# Conventional Antimicrobial and Medicinal Plants from a Traditional Medicine Market in South Africa: An Interactive Antimicrobial and Toxicity Study

## TL;DR

This study examines how medicinal plants from a South African market interact with conventional antibiotics and antifungals, finding that many combinations are harmful or ineffective.

## Contribution

The study is the first to systematically test interactions between traditional medicinal plants and conventional antimicrobials in a South African context.

## Key findings

- Over half of plant/antibiotic and plant/antifungal combinations showed antagonism.
- Artemisia afra with doxycycline and Acorus calamus with fluconazole were the most toxic combinations.
- Only a small percentage of combinations showed synergistic effects.

## Abstract

Background: The World Health Organization (WHO) has proposed the use of integrative medicine to achieve extended healthcare coverage in developing countries facing high morbidity. Traditional remedies are frequently employed to prevent and treat infections among South Africans; however, the ways in which they interact with conventional antimicrobials are largely unknown. Therefore, this study aimed to explore the interactions between commonly traded medicinal plants at a traditional medicine market in KwaZulu-Natal (KZN), South Africa, and conventional antibiotics and antifungals. Methods: To determine the interactive antimicrobial profiles for plant/conventional antimicrobial combinations, minimum inhibitory concentration (MIC) assays were performed against ESKAPE pathogens and the yeasts Candida albicans and Candida glabrata. Calculated fractional inhibitory concentration (ΣFIC) values were used to identify synergism or antagonism, with synergistic interactions further tested in vitro for toxicity. Results: A total of 952 combinations were tested, of which 5.8% and 54.6% of the plant/antibiotic combinations were synergistic and antagonistic, respectively; additionally, 1.7% and 58.6% of the plant/antifungal combinations showed synergism or antagonism, respectively. The most toxic plant/antibiotic combination was Artemisia afra with doxycycline (71.1% mortality). The most toxic plant/antifungal combination was Acorus calamus with fluconazole (78.8% mortality). Conclusions: When medicinal plants acquired from a traditional medicine market in South Africa are used in combination with conventional antibiotics and antifungals, more than half of the combinations exhibit antagonism, which is concerning.