Medicinal plants from the genus Acalypha (Euphorbiaceae)--a review of their ethnopharmacology and phytochemistry.

ETHNOPHARMACOLOGICAL RELEVANCE: Acalypha is the fourth largest genus of the Euphorbiaceae family with approximately 450-570 species. Several Acalypha species are used as medicinal plants in Africa and in the Mascarene Islands. Almost every part of the plant including the leaves, stem and roots are used as traditional remedies to treat and manage a panoply of ailments. However, there is no updated compilation of traditionally important medicinal plants from the Acalypha genus. The present review therefore, endeavors to provide for the first time an updated compilation of documented ethnopharmacological information in relation to the ethnomedicinal, ethnoveterinary, zoopharmacognosy, phytochemistry and biological activities of medicinal plants from the Acalypha genus which can subsequently open new perspectives for further pharmacological research.

MATERIALS AND METHODS: A literature search was performed on Acalypha species using ethnobotanical text books and scientific databases such as Pubmed, Scopus, EBSCO, Google Scholar and other web sources such as records from PROTA, PROSEA, and Botanical Dermatology Database. The Plant List, International Plant Name index and Kew Botanical Garden Plant name databases were used to validate scientific names.

RESULTS AND DISCUSSION: Plants from Acalypha genus are traditionally used in the treatment and/or management of diverse ailments such as diabetes, jaundice, hypertension, fever, liver inflammation, schistosomiasis, dysentery, respiratory problems including bronchitis, asthma and pheumonia as well as skin conditions such as scabies, eczema and mycoses. Approximately 124 species were listed in ethnobotanical studies with some botanical description and others mentioned from different web sources. However, only 40 species have been included in the present review due to the unavailability of ethnopharmacological data on the remaining species. Among the 40 cited species, 30 were traditionally used for the treatment and/or management of approximately 70 human diseases or health conditions. Two species, Acalypha alnifolia and Acalypha fruticosa are used as insecticides and sand fly repellent respectively. Only 2 species (Acalypha fruticosa and Acalypha indica) are used in ethnoveterinary practice and have similar human and veterinary applications. In zoopharmacognosy, only Acalypha ornata has been mentioned. Natives from Africa, Central America, North America, Southern China, India, Bangladesh, Papua New Guinea and Mascarenes islands utilize Acalypha species as ethnomedicine. Traditionally used Acalypha species have been reported to possess at least one of the following biological activities: antimicrobial, anti-diabetic, antioxidant, anti-inflammatory, larvidal, pupicidal, hepatoprotective, anticancer, leishmanicidal, antihyperglycemic, antihypertensive, anti-venom, analgesic, anthelmintic, antiemetic, laxative, expectorant, diuretic, post-coital antifertility effects and wound healing. A total of 167 compounds have been identified from 19 species, with 16 from eight species were reported to be bioactive.

CONCLUSION: The present review represents 32.3% of species from the Acalypha genus and can be considered as the first compilation of ethnopharmacologically useful plants from this genus. There is a great potential to discover new biologically active phytochemicals from the Acalypha genus because only few species have been studied comprehensively. Therefore, the clinical evaluation of species from this genus is warranted in future studies to confirm the ethnomedicinal claims and for the safety approval of therapeutic applications.