α-Glucosidase Inhibitory Activity and Quantitative Contribution of Phenolic Compounds From Vietnamese Aquilaria crassna Leaves

Abstract

Aquilaria crassna Pierre ex Lecomte, Thymelaeaceae, is cultivated for producing resinous heartwood, also called agarwood. Its leaves are a source of herbal tea in Vietnam due to its rich content of polyphenols. However, the α-glucosidase inhibition activity and the contents of phenolic compounds in leaves of different ages have not yet been determined. In the current study, 7 polyphenols [iriflophenone 3,5-C- β-D-diglucoside (1), iriflophenone 3-C- β-D-glucoside (2), mangiferin (3), iriflophenone 2- O- α-rhamnoside (4), genkwanin 5- O- β-primeveroside (5), genkwanin 4′-methyl ether 5- O- β-primeveroside (6), and genkwanin (7)] were isolated from the leaves of A crassna. Among them, genkwanin (7), an O-methylated flavone, was the most active compound that inhibited α-glucosidase activity, with an IC50 value of 24.0 μM. Molecular docking studies were performed to understand the binding interactions of the active compounds. In addition, a reliable and straightforward reversed-phase HPLC method was developed to determine the content of compounds in different leaves of A crassna. Mangiferin (3) showed the highest content. The contents of 1-4 contributed to the total polyphenolic contents and significantly decreased from the youngest to the oldest leaf. The contents of 5-7 fluctuated through various ages of leaves. Compounds 5 and 6 showed a low accumulation in the first and second leaves, then obtained high contents among middle leaves and declined in the oldest. These results suggested that A crassna and its polyphenols may prevent the development and progression of diabetes through α-glucosidase inhibition. Also, the analysis of the polyphenol content in A crassna may be helpful for tea product manufacture.

Xanthine oxidase, α-glucosidase and α-amylase inhibitory activities of the essential oil from Piper lolot: In vitro and in silico studies

“…In individuals with type 2 diabetes, their ability to regulate blood sugar levels is impaired due to insulin resistance or insufficient insulin production. Therefore, inhibiting the activities of alpha-glucosidase and alpha-amylase can be beneficial for individuals with type 2 diabetes in controlling blood sugar levels by postponing the digestion of complex carbohydrates in the intestine, leading to a slower release of glucose into the bloodstream [ [4] , [5] , [6] ]. In this study, we focused on finding natural ingredients that can inhibit the activity of these protein targets to support the treatment of gout and diabetes.…”