EFFECT OF Garcinia kola EXTRACTS ON MONOSODIUM GLUTAMATE-INDUCED ORGAN TOXICITY IN RATS

Abstract

Monosodium glutamate (MSG) is a major flavour enhancer extensively used as a food additive. Despite its taste stimulation and appetite enhancement, many studies have linked MSG to several pathological and biochemical alterations in human and animal tissues. Recent studies have focused on the use of natural products including plant materials to counter food and drug toxicity. Hence, the effect of Garcinia kola extracts (crude methanol extract, alkaloid extract and kolaviron) on MSG-induced organ toxicity in rats was evaluated in this study. One hundred male Wistar rats (200 ± 20 g) were divided into ten groups with ten animals per group. Group I served as control and received distilled water only; Group II was administered MSG only (2 g/kg); Group III and IV received MSG + 100 and 200 mg/kg kolaviron respectively; Group V and VI received MSG + 10 and 20 mg/kg alkaloid extract respectively; Group VII and VIII received MSG + 100 and 200 mg/kg Garcinia kola respectively; Group IX received MSG + quercetin 10 mg/kg; Group X was administered MSG + 100 mg/kg nicotinic acid. All animals were orally administered extracts for a period of twenty-one days. Twenty four hours after the last administration, animals were sacrificed, blood was collected for assays of lipid profile {cholesterol (CHOL), low density lipoproteins (LDL), high density lipoproteins (HDL), and triglycerides (TRG)}, enzyme activity {aspartate amino transferase (AST), alanine amino transferase (ALT), gamma-glutamyl transferase (GGT)), (creatine kinase (CKMB) and alkaline phosphatase (ALP)}, creatinine (CREA)), glucose (GLU) and electrolytes (K+, Ca2+, Na+) concentrations. Brains were excised and separated into striatum, hippocampus, and cortex for estimation of dopamine level as well as acetylcholinesterase (AChE) and lactate dehydrogenase (LDH) activities. LDH activity was also estimated in the heart homogenate. Markers of oxidative stress (maloldialdehyde, reduced glutathione, ferric reducing antioxidant power, protein carbonyl compounds, superoxide dismutase activity) as well as total protein concentration were estimated in the heart, liver, kidney, striatum, hippocampus, and cortex homogenates. Histopathological evaluations were carried out on the organs of study. Results reveal that the three extracts from Garcinia kola significantly reversed the deleterious effects of MSG administrations on plasma lipid profile and activities/levels of biomarkers of tissue injury. The extracts positively modulated level of electrolytes and metabolites linked to the health of organs under study. Markers of neurochemical dysfunction and oxidative stress were also modulated by the extracts with kolaviron showing better efficacy. In general, the relative performance of Garcinia kola and fractions (kolaviron and alkaloid fraction) showed that Garcinia kola is the most effective in ameliorating neurochemical disturbances, cardiac and hepato toxicities probably due to the synergistic mechanism of all the phytoconstituents, followed by alkaloid and kolaviron. This was also revealed by the findings from histopathological studies of the organs selected.