Effective Degradation of Free Gossypol in Defatted Cottonseed Meal by Bacterial Laccases: Performance and Toxicity Analysis

Cottonseed meal (CSM) is the major by-product of the cottonseed oil extraction process with high protein content. However, the presence of free gossypol (FG) in CSM severely restricts its utilization in the food and animal feed industries. The development of a biological strategy for the effective removal of FG in CSM has become an urgent need. In this study, three bacterial laccases including CotA from Bacillus licheniformis, CueO from Escherichia coli, and LcLac from Loigolactobacillus coryniformis were heterologously expressed and investigated for their FG degradation ability. The results showed that CotA laccase displayed the highest FG-degrading capacity among the three laccases, achieving 100% FG degradation at 37 °C and pH 7.0 in 1 h without the addition of a redox mediator. Moreover, in vitro and in vivo studies confirmed that the hepatotoxicity of FG was effectively eliminated after oxidative degradation by CotA laccase. Furthermore, the addition of CotA laccase could achieve 87% to 98% FG degradation in defatted CSM within 2 h. In conclusion, CotA laccase can be developed as an effective biocatalyst for the detoxification of FG in CSM.

Biodegradation of Gossypol by Aspergillus terreus-YJ01

Gossypol, generally found in the roots, stems, leaves, and, especially, the seeds of cotton plants, is highly toxic to animals and humans, which inhibits the use of cotton stalks as a feed resource. Here, a promising fungal strain for biodegrading gossypol was successfully isolated from the soil of cotton stalk piles in Xinjiang Province, China, and identified as Aspergillus terreus-YJ01 with the analysis of ITS. Initial gossypol of 250 mg·L-1 could be removed by 97% within 96 h by YJ01, and initial gossypol of 150 mg·L-1 could also be catalyzed by 98% or 99% within 36 h by the intracellular or extracellular crude enzymes of YJ01. Sucrose and sodium nitrate were found to be the optimal carbon and nitrogen sources for the growth of YJ01, and the optimal initial pH and inoculum size for the growth of YJ01 were 6.0 and 1%, respectively. To further elucidate the mechanisms underlying gossypol biodegradation by YJ01, the draft genome of YJ01 was sequenced using Illumina HiSeq, which is 31,566,870 bp in length with a GC content of 52.27% and a total of 9737 genes. Eight genes and enzymes were predicted to be involved in gossypol biodegradation. Among them, phosphoglycerate kinase, citrate synthase, and other enzymes are related to the energy supply process. With sufficient energy, β-1, 4-endo-xylanase may achieve the purpose of biodegrading gossypol. The findings of this study provide valuable insights into both the basic research and the application of A. terreus-YJ01 in the biodegradation of gossypol in cotton stalks.

Gossypol exposure induces mitochondrial dysfunction and oxidative stress during mouse oocyte in vitro maturation

Gossypol is a yellow natural polyphenolic compound extracted from the seeds, leaves, stems, and flower buds of the cotton plant. Several studies have shown that exposure to gossypol impacts reproductive health in both humans and animals. However, whether gossypol exposure would influence oocyte quality has not yet been determined. Here, we studied the effects of gossypol on the meiotic maturation of mouse oocytes in vitro. The results revealed that gossypol exposure did not affect germinal vesicle breakdown (GVBD) but significantly reduced polar body extrusion (PBE) rates. Moreover, we observed meiotic spindle organization and chromosome alignment were entirely disturbed after gossypol exposure. Further, gossypol exposure also caused mitochondrial dysfunction and abruptly decreased the levels of cellular ATP, and diminished the mitochondrial membrane potential (MMP). Accordingly, gossypol-induced oxidative stress was confirmed through an increased level of reactive oxygen species (ROS). Early apoptosis incidence also increased as identified by positive Annexin-V signaling. Collectively, the above findings provide evidence that gossypol exposure impaired oocyte meiotic maturation, disturbed spindle structure and chromosome dynamics, disrupted mitochondrial function, induced oxidative stress, and triggered early apoptosis. These findings emphasize gossypol's adverse effects on oocyte maturation and thus on female fertility.

Cottonseed (gossypol) intake during gestation and lactation does affect the ovarian population in ewes and lambs?

The aim of this study was to evaluate if the cottonseed intake during gestation and lactation affects the ovarian population in ewes and lambs. Therefore, 39 ewes were evaluated during 10 months under two treatments: Cottonseed and soybeans. The quantification of ovarian follicular dynamics was analyzed by ultrasound and the determination of progesterone and estradiol levels was interpreted by radioimmunoassay. After weaning, ovaries of lambs (n = 10) were collected by ovariectomy and fixed for the assessment of follicular parameters as normality, classification, diameter, ultrastructure, stereology, and as well as immunoexpression of the α-estradiol receptor α (ER-α). The results showed that the cottonseed consumption altered neither the ovarian nor the hormonal follicular dynamics of Santa Inês ewes after calving and did not affect the normality, classification, diameter, stereology and follicular ultrastructure of offspring. Nevertheless, the offspring of ewes fed with cottonseed showed high ER-α immunoexpression in the ovarian structures. It is concluded that cottonseed did not affect the maternal-descendant follicular dynamics. However, lambs' ovaries had highest α-ER immunoexpression in oocytes, granulosa and theca cells and corpus luteum. This fact warns of a possible change in the future steroidogenic response of these lambs that had progenitors consuming cottonseed in their reproductive period.

Free gossypol supplementation frequency and reproductive toxicity in young bulls

The aim of the present study was to analyze seminal quality of young bulls subjected to different frequencies of gossypol supplementation. Forty-eight Nellore bulls, with 19 months of age and weighing 357.8 ± 7.2 kg, were used in this study. Animals were fed with 10.5 kg of standard supplement containing free-gossypol from whole cottonseed (WCS) at the following frequency: 3x/week (G3x), 5x/week (G5x) or 7x/week (G7x - Control). Additionally, a negative control was provided, and the treated animals received only mineral supplement (MM) ad libtum. The experiment lasted for 84 days and semen was collected at the beginning and at the end for analysis and cryopreservation. Fresh semen was used for initial analysis and plasma membrane integrity and sperm morphology were also determined. General motility using computer assisted sperm analysis (CASA), plasma and acrosomal membranes integrity, mitochondrial activity, and induced oxidative stress were assessed in post-thawed semen. The study design was completely randomized. Parametric data were analyzed by ANOVA and non-parametric data by the Wilcoxon test, using the statistical program SAS. Level of significance was set at 5%. Supplementation with WCS, regardless the frequency, increased total (P = .009) and head (P = .005) defects in comparison to animals receiving only forage and mineral supplement. Infrequent supplementation, particularly 5 times in the week (G5X), increased head (P = .026) and midpiece (P = .014) abnormalities. Sperm motility in fresh semen was lower in animals that received daily supplementation than those supplemented on alternate days (P = .021). Additionally, animals supplemented daily showed lower percentage of spermatozoa with intact acrosome compared to those supplemented on alternate days (P = .005). Thus, regardless the frequency of supplementation, free-gossypol supplementation affects sperm quality. Although the amount of free gossypol supplied weekly was the same among treatments, daily supplementation compromised sperm kinetics, differently from infrequent supplementation that led to sperm defects developed during spermatogenesis.

Metabolic Characterization of Dairy Cows Treated with Gossypol by Blood Biochemistry and Body Fluid Untargeted Metabolome Analyses

To characterize the metabolic disorders of dairy cows treated with gossypol, 12 dairy cows were assigned to either a control group or a treatment group that was fed 1000 mg of gossypol per kilogram of dry matter feed for 28 days. Milk quality was adversely affected, as both milk protein and lactose levels were significantly decreased in the gossypol-treated group (3.40% vs 3.16%, P = 0.044; 5.15% vs 4.91%, P = 0.027; respectively). Plasma samples revealed increases in alanine aminotransferase (P = 0.092), choline esterase (P = 0.02), and glutathione transferase (P = 0.0005) and decreases in glucose (P = 0.076) in the gossypol-treated group. Mass spectrometry based comparative metabolomic analyses showed reduced concentrations of the gluconeogenesis precursor l-glutamine (P = 0.047), with significant decreases (P < 0.05) in plasma l-lysine, l-threonine, and homoserine levels after gossypol treatment. HDL-C and LDL-C levels in the gossypol-treated group were increased (P = 0.044) and decreased (P = 0.023), respectively. These results demonstrate that gossypol induced oxidative stress and hepatotoxicity; reduced peripheral lipid metabolism, and enhanced hepatic lipid accumulation; decreased amino acid bioavailability and milk protein synthesis; and decreased gluconeogenesis and milk lactose in dairy cows.

Presence of free gossypol in whole cottonseed

The European Commission asked EFSA to assess information provided by the Spanish Ministry of Agriculture, Food and Environment, on the toxicity of free gossypol in relation to the use of whole cotton seed in feed for ruminants, in particular dairy cows, and, if necessary, to update the previous opinion of the EFSA Panel on Contaminants in the Food Chain (CONTAM) on gossypol as an undesirable substance in animal feed. Gossypol is a polyphenolic compound that exists in a racemic mixture of (+)‐gossypol and (‐)‐gossypol isomers. It occurs in free or (protein‐) bound forms in cottonseeds. The most commonly used cottonseeds in feed are from Upland and Pima varieties. The Pima variety is considered more toxic due to a higher content of the (‐)‐gossypol isomer. Upland whole cottonseeds (WCS) are fed with no further processing (after delinting); Pima varieties normally undergo further processing (grinding or cracking). It is claimed that WCS have a greater retention time in the rumen, which results in an increased detoxifying activity, compared to a shorter ruminal retention time, in the case of cracked cottonseed or cottonseed meal products. Increased erythrocyte fragility has been observed in cows given WCS Upland varieties at similar exposure levels as those resulting from an inclusion rate of 10% of WCS containing gossypol at 7,000 mg/kg in feed – the maximum permitted level of gossypol in WCS suggested by the Spanish Delegation. The information from the Spanish delegation does not differentiate between varieties in their suggestion for an increase in the maximum permitted content of free gossypol for WCS. As both Upland and Pima varieties are grown in the EU and are used for animal feed, both varieties of WCS should be considered. The CONTAM Panel considered it not necessary to update the previous opinion.

Toxicity of Gossypol from Cottonseed Cake to Sheep Ovarian Follicles

Gossypol, a polyphenol compound produced by cotton plant, has proven reproductive toxicity, but the effects of gossypol on sheep ovaries are unknown. This study was aimed to determine the in vitro and in vivo effects of gossypol on the ovarian follicles of sheep. This trial was divided into two experiments. In the first one, we used twelve non-pregnant, nulliparous, Santa Inês crossbred ewes, which were randomly distributed into two equal groups and fed diets with and without cottonseed cake. Feed was offered at 1.5% of the animal’s body weight for 63 days. The concentrations of total and free gossypol in the cottonseed cake were 3.28 mg/g and 0.11 mg/g, respectively. Throughout the trial period, no animal showed clinical signs of toxicity and no effects on body weight were observed. However, there was a significantly lower number of viable ovarian follicles (20.6%) and higher number of atretic follicles (79.4%) in the gossypol-fed sheep compared to the control (85.1 and 34.9%, respectively). These findings were observed at all stages of follicular development. In the second experiment, eight ovaries from slaughterhouse were cultured with different concentrations of gossypol acetic acid (0, 5, 10 and 20 μg/mL) for 24 hours or seven days. The in vitro action of gossypol resulted in a significant decrease in viable ovarian follicles, especially the primary and transition follicles, and a significant increase in the number of atretic follicles after 24 hours of culture. These follicles were greatly affected when cultured with gossypol for seven days. It is concluded that gossypol present in cotton seeds directly acts on ovarian follicles in sheep to increase atresia.

Gossypol Content of Cotton Free Commercial Feed for Dairy Cows

Gossypol is a yellow pigment occurring in all parts of cotton plants, with the highest levels found in seeds, and it exhibits a variety of toxic effects. Few data are available on the content of gossypol in the commercial complementary feed and in feed raw materials. The present study was focused on the investigation of the presence of free gossypol in commercial complementary feed not containing cotton. A total of 50 samples of commercial complementary feed for dairy cows were performed in 29 feed mills both using and not using cotton as feed material. The free gossypol contamination resulted under the detection limit of the technique (4 mg/kg) in 12 out of 50 samples analysed and ranged from 4 to 20 mg/kg in 28 samples. In 10 samples the level of free gossypol ranged from 20 to 29.5 mg/kg. Average contamination of samples was 12.2±9.2 SD mg/kg. No significant difference (P=0.571) was shown in free gossypol concentration between feed produced in cotton free plants and in plants where cotton is used as feed material. Free gossypol content detected in the present study allows considering complementary feed for dairy cows not at risk. On the other hand, the detection of free gossypol in cotton free complementary feed, probably attributable to cross contamination of feed materials upstream of the feed mill, should be further investigated.

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.

Gossypol--a polyphenolic compound from cotton plant

Gossypol (C(30)H(30)O(8)) is a polyphenolic compound derived from the cotton plant (genus Gossypium, family Malvaceae). The presence of six phenolic hydroxyl groups and two aldehydic groups makes gossypol chemically reactive. Gossypol can undergo Schiff base formation, ozonolysis, oxidation, and methylation to form gossypol derivatives. Gossypol and its derivatives have been the target of much research due to their multifaceted biological activities including antifertility, antivirus, anticancer, antioxidant, antitrypanosomal, antimicrobial, and antimalarial activities. Because of restricted rotation of the internaphthyl bond, gossypol is a chiral compound, which has two atropisomers (i.e., (+)- and (-)-gossypol) that exhibit different levels of biological activities. This chapter covers the physiochemical properties, analyses, biological properties, and agricultural and clinical implications of gossypol.