Evaluation of Antimicrobial Activity of a Sudanese Herbal Plant (Piliostigma reticulatum)


Background: Piliostigma reticulatum is a plant that is found in a wide area of SaheloSudanian region of Africa. It is widely used in Africa as a traditional medicine for the treatment of a wide range of diseases including epilepsy, anxiety, and agitation. The leaf extract was found to have antimicrobial activity. In Sudan (Nuba mountains in particular), it is widely used to dress new wounds and as well puerperal sepsis.
Moreover it’s fruit is eaten and used to prepare juice. Reported studies concerning antimicrobial activity of the plant in Sudan could not be found. This study therefore aimed to evaluate the antimicrobial action of Ethanolic and Aqueous extract of leaves and barks of the plant.

Methods: Barks and leaves of P. reticulatum were obtained from North Kordofan State. They were then air dried in the shade and milled into powder using Mortar. Methanolic and water extract of each part of the plant was prepared using a Soxhlet apparatus. The following concentrations of extracts of each part (bark and leaves)
of the plant were prepared using Distilled water (50 mg/ml, 25 mg/ml, 12.5 mg/ml, 6.25 mg/ml, 3.125 mg/ml, and 1.56 mg/ml). Antimicrobial action of the different concentrations of the extracts of the two parts of the plant on selected bacterial and fungal species was performed using well diffusion technique. Antimicrobial
susceptibility of the tested organisms to serial concentrations (40 µg, 20 µg, 10 µg, and 5 µg) of three antibacterial (Gentamicin, Ampicillin, and Tetracycline) and 2 antifungal (Nystatin and clotrimazole) was evaluated using well diffusion method.

Results: The methanolic extract of P. reticulatum leaves showed high antibacterial activity against Bacillus subtilis (inhibition zone 22 mm), S. aureus (25 mm), P.
aeruginosa (23 mm), and E.coli (20 mm). The extract also showed antifungal activity against A. niger (23 mm) and C. albicans (23 mm). The aqueous extract revealed low activity against P. aeruginosa (10 mm) and no action on the rest of the microorganisms.

[1] Fibres. (1846). Description, original, geographic distribution, uses and production and international trade of P. reticulatum. Prota (Plant Resourcer of Tropical Africa) vol. 29, p. 299.

[2] Dosso, K., N’guessan, B. B., Bidie, A. P., et al. (2011). Antidiarrheal activity of an ethanol extract of the stem bark of Piliostigma reticulatum (Caesalpiniaceae) in rats. African Journal of Traditional, Complementary and Alternative Medicines, vol. 9, no. 2, pp. 242–249.

[3] Sidiki, N., Djafsia, G., Njapdounke, K. J. S., et al. ( January–March 2013). Anxiolytic and antipyretic activities in the decoction of leaves of Piliostigma reticulatum. Asian Journal of Pharmaceutical and Health Sciences (AJPHS), vol. 3, no. 1.

[4] Olalekan, J., Babajide, et al. (2008). Flavonols and an oxychromonol from Piliostigma reticulatum. Phytochemistry, vol. 69, no. 11, pp. 2245–2250.

[5] Akinsinde, K. A. and Olukoya, D. K. (1995). Vibriocidal activities of some local herbs. Journal of Diarrhoeal Diseases Research, vol. 13, no. 2, pp. 127–129.

[6] Miles, M. and Misra, S. S. (1938). The estimation of the bacterial power of the blood. Journal of Hygiene, vol. 38, pp. 7–32.

[7] Collee, J. G., Barrie, P. M., Andrew, G. F., et al. (1996). Practical medical microbiology. Specimen collection, culture container and media (fourteenth edition), section A, vol. 5, pp. 95–109. Singapore: Longman Singapore Publisher Ltd.

[8] NCCLS. (1999). Methods for determining bactericidal activity of antibacterial agents: Approved guideline. NCCLS document M26-A. Villanova, PA: NCCLS.

[9] Abd-Ulgadir, K. S., Suliman, S. I., Zakria, I. A., et al. (2015). Antimicrobial potential of methanolic extracts of Hibiscus sabdariffa and Ricinus communis. Advancement in Medicinal Plant Research, vol. 3, no. 1, pp. 18–22.

[10] Aderogba, M. A., Okoh, E. K., Okeke, I. N., et al. (2006). Antimicrobial and antiinflammatory effects of Piliostigma reticulatum leaf extract. International Journal of Pharmacology, vol. 2, no. 1, pp. 70–74.

[11] Daniels, A. O. and Malomo, O. (2014). Preliminary studies on the antimicrobial effect and phytochemicals studies of some Nigerian medicinal plant on some human pathogens. International Journal of Current Microbiology and Applied Science, vol. 3, no. 3, pp. 910–923.

[12] Awe, S. and Omojasola, P. F. (2009). A comparative study of the antibacterial activity of Piliostigma reticulatum bark extract with some antibiotics. Ethnobotanical Leaflets, vol. 2009, no. 9, article 11.