An appraisal of documented medicinal plants used for the treatment of cancer in Africa over a twenty-year period (1998–2018)

Over the years, appreciable advancements have been made in the treatment and control of cancer incidence and progression globally. However, the conventional treatment method is often accompanied with serious and sometimes devastating side effects, besides the treatment cost, which is usually so high that it remains unaffordable to many cancer sufferers in developing countries. Some of such sufferers are left with alternative or traditional medicine involving the use of medicinal plants as the only option for meeting their health-care needs. The present review was conducted to evaluate the available published literature reporting on plant species used for the treatment of cancer over the past twenty years (1998 – 2018) in Africa. A total of 212 articles containing information on medicinal plants used for cancer treatment in Africa were retrieved from scientific databases such as Google scholar, PubMed, and Web of science. A total of 207 plant species from 70 different plant families were recorded in this review. Forty-eight percent (48%) of the documented plant species were reported with cytotoxic activity against different cancer cell lines in vitro and in vivo. The dominant plant families documented for use in cancer treatment included Asteraceae and Fabaceae. Plant species such as Artemisia afra Jacq., Artemisia armeniaca Lam., Bidens pilosa L., Solanecio mannii (Hook.f.) C. Jeffrey, and Solanecio nandensis (S. Moore) C. Jeffrey were reported for the treatment of different cancer types such as skin, breast, and colorectal cancer in southern Africa. Most of the studies were on breast, skin, colorectal, cervical, leukemia, and prostate cancer with less attention to other forms of cancer. While these cancer types might recieve more attention in the preliminary phase, there is a need for further in-depth studies on the promising medicinal plants against other forms of cancer. Some of the identified ‘potent’ medicinal plant species from in vitro screening need to be evaluated in vivo as part of the drug design pipeline. The mechanism(s) of action, other pharmacological activities including cytotoxicity against non-targeted cells and potential in cancer therapy development of the identified ‘potent’ extracts and isolated plant compounds are other areas that require more research attention.