Pharmacological studies of Crinum, Ammocharis, Amaryllis and Cyrtanthus species of the South African Amaryllidaceae

Abstract

The plant family Amaryllidaceae has attracted widespread attention in view of the interesting biological properties of its alkaloid principles. Many of these discoveries are based on the traditional usage of its members in regions where they are prominent. Over a third of its complement is found in southern Africa, hence the heightened interest in the Amaryllidaceae from this territory. Up to 2012, over 80 species were examined, mainly for their alkaloid constitution. Given the medicinal potential of the family as well as its widespread usage in South African traditional medicine, efforts over the past decade have intensified in understanding its biological properties. This account focuses on the biological activities that have been reported since 2013 for extracts of four genera of the South African Amaryllidaceae, viz Crinum, Ammocharis, Amaryllis and Cyrtanthus. Fourteen related species were assayed during this period, with Crinum (5 species) and Cyrtanthus (6 species) affording the bulk of the targets. Although most studies utilized the bulbous extracts, there were some instances involving the use of root, leaf and flower materials. The extractants used ranged from water to hexane, with a few examples addressing the outcomes of environmentally-benign extraction procedures. Close to twenty different areas were identified wherein the biological properties of the extracts were examined including, cytotoxicity, AChE and BuChE inhibition, cardio and hypertensive effects, antioxidant and anti-inflammatory effects, as well as antibacterial, antifungal and antiparasitic effects. Some studies also probed the mechanistic basis to these activities, notably in regards to their cytotoxic and anti-inflammatory effects.