Anti-inflammatory and phytochemical properties of twelve medicinal plants used for treating gastro-intestinal ailments in South Africa

Ethnopharmacological relevance: The investigated medicinal plants are commonly used for the treatment of pains and cramps related to gastro-intestinal tract infections in South African traditional medicine. Aims of the study: This study aimed to evaluate the ability of the plant extracts to inhibit cyclooxygenase enzymes. Phytochemical analysis was also carried out in the quest to determine some plant metabolites that may be responsible for the observed anti-inflammatory activity. Materials and methods: The cyclooxygenase assay was used to test for the anti-inflammatory activity of the plant extracts using cyclooxygenase-1 and -2 (COX-1 and COX-2) enzymes. Total phenolic compounds including condensed tannins, gallotannins and flavonoids were quantitatively determined using spectrophotometric methods. Qualitative tests for alkaloids and saponins were also carried out. Results: Most of the plant extracts evaluated showed dose dependent activity against COX-1 and/or COX-2 enzymes. Agapanthus campanulatus root dichloromethane extract showed the highest COX-2 inhibitory activity (83.7%) at 62.5 μg/ml. The presence and/or amounts of phenolics, condensed tannins, gallotannins, flavonoids, alkaloids and saponins varied with plant parts and species. Conclusion: The results support the use of the investigated plant in treating pain and cramp related to gastro-intestinal tract infections. To some extent, the observed anti-inflammatory activity could be attributed to the various plant secondary metabolites detected in the plant materials.