Ethnomedicinal and phytochemical properties of sesquiterpene lactones from Dicoma (Asteraceae) and their anticancer pharmacological activities: A review

Abstract

Dicoma species belonging to the Asteraceae family are commonly utilized as traditional medicine in Southern Africa. Dicoma anomala, Dicoma capensis, Dicoma schinzii and Dicoma zheyeri are the most common ethnomedicinal plant species used in Southern Africa. The plant species of Dicoma genus are identified as the main source of sesquiterpene lactones. Dicoma species are associated with pharmacological properties such as antiviral, antibacterial, antihelminthic, antispasmodic antiplasmodial, as analgesic, antiinflammatory, anticancer, and wound healing properties. The plant species of Dicoma genus are identified as the main source of sesquiterpene lactones. In this review, the authors report the ethnomedicinal and phytochemical properties, and pharmacology of sesquiterpene lactones from the genus Dicoma from 1978 to 2020. There are over eighty (80) reported sesquiterpene lactones isolated from Dicoma species including, germacronolides, eudesmanolides, melampolides, guaianolides and pseudoguaianolides. Sesquiterpene lactones possess antimalarial, anticancer and antiinflammation activities due to their structural diversity. The diagnostic search on phytochemistry of sesquiterpene lactones from Dicoma carried out in the 70’s has limited pharmacological screening activities; hence these may need to be revisited and explored. Furthermore, the literature search conducted in this review showed that out of the 35 Dicoma species, seven species were investigated, and their medicinal uses, pharmacology and photochemistry reported. The recommendation drawn is that Dicoma species that are not investigated and not fully exploited should be studied for their phytochemicals and efficacy. The information compiled in this review on the pharmacological, phytochemistry and ethnomedicinal activities of genus Dicoma was obtained from relevant literature sources, including books, book chapters, websites, theses, reviews and research articles from databases such as Web of Science, Scopus, Science Direct, BioMed Central, Springer link, PubMed, and Google Scholar.