Abstract:To clarify the postprandial glucose suppression effects of phenols from Toona sinensis leaves, its inhibitory effects against key enzymes (porcine pancreatic α-amylase, rat intestinal sucrase and maltase) linked to type 2 diabetes were investigated. Results showed that the crude extract of Toona sinensis leaves had significant enzyme inhibitory activities. Its IC50 values for the three key enzyme activities were 0.45, 1.29, and 1.41 mg/mL, respectively. The 70% ethanol sub-fraction of the ethyl acetate fraction was mainly responsible for enzymes inhibitory activities, which showed the strongest enzyme inhibitory activities with IC50 values of 0.091, 0.97, and 1.00 mg/mL, respectively, on porcine pancreatic α-amylase, rat intestinal sucrase and maltase. PGG (1, 2, 3, 4, 6-penta-O-galloyl-β-D-glucopyranose) and EG (ethyl gallate) isolated from 70% ethanol sub-fraction were identified as the active monomer compounds. PGG exhibited significant enzyme inhibitory activity against α-amylase with IC50 value of 0.069 mg/mL. The EG had inhibitory effects on sucrase and maltase to some extent. Its IC50 value for sucrase and maltase were 0.82 and 0.81 mg/mL, respectively. This study revealed that Toona sinensis leaves may be helpful to develop drug and functional foods for diabetes and related symptoms.
