Ethiopian Medicinal Plants Used for Respiratory Tract Disorders: Ethnomedicinal Review

Respiratory tract infections (RTIs) refer to infections in any part of the respiratory tract, which are common, with most of the world's population contracting at least one infection annually. These infections are becoming important causes of death and morbidity due to the rapid development of antimicrobial resistance that has resulted in reduced efficacy of existing drugs. Different local societies residing in Ethiopia have been reported to use traditional medicinal plants to treat RTIs. Nevertheless, up-to-date summarized data on the diversity of plants used in the traditional medicine system to treat RTIs in Ethiopia are lacking. The purpose of this review was to assess plant species used in traditional medicine to treat respiratory tract infections in Ethiopia. It attempts to compile available data required for undertaking further scientific investigations. The data were collected by searching for published scientific articles and other grey literature. Following this, medicinal plant (MP) diversity, growth forms, plant parts used, modes of remedy preparation and application, sources and distributions, and frequently treated respiratory disorders were examined. An Excel spreadsheet and SigmaPlot software were used to summarize and present the data. Two hundred twenty-nine (229) plant species that have been used to treat respiratory disorders in Ethiopia were documented. Lamiaceae was the most cited family (27 species), followed by Asteraceae (23 species), and Fabaceae (18 species), whereas cough was primarily cited as being treated by MPs and scored the highest frequency of citation (FOC = 243), followed by the common cold (FOC = 151) and asthma (FOC = 63). The top-cited plant species used in the treatment of RTIs were Eucalyptus globulus (6.8%), Allium sativum (5.5%), Zingiber officinale (4.2%), Ruta chalepensis (3.8%), and Ocimum lamiifolium (2.8%). Herbs were the dominant plant growth form (46%) used to treat respiratory diseases, and the most commonly used MP parts were leaves (37%). The leading traditional method used for preparation was decoction (25.5%), and the remedies were usually administered orally (64.6%). The MP origin reported was mainly from the wild (59%). High diversity of medicinal plants was reported as being used to treat various RTIs in Ethiopia. Information obtained from this review could be used as a reference for the selection of plants for further pharmacological, phytochemical, and toxicological investigations for their possible therapeutic applications and the development of new plant-based drugs.