The effects of commercially available herbal teas on the human microbiota

Okeyoyin, Oluwadamilola Racheal; O, Gould; E, Adukwu

Abstract

Background: For centuries, herbal teas have been consumed by people of all ages and has been used for therapy in different civilisations and medical systems such as the Chinese, Indian, indigenous, and African. The aphorism- ‘Nature is the best chemist’ has a long historical pedigree and it is believed that bioactive compounds- phytochemicals contained in herbal teas have a wide range of biological effects. Research shows that herbal teas can contribute to health via the microbial flora which is found majorly in the gut and oral cavity. However, the mechanisms by which they contribute to health and wellness is not well established.

Aim and Objectives: The aim of this research is to determine the effects of selected herbal teas on oral and gut bacterial species and their mechanisms of action. Some of the objectives include determining the volatile phytochemical composition of the selected herbal teas; determining the susceptibility of the microorganisms when treated with the herbal teas and determining the metabolic activity of the microorganisms’ post treatment with the herbal teas.

Methodology: The herbal blends investigated include mint, ginger, and lemongrass tea blends. The microorganisms investigated include Streptococcus mutans, Streptococcus pyogenes, Methicillin-resistant Staphylococcus aureus, Methicillin-susceptible Staphylococcus aureus (MSSA) and Escherichia coli strain (ATCC 25922). Head Space Gas Chromatography Mass Spectrometry (HS-GC-MS) was used to determine the volatile phytochemical composition of the herbal brews; the antimicrobial effects of the herbal teas on the microorganisms were determined using agar dilution, disk diffusion and broth microdilution assays; and the effect of the teas on bacterial metabolism was determined using GC-MS with Solid-phase microextraction (SPME).

Results: This research show that the herbal tea vapours have extensive volatile phytochemical profiles with some key Volatile Organic Compounds (VOC’s) identified. For example, menthol was identified in the 3-mint tea as the most abundant VOC in its steam, eucalyptol the most abundant VOC in the ginger tea and anethole the most abundant VOC in the steam of the fennel tea. Furthermore, the herbal teas showed some antimicrobial activity on the microorganisms with the most effective herbal blend being the ginger tea. The most susceptible bacterial specie was S. pyogenes and least susceptible, E. coli.

Conclusion: The results show that herbal teas do have inhibitory effects on the growth of certain bacterial species however, further research is required to determine the mechanism by which they exert their antimicrobial effects.

• Presentation Conference Type: Presentation / Talk
• Conference Name: Annual Biomedical Research Conference for Minoritized Scientists (ABRCMS) conference
• Start Date: Nov 15, 2023
• Deposit Date: Mar 8, 2024
• Public URL: https://uwe-repository.worktribe.com/output/11768939