Ascorbic Acid from Citrus limon (L.) Osbeck Fruit Source: A Promising Natural Agent for Caries Prevention and Management

Dental caries is an age-old oral disease afflicting humans irrespective of gender, age, socio-economical background, and geographical location. Despite extensive research being done worldwide to prevent dental caries, it is undoubtedly still a significant public health issue. Streptococcus mutans, a commensal bacteria of the oral microflora, is the primary etiological agent strongly linked to dental caries. In recent years, medicinal plant-based phytotherapy has drawn great attention towards managing various diseases as it is effective and safe. The aim of the investigation was to evaluate the antibacterial activity of fresh Citrus limon fruit juice against S. mutans and to quantify its ascorbic acid (Vitamin C) concentration. Additionally, to determine the MIC, MBC and growth curve assay of standard ascorbic acid against S. mutans. Fresh C. limon fruit juice demonstrated significant antimicrobial activity against the S. mutans reference strain (MTCC 497) by the agar well diffusion method. The ascorbic acid concentration of C. limon juice was found to be 0.194 % w/w by HPLC technique. The MIC and MBC values of standard ascorbic acid against S. mutans were found to be 12.5 mg/ml and 25 mg/ml, respectively. The growth curve assay demonstrated that ascorbic acid at a sub-MIC concentration of 6.25 mg/ml did not display any significant variations in the growth rate of S. mutans. To summarize, C. limon fruit juice is a potential source of natural antibacterial metabolites against S. mutans. Ascorbic acid, one of the chief components of C. limon fruit, is a promising agent for the development of anti-caries products. Further studies are warranted for developing novel formulations using ascorbic acid with other natural metabolites for the prevention and better management of caries.