COX-1 and COX-2 inhibitory activity in extracts prepared from Eucomis species, with further reference to extracts from E. autumnalis autumnalis

Abstract

Prostaglandins are important mediators of the body’s response to pain and inflammation, and are formed from essential fatty acids found in cell membranes. This reaction is catalysed by cyclooxygenase, a membrane-associated enzyme occurring in two isoforms, COX-1 and COX-2. Non-steroidal anti-inflammatory drugs (NSAIDs) act by inhibiting the activity of COX. The investigation of Eucomis species (a popular South African medicinal plant) for potential anti-inflammatory activity showed high levels of COX-1 and -2 inhibitory activity associated with several species, specifically E. autumnalis and E. humilis. Further investigation was conducted using E. autumnalis subspecies autumnalis, as this is the species that is most widely utilised by traditional healers in southern Africa. The bulb extracts from this species were characterised by higher IC 50 values for both COX-1 and COX-2 inhibition than obtained for the leaf and root extracts. The ratio of COX-2/COX-1 inhibitory activity was, however, similar to that of the root extracts, both values being less than one. The leaf extracts showed higher COX-1 than COX-2 inhibitory activity, with a ratio of 1.9. Most traditional remedies utilising Eucomis, are prepared from the bulbs (possibly including some root material) of this species.