地肤子总皂苷提取工艺的优化及其对α-葡萄糖苷酶抑制活性研究

目的优化地肤子总皂苷的超声提取工艺,并对其活性进行研究。方法以地肤子总皂苷得率为指标,通过单因素试验及Box–Behnken响应面法优化地肤子总皂苷的提取工艺。并对最优提取工艺下的地肤子总皂苷提取液进行抗α–葡萄糖苷酶实验。结果地肤子总皂苷的最佳提取工艺:乙醇体积分数为71%,提取时间为33 min,液料比为44 mL/g,地肤子总皂苷的得率为(7.69±0.28)%,且地肤子总皂苷具有体外α–葡萄糖苷酶抑制活性。结论建立的提取工艺稳定、可行,为地肤子总皂苷的合理开发、应用提供参考。

α-Glucosidase Inhibitors from Glycyrrhiza uralensis Fisch.

Aim To screen for α-glucosidase inhibitor from Glyeyrrhiza uralensis Fisch.. Methods Glycyrrhizic acid, glycyrrhetinic acid, flavonoids of glycyrrhiza, alkaloids of glycyrrhiza, and glycyrrhiza polysaccharides were isolated from the root of Glycyrrhiza uralensis Fisch. respectively. Three compounds were isolated from the flavonoids of glycyrrhiza as guided by the α-glucosidase inhibitory test in vitro. Moreover, the characteristics of inhibitory kinetics of glycyrol and glycyrrhetinic acid were investi- gated. Results The flavonoids of glycyrrhiza and glycyrrhetinic acid had the strongest α-glucosidase inhibitory activity. Glycyrol,β-sitosterol and liquifitin were isolated and identified. Glycyrol was a fast- binding, reversible, noncompetitive α-glucosidase inhibitor, showing IC50 at 0.26 μg·mL^-1 Glycyrrhetinic acid was a fast-binding, irreversible α-glucosidase inhibitor, showing IC50 at 102.4 μg·mL^-1. Conclusion Glycyrol is an effective α-glucosidase inhibitor.

Effects of α-glucosidase Inhibitors on the Function of Mulberry Leaf Extract as an Additive in Feedstuff

The mulberry juice contains high concentrations of α-glucosidase inhibitors that affect glycometabolism and cause diarrhea in animals, thereby affecting the de-velopment and application of mulberry （Morus alba L.） as feedstuff resources. ln this study, the effects of mulberry leaf extract with and without removal of mulberry juice on starch metabolism were analyzed and compared. The results showed that mul-berry leaf extract with removal of mulberry juice exhibited significantly lower inhibi-tion rate on starch metabolism compared with mulberry leaf extract without removal of mulberry juice. ln animal feeding trials, piglet feedstuff was added with 10% mul-berry leaf powder; compared with mulberry leaf powder without removal of mulberry juice, experimental piglets fed with mulberry leaf powder with removal of mulberry juice exhibited significantly improved weight gain and significantyl reduced diarrhea rate.

一种四环吲哚衍生物降血糖和降血脂活性评价与作用机制

四环吲哚衍生物7i是前期研究发现的高活性α–葡萄糖苷酶抑制剂,但其作用机制以及体内降血糖和降血脂活性尚不明确.本研究通过体外酶水平的透析实验和荧光探针分析等手段揭示了化合物7i以不可逆的方式与α–葡萄糖苷酶结合并抑制其活性.通过3T3-L1和HepG2细胞模型分析发现,化合物7i显著提高磷酸腺苷活化蛋白激酶(AMPK)和乙酰辅酶A羧化酶(ACC)蛋白磷酸化水平,降低脂质积累.另外,利用糖尿病小鼠模型研究发现,化合物7i能够有效抑制糖尿病小鼠的餐后血糖水平,改善葡萄糖耐量,降低血清中甘油三酯和胆固醇的含量,并且能够改善糖尿病小鼠肝脏的水肿和脂肪变性.因此,化合物7i通过抑制α–葡萄糖苷酶和调节AMPK/ACC磷酸化水平的双重作用机制起到降低血糖和血脂的作用,为其开发成为新型抗糖尿病药物奠定了基础.

Ultrasonic Extraction of Polysaccharides from Laminaria japonica and Their Antioxidative and Glycosidase Inhibitory Activities

In the present study, ultrasonic extraction technique （UET） is used to improve the yield of polysaccharides from Lami- naria japonica （LJPs）. And their antioxidative as well as glycosidase inhibitory activities are investigated. Box-Behnken design （BBD） combined with response surface methodology （RSM） is applied to optimize ultrasonic extraction for polysaccharides. The optimized conditions are obtained as extraction time at 54 min, ultrasonic power at 1050 W, extraction temperature at 80℃ and ratio of material to solvent at 1：50 （g mL-1）. Under these optimal ultrasonic extraction conditions, an actual experimental yield （5.75% ＋ 0.3%） is close to the predicted result （5.67%） with no significant difference （P〉0.05）. Vitro antioxidative and glycosidase inhibitory activities tests indicate that the crude polysaccharides （LJP） and two major ethanol precipitated fractions （LJP1 and LJP2） are in a concentration-dependent manner. LJP2 （30%-60% ethanol precipitated polysaccharides） possesses the strongest α-glucosidase in- hibitory activity and moderate scavenging activity against hydroxyl radicals （66.09% ±2.19%, 3.0 mg mL-l）. Also, the inhibitory activity against a-glucosidase （59.08% ± 3.79%, 5.0 mg mL-1） is close to that of acarbose （63.99% ± 3.27%, 5.0 mg mL-l）. LJP 1 （30% ethanol precipitated polysaccharides） exhibits the strongest scavenging activity against hydroxyl radicals （99.80%q-0.00%, 3.0mg mL-1） and moderate a-glucosidase inhibitory activity （47.76%± 1.92%, 5.0 mgmL-1）. LJP shows the most remarkable DPPH scav- enging activity （66.20%±0.11%, 5.0mgmL-1） but weakest a-glucosidase inhibitory activity （37.77%±1.30%, 5.0mgmL-1）. How- ever, all these LJPs exert weak inhibitory effects against a-amylase. These results show that UET is an effective method for extract- ing bioactive polysaccharides from seaweed materials. LJP 1 and LJP2 can be developed as a potential ingredient in hypoglycemic agents or functional food for the management of diabetes. This study provides scientific evidence and advances in the preparation technology and a hypoglycemic activities evaluation method for seaweed polysaccharides, especially glycosidase inhibition in com- bination with an antioxidative activity evaluation method.

Macroalage as a source of alpha-glucosidase inhibitors

Alpha-glucosidase inhibitors were screened from organic solvent extracts of macroalgae by a spec- trophotometrical method with p-nitrophenyl-D-glucopyranosidase as the substrate. The result indicates that or- ganic crude extracts from some macroalgae such as Rhodomela confervoides (Huds.) Silva, Gracilaria textorii (Suringar) DeToni, Plocamium telfairiae Harv., Dictyopteris divaricata (Okam.) Okam, Ulval pertusa and En- teromorpha intestinalis (L.) Link et al. show strong inhibitory activity of alpha-glucosidase at concentration of 79.6 μg/ml.

Screening and functional evaluation of the glucose-lowering active compounds of total saponins of Baibiandou(Lablab Semen Album)

Objective To screen forα-glucosidase inhibitor active compounds in the total saponins of Baibiandou(Lablab Semen Album)based on UHPLC-Q-Exactive Orbitrap MS technology and to evaluate its hypoglycemic activity in vivo.Methods Acarbose was used as the positive control,and the median inhibitory concentration(IC50)was used as the evaluation index ofα-glucosidase inhibitory activity to establish an in vitroα-glucosidase inhibition model.Further,UHPLC-Q-Exactive Orbitrap MS technology was used to screen and identify the active compounds ofα-glucosidase inhibitors in the total saponins of Baibiandou(Lablab Semen Album)in order to further verify the activity of the main active monomer and to perform homologous modeling and molecular docking of yeast-derivedα-glucosidase and human-derivedα-glucosidase,while the hypoglycemic activity was evaluated in diabetic mice.Results This study successfully identified 15 compounds with potentialα-glucosidase inhibitory activity,including Chikusetsusaponin IVa,from the total saponins of Baibiandou(Lablab Semen Album).Simultaneously,we verified the activity of the main active monomer Chikusetsusaponin IVa,and showed that it has strongα-glucosidase inhibitory activity.Theα-glucosidase inhibitory concentration IC50 was(565.2±1.026)μg/m L,and the IC50 of acarbose,which was lower than the positive control,was(706.6±1.058)μg/m L.The docking energies of Chikusetsusaponin IVa were–6.1 and–7.7 kcal/mol with yeast-derivedα-glucosidase and human-derivedα-glucosidase molecules,respectively.Both showed strong binding activity,and the levels of alanine aminotransaminase(ALT),aspartate aminotransaminase(AST),UREA,Creatinine(CREA),and cholesterol(CHO)were significantly decreased by Chikusetsusaponin IVa(P<0.05).In addition,it could repair damaged liver and pancreas cells of diabetic mice to some extent.Conclusion This study provides a basis for screeningα-glucosidase inhibitors and structural modifications of the total saponins of Baibiandou(Lablab Semen Album).

α-Glucosidase Inhibitory Activity-guided Identification of Compounds from Clerodendrum bungei Steud by HPLC-ESI-QTOF-MS/MS

Objective To identify the compounds withα-glucosidase inhibitory activity from Clerodendrum bungei Steud(Chou Mu Dan,臭牡丹)using HPLC-ESI-QTOF-MS/MS.Methods The ethanol extracts of Clerodendrum bungei Steud(Chou Mu Dan,臭牡丹)were partitioned with petroleum ether,ethyl acetate,n-butanol,and water.The assay forα-glucosidase inhibitory activity revealed strongα-glucosidase inhibitory activity in the ethyl acetate fraction,and the bioactive compounds present in this fraction were identified by the HPLCESI-QTOF-MS/MS method.Results A total of 29 compounds were determined,among the identified bioactive components;these included 12 phenylethanoid glycosides(compounds 5,6,17,20-22,24),7 flavonoids(compounds 10,19,23,25-28),5 phenolic acids(compounds 2-4,7,9),and 5 other compounds.Compounds 2-4,7,9-10,12-13,15,19,and 26,with a potentialα-glucosidase inhibitory activity,have been reported previously.Conclusions Our results show that the methodology used in this study is feasible,credible,and rapid in identifying known compounds and also for characterizing new natural glucosidase inhibitory candidates from Clerodendrum bungei Steud(Chou Mu Dan,臭牡丹).

Mangiferin ameliorates hyperglycemia by inhibiting oxidation and α-glucosidase activity

Objective： Mangiferin （MF） is a polyphenol isolated from the root of Anemarrhena asphodeloides Bge.. This study wasaimed to investigate the effects of MF on hyperglycemia in animal models of insulin resistance and streptozotocin（STZ）-induced diabetes. Methods： The diabetes mellitus model was established in mice by receiving a multiplehypodermic injection of hydrocortisone sodium succinate （HCSS） （70 mg/kg） or a single intravenous injection of STZ（130 mg/kg）. Meanwhile MF at different dosage （50, 100 and 200 mg/kg） were oral administrated for consecutive 10days. Data of blood glucose were collected at different time after intraperitoneal injection of insulin （0.5 U/kg） toinvestigate the insulin resistant. As well as the oxygen radical absorbance capacity （ORAC） and superoxide dismutase（SOD） activity of kidney were measured. The in vitro experiment was established to investigate the inhibitory capacity ofMF to α-glucosidase. Results： Oral administration of MF significantly prevented insulin resistance caused by HCSSinjection. STZ-induced diabetic symptoms were also improved, including fasting blood glucose, glycated hemoglobin,plasma triglycerides, hepatic glycogen, kidney SOD and ORAC level. The in vitro experiment demonstrated that MF hadpotent α-glucosidase inhibitory activity. Conclusion： The obtained results demonstrate that MF ameliorates insulinresistance and STZ-induced glucose metabolism disturbance. The MF exerts the protective effects through improving theantioxidant ability, promoting hepatic glycogen synthesis and inhibiting α-glucosidase activity.

In vitro antioxidant activity and potential inhibitory action against α-glucosidase of polysaccharides from fruit peel of tea(Camellia sinensis L.)

The conditions for extracting polysaccharides from tea （Camellia sinensis L.） fruit peel （TFPPs） were studied. Three parameters （temperature, time, and liquid/solid ratio） affecting the extraction of TFPP were optimized using response surface methodology （RSM）. Under the optimized conditions, the yield of TFPP was predicted to be 4.98%. The physicochemical properties, in vitro antioxidant activities, and inhibitory effects on α-glucosidase of frac- tionated TFPPs （TFPP-0, TFPP-20, TFPP-40, and TFPP-60） were investigated. We found that the TFPPs were all acid protein-bound heteropolysaccharides, although with different chemical compositions. They had not only re- markable scavenging activity on 2,2＇-azinobis（3-ethylbenzothiazoline-6-sulfonic acid） diammonium salt （ABTS） and reducing activity, but also excellent inhibitory potential against α-glucosidase in vitro. Our results suggest that tea fruit peel could be treated as a potential bioresource for the development of polysaccharide antioxidants.

Two novel resin glycosides isolated from Ipomoea cairica with α-glucosidase inhibitory activity

In the present study, two new compounds from Ipomoea cairica were identified and demonstrated to have a-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 a-glucosidase inhibitory activity by the MTT method, with the ICs0 values being 25.3 ± 1.6 and 28.5± 3.3 μmol·L-1, respectively.

Effect of Honghua (Flos Carthami) on nitric oxide production in RAW 264.7 cells and α-glucosidase activity

OBJECTIVE： To study the effects of extracts from Honghua （Flos Carthaml~ on lipopolysaccharide in- duced nitric oxide （NO） production in RAW 264.7 cells and the influence of the extracts on yeast a-glucosidase activity. The total flavonoid content of the extracts was also determined. METHODS： Cytotoxicity of the extracts to RAW 264.7 cells was evaluated by the ATPliteTM method. Inhibitory effects of the extracts on NO production were evaluated by Griess assay. Curcumin was used as a positive control. Screening of extracts for po- tential a-glucosidase inhibitors was done by a fiuo- rometric assay. The assay was based on the hydroly- sis of 4-methylumbelliferyl-a-D-glucopyranoside toform the fluorescent product, 4-methylumbellifer- one. Acarbose was used as a positive control. The total t3avonoid content was tested using kaempfer- ol as the standard. RESULTS： There were significant inhibitory effects on NO production when the extracts were 25-100 μg/ mL （P〈0.05） and curcumin was 2-4 μg/mL （P〈 0.001）. The extracts showed an inhibitory effect on a-glucosidase activity at the concentrations of 15.6-125 μg/mL with a half maximal （50%）inhibito- ry concentration （ICs0） of （32.8± 5.7） μg/mL, com- pared with the ICs0 of acarbose at （1.8±0.4） μg/mL. There was a significant difference between the two IC50 values （P〈0.001）. The total content of flavo- noids per gram of dried herb was 1.14 mg. CONCLUSION： Honghua （Flos Carthami） showed in- hibitory effects on NO production in activated RAW 264.7 macrophage cells and an inhibitory effect on yeast a-glucosidase. There might be a relationship between these pharmacological effects and its fla- vonoid content.

A-type procyanidin derivatives with antioxidant and much enhancedα-glucosidase inhibitor activities

Procyanidins are natural compounds with good biological activity.However,due to a large number of phenolic hydroxyl groups in the structure,they have high polarity and low bioavailability.The preparation of A-type proanthocyanidin derivatives is an effective way to change their polarity and biological activity.In this paper,a series of A-type procyanidin derivatives were designed and synthesized by two practical and safe methods,and two new dimeric A-type procyanidin derivatives,procyanidin A1-acetone conjugate(6)and procyanidin A2-cystein conjugate(9)were obtained and reported for the first time.Their structures were characterized and confirmed by ^(1)H NMR,^(13)C NMR,HMBC,^(1)H-^(1)H COSY and MS.All the compounds showed strong DPPH scavenging activities.Compound 6 showed inhibitory effects onα-glucosidase with an IC_(50) value of 8.7μg/mL,while its parental compound,procyanidin A1,had no inhibitory effects.Degradation of procyanidins from peanut skin by L-cystein was studied.The results showed that the main structural unit of procyanidins in peanut skin was A-type proanthocyanidins dimer.

Chemical constituents of the aerial parts of Glycyrrhiza uralensis and their inhibitory activities against PTP1B andα-glucosidase

In the present study,a total of 11 compounds were isolated from the aerial parts of Glycyrrhiza uralensis,including two new compounds,glycyuralin Q(1)and glycyuralin R(2),and nine known compounds,including licoriphenone(3),orobol(4),trifoliol(5),7,2′,4′-trihydroxy-5-methoxy-3-arylcoumarin(6),11-hydroxy-9(Z),12(Z)-octadecadienoic acid(7),11-hydroxy-9(E),12(E)-octadecadienoic acid(8),licoricone(9),glycyrin(10),and 2′-hydroxyformononetin(11).Structures of the new compounds were identified by 1 D,2 D NMR and HR-MS data analyses.Compounds 1,2 and 10 showed potent inhibitory activities against PTP1 B,with IC50 values of 1.43,4.71 and 3.79μM,respectively.Compounds 2,4 and 10 inhibitedα-glucosidase with IC50 values of 13.61,11.13 and 17.48μM,respectively.

Biological investigation of phenyl benzoate, benzophenone, and xanthone compounds

In the present study, we evaluated the antitumor, anti-tyrosinase, anti-pancreatic lipase, antibacterial, antifungal, and anti-α-glycosidase activities for all or a subset of 20 known compounds. They included 8 phenyl benzoates, 10 benzophenones, and 2 xanthones. Phenyl benzoate compounds 1–8 did not exhibit evident antitumor activity, which was consistent with existing theories. Compounds 16, 17, and 18 exhibited moderate anti-tyrosinase activity. In addition, compounds 11 and 18 exhibited moderate inhibitory activity against Candida albicans, and compound 20 exhibited stronger anti-α-glycosidase activity than quercetin, with an IC_(50)of approximately 2.45 μM. These results demonstrated that compounds 11, 16–18, and 20 were promising leads for further structural modification.