Evaluation of the antibacterial activity of lemon fruit juice, Mondia whitei ethanolic extract, and their combination against Streptococcus mutans

Author(s): Markarius Katuromunda*, Kenneth Ssekatawa, Silivano Niwagaba

Dental caries has gained momentum as one of the main public healthcare concerns worldwide. Due to the ability to synthesize extracellular polysaccharides that facilitate the formation of plaque biofilm on the teeth enamel which is vital for carcinogenicity, Streptococcus mutans has been implicated as the major causative agent of dental caries. Although the occurrence of dental caries in Uganda is on the rise, little or no attention has been paid to promoting oral healthcare in the country. Thus, this study was aimed at evaluating the citrus lemon fruit juice and ethanolic extract of Mondia whitei root bark as candidate alternative therapeutic agents for Streptococcus mutans the causative agent of dental caries. In this study, the lemon juice, pulp lemon juice, and Mondia whitei ethanolic extract were screened for phytochemicals. Furthermore, the anti-Streptococcus mutans activity of the lemon juice, lemon pulp juice, and Mondia whitei ethanolic extract was determined by the agar well diffusion method while the minimum inhibitory concentration and minimum bactericidal concentration were determined by serial broth dilution. Phytochemical screening revealed the presence of alkaloids, flavonoids, terpenoids, and tannins in the ethanolic extract of Mondia whitei and lemon and lemon pulp juice, while glycosides were detected only in juices obtained from the lemon. The zones of inhibition of ethanolic extract of Mondia whitei, citrus lemon juice, citrus lemon pulp juice, and the cocktail were 13.67 ± 0.33, 18.67 ± 0.33, 18.33 ± 0.67 and 18.00 ± 0.58 respectively, The lemon juice and lemon pulp juice exhibited significantly lower MIC of 0.195 mg/ml, and 0.391 mg/ml respectively. The efficacy of the extract/juices increased with an increase in the concentration. Conclusively, the findings of this study indicated that the Mondia whitei ethanolic extract, lemon juice, and lemon pulp exhibited significant antibacterial activity against Streptococcus mutans the main causative agent of dental caries, and can be further explored for the formulation of herbal concoction for the prevention and treatment of oral cavities in resources-limited low-income communities.

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