphatase is the target for the immunosuppressant drugs FK506 and cyclosporine-A. These established calcineurin inhibitors each require an immunophilin protein cofactor. Gossypol, a polyphenol produced by the cotton plant, inhibits calcineurin (IC50=15 microM), in a noncompetitive, reversible manner, and is independent of any cofactor. We found that gossypol acts by at least two mechanisms to inhibit calcineurin phosphatase activity. A calmodulin-independent form of calcineurin was less sensitive to inhibition by gossypol than native calcineurin (IC50=41 and 18 microM, respectively) indicating that gossypol may interfere with calmodulin binding. A fluorescence polarization based assay demonstrated that 100 microM gossypol reduced the affinity of calmodulin for calcineurin (from K(d)=2.4 to 250 nM). Inhibition of calcineurin phosphatase activity by gossypol could not be overcome by adding excess calmodulin or by testing the inhibition toward a calmodulin-independent calcineurin indicating that gossypol acts at a site different from the calmodulin-binding site. Gossypol decreased the affinity of calcineurin for immunosuppressant/immunophilin complexes only in the presence of calmodulin, indicating that gossypol blocks the effects of calmodulin binding to calcineurin. In addition, gossypol had a stimulatory effect on native calcineurin in the absence of calmodulin, possibly indicating a calmodulin mimetic effect. Gossypol exists in two enantiomeric forms which are reported to have different potency for cell toxicity. (+) and (-) gossypol had equivalent potency for inhibition of native and calmodulin-independent calcineurin phosphatase activity, and for inhibition of calmodulin binding. The inhibition of calcineurin by gossypol via multiple binding sites without stereo-specificity indicates that gossypol is not a specific calcineurin inhibitor.

Relative toxicity of gossypol enantiomers in broilers

Use of cottonseed meal in poultry diets has been avoided in large part because of fear of gossypol toxicity. Gossypol exists naturally as a mixture of 2 enantiomers that exhibit different biological activities. Two experiments were conducted to determine the relative toxicity of gossypol enantiomers on broilers. In the first experiment, 3-d-old broilers were fed a standard diet containing 0, 100, 200, 300, or 400 mg of gossypol from gossypol acetic acid per kilogram of diet from 3 to 42 d of age. This form of gossypol contains both enantiomers in an equimolar ratio. Each dietary treatment consisted of 6 replicate pens of 4 birds. In the second experiment, 3-d-old broilers were divided into 15 pens of 4 birds each and fed a standard diet supplemented with either no gossypol or one of the gossypol enantiomers at 200 or 400 mg/kg of diet from 3 to 21 d of age. In both experiments, feed intake and BW gain were measured. In addition, several organ and tissue samples were collected at 21 d (experiments 1 and 2) and 42 d (experiment 1) of age and analyzed for gossypol. In experiment 1, feed consumption and BW gain were reduced (P < 0.05) at 21 and 42 d for the birds fed the highest level of gossypol. The concentration of gossypol in the heart, kidney, and plasma were equivalent at 21 and 42 d of age. In experiment 2, total feed consumption was reduced only in birds consuming (-)-gossypol, but BW gains were lower for birds fed either enantiomer. However, (-)-gossypol was more detrimental to growth than (+)-gossypol. The liver had the highest tissue concentration of both enantiomers, and accumulation of (+)-gossypol was higher than (-)-gossypol in all tissues examined. No racemization of the enantiomers was apparent in the tissues analyzed. Our results indicated that both gossypol enantiomers were toxic to broilers but that (-)-gossypol was more harmful to efficient broiler production than (+)-gossypol.

Preparation of enantiomeric gossypol by crystallization

Large enantiomorphic crystals of gossypol-acetone (1:3) were grown from acetone solutions of rac-gossypol-acetic acid (1:1) at 4 degrees C. By controlling the initial gossypol concentration, crystallization time, and solution volume, single crystals were grown that weighed >50 mg, equivalent to >37 mg of enantiomeric gossypol. Even larger crystals were possible, but it was difficult to produce these reliably without contamination of the antipode. Essentially all of the acetone within the crystal form was removed by storing the crystals under vacuum for 3-4 days. By employing these techniques, gram quantities of enantiomeric gossypol were prepared in high chemical and optical purity. Based on measured and reported optical rotations, the optical purity of samples prepared by crystallization was greater than the optical purity of samples prepared by chromatographic separation of gossypol-amine diastereomers. The principal limitation of crystallization as a preparative method is the need to determine the chirality and purity of each product crystal. Nevertheless, the method competes favorably with preparative-scale chromatographic procedures.

High-performance liquid chromatographic determination of gossypol and gossypolone enantiomers in fish tissues using simultaneous electrochemical and ultraviolet detectors

There is a need to measure dietary transfer of gossypol and its metabolite, gossypolone in aquatic animals because of common use of cottonseed meal as a feed ingredient and fertilizer. The analytical method for gossypol and gossypolone enantiomers, therefore, becomes important. HPLC techniques have been developed by using mainly UV detection. We simultaneously used both UV and electrochemical (EC) detectors, and found that each individual detector has its own advantage which can increase accuracy and ease of identification. EC detection (2.5 and 50 ng/ml) exhibited a significantly lower detection level for both gossypol and gossypolone enantiomers than the UV detection (40 and 300 ng/ml) in the rainbow trout tissues, while UV detectors showed more stable detection than EC. We were able to detect a very low concentration of each gossypol enantiomer by EC but not UV detection especially in seminal plasma. For the first time gossypolone enantiomers were quantified in fish tissues by HPLC and its method was described. The technique, simultaneous adoption of both UV and EC detectors, could be helpful for a very low concentration of gossypol and/or gossypolone enantiomers in tissues of other animals and humans.

A mixture of cottonseed meal, soybean meal and animal byproduct mixture as a fish meal substitute: growth and tissue gossypol enantiomer in juvenile rainbow trout (Oncorhynchus mykiss)

Diets incorporating three different sources of extracted cottonseed meal (CM), soybean meal and an animal protein mixture were evaluated for juvenile rainbow trout. Fish averaging 0.96 g were divided into groups of 30; 3 groups per treatment, and each group was fed one of four diets for a 16-week period. Fish meal (FM) was replaced on a 25% protein basis by each of three different sources of CM from California (CA), Tennessee (TN), and Arkansas (AR), U.S.A. In the three CM-containing diets another 25% soybean meal protein and 50% animal protein mixture were also incorporated to completely replace FM protein. The results of growth rate and feed utilization showed that FM could be entirely replaced by a mixture of plant proteins (CM and soybean meal) and animal by-product proteins. Hematocrit levels were significantly lower in the group fed CM-containing diets than in the control. The findings suggest that CM can be used as a good protein source by the incorporation of at least 15% in diets (25% of fish meal protein replacement), and that the nutritive values of CM in juvenile trout can be different due to their different origin. Significantly higher concentrations of total gossypol were found in faeces of CM-TN (5.8 +/- 0.4 micromol/g) and CM-AR (5.6 +/- 0.6) groups than in that of CM-CA (3.7 +/- 0.4) group. It was documented that gossypol enantiomers, present in an equal proportion in diets, selectively accumulated in liver and bile, whereas equal proportions of (+)- and (-)-enantiomers were found in whole-body and faeces. Depending on CM source, fish can absorb approximately 35-50% of dietary gossypol, and the majority of the absorbed gossypol seemed to be excreted.

Tissue distribution of gossypol enantiomers in broilers fed various cottonseed meals

Plasma and tissue concentrations of total, (+)- and (-)-gossypol were determined in broilers fed cottonseed meals (CSM) from eight oil mills (five expander solvent, two expeller, and one direct solvent). Free gossypol in the meals ranged from 0.033 to 0.180%, and total gossypol ranged from 0.974 to 1.459%. The (+)-enantiomer of gossypol varied from 53.8 to 61.3% of total gossypol. Eight CSM diets containing 28% CSM and a soybean meal control diet were fed to 162 1-d-old male broiler chicks during a 3-wk starter period. Concentrations of free gossypol in the CSM diets ranged from 92 to 504 microg/g, and total gossypol ranged from 2,626 to 4,085 microg/g. All diets were formulated with the same concentrations of digestible lysine and methionine and were fed ad libitum. At 21 d of age, there were no significant differences in body weights, feed conversions, or mortality of birds fed the CSM diets when compared to birds fed the soybean meal diet. Concentrations of (+)- and (-)-gossypol in plasma, liver, kidney, and muscle increased linearly as the level of free gossypol increased in the diets. Liver had the highest concentration of total gossypol (71.4 to 313.6 microg/g DM) followed by kidney (9.2 to 36.3 microg/g DM), plasma (3.0 to 14.6 microg/mL), and muscle (2.1 to 9.8 microg/g DM). The proportion of (-)-gossypol was higher in plasma (26.7%) and kidney (25.6%) than in muscle (19.1%) and liver (16.0%). Performance data from this study indicate CSM can be used successfully in chick starter diets at levels up to 28% when diets are formulated on a digestible amino acid basis.

Long-term effects of feeding gossypol and vitamin E to dairy calves

Male Holstein calves were used to test the effect of feeding 400 mg of free gossypol/kg of diet and to determine whether vitamin E could counteract gossypol toxicity. Fifty-two calves were allotted to treatments as follows: 1) soybean meal-based starter; 2) cottonseed meal-based starter; 3) cottonseed meal-based starter + 2000 IU of vitamin E/d per calf, and 4) cottonseed meal-based starter + 4000 IU of vitamin E/d per calf. Vitamin E supplementation (treatments 3 and 4) improved weight gain and feed intake over calves on treatment 1. Gossypol concentrations in plasma were higher in calves on treatments 2, 3, and 4 than in calves on treatment 1; however, no differences were observed among animals receiving the three cottonseed meal diets. Hemoglobin and hematocrit were decreased in calves receiving treatment 2, and vitamin E supplementation counteracted this effect (treatments 3 and 4). Plasma alpha-tocopherol concentrations were not affected by gossypol intake and followed the vitamin E supplementation pattern During the experimental period, 10 calves died, six from treatment 2 and two each from treatments 3 and 4. Necropsy findings from 4 of 10 calves were suggestive of gossypol toxicity. Histopathological examination revealed centrilobular necrosis in the liver and atrophy and vacuolation of cardiocytes. Feeding cottonseed meal caused death of some calves with gossypol related toxicity signs, but did not decrease plasma alpha-tocopherol; however, vitamin E supplementation increased performance and may have conferred some protection against gossypol toxicity.

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.

Gossypol: reasons for its failure to be accepted as a safe, reversible male antifertility drug

Following clinical trials conducted in China in the 1970s, gossypol was proposed as a drug for male contraceptive use. This review summarizes the extensive investigations on formal animal toxicology and on the recovery of fertility in men after stopping gossypol treatment which led to the decision by the Special Programme of Research, Development and Research Training in Human Reproduction (HRP) at the World Health Organization (WHO), that gossypol would not be acceptable as an antifertility drug. It is concluded that the assessment of gossypol reinforces the mandatory requirement that future contraceptive drugs must be developed by the established routes of appropriate animal toxicology and phased clinical studies.