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.

Chemical Composition, Anti-α-Glucosidase Activity, and Molecular Modelling Studies of Cleistocalyx operculatus Essential Oil

“…The simulation protocol followed in this study was based on our previous work [6]. Molecular dynamics simulations were conducted using GROMACS 2020.4 to assess the stability of the complexes between ligands and α-glucosidase.…”

“…Inhibitors of α-glucosidase are compounds utilized to block or decrease the activity of the enzyme. They find applications in the treatment of conditions like type 2 diabetes, and serve as potential targets for drug design [6]. α-glucosidase inhibitors can bind to the enzyme's active site either competitively or non-competitively, thereby preventing the substrate from binding or interfering with the catalytic mechanism [3].…”

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“…The anti-inflammatory activities are revealed as the aqueous extract expressed strong IL-1α and IL-8 inhibitions, while the 70% ethanolic extract showed IL-1α and NO inhibition. A. crassna Pierre ex Leomte is a highly valuable medicinal plant that belongs to the family Thymelaeaceae 18 . Found in the rainforests throughout Southeast Asia.…”

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.…”