Chapter 25 - Xysmalobium undulatum

Abstract

Xysmalobium undulatum (L.) Aiton (Apocynaceae), commonly referred to as ‘Uzara’, is a large perennial herb that grows up to 2m in height and is widely distributed in the eastern parts of southern Africa. The plant bears creamy-green to yellow flowers, hairy fruits, and fleshy carrot-like roots, characterised by a nauseating smell. Xysmalobium undulatum is one of many South African medicinal plants widely used for the treatment of various diseases by several South African ethnic groups. The root is mostly used to treat different disease conditions, including gastrointestinal disorders, wound healing, hysteria, fevers, headaches and skin diseases. Uzara is one of the highly traded medicinal plants on the informal markets in South Africa, while formulations containing uzara have been successfully marketed by a number of pharmaceutical companies. The plant is also believed to possess diuretic properties and possible cardiotoxicity effects that may manifest due to the presence of cardenolide glycosides with digitalis-like action on the heart. This monograph represents a summary of the ethnobotany, phytochemistry, the in vitro and in vivo biological and pharmacological properties of X. undulatum, and its toxicity profile. Chemical profiling of the non-volatile constituents (methanol extract) was performed using high-performance thin-layer chromatography (HPTLC), ultra-performance liquid chromatography coupled to mass spectrometry (UPLC–MS), and mid-infrared (MIR) spectroscopy. The major compounds reported in the root extract are uzarin and its isomer allouzarin, as well as xysmalorin and alloxysmalorin. The marker compound, uzarin, was identified based on both HPTLC and UPLC–MS analysis and its isomer, xysmalorin, was identified by UPLC–MS in the methanol root extracts.