In vitro and in vivo anti-inflammatory activity of Tetrastigma sulcatum leaf extract, pure compound and its derivatives

Abstract

The severity and perseverance of inflammation have been demonstrated in many health conditions. The limitations of existing medications suggest the need for new alternative anti-inflammatory medications. In our earlier studies, we demonstrated the topical anti-inflammatory potential of the crude ethanolic extract of Tetrastigma sulcatum leaves and its fractions. In the present study, we further explored the anti-inflammatory activity of T. sulcatum extract, fractions, pure compound and its derivatives using in vitro and in vivo bioassay techniques. We attempted to isolate a pure compound from the leaf extract and identified it as a Friedelan-3β-ol (CI). Furthermore, Friedelinol acetate (C II) and friedelinol methyl ether (C III), derivatives of Friedelan-3β-ol (CI) were synthesised. LPS-induced inflammatory RAW 264.7 macrophages were used as in vitro model to study anti-inflammatory and anti-oxidative effects. Inflammation-induced oxidative damage was found to be restricted significantly (P < 0.001), with scavenging activity and increased SOD activity of crude extract and fractions. Treatment with crude extract (TSETOH) and fractions (TSHEX, TSTOL) significantly reduced (P < 0.001) the mRNA expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and nitric oxide (NO) production in LPS-stimulated inflammation in RAW 264.7 cells in a dose-dependent manner. Likewise, compounds CI and CIII showed a similar pattern of significant inhibition (P < 0.001) of pro-inflammatory cytokines and NO production in a dose-dependent manner. An in vivo study in a carrageenan-induced mouse paw oedema model demonstrated reduced paw oedema and pro-inflammatory cytokines in a dose-dependent manner upon treatment with the extract, its fractions, pure compound (CI), and their derivatives (CII, and CIII). The present study confirmed the anti-inflammatory activity of T. sulcatum, suggesting that Friedelan-3β-ol is an active component of the crude extract.

Keywords: Anti-inflammatory activity; Antioxidant activity; DPPH assay; FRAP assay; Friedelan-3β-ol; Inflammatory cytokines; NO production; ROS; SOD; Tetrastigma sulcatum.