Background
Sida linifolia L. is a weed ubiquitously found in Africa with several folkloric applications. Traditional healers in the Southeastern part of Nigeria employ the alcoholic concoction of S. linifolia leaves as antidepressants, anti-malaria, antihypertensive, anti-abortifacients, and for managing painful whitlow; however, these claims lack scientific validation. The present study was aimed to explore the phytochemical profile of the plant, S. linifolia with special emphasis to its antioxidant and inhibitory actions on enzymes linked to inflammation, diabetes, and neurological disorders. Phytochemical profiling and in vitro antioxidant and enzyme inhibition assays were employed to assess the pharmacological profile of S. linifolia ethanolic leaf fraction (SLELF).
Results
Preliminary phytochemical screening of SLELF revealed appreciable amounts of total phenolics (91.64 ± 7.61 mg GAE/g), total tannins (62.44 ± 3.86 mg TAE/g), and total flavonoids (27.35 ± 1.48 mg QE/g) present in SLELF. Results of HPLC analysis of SLELF revealed rich composition in bioactive compounds such as ellagic acid, quercetin, ferulic acid, 3,4-dimethoxy benzoic acid, gallic acid, 4-methoxy cinnamic acid, sinapic acid, vanillic acid, and chlorogenic acid. Enzymatic antioxidants (catalase and superoxide dismutase), non-enzymatic antioxidants (reduced glutathione (GSH), Vit A, C, and E), elemental minerals (Cu, Mn, Zn, Cr, Fe, and Ca), and γ-aminobutyric acid (GABA) were present in SLELF in appreciable levels. At various concentrations (0.2–1.0 mg/ml), SLELF exhibited potent and concentration-dependent hydrogen peroxide (H2O2) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) radical scavenging activities and exerted moderate inhibitory actions on enzymes associated with inflammation (cyclooxogenase-2 (COX-2) and lipoxygenases (LOXs), diabetes (α-amylase, α-glucosidase), and neurological disorders (butyrylcholinesterase (BChE) and γ-aminobutyric acid transaminase (GABA-T), compared to respective standards (ascorbic acid, acarbose, indomethacin, galanthamine, and vigabatrin). Perhaps, the observed potent pharmacological activities of SLELF could be anchored to its phytoconstituents. Furthermore, the slightly higher ranges of IC50 values (0.57–0.87 mg/ml) of SLELF compared to standards (0.44–0.68 mg/ml) suggest moderation in enzyme inhibition that may preclude adverse side effects.
Conclusion
This study lends credence to the folklore claims of S. linifolia leaves and revealed its potential as possible source of bioactive compounds for medicinal and pharmaceutical exploration.
