Inhibition and reversal of formaldehyde-induced inflammation in rats by active compounds isolated from leaf extract of Chikadoma plant (<i>Duranta repens</i>)

Purpose: To investigate the anti-inflammatory activity of the leaf extracts of Duranta repens. Methods: Methanol, ethyl acetate, and hexane fractions from the methanol crude extract of Duranta repens leaves were obtained using gradient mixture elution in bioactivity-guided silica gel column chromatography. A mixture of spectrochemical, infrared (IR), nuclear magnetic resonance (NMR), and gas chromatographic/mass spectroscopic (GC/MS) investigations were used to clarify the structures of the identified active chemicals. A total of 50 Wistar rats randomized into 10 groups (n = 5) were given either 200 mg/kg of Hexane fraction (HFCP) or ethylacetate fraction (EAFCP) intraperitoneally. A subplantar injection of 0.1 mL 2.5 % formaldehyde solution was used to induce inflammation 1 h later, and this procedure was repeated on day three. After five days, the compounds were administered once daily, and then every other day for the next five days. Using a plethysmometer, the rat paw volume was measured every day following a 1 h drug delivery period. Diclofenac was used as the control. Results: Compounds isolated belong to the following groups: flavonol glycoside, stigmast steroid and triterpenehydroxyl acid. The molecules identified by their structures are ursolic acid, stigmastene 3, 6- dione, and tetrahydroxy flavone-3α-rhamnoside, respectively. In rats, the combination of these compounds showed significant (p < 0.05) biological action against formaldehyde-induced inflammation, exceeding the respective percentage inhibition of individual compounds (62.60, 82.60, and 62.60 %; p < 0.05). Conclusion: There is a significant anti-inflammatory activity of active compounds from the leaves of Chikadoma plant. The mechanism of this anti-inflammatory activity is through synergism. Clinical studies are necessary to advance the safety and toxicity profiles of these products.