Effect of Smallanthus sonchifolius extracts on croton oil-induced oedema and neutrophil migration to the ear skin tissue of mice

Smallanthus sonchifolius (yacón) is an Andean species whose leaves have glandular trichomes rich in sesquiterpene lactones (STLs). The chemical profile of the leaf rinse extract (RLE) of yacón showed several STLs [1]. The major STL isolated were quantified [2] and the in vitro anti-inflammatory effect of the two major STLs was evaluated [1]. However, STLs are known for their oral toxicity and the study of topical applications can be an alternative to the use of these anti-inflammatory substances. Thus, the aim of this work was to evaluate the in vivo topic anti-inflammatory potential of yacón. The RLE was obtained from entire dried leaves rinsed with acetone. After liquid-liquid partition with n-hexane the resulting hydromethanolic fraction was evaluated using the croton oil ear oedema assay in mice [3]. Subsequently, fragments of ears were used for myeloperoxidase (MPO) determination in order to evaluate leukocyte migration to the subcutaneous tissue. IR spectrum and HPLC-UV-DAD analysis demonstrated that the RLE is a STL-rich extract, which showed anti-oedematogenic activity (Image 1A) followed by inhibition of neutrophil migration to the inflamed tissue in all tested doses (Image 1B). Plant extracts that decrease oedema and leukocytes migration can be an useful alternative to the treatment of topical inflammatory injuries. Thus, the STL-rich extract of yacón can be a promising phytotherapeutic agent for topic application in the inflammatory process.

Fig.1: Topical anti-inflammatory activity of the RLE. A. Croton oil assay. B. MPO quantification. Mean±S.E.M, ANOVA one-way, Tukey's post-test. * P<0.05 in relation to the control. N=10 animals.

Acknowledgements: FAPESP, CAPES.

References: 1. Schorr, K. et al. (2007) Nat. Prod. Commun. 2:367–374.

2. Schorr, K. et al. (2005) Phytochem. Anal. 16:161–165.

3. Tubaro, A et al. (1985). Agents and Actions. 17:347–349.