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. 2025 Jan 5;17(1):e76948.
doi: 10.7759/cureus.76948. eCollection 2025 Jan.

Evaluation of Antimicrobial Effectiveness of Lemongrass, Ash Gourd, Watermelon, Guava Extracts, Chlorhexidine Against Streptococcus mutans: An In Vitro Study

Gauri Nair  1 , Rhujuta Mokal  1 , Amit Patil  1 , Minakshi Bhattacharjee  2 , Sheetal Mali  1 , Ashwini S Panchmahalkar  2 , Sanpreet S Sachdev  3
Affiliations

Evaluation of Antimicrobial Effectiveness of Lemongrass, Ash Gourd, Watermelon, Guava Extracts, Chlorhexidine Against Streptococcus mutans: An In Vitro Study

Gauri Nair et al. Cureus. .

Abstract

Introduction The oral cavity holds a vital role, as it harbors diverse microbial communities, with Streptococcus mutans being a major contributor to dental caries. While antimicrobial agents such as chlorhexidine target oral bacteria, their use may lead to genotoxic effects, highlighting the need for safer alternatives. This study investigates the antimicrobial properties of lemongrass, ash gourd, watermelon, and guava against S. mutans. Materials and methodology Extracts of lemongrass, ash gourd, watermelon, and guava were evaluated using the well diffusion method, measuring the zone of inhibition around each well. Each extract was tested in triplicate for effective individual assessment of results. Results Lemongrass extract demonstrated the highest zone of inhibition at 28 mm, followed by guava extract at 22 mm. In contrast, watermelon and ash gourd extracts showed no inhibitory activity. Conclusion Lemongrass exhibits the strongest antimicrobial efficacy against S. mutans, with guava as a secondary option, while watermelon and ash gourd were ineffective. Further clinical trials are recommended to explore lemongrass and guava as potential antimicrobial agents in oral health management.

Keywords: anti-bacterial action; anti-inflammatory action; dental caries; streptococcus mutans; zone of inhibition.

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Conflict of interest statement

Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Biomedical Ethics Committee issued approval IEC358072022. The study protocol was approved by the institutional ethical review board of the Bharati Vidyapeeth (Demeed to be University) Dental College and Hospital, Navi Mumbai (Reference ID: IEC358072022). Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. A) Chopped pieces of ash gourd (1), lemongrass (2), guava (3), and watermelon (4). B) Ethanolic extracts of the fruits and leaves. C) Filtrates kept in water bath for evaporation of the solvent. D) Final extracts of all the fruits used for antimicrobial sensitivity analysis.
Figure 2
Figure 2. (A) Lemongrass extract exhibited the highest zone of inhibition against Streptococcus mutans. (B) Guava extract exhibited the lowest zone of inhibition against S. mutans. (C) Ash gourd extract showed no antimicrobial activity. (D) Watermelon extract showed no antimicrobial activity.
Figure 3
Figure 3. Ethical approval letter first page
Figure 4
Figure 4. Ethical approval letter second page
See this image and copyright information in PMC

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