Identification and Evaluation of Immuno-modulatory Properties of Prebiotics Extracted from Vernonia amygdalin

ABSTRACT

Vernonia amygdalina leaves, commonly called bitter leaf is widely consumed in Africa especially in Nigeria. The leaf extract has been reported to have prebiotic potentials but limited information is available on the immune-modulatory effects. This study evaluated the immuno-modulatory properties of the leaf extract and identified the prebiotic components. The aqueous extract was separated into fractions by Liquid-liquid fractionation and the prebiotic compounds were identified through Thin Layer Chromatography (TLC).The evaluation was conducted by monitoring the effects of oral administration of the aqueous extract on the immunological, haematological and lipid profiles of Rattus norvegicus. The animals were distributed into six groups with six animals in each group. One group was designated control while the other five groups were administered different concentrations of aqueous extracts. The control group was administered distilled water and the other groups 50, 100, 200, 400 and 800 mg/kg of aqueous extract respectively, twice daily for three weeks. Blood was collected through the orbital-plexus of the rats to evaluate  the effect of the extract on CD4+ cells,  packed cell volume (PCV), white blood cell count (WBC), haemoglobin (Hb) levels and lipid profile. Five fractions designated E1 to E5, were obtained from the extract. Thin Layer Chromatography analysis of these fractions revealed the presence of fructo-oligosaccharides and galacto-oligosaccharides suggesting that these are the prebiotic compounds of the plant extract. The aqueous extract of the plant showed increased significant (p < 0.05) effects on the CD4+ cells count, WBC including lymphocytes and neutrophils, Total Cholesterol (TC), High Density Lipid-Cholesterol (HDL-C) and significant (p< 0.05) decrease in Low Density Lipid-Cholesterol (LDL-C), with no significant difference (p > 0.05) on haemoglobin (Hb) and packed cell volume (PCV) levels. This study confirms that Vernonia amygdalina leaf extracts contain prebiotic compounds and can play important roles in the modulation of the immune system.