Ethnobotanical study of medicinal plants used by traditional healers for the treatment of oxidative stress-related diseases in the Congo Basin

This paper identifies the medicinal plants used for the treatment of oxidative stress-related diseases by the Congolese population. The objective of the present survey was to list the major plants used in Congolese traditional folk medicine for the treatment of oxidative stress-related diseases as well as to review the phytogeographical distribution of these plants, their natural habitats, plant parts used, routes of administration and administered doses. Several methods have been used to fulfil the aim of the study: an ethnobotanical survey, observation of the practices of traditional healers, and bibliographical research focused on the ethnobotany and antioxidant power of sub-Saharan African medicinal plants. From a questionnaire, a guided semi-structured interview was carried out to obtain information from independent traditional healers in the Republic of the Congo.A total of 70 plants distributed among 47 families were identified. These plants were mainly employed to treat hypertension, diabetes, and anaemia, but they also were used to a lesser extent for fighting other pathologies such as infertility, asthma, ulcer, cough, and viral hepatitis. Analgesic, antiseptic, and aphrodisiac activities of the medicinal plants as well as their ability to improve visual acuity were also reported. Most of the plant preparations were taken orally as a decoction or infusion or taken directly as a powder. Treatments generally involved only one plant but mixtures of several plants were also used. Other ingredients, such as lemon, milk and honey were sometimes added to preparations to facilitate their ingestion. Among the total of 70 species of plants that were identified in the study, it is noteworthy that three plants (Syzygium brazzavillense Aubrév. & Pellegr., Parinari congensis Didr., and Croton dybowskii Hutch.) have never been studied for their medicinal properties. According to the traditional healers, these plants showed efficacy in the treatment of oxidative stress-related pathologies. The reported dosage of the plant preparations depends on several factors, particularly plant type, amounts of powder and water used for its reconstitution (i.e. powder to water ratio), and patient age. Treatments were reported to last a maximum of one month. The current ethnobotanical study allowed the identification of some plants which are endemic to the Republic of the Congo (e.g., Syzygium brazzavillense Aubrév. & Pellegr.) and some growing only in a specific zone of the country (e.g., Croton dybowskii Hutch.). The traditional knowledge of these plants will guide future research of the antioxidant power of African plant powders.