Inhibitory effects of flavonoids isolated from Givotia rottleriformis bark and Cassia tora leaves on the production of pro-inflammatory cytokines in LPS stimulated human whole blood

The plants Givotia rottleriformis bark and Cassia tora leaves were used in indigenous medicine in the treatment of chronic inflammatory diseases like psoriasis. In previous work, three flavonoids namely Rutin (I), Luteolin-7-O-β-D-Glucuronide (II) and Kaempferol 3-O-[2-O-(6-O-feruloyl)-β-D-glucopyranosyl]-β-D-galactopyranoside (III) were isolated from G. rottleriformis bark and three flavonoids viz quercetin-3-O-β-d-glucuronide (IV), Luteolin-7-O-β-glucopyranoside (V) and Formononetin-7-O-β-D-Glucoside (VI) were isolated from C. tora leaves and evaluated for antipsoriatic activity. The cytotoxic effect of isolated compounds I-VI was evaluated using HaCaT cells, a rapidly multiplying human keratinocyte cell line, as a model of epidermal hyperproliferation in psoriasis. Among the isolated compounds, compound II, III and VI showed significant antiproliferant activity in HaCaT cells. Pro-inflammatory cytokines viz., IL-1α, IL-1β, IL-6, IL-8, IL-17 and TNF-α contributes to the pathogenesis of chronic inflammatory skin diseases such as psoriasis and has been a target for the development of the new anti-psoriatic drug. Hence the present study aimed to evaluate inhibitory effects of ethanol extract of selected plants and isolated compound II, III and VI (5-40 mg/mL) on lipopolysaccharide (LPS) induced pro-inflammatory cytokines viz., IL-1α, IL-1β, IL-6, IL-8, IL-17 and TNF-α production. The level of IL-1α, IL-1β, IL-6, IL-8, IL-17 and TNF-α pro-inflammatory cytokines were detected using enzyme-linked immunosorbent assay. The ethanol extract of both the plants was standardized by HPLC using chemical markers. Preincubation with isolated compounds II, III, VI and ethanol extract of selected plants strongly attenuated LPS-induced increase in the concentrations of IL-6 (50-73 %) and TNF-α (64-90 %). The compound II and III also showed significant inhibition (*p ≤0.05) of IL-1β, IL-8 and IL-17. The results showed that the selected plants and isolated flavonoids have potential effects as anti-inflammatory agents by inhibiting the release of pro-inflammatory cytokines supporting the folkloric utilization.