Phytochemical constituents and antibacterial activities of indigenous chewing stick (Anogeissus leiocarpus) stem

Abstract

The stems from Anogeissus leiocarpus are commonly used as chewing sticks in Northern Nigeria. If properly used, the chewing sticks have proven to be effective in removing dental plaque due to mechanical cleaning and enhanced salivation. Chewing sticks from other plants have been shown to display antimicrobial activities against a broad spectrum of microorganisms. However, there is limited information available in Northern Nigeria on the chemical composition, antimicrobial properties and the ability of the plants under study to prevent bacterial adhesion to tooth surface. Therefore, the purpose of this study was to ascertain the phytochemical and antibacterial properties of Anogeissus leiocarpus and correlate the results obtained to their ethnomedicinal uses as chewing sticks. Powdered stem was exhaustively extracted using methanol at room temperature for 72 hours. Antibacterial activities of the methanol extract was assessed using the agar well diffusion methods against the oral pathogens, Staphylococcus aureus, Streptococcus salivarius, Streptococcus pyogenes, Streptococcus mutans and Streptococcus sanguinis. Acute toxicity study was achieved using Lorke method. Phytochemicals which include flavonoid, steroid, triterpenes, alkaloids, tannins, carbohydrate, glycoside, phenols were detected in the extracts while anthraquinones was absent. The antibacterial results revealed that, the methanol extract had promising antibacterial activity. S. aureuswas found to be the most susceptible bacteria at 500mg/ml with inhibition of 22 mm, Streptococcus salivarius, Streptococcus pyogenes and Streptococcus sanguinis were inhibited at 16 mm while Streptococcus mutans showed inhibition of 14 mm. The extract have MIC and MBC of 31.25 mg/ml and 62.5 mg/ml respectively against all the tested clinical isolates. The LD₅₀ of Anogeissus leiocarpus was found to be greater than 5000 mg/kg and could be considered safe for consumption.