Comparative evaluation of the antimicrobial activity of various concentrations of nonalcoholic extracts of crude coconut shell oil, orange peel, and mango leaf with that of xylitol on Streptococcus mutans and Candida albicans: An in vitro study

Background: The use of plant extracts, as well as other alternative forms of medical treatments, is enjoying great popularity since late 1990s. Scientists from all over the have found literally thousands of phytochemicals which have inhibitory effects on all types of microorganisms in vitro. Moreover, there are the reports of potential hazards and microbial resistance against the commonly used antibiotics. Aim: The objective of this study is to evaluate the antimicrobial effect of various concentrations of nonalcoholic extracts of crude coconut shell oil, orange peel, and mango leaf with that of xylitol on Streptococcus mutans and Candida albicans. Materials and Methods: Microbial strains were procured and revived on nutrient agar media. Coconut shell oil extract was prepared by heating ground shell in an earth pot for 3 h. Mango leaf extract was collected by powdering them using a blender and water extracts were prepared using agitation method. Orange peel extract was collected from the fresh peels of oranges which was pureed in a blender. The puree was subjected to hydrodistillation. The oil was separated. 10 g of Xylitol was dissolved in 10 ml of distilled water for base extract. 25%, 50%, 100%, and 200% dilutions of the extracts and xylitol were prepared. The susceptibility of the oral pathogens was determined by the well diffusion method. The extracts were pipetted into the wells and then incubated at 37°C overnight. After overnight incubation, the diameter of the clear zone produced was measured in cm. Minimum inhibitory concentration (MIC) of the extracts was evaluated by the microdilution method. Serial dilutions of the extracts and xylitol were added to the wells prepared in the agar plate along with nutrient broth and culture. The plates were placed in an incubator at 37°C for 24 h. The absence of turbidity in the wells was recorded as MIC. Results: Highest zone of inhibition was recorded for coconut shell extract against both the test organisms followed by Xylitol. Mango leaf extract and orange peel extract could not demonstrate statistically significant results. The inhibitory effect increased with increasing concentration. MIC of coconut shell extract against C. albicans and S. mutans was found out to be 37.5 mg and 25 mg, respectively. Conclusion: Based on the results of the study, it may be concluded that antibacterial and antifungal effect of nonalcoholic extracts of crude coconut shell extract is more when compared to mango leaf, orange peel, and xylitol. Mango leaf and orange peel extracts showed minimum activity.