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Utilizing Resazurin Assays to Screen Herbal Extracts for Antimicrobial Activity Against Oral Streptococcus mutans

CSEF · 2023 Microbiology (General) Honorable_mention Award

Wang John · 11

Overview

Streptococcus (S.) mutans, a gram-positive, anaerobic bacterium, is a major contributor in the formation of dental caries. The effective way for prevention and treatment of dental caries is through antibiotics. However, reckless use of antibiotics has led to a rapid increase in bacterial resistance, creating an urgent need to develop novel antimicrobial agents against S. mutans. Plants are rich in potentially therapeutic compounds, making them promising candidates for developing alternative treatments. This study aimed to analyze the antibacterial properties of aqueous extracts from six plants on S. mutans. It was hypothesized that some aqueous herbal extracts of the plants would exhibit antimicrobial activity against S. mutans. Aqueous herbal extracts of dried herbs were prepared by decoction, then sterilized and diluted in PBS (pH 7.4). S. mutans in Mueller Hinton broth with an OD600 of 0.0001 was used in Resazurin assays on 96-well plates. The minimum inhibitory concentrations (MIC) were determined based on color change and the half maximal inhibitory concentrations (IC50) were estimated by non-linear curve fitting with fluorescence signals. The extracts of green tea, peppermint and thyme exhibited dose-dependent inhibitions on S. mutans growth, with MICs of 0.5%, 1%, 1%, and IC50s of 0.21%, 0.40%, 0.43%, respectively. Significant additive/synergistic effects between the three extracts were observed even at low concentrations. The results demonstrate that herbal extracts contain compounds directly inhibiting S. mutans. The findings indicate that alternative treatments to dental caries can be developed from aqueous herbal extracts.

Source coverage

This record comes from a published award list, not a complete project archive. Its abstract comes from CSEF's public project showcase as archived by the Internet Archive before judging (https://web.archive.org/web/20230401224130/https://ca-csef.zfairs.com/showcase/ShowcaseInfo?f=838e60b7-ea75-46e8-865c-fde4864244b3); the version presented may differ.

Awards (1)

  • Category Award: HM

Competition history

  • CSEF 2023 Microbiology (General) · Entry S1514

Resources

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