Cryptocarya species--substitute plants for Ocotea bullata? A pharmacological investigation in terms of cyclooxygenase-1 and -2 inhibition.

In response to the serious scarcity of Ocotea bullata (Burch.) Baillon (Lauraceae), an important medicinal plant in South Africa, Cryptocarya species (Lauraceae) are frequently used as substitute plants. Our investigation was aimed at a pharmacological comparison of O. bullata and the Cryptocarya species C. latifolia Sonder, C. myrtifolia Stapf., C. transvaalensis Burtt Davy, C. woodii Engl. and C. wyliei Stapf., in terms of in vitro cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibition, as an indication of O. bullatas' repute as a remedy against headache. Furthermore, we also compared bark and leaf extracts of the species investigated in order to address the problem of destructive ring-barking. The utilization of leaves instead of bark would help in the management of threatened medicinal plants. All Cryptocarya species were superior to O. bullata with regard to bark extracts. C. woodii bark extracts showed outstanding equipotent activity towards COX-1 and COX-2. The activity of extracts of fresh leaves was comparable to the activity of the respective bark extracts. Drying the leaves before extraction resulted in a loss of activity, with the exception of C. wyliei. Extracts of dried C. wyliei leaves exhibited high inhibitory activity, with a COX-2/COX-1 ratio of 5.8.