Toxicological investigations of polyphenol-rich Sorghum bicolor supplement in Wistar rats

Abstract

Sorghum bicolor is a rich source of antioxidant-polyphenols, with proven multiple health-promoting benefits in several diseases linked to oxidative stress, inflammation and neurodegeneration. Despite the wide claims of the various health benefits of the polyphenol-rich Sorghum bicolor supplement (SBS) and extensive pharmacological studies, there is paucity of information on its toxicological profiles and tolerability. This study presents detailed toxicological evaluation of the acute and subacute administration of SBS in male and female Wistar rats ( Rattus norvegicus ). The acute toxicity study was carried out using modified OECD 423 guidelines, which involved administration of oral doses of SBS (2000 mg/kg) to three male and three female Wistar rats. Thereafter, the animals were monitored for signs of toxicity and mortality for 14 days. The sub-acute toxicity study was done using OECD 407 guidelines wherein the male or female Wistar rats were randomly distributed into three groups ( n =7 per group). Group 1 received distilled water (10 mL/kg) while groups 2 to 3 had SBS (125 mg/kg and 250 mg/kg), orally for 28 days. The neurobehavioral changes were assessed on days 27–28 using open field, elevated plus maze, Y-maze and forelimb hanging wire tests prior to hematological and biochemical studies. Histomorphological evaluations of the brain, liver and kidney tissues were performed. The SBS (2000 mg/kg) did not cause discernable signs of toxicity or death. Sub-acute exposure to the supplement (125 mg/kg and 250 mg/kg), did not adversely affect the motor performance, muscle strength and anxiety level but impaired memory function in both genders at high dose. The SBS at 125 mg/kg did not cause increases in abnormal lipids distribution, atherogenic index and coronary risk factors. The supplement had variable effects on serum albumin, bilirubin, urea and creatinine levels. The SBS altered the antioxidant profiles and histomorphological features of the brain, liver and kidney tissues of rats at high dose. The results of this study suggest that the exposure of rats to SBS at high dose produced deleterious effects on the liver, kidney and brain tissues. These findings underscore the important of the determination of the appropriate therapeutic doses of Sorghum bicolor supplement for specific disease conditions.