Characterization and optimization of phenolics extracts from Acacia species in relevance to their anti-inflammatory activity

Three Acacia species: A. farnesiana, A. tortilis and A. longifolia, were investigated for seasonal variations of the phytochemical constituents and their influence on in-vitro anti-inflammatory activities. Samples of leaves and bark of the three species were collected in two different seasons and extracted using 50% and 70% ethanol. LC-MS analysis revealed the presence of rutin in the leaves of all three species, while catechin was commonly present in the bark. Other major components included vicenin 2, isoquercitrin, kaempferol 3-O-rutinoside and isorhamnetin 3-O-rutinoside in A. farensiana leaves, while A. longifolia leaves contained myricetin 3-O-rhamnoside, quercitrin and luteolin. The level of rutin varied according to the flowering period being highest in winter in A. tortilis (245.4 μg/mg) and A. longifolia (3.0 μg/mg). The content of total phenolics (TPC) showed a marked variation among the three species, which was reflected to some extent in the COX-1 and COX-2 enzymes inhibition. Optimization modeling was performed for better visualization and utilization of the data showing a strong inverse correlation between TPC and the mean inhibition of COX-2 in case of the leaves (r = 0.783). Finally, cluster analysis of the data obtained from the leaf samples reflected on the taxonomical classification of the species.