Anti-inflammatory action of hydroalcoholic extract, dichloromethane fraction and steroid α-spinasterol from Polygala sabulosa in LPS-induced peritonitis in mice

Ethnopharmacological relevance: Polygala sabulosa A. W. Bennett is a small herb popularly known as "timutu-pinheirinho" that is widely distributed in southern Brazil and that is used to treat disorders of the bowel and kidney and as a topical anesthetic and expectorant in folk medicine. This study was designed to investigate the anti-inflammatory properties of the hydroalcoholic extract (HEPs), CH2Cl2 fraction and the steroid α-spinasterol obtained from the aerial parts of Polygala sabulosa in a model of acute inflammation induced by intraperitoneal injection of Bacterial lipopolysaccharide in mice.

Materials and methods: The anti-inflammatory effect of HEPs (3-300 mg/kg, i.g.), CH2Cl2 fraction (0.003-30 mg/kg, i.g.) and steroid α-spinasterol (0.001-1mg/kg, i.p. or 1-10mg/kg, i.g.), were evaluated in mice subjected to the acute inflammation caused by intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 0.02 µg/kg). The anti-inflammatory activity of the HEPs, CH2Cl2 fraction and steroid were assessed by determining the total numbers of leukocytes and differential cell counts (neutrophils and mononuclear cells) and levels of pro-inflammatory (IL-1β, TNF-α, IL-6) or anti-inflammatory (IL-10) cytokines in peritoneal fluid.

Results: The administration of HEPs (3-300 mg/kg, i.g.) completely inhibited inflammatory cell infiltration (300 mg/kg, i.g.) and it reduced TNF-α (100-300 mg/kg) and IL-1β (100mg/kg) levels in LPS-injected mice. Furthermore, the administration of CH2Cl2 fraction (0.003-30 mg/kg, i.g.) or α-spinasterol (0.001-10mg/kg, by i.p. or i.g.) significantly reduces inflammatory cell infiltration in LPS-injected mice. Moreover, dexamethasone (0.5mg/kg, i.p., used as a positive control) inhibited inflammatory cell infiltration and reduced the levels of TNF-α, IL-1β and IL-6 in LPS-injected mice.

Conclusions: Taken together, these results provide the first experimental evidence demonstrating that HEPs have significant anti-inflammatory effects on LPS-induced inflammation. These effects appear to be, at least in part, due to the presence of α-spinasterol. These findings support the widespread use of Polygala sabulosa in popular medicine and demonstrate that this plant has therapeutic potential for the development of phytomedicines with anti-inflammatory properties.

Cytokines; Inflammation; Lipopolysaccharide; Polygala sabulosa; Polygalaceae; α-spinasterol.