Genus Blepharis (Acanthaceae): a review of ethnomedicinally used species, and their phytochemistry and pharmacological activities

Ethnopharmacological relevance: Blepharis is an Afro-Asiatic genus belonging to the family Acanthaceae. It comprises about 126 species that occur in arid and semi-arid habitats. Some species of Blepharis are used in traditional medicines in different countries mainly for their anti-inflammatory, wound healing activities along with treatment of gastrointestinal disorders and bone fractures. Aim of the review: The present review aims to collate and analyze the available data and information on distribution, traditional uses, chemical constituents and pharmacological activities of Blepharis. Methods: Scientific information of genus Blepharis was retrieved from the online bibliographic databases such as MEDLINE/PubMed, SciFinder, Web of Science and Google Scholar and secondary resources including books and proceedings. Results: Seven species of Blepharis were found to be reported frequently as useful in folklore in African and Asian countries. B. maderaspatensis was found to be widely used in Indian traditional medicines whereas the B. ciliaris and B. edulis were common in folklore of Egypt, Jordan, and Arabia. Active phytochemicals of Blepharis are flavonoids from B. ciliaris, alkaloids from B. sindica, phenolic acid derivatives, and phytosterols, and derivatives of hydroxamic acids from B. edulis resulted in possessing diverse biological properties such as anti-microbial, anti-inflammatory, and anti-cancer. Conclusions: Various species of Blepharis were found to be used in traditional medicine systems in African and Asian countries. Few of these species were studied for their bioactive chemical constituents however the activity guided isolation studies are not performed. Similarly, detailed pharmacological studies in animal models to explore their mechanism of action are also not reported. Future studies should focus on these aspects related to the medicinally used species of Blepharis. The detailed and comprehensive comparative analysis presented here gives valuable information of the currently used Blepharis species and pave the way to investigate other useful species of Blepharis pertaining to ethnobotany, phytochemistry and discovery of new drugs.