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CC BY 4.0 · European Journal of General Dentistry
DOI: 10.1055/s-0045-1810085
Original Article

Citral and Geraniol: Two Novel and Potent Noncarcinogenic Terpene Alternatives to Alcohol-Based Mouthwashes against Cariogenic Oral Bacteria

Nirupama Narayanan
1   Department of Biology, Manhattanville University, Purchase, New York, United States
,
Stephanie Charlton
1   Department of Biology, Manhattanville University, Purchase, New York, United States
,
Nathalie Martinez
1   Department of Biology, Manhattanville University, Purchase, New York, United States
,
Erica Sandilands
1   Department of Biology, Manhattanville University, Purchase, New York, United States
,
Chelsea Torres
1   Department of Biology, Manhattanville University, Purchase, New York, United States
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Abstract

Objective

Several recent studies have linked the high incidence of oral cancer among users with a history of prolonged use of alcohol-based mouthwashes, due to increased topical acetaldehyde, a carcinogen made from alcohol breakdown. Our research has previously shown that two volatile oils, Cymbopogon winterianus (Lemon grass) and Cymbopogon flexuosus (Citronella Java), exhibit significant antibacterial activity on four commonly occurring cariogenic oral bacteria. We have also demonstrated that these oils are mainly composed of four terpenes: citronellal, citronellol, geraniol, and citral. In this follow-up study, we wanted to determine which of these specific terpene constituents was responsible for the antibacterial activity of these two volatile oils.

Materials and Methods

In this study, we tested these terpenes on our selected panel of oral bacteria, namely Micrococcus luteus, Streptococcus salivarius, Streptococcus mutans, and Enterococcus faecalis in several qualitative assays such as Kirby–Bauer disc diffusion, minimum inhibitory concentration determination, minimum bactericidal concentration determination, and time-kill kinetics to evaluate their effectiveness as antibacterial agents.

Results

Citral and geraniol emerged as the most potent broad-spectrum antibacterial agents among all four terpene candidates. More specifically, citral was most effective on both oral streptococcal strains followed by geraniol, while geraniol exhibited the highest antibacterial activity against E. faecalis. Both terpenes showed a similar pattern of killing as seen with oral streptococci when tested against M. luteus.

Conclusion

We hypothesize that these two terpenes may serve as safer, better alternatives to alcohol-based mouthwashes.

Keywords

volatile oils - alcohol-based mouthwashes - microbiota - terpenes - acetaldehyde


Publication History

Article published online:
12 August 2025

© 2025. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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