Ethnobotanical uses, biological activities and chemical properties of Kei-apple [Dovyalis caffra (Hook.f. & Harv.) Sim]: An indigenous fruit tree of southern Africa

Abstract

Ethnopharmacological relevance: Dovyalis caffra (Hook.f. & Harv.) Sim (commonly called Kei-apple) is an indigenous fruit tree that has medicinal values for various ethnic groups in southern Africa.

Aim of the review: This review aims to provide a critical appraisal of the existing knowledge on the ethnobotanical value, biological activities and phytochemicals of Dovyalis caffra. In addition, the potential of producing a functional health product from Kei-apple due to its therapeutic effects and rich pool of phytochemicals was explored.

Methods: A detailed literature search was conducted using various online search engines, such as Scopus, Google Scholar, Mendeley and Web of Science. Additional information was sourced from ethnobotanical literature focusing on southern African flora.

Results: Dovyalis caffra has diverse uses in local and popular medicine, specifically for relieving pain and rheumatism in humans. Ethno-veterinary potential of Kei-apple has also been documented in East Africa. Non-medicinal uses of the tree include its role in biological hedging and as a traditional herb for African magical purpose. Regarding its biological activities, polar extracts from the seeds exhibited noteworthy antibacterial (minimum inhibitory concentration of 1 μg/ml against Staphylococcus aureus) activity. Quantitative analysis (e.g. GC-MS, HPLC) indicated the presence of a rich (>80) pool of chemicals, including sterols, phenolic acids and fatty acids from different parts of the plant while 11 compounds have been isolated from its leaves and twigs.

Conclusions: Dovyalis caffra has been tested for various biological activities and the extracts (seeds in particular) demonstrated promising antibacterial potential. A lack of alignment between the ethno-medicinal uses and existing biological screenings was observed, indicting the need for anti-inflammatory and anti-rheumatism potential of Dovyalis caffra to be explored. In vivo validation of antibacterial and anti-parasitic activities against clinical bacterial strains and parasites, respectively is required. Other areas that need investigation are safety evaluations and development of integrated cultivation approach in order to fully explore the plant's potential.

Keywords: Antimicrobial; Antioxidants; Phytochemicals; Rheumatism; Salicaceae; Wild fruit.