Screening of flavonoid "quercetin" from the rhizome of Smilax china Linn.for anti-psoriatic activity

Objective:To assess anti-psoriatic activity of the methanol extract and the isolated flavonoid quercetin from the rhizome of Smilax china（S.china） Linn.Methods:Mouse tail test was used for the evaluation of anti-psoriatic activity.Methanol extract（100 and 200 mg/kg b.w.） and isolated flavonoid quercetin（25 and 50 mg/kg b.w.） were tested in Swiss albino mice.Parameters studied in the mouse tail test were changes in epidermal thickness and percentage orthokeratotic values.The anti-inflammatory role of the methanol extract and isolated flavonoid quercetin was evaluated using carrageenan-induced pleurisy in rats.In vitro antiproliferant assay on HaCaT cell lines was also carried out.Results:The isolated flavonoid quercetin from the rhizome of S.china produced significant orthokeratosis（P<0.01） in the mouse tail test.In epidermal thickness,a significant reduction with respect to control was observed in groups treated with retinoic acid and isolated flavonoid quercetin.The methanol extract（200 mg/kg） and isolated flavonoid quercetin（50 mg/kg） showed anti-inflammatory effect in terms of significant inhibition（P<0.001） in leukocyte migration.Maximum antiproliferant activity was shown by isolated flavonoid quercetin(IC50,62.42± 10.20 μg/mL).Conclusions:From the above data,the flavonoid quercetin shows significant orthokeratosis,anti-inflammatory and maximum antiproliferant activities.To our knowledge,this is the first report on the anti-psoriatic effect of the flavonoid quercetin which is promising for further investigations to prove its anti-psoriatic activity.