Anti-psoriatic activity of flavonoids from Cassia tora leaves using the rat ultraviolet B ray photodermatitis model

The plant Cassia tora L., Fabaceae, traditionally, is claimed to be useful in the treatment of psoriasis and other skin diseases. In order to evaluate this information, antipsoriatic activity of three flavonoids, namely luteolin-7-O-β-glucopyranoside (1), quercetin-3-O-β-D- glucuronide (2) and formononetin-7-O-β-D-glucoside (3), isolated from the ethanol extract of C. tora leaves were investigated using UV-B induced photodermatitis model. Further, the flavonoids present in the ethanol extract were identified using HPLC by comparing their retention time with known standard luteolin, quercetin and formononetin. In the UV induced photodermatitis model, histopathological analysis of the section revealed the absence of Munro's microabscess, elongation of rete ridges, and capillary loop dilation in ethanol extract (400 mg/kg), isolated compound 2, 3 and standard group. The ethanolic extract (400 mg/kg) and isolated compounds 1, 2 and 3 exhibited a significant (p < 0.01) percentage reduction of relative epidermal thickness when compared with a positive control. In the HPLC analysis, three flavonoids were identified by comparison of the retention times of standard marker, namely luteolin, quercetin and formononetin. We concluded, using animal model, that the flavonoids from Cassia tora leaves have significant antipsoriatic activity.