Evaluation of the Antibacterial Activity, Acute Toxicity and Immuno-stimulatory Potential of Adenodolichos paniculatus root Extract

Abstract

Medicinal plants have been used in the treatment of illnesses from time immemorial. In Nigeria today a large population of people still depend on herbal medicines for their health needs. The medicinal plant, Adenodolichos paniculatus has been used traditionally as a remedy for mouth and throat infections in Pushit community of Plateau state, Nigeria. Five solvents (hexane, chloroform, ethyl acetate, methanol and water) were used sequentially for the isolation of bioactive compounds from the root of the plant Adenodolichos paniculatus and concentrated on rotary vacuum evaporator. Concentrated extracts were tested for their antibacterial activities against Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa and E. coli by agar-well diffusion method. Ofloxacin was the referenced drug. Chloroform root extract was more potent than the remaining four extracts. The extract at 100 mg/ml was active against only three (3) of the four (4) pathogens tested namely Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa with zones of inhibition measuring 25.00, 21.00 and 11.75 mm respectively. The minimum inhibitory concentration of the extract against the test organisms were 1,560, 6,250 and 25,000 µg/ml respectively. The minimum bactericidal concentration was 3,120, 12,500 and 50,000 µg/ml against the three organisms. The extract was found to be nontoxic with LD50 of above 2000 (mg//kg body weight) when administered orally in mice. The plant extract has immunostimulatory activity with a significant increase (p<0.05) in white blood cell proliferation when administered into mice at doses of 50, 25 and 100 mg/kg. Conclusion: The result of this investigation supports the use of this plant for the traditional remedy of mouth and throat infections possibly caused by these test organisms. The extract can serve as lead in phytomedicine development for the treatment of throat related infections.