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).

探讨精浆SEMG1蛋白和精浆生化对精子活力及其受精结局的影响

目前影响男性不育的原因是多因素的,包括环境,营养,行为和遗传因素都会影响男性的生育能力。传统上,男性不育的诊断取决于描述性评估,重点是精子浓度,运动性和形态,大部分不育男性显示精子活力低,因此被定义为弱精子症[1]。然而,这些临床参数并不总是与了解男性不育的病因有关,少部分的男性不育症患者没有明确的原因。临床和实验室证据也表明精子功能障碍并不是常见的精液分析能得到的结果,而这些功能障碍也可导致不育。

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.

虚拟筛选荭草素和异荭草素降血糖靶点和体外活性评价

目的研究荭草素和异荭草素降血糖的靶点及其体外活性。方法从蛋白质数据库(www.rcsb.org)获取糖尿病相关靶点蛋白结构,利用虚拟分子对接打分评价荭草素和异荭草素与糖尿病相关靶点的结合强弱;基于分子对接的结果,采用荧光标记的1-脱氧葡萄糖(1-NBDG)、4-硝基苯基-α-D-葡萄糖苷PNDG(PNPG)、对硝基苯酚磷酸酯(pNPP)作为底物对荭草素和异荭草素进行体外抑制α-葡萄糖糖苷酶、钠–葡萄糖协同转运蛋白2(SGLT2)和蛋白酪氨酸磷酸酶1B(PTP1B)活性评价。结果荭草素与α-葡萄糖苷酶、SGLT2、和PTP1B的分子对接得分分别为-5.67、-9.32、-4.75,异荭草素与α-葡萄糖苷酶、SGLT2和PTP1B的分子对接得分分别为-5.34、-8.63、-4.93,而阳性对照药与靶标的分子对接打分依次是-5.58、-9.79、-9.28。体外实验显示,荭草素对α-葡萄糖苷酶、SGLT2、PTP1B的抑制率依次是(16.7±5.8)%、(15.4±1.2)%、(3.0±0.5)%,异荭草素对α-葡萄糖苷酶、SGLT2、PTP1B的抑制率依次是(11.8±3.8)%、(9.4±1.1)%、(-3.8±0.6)%,而阳性对照对α-葡萄糖苷酶、SGLT2、PTP1B的抑制率依次为(63.7±5.8)%、(92.7±8.8)%、(73.4±8.3)%。结论荭草素和异荭草素对SGLT2和α-葡萄糖苷酶具有一定的抑制活性,对PTP1B几乎没有抑制作用,且荭草素的体外活性略强于异荭草素,荭草素有可能作为一类具有双靶点作用的降血糖药物的先导化合物。

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.