In Vitro Activity of Selected West African Medicinal Plants against Mycobacterium ulcerans Disease.

Patrick Tsouh Fokou,Regina Appiah-Opong,Abena Kissi-Twum,Fabrice Fekam Boyom,Dorothy Yeboah-Manu,Phyllis Addo,Lauve Tchokouaha Yamthe,Alexander Nyarko,Alvine Ngoutane Mfopa

doi:10.3390/molecules21040445

Abstract

Buruli ulcer (BU) is the third most prevalent mycobacteriosis, after tuberculosis and leprosy. The currently recommended combination of rifampicin-streptomycin suffers from side effects and poor compliance, which leads to reliance on local herbal remedies. The objective of this study was to investigate the antimycobacterial properties and toxicity of selected medicinal plants. Sixty-five extracts from 27 plant species were screened against Mycobacterium ulcerans and Mycobacterium smegmatis, using the Resazurin Microtiter Assay (REMA). The cytotoxicity of promising extracts was assayed on normal Chang liver cells by an MTT assay. Twenty five extracts showed activity with minimal inhibitory concentration (MIC) values ranging from 16 µg/mL to 250 µg/mL against M. smegmatis, while 17 showed activity against M. ulcerans with MIC values ranging from 125 µg/mL to 250 µg/mL. In most of the cases, plant extracts with antimycobacterial activity showed no cytotoxicity on normal human liver cells. Exception were Carica papaya, Cleistopholis patens, and Polyalthia suaveolens with 50% cell cytotoxic concentrations (CC50) ranging from 3.8 to 223 µg/mL. These preliminary results support the use of some West African plants in the treatment of Buruli ulcer. Meanwhile, further studies are required to isolate and characterize the active ingredients in the extracts.

Highlights

Medicinal plants are used around the world as either prescriptions and/or over-the-counter therapeutics for the prevention and treatment of diseases [1]
The successful implementation of rifampicin-streptomycin combination therapy as the first-line treatment option for Buruli ulcer disease and early case detection have significantly reduced the number of surgical interventions associated with BU, long stays in health facilities and relapse rates
In our search for natural products with antimycobacterial activity, 27 native plants of Cameroon and Ghana belonging to 12 plant families were selected based on their use to treat Buruli ulcer, wounds, and related symptoms

Summary

Introduction

Medicinal plants are used around the world as either prescriptions and/or over-the-counter therapeutics for the prevention and treatment of diseases [1]. Molecules 2016, 21, 445 mycolactone, a lipidic exotoxin encoded by M. ulcerans’ specific giant plasmid that has cytotoxic and immunosuppressive properties [5]. It is the third most common mycobacterial infection in the world, after tuberculosis and leprosy, and one of the most neglected but treatable tropical diseases [6]. Amongst health priorities in the world, the control of infectious diseases including Buruli ulcer ranks high. The successful implementation of rifampicin-streptomycin combination therapy as the first-line treatment option for Buruli ulcer disease and early case detection have significantly reduced the number of surgical interventions associated with BU, long stays in health facilities and relapse rates

Objectives

Methods

Results