ABSTRACT
Today, traditional medicine is still used by many people all over the world. The medical benefit of medicinal plants is due to a number of chemical components that have been shown to have specific effects on both humans and animals. Aframomum melegueta, a herbaceous plant used as a culinary spice and traditionally to treat common illnesses, is a member of the Zingiberaceae family. The aim of this study was to evaluate the antibacterial and immunomodulatory potentials of A. melegueta in some bacterial isolates and Wistar rats respectively. The antibacterial efficacy of the both ethanolic and aqueous extracts against Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus mutans, and Pseudomonas aeruginosa was evaluated using the agar well diffusion technique. The immunological activity of the plant extract was assessed by analyzing the humoral immune response and delayed type hypersensitivity (Hemagglutinin and DTH assay). Six treatment groups of albino rats were administered different concentrations of the extract and challenged with sheep red blood cells (SRBC). The hematological parameters of the ethanolic extract of A. melegueta were determined using an auto hematological analyzer. The phytochemical properties were evaluated utilizing standard methods. The effects of A. melegueta on the liver, kidney and spleen were also evaluated using histopathological techniques. At concentrations of 20, 40, 60, and 80 mg/ml, the ethanolic and aqueous extract of A. melegueta exhibited antibacterial activity against the test isolates. When compared to the ethanolic extract, it was discovered that the aqueous extract was less efficient. Results of immunomodulatory activity showed that A. melegueta stimulated cellular immune response as measured by the size of footpad oedema at 50 and 100 mg/kg in response to SRBCs. A. melegueta lowered circulating antibodies at 100 and 200 mg/kg compared to the positive control group, and there was a significant decrease of the negative control group, based on the hemagglutinin antibody titre values. The experimental groups demonstrated significant differences in several hematological parameters when compared to the positive control group. These differences showed an increase in platelet count for negative control, increase in hemoglobin at 100 and 200 mg/kg, increase in mean corpuscular hemoglobin at 200mg/kg, granulocytes at 25 mg/kg, and a decrease in packed cell volume of the experimental groups. Both the ethanolic and aqueous extracts of A. melegueta demonstrated the presence of saponins, tannins, phenolics, glycosides, flavonoids, alkaloids, steroids, and terpernoids in xvi their qualitative phytochemical composition. According to the quantitative phytochemical analysis, phenolics and glycosides had the highest concentrations in ethanol and aqueous extract respectively. The results of the histological analysis showed that there was no observable effect on the positive and negative control groups but the experimental groups had observable effects. The results of this study suggest that A. melegueta seed extract stimulated both cellular and humoral immune responses.
