STUDIES ON MYCOFLORA AND MYCOTOXINS IN ACHA, MAIZE AND COTTON SEED

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STUDIES ON MYCOFLORA AND MYCOTOXINS IN ACHA, MAIZE AND COTTON SEED IN PLATEAU STATE, NIGERIA

 

Abstract

 

The extracts of the A. quadrilineatus; the petroleum ether soluble extract (PER) and the petroleum ether defatted crude extract (PEDCR) were tested for acute and chronic toxicity in mice, chicks and cattle. The per os_LD50 of PER was 1148mg/kg and that of PEDCR was 507mg/kg in mice, and 556mg/kg in chicks. The intraperitoneal LD50 of PEDCR in mice was 20.8mg/kg. The toxic signs of PER and PEDCR in mice and chicks included tachypnea, tachycardia, anorexia, somnolence, diarrhoea, coma and death. The main post mortem findings in acute toxicity were congestion of heart, liver, kidney and lungs and sloughing of the wall of stomach and haemorrhagic entiritis. The histopathologic findings in dead animals included oedema and mild degeneration of the myocardium, necrosis of kidney tubular epithelial cells, hepatocytes and bronchioles. The only clinical observation in calf acutely dosed with culture of A. quadrilineatus on maize were transient whole body tremors which occurred one hour after dosing, tachycardia and profuse salivation. No significant histopathologic changes were found in the organs of the sacrificed calf. Rats fed on diets containing different percentages of A. quadrilineatus cultured maize gained less weight as compared with those on normal diets. – xiii – Other clinical signs in rats included soft faeces, lethargy, arched back, rough hair coat and death in the case of rats on 100% substituted diet. No abnormal clinical signs were seen in cattle on substituted diets except that cattle on normal diet had superior weight gain as compared to those on substituted diets. Post mortem findings in rats included hyperaemia of the mucosa of the stomach and intestine, sloughing of the mucosa of the stomach, petechial haemorrhages on the liver and gastro-enteritis. No significant post mortem findings were observed in cattle on substituted diet except that the mucosa of the stomach and duodenum of cattle on 100% substituted diet were sloughed off. Histopathologic findings in rats included liver congestion, hepatocellular degeneration and necrosis, congestion of the venous sinuses of spleen characterised in some cases by mild to moderate lymphocytes depletion of the periarteriolar lymphatic sheath. Varying degrees of interstitial inflamation with peribronchiolitis and atelectasis and severe alveolar oedema were seen in lungs of some rats. – xiv – Submucosal oedema of the stomach and granular degeneration of the tubular epithelial cells of the kidney particularly of the medulla were seen. Severe meningeal congestion, haemorrhage and sub-meningeal degeneration were seen. In cattle the histopathological findings included degeneration and necrosis of the liver. Multifocal areas of haemorrhage in the liver and extensive tubular necrosis and degeneration of glomerular tufts were seen. Chronic feeding of A. quadril ineatus substituted diets to cattle had an increasing effects on PCV, neubrophils, serum cholesterol, triglyceride, SGOT, serum alkaline phosphatase and lactate dehydrogenase, and it had a decreasing effect on lymphocytes, monocytes, Hb, and albumin when compared to control animals values. The mycotoxins produced by A. quadrilineatus were extractable from rice culture by chloroform. Column chromatographic separations in silica gel using different elution solvents and biological tests showed that the mycotoxins came off in the diethylether, chloroform and mostly in ethylacetate fractions. Use of different available mycotoxin standards on silica gel G coated chromatoplates revealed that sterigmatocystin is one of the minor metabolites –

 

 

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