Enhanced Bioactive Constituents and Improved AMPK and GLUT Dependent Glucose Uptake Effect of Thunbergia Laurifolia Leaves by Calcium Chloride and Yeast Extract Elicitors in Postharvest Treatment

Thunbergia laurifolia Lindl., Acanthaceae, leaves are a well-known commercialized infusion tea for health-supplement proposes. Its major phytochemical compounds are phenolic acids and flavonoids, which exhibited 5 ' adenosine monophosphate activated protein kinase (AMPK) and insulin-regulated glucose transporter (GLUT) mechanisms on glucose uptake activity. This study developed the postharvest process in T. laurifolia leaves by yeast extract and CaCl2 treatments. The results showed that rosmarinic acid, vicenin-2, and rutin contents in the treatment with 1% of yeast extract for 20 min were increased up to sixfold, fourfold, and 215-fold over the control, respectively. In addition, rutin and caffeic acid contents were obtained more than threefold and fourfold, respectively, using 1% of CaCl2 treatment for 10 min. The higher phenolic acids and flavonoids contents could correlate with a key gene expression level in the plant biosynthesis pathway and enzymatic activity. The treated T. laurifolia leaves enhanced the glucose uptake via regulation of AMPK and GLUT on rat skeletal muscle (L6) cells. Our findings suggest that yeast extract and CaCl2 can enhance phenolic acids and flavonoids contents by postharvest treatment and improved health-promoting supplements with anti-diabetic activity in T. laurifolia leaves.