Inhibition of protein tyrosine phosphatase 1B and regulation of insulin signalling markers by caffeoyl derivatives of chicory ( Cichorium intybus) salad leaves.

Evaluations of molecular mechanisms of dietary plants with their active molecules are essential for the complete exploration of their nutritive and therapeutic value. In the present study, we investigated the effect of chicory (Cichorium intybus) salad leaves in inhibiting protein tyrosine phosphatase 1B (PTP1B), and evaluated their role in modulating the key markers involved in insulin cell signalling and adipogenesis using 3T3-L1 adipocytes. Bioactivity-directed purification studies enlightened the additive effects of chlorogenic acid (CGA) along with other caffeic acid derivatives present in methanolic extract of C. intybus (CME). Incubation of CME and CGA with 3T3-L1 adipocytes significantly enhanced the 2-deoxy-d-3[H]-glucose uptake and inhibited adipogenesis through altering the expressions of insulin signalling and adipogenesis markers. Extending to an in vivo model, the effect of CME was also investigated on insulin sensitivity in high-fat diet with low streptozotocin-induced diabetic rats. Supplementation of CME for 2 weeks reinstated the insulin sensitivity along with plasma metabolic profile. The present results demonstrate that the caffeoyl derivatives of chicory salad leaves show promising pharmacological effect on energy homoeostasis via PTP1B inhibition both in vitro and in vivo.