动物源性降糖肽的研究进展

一些食源性活性肽降糖效果显著,具有开发成功能性食品的潜力,在世界范围内引起广泛关注。其中广泛存在于食物蛋白水解物中的动物源性活性肽具有较好的降血糖特性,其潜在机制包括抑制α-葡萄糖苷酶或二肽基肽酶-4(dipeptidyl peptidase-4,DPP-4)等。本文介绍了动物源性降糖肽的制备方法、作用机理及降糖效果的评价方法,重点综述了来源于畜禽肉、鱼类、血液、乳类和蛋类等动物性食物的降糖肽的现有研究成果,为预防和辅助治疗糖尿病及相关功能性食品的开发提供了理论依据。

超声-低共熔溶剂提取玉米芯黄酮的纯化与活性测定

为获得超声-低共熔溶剂提取的玉米芯总黄酮的最佳纯化条件和测定纯化黄酮的活性,先对常用大孔吸附树脂进行筛选并优化了吸附纯化工艺,再以对1,1-二苯基-2-三硝基苯肼自由基(DPPH·)和2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基(ABTS·)的清除能力为指标,评价纯化前、后玉米芯黄酮的抗氧化性;通过体外抑制大肠杆菌、金黄葡萄球菌和枯草芽孢杆菌生长试验测定黄酮的抑菌性;最后,通过体外抑制α-淀粉酶活性试验测定其降糖活性。结果表明,XAD-2树脂适于纯化玉米芯黄酮,其最佳条件是浓度1.00 mg/mL、pH 4.0、流速为15 mL/h的上样液进行吸附,吸附完成后以流速为60 mL/h、70 mL的70%乙醇进行洗脱,此条件下可将玉米芯黄酮纯化2.65倍。玉米芯黄酮纯化后对DPPH·和ABTS·有更强的清除能力,但较维生素C弱;纯化玉米芯黄酮的抑菌性增强,抑菌强度大小顺序为金黄葡萄球菌>大肠杆菌>枯草芽孢杆菌;玉米芯黄酮有降糖活性,其纯化产物的降糖能力与阿卡波糖相当。可知超声辅助低共熔溶剂提取的玉米芯黄酮有抗氧化、抑菌和降糖活性,XAD-2大孔树脂纯化玉米芯黄酮效果好。

Antioxidant Activity of Polysaccharides in Yam Bulbils and Their Hypoglycemic Effect in Diabetic Mice

The polysaccharides in yam bulbils were extracted, and their antioxidant activity and hypoglycemic effect in diabetic mice were discussed. The results showed that the antioxidant activity of polysaccharides in yam bulbils was signifi- cantly enhanced with the increase of concentration; they showed a strong scaveng- ing ability against DPPH. and .OH, and the scavenging ability was dose dependent to some extent; the scavenging rates reached 91.15% and 89.06% respectively when the dose reached 4.0 mg/ml; the polysaccharides in yam bulbils significantly educed the blood glucose in model rice, and the hypoglycemic effect of large-dose polysaccharides was more obvious. The polysaccharides in yam bulbils has good antioxidant activity and hypoglycemic effect, which provides a new source for devel- opment of safe and natural food antioxidants and blood sugar-lowering agents.

Study on Anti-oxidation and Inhibitory Effect on Nonenzymatic Glycation Reaction of Fermentation Extract from Biotransformation of Ginkgo biloba L. (EGB) by Hericium erinaceus

[ Objective] In order to study the anti-oxidation and inhibitory effect on nonenzymatic glycation reaction of EGB fermentation extraction biotransformed by Hericium erinaceus. [ Method ] The free radical scavenging ability and reducing capacity of DPPH as well as inhibitory rate of nonenzymatic glycation reaction were measured targets for comparing changes of anti-oxidation and inhibitory effect on nonenzymatic glycation reaction of fermentation lyophilizer and fermentation extraction before and after EGB fermention adsorbed by AB-8 macroporous resin. The EGB fermention was biotransformed by Hericium erinaceus. [ Result ] After adsorbed by AB-8 macroporous resin, the bioactive matters were concentrated and separated. The free radical scavenging rate, reducing capacity and inhibitory rate of nonenzymatic glycation reaction were increased significantly after adsorbed by AB-8 macroporous resin. [ Conclusion] AB-8 macroporous resin could be used for preliminary concentration of EGB fermentation which was biotransformed by Hericium erinaceus.

Silkworm Extract Ameliorates Type 2 Diabetes Mellitus and Protects Pancreaticβ-cell Functions in Rats

Objective The aim of the present study was to investigate the hypoglycemic effects of silkworm extract(SE)on experimental type 2 diabetes mellitus(T2DM)rats.Methods SE was prepared by dissolving freeze-dried silkworm powder in 70%(v/v)aqueous ethanol.T2DM rats were induced by feeding them a high fat diet and an intraperitoneal injection of streptozotocin(STZ).The blood glucose,free fatty acid(FFA),malondialdehyde(MDA),tumor necrosis factor alpha(TNF-α)and superoxide dismutase(SOD)levels were detected by enzyme-linked immunosorbent assay(ELISA).The quality of SE was controlled by high performance liquid chromatography(HPLC;Agilent 1260,Agilent,USA).Hematoxylin-eosin(HE)staining was performed for histological evaluation.Antibody expression was assessed via immunohistochemistry(IHC)staining.Results SE could improve insulin resistance and islet cell function by reducing FFA,MDA and TNF-αlevels and increasing SOD level.In addition,pancreatic HE staining analysis revealed that SE has a protective effect on isletβ-cells.Conclusions The present study indicates that SE has hypoglycemic as well as pancreatic protective effects in T2DM model rats.

Pharmacokinetics and Biodegradation Performance of a Hydroxypropyl Chitosan Derivative

Hydroxypropyl chitosan(HP-chitosan) has been shown to have promising applications in a wide range of areas due to its biocompatibility, biodegradability and various biological activities, especially in the biomedical and pharmaceutical fields. However, it is not yet known about its pharmacokinetics and biodegradation performance, which are crucial for its clinical applications. In order to lay a foundation for its further applications and exploitations, here we carried out fluorescence intensity and GPC analyses to determine the pharmacokinetics mode of fluorescein isothiocyanate-labeled HP-chitosan(FITC-HP-chitosan) and its biodegradability. The results showed that after intraperitoneal administration at a dose of 10 mg per rat, FITC-HP-chitosan could be absorbed rapidly and distributed to liver, kidney and spleen through blood. It was indicated that FITC-HP-chitosan could be utilized effectively, and 88.47% of the FITC-HP-chitosan could be excreted by urine within 11 days with a molecular weight less than 10 k Da. Moreover, our data indicated that there was an obvious degradation process occurred in liver(< 10 k Da at 24 h). In summary, HP-chitosan has excellent bioavailability and biodegradability, suggesting the potential applications of hydroxypropyl-modified chitosan as materials in drug delivery, tissue engineering and biomedical area.

Antidiabetic therapy and increased risk of hepatocellular carcinoma in chronic liver disease

AIM： To explore the association between hepatocellular carcinoma （HCC） and type 2 diabetes mellitus, describe the temporal relations between the onset of diabetes and the development of HCC and evaluate the possible effects of antidiabetic therapy on HCC risk,METHODS： We recruited 465 HCC patients, 618 with cirrhosis and 490 control subjects. We evaluated the odds ratio （OR） for HCC by univariate and multivariate analysis. Moreover, OR for HCC in diabetic subjects treated with insulin or sulphanylureas and with metformin were calculated.RESULTS： The prevalence of diabetes mellitus was 31.2% in HCC, 233% in cirrhotic patients and 12.7% in the Control group. By univariate and multivariate analysis, the OR for HCC in diabetic patients were respectively 3.12 （CI 2.2-4.4, P 〈 0.001） and 2.2 （CI 1.2-4.4, P = 0.01）. In 84.9% of cases, type 2 diabetes mellitus was present before the diagnosis of HCC. Moreover, we report an OR for HCC of 2.99 （CI 1.34-6.65, P = 0.007） in diabetic patients treated with insulin or sulphanylureas, and an OR of 0.33 （CI 0.1-0.7, P = 0.006） in diabetic patients treated with metformin.CONCLUSION： Our study confirms that type 2 diabetes mellitus is an independent risk factor for HCC and pre-exists in the majority of HCC patients. Moreover, in male patients with type 2 diabetes meUitus, our data shows a direct association of HCC with insulin and sulphanylureas treatment and an inverse relationship with metformin therapy.

Biodegradation ofEnteromorpha Polysaccharides by Intestinal Micro-Community from Siganus oramin

Micro-communities are supposed to have more potential functions of biodegradation of polysaccharides than single strain; however, the intestinal mi ties involved in the biodegradation of Enteromorpha polysaccharides （EP） were sel- dom reported. In order to obtain the EP-degrading micro-community, the intestines of Siganus oramin was obtained to isolate the micro-communities, which were enriched by 0.3% of EP as the sole carbon source. A stable micro-community with EP degradative capability was achieved after seven generations of subculture, named H1. Results showed that H1 was able to degrade 75% of EP within 24 hours, and the activity of EP lyases reached 500 U mL-1 in 32 hours. With denaturing gradient gel electrophoresis （DGGE） and 16S rRNA gene clone library analysis, ten bacteria closely related to Marinomonas pontica, Microbacterium sp., Leucobacter chironomi, Cyclobacterium sp., Algoriphagus winogradskyi, Pseudoalteromonas sp. and Vibrio sp. were determined. Furthermore, compared with the DGGE bands sequence and the clone library analysis, the dominant bacteria of the EP-biodegrading mi- cro-community were Pseudoalteromonas sp. and Vibrio sp., with the respective proportion of 38% and 46%, and they should play an important role in EP degradation together with other degrading bacteria in the micro-community H1.

Anaerobic biodegradation of RDX and HMX with different co-substrates

Simulated wastewater of hexahydro-l,3,5-trinitro-l,3,5-triazine （RDX） and octahydro- 1,3,5,7-tetranitro- 1,3,5,7- tetrazocine （HMX） was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex- trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation. With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1% and 98.5% was achieved for RDX and HMX, respectively, after treatment for 7 days. When so- dium acetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degrada- tion. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A well-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.

Antioxidant Activity and Anti-Hyperglycemic Effect of Lagenaria Siceraria Fruit Extract

Lagenaria siceraria （Molina） Standl., known as bottle gourd is widely available throughout Vietnam as an edible vegetable. Bottle gourd is a commonly fruit but there are little reports about its biological activities. The aim of the present study was to evaluate antioxidant activity and anti-hyperglycemic potential of ethanolic extract of bottle gourd. The ethanolic extract was tested for its antioxidant activity on chelating power, the ferric reducing/antioxidant power assay （FRAP） and the 1, 1-diphenyl-2-picryl-hydrazyl （DPPH） free radical scavenging assay. The results showed that chelating activity was 80.02%, FRAP value was 92.84 μmol Fe^2＋/g and active radical scavenging which showed an IC50 was 49.50 μg/ml. The five different doses of ethanolic extract were treated by oral tolerance to mice body before oral glucose tolerance and blood glucose level was measured using glucose oxidase method. The result indicated that inhibition percentage of ethanolic extract of bottle gourd at the dose of 400 mg/kg in glucose-induced hyperglycemic mice was effectively similar to standard drug glibenclamide. The results obtained indicate that ethanolic extract from bottle gourd is the potential antioxidant and anti-hyperglycemic agent.

An UPLC-MS/MS application to investigate chemical compositions in the ethanol extract with hypoglycemic activity from Zingiber striolatum Diels

Zingiber striolatum Diels （Zingiberaceae） is an edible plant resource in the Chinese folk with special efficacy in relieving diabetes and constipation, which has been documented in the Compendium ofMateria Medica. However, its hypoglycemic activity and constituents have not been reported yet. In the present study, we evaluated the hypoglycemic activity of Z. striolatum in insulin-resistant HepG2 cells, and we developed ultra performance liquid chromatography coupled with tandem mass spectrometry （UPLC-MS/MS） based chemical profiling method for rapid analysis of Z. striolatum. As a result, the ethanol extract from Z. striolatum showed significant hypoglycemic activity in HepG2 cells, and 22 flavonoids compounds were tentatively characterized by comparing the retention time and mass spectrometry data. In conclusion, the method of hypoglycemic screening in insulin-resistant HepG2 cells coupled with UPLC-MS/MS is a feasible and credible technique to separate and identify the active constituents in complex matrices of traditional Chinese medicine.

An UPLC-MS/MS application to investigate the chemical composition of the ethanol extract from Anoectochilus chapaensis and its hypoglycemic activity in insulin-resistant HepG2 cells

Anoectochilus chapaensis Gagnep. （Orchidaceae） was named as the ＂king of medicine＂ because of its excellent efficacy for the treatment of diabetes. However, the bioactive constituents are unknown. An ethanol extract from A. chapaensis showed significant stimulating effect on glucose consumption in HepG2 cells. The chemical composition was investigated by UPLC-MS/MS in negative electrospray ionization （ESI） mode, and 63 compounds including flavonoids, triterpenoids, and aliphatic acids were tentatively identified by accurate mass and characteristic fragments. Moreover, the method of hypoglycemic screening with insulin resistant HepG2 cells and UPLC-MS/MS might be potentially useful in rapid and efficient characterization and primary prediction of natural products prior to traditional isolation.

Antihyperglycemic, insulinsensitizing and antioxidant activities of the active fractions from Anoectochilus chapaensis

Anoectochilus chapaensis Gagnep. （Orchidaceae）, an indigenous and valuable Chinese folk medicine, has been widely used in China to treat diabetes. However, few reports are available about its constituents and activity. The present experiment was conducted to investigate the active fractions from A. chapaensis in diabetic rat model induced by high-fat diet plus streptozotocin. The total EtOH extract from the whole herbs ofA. chapaensis, half of which was partitioned in sequence with petrol ether （PE）, ethyl acetate （EtOAc）, n-BuOH and H2O, thus yielding four fractions, all of them were orally administered with an identical dose amount to 4 g/kg dried crude herbs once a day for consecutive two weeks to further investigate the antihyperglycemic activity. The EtOAc fraction caused a significant fall in the non-fasting blood glucose level of diabetic rats from （402.66±82.26） to （226.26±62.10） mg/dl, which may be attributed to ameliorating insulin resistance, modulating the activity of enzymatic antioxidants, reducing the content of NO, etc. Much more intact β cells in the islets of Langerhans in EtOAc fraction-treated groups than the negative control were observed, which greatly supported the morphological and functional elucidation. The OGTT evidenced that EtOAc fraction could promote the endurance capacity of acute glucose increase in diabetic rats. The EtOAc fraction of A. chapaensis contains some hypoglycemic and antioxidant principles with the potential to be developed further for the treatment of diabetes specifically associated with an insulin resistance state.