Evaluation of in-vitro glycemic regulatory and cholesterol lowering activity of two varieties of Cinnamomum zeylanicum Blume

Abstract

Cinnamomum zeylanicum Blume is a well-known medicinal plant and Sri Lanka has two main varieties as Sri Gemunu (SG) and Sri Wijaya (SW). Present study aimed to comparatively evaluate the in-vitro glycemic regulatory and cholesterol-lowering activity in leaves and barks of SG and SW varieties. Aqueous extracts of leaves of SG (SGL), leaves of SW (SWL), barks of SG (SGB), and barks of SW (SWB) were obtained and glycemic regulatory activity was evaluated by in-vitro alpha-amylase (AAM), alpha-glucosidase (AGU), anti-glycation (AGY) assays. Cholesterol-lowering activity was evaluated by Lieberman-Burchard method. IC50 values for standard acarbose, SGL, SWL, SGB, and SWB in AAM assay were 0.08±0.00, 1.24±0.08, 1.13±0.05, 0.20±0.01, and 0.13±0.03 in mg/mL respectively while in AGU assay they were 186.70±4.38, 102.00±3.24, 96.68±3.14, 10.43±0.75, and 9.47±0.72 in µg/mL. Standard rutin, SGL, SWL, SGB, and SWB gave IC50 of 250.4±4.35, 212.4±8.60, 187.5±1.63, 52.07±2.13 and 45.35±6.46 in µg/mL for AGY assay. IC50 values of 17.75±2.23, 201.7±8.22, 175±7.00, 110.8±4.49 and 85.02±7.63 in µg/mL were given by standard atorvastatin, SGL, SWL, SGB, and SWB respectively for cholesterol-lowering assay. Leaves and barks have shown significantly higher glycemic regulatory activity (except in AAM) than the respective standards (p<0.05). Comparable glycemic regulatory and cholesterol-lowering activity (p>0.05) were shown among barks and among leaves (except in AGY) in the two varieties. Barks and leaves in the same variety have shown significant difference (p<0.05) in glycemic regulatory and cholesterol-lowering activity. It was concluded that both leaves and barks in C. zeylanicum varieties can be considered as potential glycemic regulatory and cholesterol-lowering natural agents. However, their potentials vary according to the variety.