Free radical scavenging activities and inhibition of inflammatory enzymes of phenolics isolated from Tripodanthus acutifolius

Ethnopharmacological relevanceLeaf extracts from Tripodanthus acutifolius (Ruiz and Pavón) Van Tieghem have long been used in argentinean traditional medicine as anti-inflammatory, however, there is no scientific evidence which supports this use in the literature.Aim of the studyThe present study was conducted to evaluate the ability of five phenolic compounds purified from infusion prepared from Tripodanthus acutifolius leaves to inhibit key enzymes in inflammatory processes. As anti-inflammatory compounds frequently possess free radical scavenging activities, purified substances were comparatively evaluated to asses their free radical scavenging properties. Genotoxic effects were also evaluated.Materials and MethodsCompounds were evaluated on their ability to inhibit hyaluronidase and cyclooxygenase-2 (COX-2) activities to assess their anti-inflammatory capacities. Free radical scavenging activity was assessed by: 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH), superoxide anion assay and the inhibition on lipid peroxidation. Genotoxicity was evaluated by Bacillus subtilis rec assay.ResultsFractionation of Tripodanthus acutifolius infusion yielded a novel phenylbutanoid derivative (tripodantoside) and four known flavonoid glycosides (rutin, nicotiflorin, hyperoside and isoquercitrin). Flavonoids produced higher inhibition on hyluronidase activity (IC50 ≈ 1.7 mM) than tripodantoside (IC50 = 27.90 mM). A similar COX-2 inhibition activity was exerted by tripodantoside and monoglycosilated flavonoids (IC50 ∼ 50 μM). Compounds were strong radical scavengers, with effective concentration 50 (EC50) values for DPPH in the range of 2.7–6.3 μg/mL, and for superoxide anion in the range of 3.9–8.7 μg/mL. All compounds scavenged peroxyl radicals in the lipid peroxidation assay. The substances showed no genotoxic effects.ConclusionsThe anti-inflammatory effects, free radical scavenging activities and lack of genotoxicity of purified compounds may support the folk use of infusion from Tripodanthus acutifolius leaves as anti-inflammatory.

Graphical abstractLeaf extracts of Tripodanthus acutifolius (Ruiz and Pavón) Van Tieghem are used in argentinean folk medicine as antiinflammatories. A free radical scavenging activity guided fractionation was performed from Tripodanthus acutifolius leaf infusion. A novel phenylbutanoid glycoside: “tripodantoside”, and four flavonoids were purified, identified and evaluated for their ability to inhibit inflammatory key enzymes, free radical scavenging activities and genotoxicity. The obtained results support the efficacy of the traditional use of Tripodanthus acutifolius extracts in the treatment of inflammatory processes.Figure optionsDownload full-size imageDownload as PowerPoint slide