Phytochemical and antibacterial activity of the extracts of <i>Fagara zanthoxyloides </i> on selected cariogenic and enteric bacterial isolates

Abstract

Background: Fagara zanthoxyloides belongs to the family Rutaceae. The stem and the root of the plant are both used as chewing stick in Nigeria particularly among the Yoruba ethnic group in the South-Western part of the country. This study determined the antimicrobial activity of the extracts from F. zanthoxyloides on selected cariogenic and enteric bacterial isolates. Methods: Crude extracts were obtained by cold extraction method of the powdered stem in methanol-water mixture (MW) in ratio 3:2 and phosphate buffer saline (PBS). Filtrates obtained were concentrated in a rotary evaporator and lyophilized. Antimicrobial activity of the extracts, at a concentration of 25 mg/ml was tested against four bacterial isolates using agar well diffusion method. Phytochemical analysis of the plant extract for the presence of tannins, saponins, alkaloids and flavanoids was based on chemical examination. Results and discussions: Extracts from methanol-water mixture showed some antimicrobial activity against Lactobacillus brevis (NCIMB 4617), L. plantarum (NCDO 1752) and Escherichia coli and Proteus vulgaris. The minimum inhibitory concentration (MIC) of extracts ranged between 1.57 and 12.5 mg/ml except in E. coli with value greater than 12.5.mg/ml. The phytochemical screening indicated that the extract tested positive for tannin, saponin, flavonoids and alkaloids. Results showed that F. zanthoxyloides would be valuable in the treatment of microbial diseases particularly those of the oral cavity. The considerable antibacterial activities exhibited by the extract of the plant thus justify the use as a teeth cleansing agent in the local setting. The problem of antibiotics resistance to synthetic drugs is also expected to be mitigated with the use of natural drugs.