A scoping review on efficacy and safety of medicinal plants used for the treatment of diarrhea in sub-Saharan Africa

In sub-Saharan Africa (SSA), significant morbidity and mortality have been linked to diarrhea, which is frequently caused by microorganisms. A rise in antimicrobial-resistant pathogens has reignited the search for alternative therapies. This scoping review aims to map the literature on medicinal plants in relation to their anti-diarrheal potential from SSA. Studies published from 1990 until April 2022 on medicinal plants used for the treatment of diarrhea from each country in SSA were searched on Scopus, Web of Science, Science Direct and PubMed. The selection of articles was based on the availability of data on the in vitro and/or in vivo, ethnobotanical, and cross-sectional studies on the efficacy of medicinal plants against diarrhea. A total of 67 articles (ethnobotanical (n = 40); in vitro (n = 11), in vivo (n = 7), cross-sectional (n = 3), in vitro and in vivo (n = 2) and ethnobotanical and in vitro (n = 2), were considered for the descriptive analysis, which addressed study characteristics, herbal intervention information, phytochemistry, outcome measures, and toxicity findings. A total of 587 different plant species (from 123 families) used for diarrhea treatment were identified. Most studies were conducted on plants from the Fabaceae family. The plants with the strongest antimicrobial activity were Indigofera daleoides and Punica granatum. Chromatographic methods were used to isolate six pure compounds from ethyl acetate extract of Hydnora johannis, and spectroscopic methods were used to determine their structures. The majority of anti-diarrheal plants were from South Africa (23.9%), Ethiopia (16.4%), and Uganda (9%). This study highlights the value of traditional remedies in treating common human diseases such as diarrhea in SSA. Baseline knowledge gaps were identified in various parts of SSA. It is therefore recommended that future ethnobotanical studies document the knowledge held by other countries in SSA that have so far received less attention. Additionally, we recommend that future studies conduct phytochemical investigations, particularly on the widely used medicinal plants for the treatment of diarrheal illnesses, which can serve as a foundation for future research into the development of contemporary drugs.