Evaluation of the Analgesic, Anti-Inflammatory and Antimicrobial Activities of Leaf Extracts of Breynia nivosa

Breynia nivosa is used in treating headaches, toothaches and tooth infections. This study evaluated some ethnomedicinal uses of leaves of the plant. B. nivosa leaves were extracted with ethanol, and then fractionated using methanol, ethyl acetate and dichloromethane. The phytochemical screening of the plant was evaluated and the analgesic, anti-inflammatory, and antimicrobial activities of the extracts/fractions were determined using standard methods. The phytochemical screening of the plant leaves revealed the abundance of alkaloids and flavonoids. Glycosides, tannins, and starch were present in moderate amounts, while saponins were detected in lower quantities. Analgesic activity was recorded by all extracts/fractions of the plant, but best activity was recorded by the dichloromethane fraction whose percentage analgesia was higher than that recorded for the standard drug Diclofenac at all concentrations analyzed (50-200 mg/mL). Anti-inflammatory activity was recorded for all the extracts of B. nivosa at 50, 100, and 200mg/mL. But compared to the standard drug Diclofenac (50mg/mL), a higher anti-inflammatory activity was recorded only for the crude ethanol extract and methanol fraction at concentrations of 100 and 200 mg/mL. In the antimicrobial evaluation of the crude ethanol extract of the B. nivosa, the plant recorded antimicrobial activity against S. aureus, S. typhi and B. subtilis , with best activity against S. typhi. It had no activity against E. coli, A. fumigatus and C. albicans. The extracts of B. nivosa leaves are natural analgesic, anti-inflammatory and antimicrobial agent and could have therapeutic potential in the management of various chronic diseases. The agar well diffusion assay method described by Perez et al . [11] was used to evaluate the antibacterial and antifungal activities of the ethanol extract of B. nivosa against the test microorganisms. Dilutions of 250, 125, 62.5, 31.25, and 15.625mg/mL were prepared from the 500mg/mL stock solution of the plant extract in a 2-fold dilution process. Twenty (20) mL of molten Mueller Hinton Agar (MHA) and Sabouraud Dextrose Agar (SDA) (for bacterial and fungal isolates respectively) were poured into sterile Petri dishes (90 mm) and allowed to set. Standardized concentrations (McFarland 0.5) of overnight cultures of test isolates were swabbed aseptically on the agar plates and holes (6mm) were made in the agar plates using a sterile metal cork-borer. Twenty (20µl) of the various dilutions of the plant extract and control were put in each hole under aseptic condition, kept at room temperature for 1 hour to allow the agents to diffuse into the agar medium and incubated accordingly. Gentamicin (10μg/mL) and fluconazole (50µg/mL) were used as positive controls in the antibacterial and antifungal evaluations respectively; while DMSO was used as the negative control. The MHA plates were then incubated at 37 o C for 24hrs, and the SDA plates were incubated at room temperature (25-27 o C) for 2-3days. The inhibition zones diameters (IZDs) were measured and recorded. The size of the cork borer (6mm) was deducted from the values recorded for the IZDs to get the actual diameter. This procedure was conducted in duplicate and the mean IZDs calculated and recorded. Determination of Minimum Inhibitory Concentration (MIC) of the Crude Extracts on Test Isolates Minimum inhibitory concentration (MIC)