Phytochemical and in-vitro antimicrobial activity of Zanthoxylum zanthoxyloides (Rutaceae), Terminalia glauscens (Combretaceae) and Pseudocedrela kotschyii (Meliaceae) three Nigerian Chewing Sticks

Streptococcus mutans has been reported to be the chief etiological agent implicated in dental caries along with other oral flora. The use of chewing sticks as a means of oral maintenance is common in most countries in Africa and Asia. The antimicrobial activities of three Nigerian chewing sticks tagged Zanthoxylum zanthoxyloides (Zx), Tg Terminalia glauscens (Tg) and Pseudocedrela kotschyii (Pk) were studied in vitro against seven isolated strains of Streptococcus mutans from different patients and two Candida sp. isolated from saliva and plaque samples. The susceptibiltiy of these isolates against the plant extracts were determined by agar diffusion method using Mueller Hinton agar supplemented with sheep blood. The largest zone of growth inhibition for the extracts was recorded with Streptococcus mutans with a zone diameter of 22mm at 200mg/mL, while the largest zone of 18mm at 200mg/ml concentration was recorded for Candida sp. Zx gave the largest zone of inhibition against Streptococcus mutans while Tg gave the largest zone of inhibition against Candida sp. The Minimum inhibitory concentration (MIC) of the crude extracts against the test isolates was determined using agar dilution method and these ranged from 12.5–50mg/ml. Phytochemical study of the plants revealed the presence of alkaloids, amides, lignans, coumarins and tannin, which were believed to be responsible for the above activities. The chewing sticks contained both antibacteria and antifungal agents though the concentrations and composition of the bioactive substances may differ amongst the plants. The result of this study thus justifies their use as an alternative mouth cleansing agent.

Acknowledgements: This project was facilitated by the Senate Research Grant, University of Ibadan, Nigeria given to Adeniyi, CBA