This study employed the α-glucosidase inhibitory activity model as an anti-diabetic assay and implemented a bioactivity-guided isolation strategy to identify novel natural compounds with potential therapeutic properties. Hypericum sampsoniiwas investigated, leading to the isolation of two highly modified seco-polycyclic polyprenylated acylphloroglucinols (PPAPs) (1 and 2), eight phenolic derivatives (3-10), and four terpene derivatives (11-14). The structures of compounds 1 and 2, featuring an unprecedented octahydro-2H-chromen-2-one ring system, were fully characterized using extensive spectroscopic data and quantum chemistry calculations. Six compounds (1, 5-7, 9, and 14) exhibited potential inhibitory effects against α-glucosidase, with IC₅₀ values ranging from 0.050 ± 0.0016 to 366.70 ± 11.08 μg·mL^-1. Notably, compound 5 (0.050 ± 0.0016 μg·mL^-1) was identified as the most potential α-glucosidase inhibitor, with an inhibitory effect about 6900 times stronger than the positive control, acarbose (IC₅₀ = 346.63 ± 15.65 μg·mL^-1). A docking study was conducted to predict molecular interactions between two compounds (1 and 5) and α-glucosidase, and the hypothetical biosynthetic pathways of the two unprecedented seco-PPAPs were proposed.
Molecular Structure ; Hypericum/chemistry* ; alpha-Glucosidases ; Magnetic Resonance Spectroscopy ; Glycoside Hydrolase Inhibitors/pharmacology*

Based on the idea of plant metabolomics, ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS/MS) was used to compare the chemical composition between 6 batches of fruit vinegar brewed from Choerospondias axillaris fruit peel and 6 batches of apple vinegar purchased from 3 companies. Antioxidant and α-glucosidase inhibition activities were also tested in vitro. A total of 43 compounds were identified by reference substance, liquid chromatography-mass spectrometry(LC-MS/MS) fragmentation information or literature data. A total of 40 compounds were identified in the C. axillaris fruit peel vinegar. A total of 16 compounds were identified in apple vinegar. There were 13 common ingredients including organic acids and esters such as citric acid, 2-isopropyl malic acid, and triethyl citrate. The results of partial leastsquares-discriminant analysis(PLS-DA) indicated that they had 33 significantly different compounds such as proanthocyanidin oligomer, quercetin-3-O-rhamnoside and heptadecanoic acid. The proanthocyanidins and flavonoid glycosides in C. axillaris peel vinegar were more abundant than apple vinegar, so it had better health function than ordinary fruit vinegar. The results showed that C. axillaris fruit peel vinegar had stronger antioxidant and α-glucosidase inhibition activities in vitro. The vinegar brewed from waste C. axillaris fruit peel had more chemical ingredients than the apple vinegar. C. axillaris fruit peel vinegar had better biological activity and health function, so it had good development prospect. This study provided the scientific evidence for exploiting the C. axillaris fruit peel into high value-added products. It also provided ideas for the comprehensive development and utilization of similar Chinese medicine waste.
Acetic Acid/pharmacology* ; Anacardiaceae/chemistry* ; Antioxidants ; Chromatography, High Pressure Liquid ; Fruit/chemistry* ; Glycoside Hydrolase Inhibitors/pharmacology* ; Malus/chemistry* ; Plant Extracts ; Tandem Mass Spectrometry ; alpha-Glucosidases

The aim of the study was to determine the feasibility of the Vitellaria paradoxa nutshell as a new medicinal resource for treating diabetes. A total of forty-one compounds were identified by HPLC-DAD-Q-TOF-MS and phytochemical methods in V. paradoxa nutshell methanol extract. Based on HPLC fingerprints, four characteristic constituents were quantified and the origin of twenty-eight V. paradoxa nutshells from seven sub-Saharan countries was compared, which were classified into three groups with chemometric method. Twenty-eight samples contained high total phenolic content, and exhibited moderate-higher antioxidant activity and strong α-glucosidase inhibitory activity. Furthermore, all fractions and isolated compounds were evaluated for their antioxidant and α-glucosidase inhibitory activities, and α-glucosidase inhibitory action mechanism of four characteristic constituents including protocatechuic acid, 3, 5, 7-trihydroxycoumarin, (2R, 3R)-(+)-taxifolin and quercetin was investigated via molecular docking method, which were all stabilized by hydrogen bonds with α-glucosidase. The study provided an effective approach to waste utilization of V. paradoxa nutshell, which would help to resolve waste environmental pollution and provide a basis for developing potential herbal resource for treating diabetes.
Africa South of the Sahara ; Chromatography, High Pressure Liquid ; Diabetes Mellitus ; drug therapy ; enzymology ; Glycoside Hydrolase Inhibitors ; chemistry ; pharmacology ; Humans ; Hypoglycemic Agents ; chemistry ; pharmacology ; Molecular Docking Simulation ; Plant Extracts ; chemistry ; pharmacology ; Plants, Medicinal ; chemistry ; Sapotaceae ; chemistry ; alpha-Glucosidases ; metabolism

Six compounds were isolated from the aerial part of cultivated Clerodendranthus spicatus in Hainan with various chromatographic techniques,and their structures were determined as:1-dehydroxy-1-oxo-rupestrinol(1),N-trans-feruloyltyramine(2),methyl 3,4-dihydroxyphenyllactate(3),caffein acid(4),methyl caffeate(5) and ethyl caffeate(6),via analysis of physicochemical properties and spectroscopic evidence.Compound 1 was a new compound,while compounds 2 and 3 were isolated from C.spicatus for the first time.Biological activity results showed that compounds 2-4 exhibited α-glucosidase inhibitory activity with different inhibition ratio.
China ; Glycoside Hydrolase Inhibitors ; isolation & purification ; pharmacology ; Lamiaceae ; chemistry ; Molecular Structure ; Phytochemicals ; isolation & purification ; pharmacology ; Sesquiterpenes, Eudesmane ; isolation & purification ; pharmacology

OBJECTIVEThe current study was designed to evaluate the various antioxidant potentials and inhibitory effects of phenolic-rich leaf extracts of Bridelia ferruginea (BF) on the in vitro activities of some key enzymes involved in the metabolism of carbohydrates.

METHODSIn this study, BF leaf free and bound phenolic-rich extracts were used. We quantified total phenolic and flavonoid contents, and evaluated several antioxidant activities using assays for ferric reducing antioxidant power, total antioxidant activity (phosphomolybdenum reducing ability), 1,1-diphenyl-2-picrylhydrazyl and thiobarbituric acid reactive species. Also, extracts were tested for their ability to inhibit α-amylase and α-glucosidase activity.

RESULTSThe total phenolic and total flavonoid contents in the free phenolic extract of BF were significantly greater than in the bound phenolic extract. Also, all the antioxidant activities considered were significantly greater in the free phenolic extract than in the bound phenolic extract. In the same vein, the free phenolic-rich extract had a significantly higher percentage inhibition against α-glucosidase activity (IC = 28.5 µg/mL) than the bound phenolic extract (IC = 340.0 µg/mL). On the contrary, the free phenolic extract (IC = 210.0 µg/mL) had significantly lower inhibition against α-amylase than the bound phenolic-rich extract (IC = 190.0 µg/mL).

CONCLUSIONThe phenolic-rich extracts of BF leaves showed antioxidant potentials and inhibited two key carbohydrate-metabolizing enzymes in vitro.

Animals ; Antioxidants ; chemistry ; pharmacology ; Diabetes Mellitus, Type 2 ; enzymology ; metabolism ; Enzyme Inhibitors ; chemistry ; pharmacology ; Glycoside Hydrolase Inhibitors ; chemistry ; pharmacology ; Humans ; Iron ; adverse effects ; Magnoliopsida ; chemistry ; Oxidative Stress ; drug effects ; Pancreas ; drug effects ; enzymology ; metabolism ; Phenols ; chemistry ; pharmacology ; Plant Extracts ; chemistry ; pharmacology ; Rats ; Swine ; alpha-Amylases ; antagonists & inhibitors ; chemistry ; alpha-Glucosidases ; chemistry

The present study compared active ingredients of tea from different sources to select tea type and the fraction of tea extracts for the highest anti-hyperglycemic activity, and to verify anti-hyperglycemic activity of the selected tea extract. Tea extracts were separated and enriched by molecular weight using ultra-filtration technology. The extracts were first screened by -glucosidase inhibition assay, followed by using a rat inverted intestine sac system to measure the effect on glucose transport. Both alloxan-induced diabetic rat model and high-fat diet combined with streptozotocin-induced rat diabetes mellitus model were used to study the effects of active components on blood glucose, body weight, insulin resistance. The experimental results showed that the different kinds of tea extracts had different inhibitory effects on -glucosidase, and the inhibitory effect of tea extract E on -glucosidase was stronger. The effects of different components of tea extract E also varied greatly, of which Fraction AN protein had stronger inhibitory effect on -glucosidase than other fragments, and Fraction AN protein had a strong inhibitory effect on glucose transport, reduced blood sugar and normalized insulin secretion in diabetic rats. The results suggest that a glycol-protein fraction(AN) from the extracts might be responsible for the anti-hyperglycemic activity of tea polysaccharides. The AN glycol-protein fraction has strong inhibitory effects on both -glucosidase activity and glucose transport by the small intestine. It also reduced blood glucose level and normalized insulin secretion in diabetic rats, and has a protective effect on diabetic rats.
Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; drug therapy ; Glycols ; pharmacology ; Glycoside Hydrolase Inhibitors ; Hypoglycemic Agents ; pharmacology ; Plant Extracts ; chemistry ; Rats ; Tea ; chemistry ; alpha-Glucosidases

Three new labdane diterpenoids, leojaponicone A (1), isoleojaponicone A (2) and methylisoleojaponicone A (3), were isolated from the herb of Leonurus japonicus. The chemical structures of these secondary metabolites were elucidated on the basis of 1D and 2D NMR, including HMQC, and HMBC spectroscopic techniques. All the new compounds were tested in vitro for their acetylcholinesterase and α-glucosidase inhibitory activity. Compounds 1-3 exhibited low inhibitory effects on α-glucosidase with respect to acarbose and exhibited high inhibitory effects on acetylcholinesterase with respect to huperzine A.
Acetylcholinesterase ; metabolism ; Cholinesterase Inhibitors ; chemistry ; isolation & purification ; pharmacology ; Diterpenes ; chemistry ; isolation & purification ; pharmacology ; Glycoside Hydrolase Inhibitors ; chemistry ; isolation & purification ; pharmacology ; Leonurus ; chemistry ; Magnetic Resonance Spectroscopy ; Molecular Structure ; Plant Extracts ; chemistry ; pharmacology

The present study was designed to characterize the polyphenols isolated from Acacia mearnsii bark crude extract (B) and fractions (B1-B7) obtained by high-speed counter-current chromatography (HSCCC) and evaluate their anti-inflammatory and carbolytic enzymes (α-glucosidase and α-amylase) inhibitory activities. Fractions B4, B5, B6, B7 (total phenolics 850.3, 983.0, 843.9, and 572.5 mg·g, respectively; proanthocyanidins 75.7, 90.5, 95.0, and 44.8 mg·g, respectively) showed significant activities against reactive oxygen species (ROS), nitric oxide (NO) production, and expression of pro-inflammatory genes interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) in a lipopolysaccharide (LPS)-stimulated mouse macrophage cell line RAW 264.7. All the extracts suppressed α-glucosidase and α-amylase activities, two primary enzymes responsible for carbohydrate digestion. A. mearnsii bark samples possessed significantly stronger inhibitory effects against α-glucosidase enzyme (IC of 0.4-1.4 μg·mL) than the pharmaceutical acarbose (IC 141.8 μg·mL). B6 and B7 (IC 17.6 and 11.7 μg·mL, respectively) exhibited α-amylase inhibitory activity as efficacious as acarbose (IC 15.4 μg·mL). Moreover, B extract, at 25 µg·mL, significantly decreased the non-mitochondrial oxidative burst that is often associated with inflammatory response in human monocytic macrophages.
Acacia ; chemistry ; Animals ; Anti-Inflammatory Agents ; isolation & purification ; pharmacology ; Carbohydrate Metabolism ; drug effects ; Glycoside Hydrolase Inhibitors ; pharmacology ; Inflammation ; metabolism ; Interleukin-1beta ; metabolism ; Lipopolysaccharides ; Macrophages ; drug effects ; Mice ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase Type II ; metabolism ; Plant Bark ; chemistry ; Plant Extracts ; chemistry ; pharmacology ; Polyphenols ; isolation & purification ; pharmacology ; Proanthocyanidins ; pharmacology ; RAW 264.7 Cells ; alpha-Amylases ; antagonists & inhibitors ; alpha-Glucosidases ; metabolism

In order to develop potent antidiabetic agents that have inhibitory effect to a-glucosidase, twelve β-acetamido ketone derivatives such as N-{[(substituted-4-oxo-thiochroman-3-yl)phenyl]-methyl}acetamide are designed and synthesized through one-pot Dakin-West reaction. Their chemical structures are confirmed by 1H NMR, 13C NMR, IR and HR-MS. In vitro α-glucosidase inhibition assays of compounds 4a-41 were carried out using glucose oxidase method. The result indicated that most of them possess inhibitory activity in vitro. Compound 4k showed the most potent inhibitory activity with 87.3% inhibition of α-glucosidase at the concentration of 5.39 mmol x L(-1). The structure-activity relationship of these β-acetamido ketone derivatives was discussed preliminarily. Moreover, the molecular docking method was used to study the interaction mode of compound 4k and α-glucosidase. Our results will be helpful for designing of α-glucosidase inhibitors in the future.
Acetamides ; Glycoside Hydrolase Inhibitors ; chemical synthesis ; pharmacology ; Hypoglycemic Agents ; chemical synthesis ; pharmacology ; Molecular Docking Simulation ; Structure-Activity Relationship ; alpha-Glucosidases ; metabolism

In the present study, two new compounds from Ipomoea cairica were identified and demonstrated to have α-glucosidase inhibitory activity. They were isolated by column chromatography on silica gel and sephadex LH-20 and finally purified by prep-HPLC, with their structures being elucidated by spectroscopic methods, such as 1D- and 2D-NMR and HR-TOF-MS, and chemical methods. Compounds 1 and 2, named cairicoside A and cairicoside B, were evaluated for α-glucosidase inhibitory activity by the MTT method, with the IC50 values being 25.3 ± 1.6 and 28.5 ± 3.3 μmol·L(-1), respectively.
Glycoside Hydrolase Inhibitors ; isolation & purification ; pharmacology ; Ipomoea ; chemistry ; Molecular Structure ; Plant Extracts ; pharmacology ; Resins, Plant ; isolation & purification ; pharmacology ; Spectrum Analysis ; alpha-Glucosidases