Inhibitory effect of Terminalia chebula Retz. fruit extracts on digestive enzyme related to diabetes and oxidative stress

Terminalia chebula fruit extracts were prepared sequentially with hexane, ethyl acetate, methanol and methanol–water (70:30) and tested for their α-glucosidase inhibitory and antioxidant potential. The study resulted in the formulation of an extract with high α-glucosidase inhibitory potential (IC₅₀ 0.19?±?0.03 µg mL^?1) enriched with hydrolysable tannins. Also, each of the extract was chemically characterized by reversed-phase high-performance liquid chromatography on the basis of their marker compounds chebulagic acid, chebulinic acid and corilagin in order to give explanation to the significant activity shown by the extracts. The antioxidant potential of the highly active extract was evaluated in the cellular level also using superoxide dismutase, glutathione S-transferase and induced oxidative stress assays. The results indicated the possibility of using the extract as a nutraceutical health supplement in the management of type 2 diabetes.     

Antioxidant and Antidiabetic Properties of Extracts from Three Underutilized Food Plants of North East India

Three underutilized leafy vegetables Sarcochlamys pulcherrima (Roxb.) Gaudich (SP), Ipomoea aquatica Forssk. (IA) and Zanthoxylum rhetsa (Roxb.) DC (ZR) were extracted with different solvents viz. 95 % ethyl alcohol, methanol and hot water. The extracts were evaluated for their antioxidant potential via DPPH, ABTS and FRAP assay along with electroanalytical studies using cyclic voltammetry. The antidiabetic potential was determined by recording their α-amylase and α-glucosidase inhibitory assay. The total phenolic content (TPC), total flavonoid content (TFC) and the liquid chromatography-mass spectrometry (LC/MS) based phytochemical profiles of the extracts were also determined. All three extracts of SP exhibited significant antioxidant capacity. The antidiabetic potential of the IA and ZR extracts was found to be higher than or at par with that of standard acarbose. LC/MS studies reveal the presence of hitherto reported antioxidant and antidiabetic compounds like gamma-aminobutyric acid, cinnamic acid, caffeic acid, α-viniferin, piperlonguminine, niacin, kaempferol, etc., in the extracts.     

Characterization of saponins and phenolic compounds: antioxidant activity and inhibitory effects on α-glucosidase in different varieties of colored quinoa (Chenopodium quinoa Willd)

ABSTRACT

This study investigated the contents of saponins and phenolic compounds in relation to their antioxidant activity and α-glucosidase inhibition activity of 7 colored quinoa varieties. The total saponin content was significantly different among 7 varieties and ranged from 7.51 to 12.12 mg OAE/g DW. Darker quinoa had a higher content of phenolic compounds, as well as higher flavonoids and antioxidant activity than that of light varieties. Nine individual phenolic compounds were detected in free and bound form, with gallic acid and ferulic acid representing the major compounds. The free and bound phenolic compounds (gallic acid and ferulic acid in particular) exhibited high linear correlation with their corresponding antioxidant values. In addition, the free phenolic extracts from colored quinoa exhibited higher inhibitory activity against α-glucosidase than the bound phenolic extracts. These findings imply that colored quinoa with abundant bioactive phytochemicals could be an important natural source for preparing functional food.     

内蒙古产柽柳和多枝柽柳α-葡萄糖苷酶抑制活性

首次利用体外α-葡萄糖苷酶抑制模型以96微孔板法,对内蒙古产2种柽柳属植物不同溶剂提取物进行活性评价,并与阳性对照Acarbose比较,发现6种提取物均有较好的α-葡萄糖苷酶抑制作用,远远强于阳性对照Acarbose(IC50=1103.01μg·mL-1)的抑制活性。结果显示,同一植物不同溶剂提取物相比较,两者石油醚提取物α-葡萄糖苷酶抑制活性不及乙酸乙酯和正丁醇提取物;不同植物同一溶剂的提取物抑制活性也不同,6种提取物中,多枝柽柳的正丁醇和柽柳的乙酸乙酯提取物抑制活性最高(IC50=13.36和17.35μg·mL-1)。所有提取物对α-葡萄糖苷酶活性的抑制效果均很好,且多枝柽柳抑制活性整体上较柽柳好,具有良好的潜在开发价值。     

朱砂根抑制α-葡萄糖苷酶与抗氧化活性研究

对朱砂根抑制α-葡萄糖苷酶与抗氧化活性进行研究.利用96微孔板法筛选α-葡萄糖苷酶抑制活性;采用DPPH、ABTS和FRAP方法分析抗氧化活性.结果表明,乙酸乙酯部位抑制α-葡萄糖苷酶的活性最高(IC50=39.27 μg/mL),石油醚部位次之(IC50 =56.11 μg/mL),正丁醇部位活性最弱(IC50=62.05μg/mL),但均远大于阳性对照Acarbose(IC50=1081.27 μg/mL);乙酸乙酯部位抗氧化能力最强,正丁醇部位次之.乙酸乙酯部位清除DPPH自由基(IC50=38.55 mg/L)的能力比BHT( IC50=18.71 mg/L)低1/2,清除ABTS自由基的能力(IC50=3.60 mg/L)比BHT(IC50=7.44 mg/L)强,但比BHA(IC50=1.74 mg/L)弱,还原Fe3+的能力(FRAP=512.99 ±6.80 μmoTE/g)为BHT(FRAP=1581.68±97.41μmol TE/g)的1/3.结果显示朱砂根乙酸乙酯部位抑制α-葡萄糖苷酶和抗氧化活性最好.     

Chemical composition and biological properties of Synedrella nodiflora (L.) Gaertn: A comparative investigation of different extraction methods

Synedrella nodiflora (L.) Gaertn. (Asteraceae), is a weed with ethnomedicinal uses. To extend scientific information on this species, we evaluated the effects of different extraction procedures (maceration, Soxhlet, sonication and homogenizer-assisted extraction (HAE)) using methanol as solvent, on the chemical composition and biological potential. The chemical profiles of the extracts were identified using a chromatographic (UHPLC-HRMS) technique. The antioxidant and enzyme inhibitory activities of the studied extracts were determined. The extract obtained by Soxhlet technique showed a higher level of total phenolic (TPC) and flavonoid content (TFC) and was a superior source of antioxidant compounds. The macerated extract was the most potent inhibitor of cholinesterases and α-glucosidase, whereas the highest activity against tyrosinase was observed in the order of sonication > Soxhlet > HAE > maceration. A modest activity was observed against α-amylase for all the extracts. Multivariate analysis showed that the bioactive compounds recovery and the biological activities of S. nodiflora were mostly dependent on the nature of the extraction technique used. In conclusion, S. nodiflora extracts showed good biological potential and data massed from this study could serve as a scientific baseline for further investigation in order to exploit its potential for designing novel bio-products with therapeutic applications.     

Chemical Composition and Pharmacological Evaluation and of Toddalia asiatica (Rutaceae) Extracts and Essential Oil by in Vitro and in Silico Approaches.

Toddalia asiatica (L.) Lam. is extensively used in traditional medicinal systems by various cultures. Despite its frequent use in traditional medicine, there is still a paucity of scientific information on T. asiatica growing on the tropical island of Mauritius. Therefore, the present study was designed to appraise the pharmacological and phytochemical profile of extracts (methanol, ethyl acetate and water) and essential oil obtained from aerial parts of T. asiatica. Biological investigation involved the evaluation of in vitro antioxidant and enzyme inhibitory potentials. The chemical profile of the EO was determined using gas chromatography coupled to mass spectrometry (GC/MS) analysis, while for the extracts, the total phenolic (TPC) and flavonoid content were quantified as well as their individual phenolic compounds by LC/MS/MS. Quinic acid, fumaric acid, chlorogenic acid, quercitrin and isoquercitrin were the main compounds in the extracts. Highest total phenolic (82.5±0.94 mg gallic acid equivalent (GAE/g)) and flavonoid (43.8±0.31 mg rutin equivalent (RE/g)) content were observed for the methanol extract. The GC/MS analysis has shown the presence of 26 compounds with linalool (30.9 %), linalyl acetate (20.9 %) and β-phellandrene (7.9 %) being most abundant components in the EO. The extracts and EO showed notable antioxidant properties, with the methanol extract proved to be superior source of antioxidant compounds. Noteworthy anti-acetylcholinesterase (AChE) and anti-butyrylcholinesterase (BChE) effects were recorded for the tested samples, while only the methanol and ethyl acetate extracts were active against tyrosinase. With respect to antidiabetic effects, the extracts and EO were potent inhibitors of α-glucosidase, while modest activity was recorded against α-amylase. Docking results showed that linalyl acetate has the highest affinity to interact with the active site of BChE with docking score of −6.25 kcal/mol. The findings amassed herein act as a stimulus for further investigations of this plant as a potential source of bioactive compounds which can be exploited as phyto-therapeutics.     

内蒙古产白刺、小果白刺和霸王α-葡萄糖苷酶抑制活性

首次利用体外α-葡萄糖苷酶抑制模型对内蒙古产3种蒺藜科植物的9个提取物进行活性评价,并与阳性对照Acarbose比较,发现3种植物均有抑制α-葡萄糖苷酶活性。其中白刺石油醚提取物对α-葡萄糖苷酶的抑制活性(IC50=81.80 mg/L)最高,其余依次为小果白刺乙酸乙酯提取物(IC50=610.29 mg/L),霸王石油醚(IC50=627.22 mg/L)和乙酸乙酯提取物(IC50=838.40 mg/L),它们的抑制活性远大于阳性对照Acarbose(IC50=1103.01 mg/L)。结果发现,不同植物不同溶剂提取物的α-葡萄糖苷酶抑制活性不同。同一植物不同溶剂提取物相比较,甲醇提取物的α-葡萄糖苷酶抑制活性不及乙酸乙酯和石油醚提取物。     

Biological Insights and NMR Metabolic Profiling of Different Extracts of Spermacoce verticillata (L.) G. Mey.

Spermacoce verticillata (L.) G. Mey. is commonly used in the folk medicine by various cultures to manage common diseases. Herein, the chemical and biological profiles of S. verticillata were studied in order to provide a comprehensive characterization of bioactive compounds and also to highlight the therapeutic properties. The in vitro antioxidant activity using free-radical scavenging, phosphomolybdenum, ferrous-ion chelating and reducing power assays, and the inhibitory activity against key enzymes such as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase of S. verticillata extracts (dichloromethane, ethyl acetate, methanol and water) were investigated. The highest total phenolic and flavonoid content were observed in the methanolic and aqueous extracts. Exhaustive 2DNMR investigation has revealed the presence of rutin, ursolic and oleanoic acids. The methanolic extract, followed by aqueous extract have showed remarkable free radical quenching and reducing ability, while the dichloromethane extract was the best source of metal chelators. The tested extracts showed notable inhibitory activity against cholinesterases (AChE: 1.63–4.99 mg GALAE/g extract and BChE: 12.40–15.48 mg GALAE/g extract) and tyrosinase (60.85–159.64 mg KAE/g extract). No inhibitory activity was displayed by ethyl acetate and aqueous extracts against BChE and tyrosinase, respectively. All the tested extracts showed modest α-amylase inhibitory activity, while only the ethyl acetate and aqueous extracts were potent against α-glycosidase. This study further validates the use of S. verticillata in the traditional medicine, while advocating for further investigation for phytomedicine development.     

Metabolite profiling of Neptunia oleracea and correlation with antioxidant and α-glucosidase inhibitory activities using 1H NMR-based metabolomics

Neptunia oleracea is a plant consumed as vegetable and used as a traditional herb to treat several ailments. This study evaluated metabolite variations among N. oleracea leaf and stem subjected to air drying (AD), freeze drying (FD) and oven drying (OD) using proton nuclear magnetic resonance (¹H NMR) based metabolomics. The correlation was also studied for the metabolite content with total phenolic content (TPC), DPPH free radical scavenging and α-glucosidase inhibitory activities. A total of 18 metabolites were identified from N. oleracea extracts, including 10 primary metabolites, 5 flavonoids and 3 phenolic acids using NMR. Ultra-high performance liquid chromatography tandem mass spectrometry analysis (UHPLC-MS/MS) confirmed the presence of the secondary metabolites and revealed the flavonoid derivatives present. All the identified phenolics are first reported from this plant. Multivariate data analysis (MVDA) showed strong correlation between the metabolites with the antioxidant and α-glucosidase inhibitory activities of FD N. oleracea leaves. The compounds suggested to be responsible for the high activity of FD leaves include vitexin-2-O-rhamnoside, catechin, caffeic acid, gallic acid and derivatives of quercetin, kaempferol and myricetin. This study demonstrates that FD N. oleracea leaves are a potential natural source for antioxidant and α-glucosidase inhibitors.     

五种苦苣苔科植物α-葡萄糖苷酶抑制活性研究

利用体外α-葡萄糖苷酶抑制模型对5种苦苣苔科植物进行活性评价,并与阳性对照Acarbose进行比较,发现5种植物不同部位均有一定的α-葡萄糖苷酶抑制活性。其中,牛耳岩白菜石油醚部位的抑制活性最高(IC50=26.19μg/mL,活性均远大于阳性对照Acarbose(IC50=1081.27μg/mL)。不同植物比较,牛耳岩白菜的α-葡萄糖苷酶抑制活性最好,其3种不同溶剂提取物与Acarbose相比均有很高抑制活性;对牛耳岩白菜提取物的α-葡萄糖苷酶抑制动力学研究结果表明,石油醚和乙酸乙酯提取物对α-葡萄糖苷酶抑制作用属于非竞争性抑制类型,Ki值分别为4.24和40.04μg/mL。正丁醇提取物则属于竞争性抑制类型(Ki=205.48μg/mL)     

Biologically active compounds from two members of the Asteraceae family: Tragopogon dubius Scop. and Tussilago farfara L.

Tragopogon dubius and Tussilago farfara are consumed as vegetables and used in folk medicine to manage common diseases. Herein, the chemical compositions and biological activities of different leaf extracts (ethyl acetate, methanol, and water) of T. dubius and T. farfara were evaluated. The antibacterial, antifungal, and antioxidant abilities of the extracts were tested using different assays including free radical scavenging, reducing power, phosphomolybdenum, and metal chelating assays. Enzyme inhibitory potentials were evaluated against cholinesterases, tyrosinase, α-amylase and α-glucosidase. Complexes of bioactive compounds (chlorogenic and rosmarinic acid) were docked into the enzymatic cavity of α-glucosidase and subjected to molecular dynamic calculation, enzyme conformational stability, and flexibility analysis. T. dubius and T. farfara extracts showed remarkable antioxidant potentials. Ethyl acetate extracts of T. dubius and T. farfara were the most potent inhibitors of acetylcholinesterase and butyrylcholinesterase. T. dubius ethyl acetate extract and T. farfara methanolic extract showed noteworthy activity against α-glucosidase. High performance liquid chromatography analysis revealed the abundance of some phenolic compounds including chlorogenic and rosmarinic acids. Ethyl acetate extract of T. dubius showed notable antifungal activity against all strains. Docking studies showed best pose for chlorogenic acid was stabilized by a network of hydrogen bonds with residues Asp1157, Asp1279, whereas rosmarinic acid showed several hydrogen bonds with Asp1157, Asp1420, Asp1526, Lys1460 and Trp1369. This study further validates the use of T. dubius and T. farfara in traditional medicine, as well as act as a stimulus for further studies for future biomedicine development.

Communicated by Ramaswamy H. Sarma     

河南鼠尾草抑制体内外α-糖苷酶活性研究

本文采用96微孔板法,首次对河南鼠尾草抑制酵母和大鼠小肠α-葡萄糖苷酶活性进行研究。河南鼠尾草乙酸乙酯提取物(IC50=28.73μg/mL)和正丁醇提取物(IC50=73.90μg/mL)抑制酵母α-葡萄糖苷酶活性远高于阳性对照Acarbose(IC50=1081.27μg/mL),但只有乙酸乙酯提取物(IC50=366.79μg/mL)具有抑制大鼠小肠α-葡萄糖苷酶活性,阳性对照Acarbose未检测出其IC50。结果表明,河南鼠尾草乙酸乙酯提取物和正丁醇提取物均具有较好的酵母α-葡萄糖苷酶抑制活性,但只有乙酸乙酯提取物具有良好的大鼠小肠α-葡萄糖苷酶抑制活性。     

Antioxidant, α-glucosidase inhibitory and anti-inflammatory effects of aerial parts extract from Korean crowberry (Empetrum nigrum var. japonicum)

Crowberry (Empetrum nigrum L.) is a wild berry commonly found in the northern hemisphere. Crowberry fruits have been suggested as good resources for functional applications in the cosmetic and pharmaceutical industries, but the high polyphenolic content in crowberry leaves also indicates crowberry aerial parts as potential dietary health supplements. In this study, therefore, the biological activities of the aerial parts of Korean crowberry (E. nigrum var. japonicum) were investigated. Antioxidant activity was measured by three different assays on DPPH free radical scavenging, reducing power, and total antioxidant capacities. Dose-dependent antioxidant activities were exhibited by crude methanol extract and its fractions, suggesting that the crude methanol extract and EtOAc fraction possessed strong antioxidant activities and capacities. In addition, the crude methanol extract and EtOAc strongly inhibited α-glucosidase activity and suppressed the secretion of pro-inflammatory mediator and nitrite oxide from LPS-stimulated RAW 264.7 cells. These findings provide valuable evidence for the potential of such parts as good dietary sources of natural antioxidant, α-glucosidase inhibitory, and anti-inflammatory components, suggesting that using the non-edible parts (e.g., leaves and stems) of crowberry can be a potential natural avenue for improving human health.     

黄连提取物对α-葡萄糖苷酶抑制作用研究

利用体外α-葡萄糖苷酶抑制模型对黄连不同部位提取物进行活性评价,并与阳性对照Acarbose比较,发现黄连不同部位均有一定的α-葡萄糖苷酶抑制活性.其中,黄连根茎乙酸乙酯提取物的抑制活性最高(IC_(50)=20.72 μg/mL),黄连种子石油醚部位(IC_(50)=40.86 μg/mL)和黄连叶石油醚部位(IC_(50)=62.85 μg/mL)的活性次之.3个部位的提取物活性均远大于阳性对照Acarbose(IC_(50)=1081,27 μg/mL).不同部位比较,根茎对α-葡萄糖苷酶抑制活性最好,这3种提取物抑制活性均比阳性对照高;同一部位不同提取物比较,石油醚和甲醇提取物α-葡萄糖苷酶抑制活性一般要高于乙酸乙酯提取物.     

Chemical Characterization of Different Extracts from Artemisia annua and Their Antioxidant,Enzyme Inhibitory and Anti-Inflammatory Properties

Artemisia annua L. (Asteraceae Family) is an important plant in Asia that has been used for treating different diseases, including fever due to malaria, wounds, tubercolisis, scabues, pain, convulsions, diabetes, and inflammation. In this study we aimed to evaluate the effects of different polarity extracts (hexane, dichloromethane, ethyl acetate, ethanol, ethanol/water (70 %) and water) from A. annua against the burden of inflammation and oxidative stress occurring in colon tissue exposed to LPS. In parallel, chemical composition, antiradical, and enzyme inhibition effects against α-amylase, α-glucosidase, tyrosinase, and cholinesterases were evaluated. The water extract contained the highest content of the total phenolic with 34.59 mg gallic acid equivalent (GAE)/g extract, while the hexane had the highest content of the total flavonoid (20.06 mg rutin equivalent (RE)/g extract). In antioxidant assays, the polar extracts (ethanol, ethanol/water and water) exhibited stronger radical scavenging and reducing power abilities when compared to non-polar extracts. The hexane extract showed the best AChE, tyrosinase and glucosidase inhibitory effects. All extracts revealed effective anti-inflammatory agents, as demonstrated by the blunting effects on COX-2 and TNFα gene expression. These effects seemed to be not related to the only phenolic content. However, it is worthy of interest to highlight how the higher potency against LPS-induced gene expression was shown by the water extract ; thus suggesting a potential phytotherapy application in the management of clinical symptoms related to inflammatory colon diseases, although future in vivo studies are needed to confirm such in vitro and ex vivo observations.     

Alpha-amylase inhibitors from mycelium of an oyster mushroom

Abstract

The α-Amylase and α-glucosidase are two main enzymes involved in carbohydrate metabolism. This study was aimed at detecting alpha-amylase inhibitory activity from edible mushroom mycelia. Oyster mushroom was collected from a natural source, from Indian Institute of Technology (Banaras Hindu University) campus and was maintained in vitro in mycelial form. Chloroform, acetone, methanol, and water were used separately for extraction of an active constituent from mycelial cells grown, for 7?days, in potato dextrose broth. The extracts were tested for alpha-amylase inhibitory activity. Chloroform, acetone, and methanol extracts were found to have alpha-amylase inhibitory activity, with IC₅₀ values of 1.71, 224, and 383?μg/mL, respectively. Aqueous extract had no enzyme inhibitory activity. The acetone extract inhibited α-amylase non-competitively whereas chloroform extract showed competitive inhibition. Acetone extraction yielded highest total phenolic content (TPC) of 0.524?mM of gallic acid equivalent, whereas chloroform extraction resulted in lowest TPC of 0.006?mM. The HPLC and absorbance maxima of acetone and chloroform extracts suggest that the bioactive component responsible for enzyme inhibition could be glycoproteins in chloroform extract and catechins (flavonoids) in acetone extract. Thus, the mushroom mycelia under study may be exploited for production and purification of a lead compound for the development of the α-amylase inhibitory drug.     

肉桂抑制α-葡萄糖苷酶活性成分研究

为寻找肉桂中具有抑制α-葡萄糖苷酶活性的化学成分,采用高效液相色谱结合体外抑制α-葡萄糖苷酶活性筛选模型的方法,进行活性成分的跟踪分离,并对活性化合物进行酶抑制动力学研究.结果显示,肉桂石油醚提取物(IC50=350.37 μg/mL)的活性明显高于阳性对照阿卡波糖(IC50=1028.99 μg/mL),从中分离出2个活性成分,分别鉴定为桂皮醛( IC50 =277.89 μg/mL)和肉桂酸(IC50=286.22 μg/mL).酶抑制动力学结果表明它们对α-葡萄糖苷酶的抑制类型均为非竞争性抑制,Ki值分别为178.07 μg/mL和229.43 μg/mL.     

Chemical Characterization and Multidirectional Biological Effects of Different Solvent Extracts of Arum elongatum: in Vitro and in Silico Approaches

Arum elongatum (Araceae) is widely used traditionally for the treatment of abdominal pain, arterial hypertension, diabetes mellitus, rheumatism and hemorrhoids. This study investigated the antioxidant properties, individual phenolic compounds, total phenolic and total flavonoid contents (HPLC/MS analysis), reducing power and metal chelating effects of four extracts obtained from A. elongatum (ethyl acetate (EA), methanol (MeOH), methanol/water (MeOH/water) and infusion). The inhibitory activity of the extracts were also determined against acetylcholinesterase, butyrylcholinesterase, tyrosinase, amylase and glucosidase enzymes. The MeOH/water extracts contained the highest amount of phenolic contents (28.85 mg GAE/g) while the highest total flavonoid content was obtained with MeOH extract (36.77 mg RE/g). MeOH/water demonstrated highest antioxidant activity against DPPH⋅ radical at 38.90 mg Trolox equivalent per gram. The infusion extract was the most active against ABTS⁺⋅ (133.08 mg TE/g). MeOH/water extract showed the highest reducing abilities with the CUPRAC value of 102.22 mg TE/g and the FRAP value of 68.50 mg TE/g. A strong metal chelating effect was observed with MeOH/water extract (35.72 mg EDTAE/g). The PBD values of the extracts ranged from 1.01 to 2.17 mmol TE/g. EA extract displayed the highest inhibitory activity against AChE (2.32 mg GALAE/g), BChE (3.80 mg GALAE/g), α-amylase (0.56 mmol ACAE/g) and α-glucosidase (9.16 mmol ACAE/g) enzymes. Infusion extract was the most active against tyrosinase enzyme with a value of 83.33 mg KAE/g. A total of 28 compounds were identified from the different extracts. The compounds present in the highest concentration were chlorogenic acids, 4-hydroxybenzoic acid, caffeic acid, p-coumaric acid, ferulic acid, isoquercitrin, delphindin 3,5-diglucoside, kaempferol-3-glucoside and hyperoside. The biological activities of A. elongatum extracts could be due to the presence of compounds such as gallic acid, chlorogenic acids, ellagic acid, epicatechin, catechin, kaempferol, 4-hydroxybenzoic acid, caffeic acid, p-coumaric acid, ferulic acid, quercetin, isoquercitrin, and hyperoside. Extracts of A. elongatum showed promising biological activities which warrants further investigations in an endeavor to develop biopharmaceuticals.     

石榴皮多酚提取物及纯化物对α-葡萄糖苷酶的抑制作用研究

采用紫外分光光度法研究了石榴皮多酚提取物及其2种纯化物(P-1和P-2)对α-葡萄糖苷酶体外抑制作用以及纯化物对该酶的抑制作用类型.结果显示,石榴皮多酚提取物和纯化物对α-葡萄糖苷酶活性均表现出较强的抑制作用,且其作用大小与浓度呈明显的剂量-效应关系;3种多酚样品中,纯化物P-2的抑酶活性最强,纯化物P-1次之,提取物最弱,它们对α-葡萄糖苷酶的半数抑制浓度(IC50,mg/mL)分别为0.045、0.185和0.278.石榴皮多酚纯化物P-2对α-葡萄糖苷酶抑制作用类型为反竞争性抑制;浓度为0.01 mg/mL时该纯化物对α-葡萄糖苷酶的抑制常数Ki为1.22 μg/mL.