Bioassay guided fractionation and identification of active anti-inflammatory constituent from Delonix elata flowers using RAW 264.7 cells

Abstract

Context: Delonix elata (L.) Gamble (Fabaceae) has been used in the Indian traditional medicine system to treat rheumatism and inflammation. Aim: To assess the anti-inflammatory effect of Delonix elata flowers and to isolate the active principle. Materials and methods: The prompt anti-inflammatory constituent was isolated from Delonix elata flower extracts using bioassay guided fractionation in liposaccharide (LPS) stimulated RAW 264.7 macrophage cell line. The anti-inflammatory activity of extracts/fractions/sub-fractions/compounds (10, 25, and 50μg/ml) was evaluated by estimating the levels of nitric oxide (NO), TNF-α, and IL-1β after 24h of LPS induction (1μg/ml). The isolated active compound was subjected to NMR, IR, and UV analyses for structure determination. Results: In an attempt to search for anti-inflammatory constituents, the active pure principle was isolated and crystallized as a white compound from Delonix elata flowers methanol extract. This active compound (50μg/ml) decreased the release of inflammatory mediators levels such as NO (0.263±0.03μM), TNFα (160.20±17.57pg/ml), and IL-1β (285.79±15.16pg/ml) significantly (p<0.05); when compared to the levels of NO (0.774±0.08μM), TNFα (501.71±25.14pg/ml), and IL-1β (712.68±52.25pg/ml) from LPS-stimulated macrophage cells. The active compound was confirmed as hesperidin with NMR, IR, and UV spectroscopy data. This is the first report of this compound from Delonix elata flowers. Conclusion: The findings of the study support the traditional use of Delonix elata flowers to treat inflammation.