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α‐Amylase is an endoenzyme that catalyses the hydrolysis of internal α‐l,4 glycosidic linkages in polysaccharides to produce maltose, maltotriose, and α‐limit dextrins. It is widely used in the laboratorial and industrial workflow for several applications. There are several methods utilizing different techniques and substrates to assess α‐amylase activity, among which the spectroscopic methods have found widespread applicability due to their ease of use and cost‐effectiveness. Depending upon the reaction principle, these assays are classified into four groups: reducing sugar, enzymatic, chromogenic, and amyloclastic methods. Despite the presence of numerous methods, there is no general reliable method to assess α‐amylase activity. Each method is shown to have its own merits and demerits. Many improvements have been made to make the available methods more accurate, reliable, and easy. This communication briefly discusses the basic reaction mechanisms and critically reviews the advantages and shortcomings associated with each method. Further recommendations are made for future development. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

For the first time, a reliable, simple, rapid and high-throughput analytical method for the detection and quantification of α-amylase inhibitory activity using the glucose assay kit was developed. The new method facilitates rapid screening of a large number of samples, reduces labor, time and reagents and is also suitable for kinetic studies. This method is based on the reaction of maltose with glucose oxidase (GOD) and the development of a red quinone. The test is done in microtitre plates with a total volume of 260 μL and an assay time of 40 min including the pre-incubation steps. The new method is tested for linearity, sensitivity, precision, reproducibility and applicability. The new method is also compared with the most commonly used 3,5-dinitrosalicylic acid (DNSA) method for determining α-amylase activity. [ABSTRACT FROM AUTHOR]

• Sesbania grandiflora is an edible medicinal plant widely distributed in Asia, it exhibited diverse biological effects. • One of its folk uses is to treat or alleviate type 2 diabetes mellitus. • LC-HRMS proved that its leaves and twigs are rich in flavonoids and terpenes. • Vomifoliol, loliolide, quercetin, and kaempferol are potent inhibitors of metabolic enzymes involved in type 2 diabetes. Sesbania grandiflora L. Poir is an edible medicinal plant widely distributed in Asian countries. One of its folk medicinal uses is the alleviation or treatment of Type 2 Diabetes mellitus (T2DM). A number of animal studies confirmed its use in treating T2DM; however, none of them explored the chemistry or the possible mechanism. This study aims to unveil the chemical profile of S. grandiflora through LC-HRMS dereplication analysis, followed by isolation, identification and quantification of the major secondary metabolites with potential α-amylase and α glucosidase inhibitory effect as the potential anti-diabetic mechanism. LC-HRMS chemical profiling of its leaves and twigs identified 32 metabolites. Bio-guided fractionation and HPLC purification led to the isolation of 14 major metabolites that were screened for their α-amylase and α-glucosidase inhibitory activities. For the first time, two terpenoids; vomifoliol (11) and loliolide (14) showed inhibitory effect against α-glucosidase with IC 50 values of 64.5 and 388.48 µM, respectively. Quercetin (10) exhibited the highest α-glucosidase inhibition with IC 50 value of 17.45 µM. Further, predicated molecular modelling studies demonstrated strong binding interactions between active compounds and enzyme-substrate binding pockets supporting the observed enzyme inhibitory activity. Interestingly, the quantitative analysis of the most potent inhibitors indicated their existence at a high percentage within S. grandiflora extract. Our findings suggested S. grandiflora is a useful dietary supplement to control postprandial blood glucose. [ABSTRACT FROM AUTHOR]