In vitro inhibitory effects of mistletoes (Loranthus begwensis L.) phenolic-rich extracts on α-amylase, α-glucosidase, and angiotensin converting enzyme activities

Abstract

This study focused on the effect of phenolic-rich extracts of mistletoe from different host plants on key enzymes (α-amylase, α-glucosidase) linked to type-2 diabetes (T2D) and hypertension (angiotensin-I converting enzyme [ACE]), as well as Fe2+ and sodium nitroprusside (SNP)-induced thiobarbituric acid reactive species (TBARS) production in rat pancreas in vitro. The phenolic-rich extract was prepared using ethyl acetate and the effects on α-amylase, α-glucosidase, and ACE activities, and TBARS production was determined. The phenolic constituent of the extract was also determined. The results revealed that the extracts (CCT, KNT, AMT, BFT) inhibited α-amylase (EC50 = 2.24, 2.59, 2.36, and 1.80 µg/mL, respectively), α-glucosidase (EC50 = 1.94, 1.92, 1.96, and 8.59 µg/mL), and ACE (EC50 = 0.87, 0.67, 0.75, and 1.06 µg/mL) activities, and Fe2+ and SNP-induced TBARS production. Therefore, inhibition of α-amylase, α-glucosidase, ACE, and oxidative stress by the phenolic-rich extracts could be among the mode of actions of mistletoe toward the management of T2D and hypertension. Practical applications Dried mistletoe leaves are usually consumed as tea or decoction, and are often prescribed for hypertensive or diabetic patients while the wet leaves are used to cook soup. This study revealed the possible antidiabetic, antihypertensive, and antioxidant properties of mistletoe leaves from different host plants.