Bioactive compounds, anti-inflammatory, anti-nociceptive and antioxidant potentials of ethanolic leaf fraction of Sida linifolia L. (Malvaceae)

This study investigated the bioactive compounds, anti-inflammatory, anti-nociceptive, and antioxidant properties of the ethanolic leaf fraction of Sida linifolia (ELFSL). The in vitro anti-inflammatory study employed membrane stabilization, phospholipase A2, platelet aggregation, albumin denaturation, and protease inhibition assays. Intraperitoneal injection of freshly prepared carrageenan solution (0.1 mL of 0.01 g/mL), undiluted egg albumin (0.1 mL), acetic acid (0.6 % (v/v) (10 mL/kg bw), and formalin solution (0.02 mL of 1 % v/v) into mice hind paw, were used to evaluate the anti-inflammatory and anti-nociceptive mechanisms, respectively. In vitro antioxidant potentials were determined using 1,1-Diphenyl-2-picryl-hydrazyl (DPPH), nitric oxide (NO), ferric reducing power (FRAP), and total antioxidant capacity (TAC) assays. Varying quantities of flavonoids, phenols, tannins, saponins, terpenoids, steroids, and alkaloids, were detected in the fraction. GC-FID phytochemical profiling of ELFSL revealed a high level of epicatechin, moderate levels of catechin, kaempferol, flavone, naringenin, rutin flavanones, tannins, sapogenins, proanthocyanidin, and steroids, and small amounts of sparteine, resveratrol, and lunamarine. The ELFSL exerted excellent dose-dependent in vitro anti-inflammatory activities comparable with standard drugs (aspirin/prednisolone). The LD50 test showed safety up to 5000 mg/kg body weight (per oral) ELFSL. Interestingly, mice pre-administered various doses (200, 400, 600 mg/kg bw, po) of ELFSL showed significant (P < 0.05) reduction in edema, writhing, and time spent licking paw in all phases compared with control and were at par with 100 mg/kg bw (po) aspirin. The result also registered good concentration-dependent antioxidant potentials for ELFSL and was comparable to standards (gallic acid, butylated hydroxytoluene, and ascorbic acid). These imply that ELFSL possesses excellent antioxidant, anti-inflammatory, and anti-nociceptive potentials mediated by peripheral and central mechanisms.