Optimized Degradation and Inhibition of α-glucosidase Activity by Gracilaria lemaneiformis Polysaccharide and Its Production In Vitro

Gracilaria lemaneiformis polysaccharide (GLP) exhibits good physiological activities, and it is more beneficial as it is degraded. After its degradation by hydrogen peroxide combined with vitamin C (H₂O₂-Vc) and optimized by Box–Behnken Design (BBD), a new product of GLP-HV will be generated. While using GLP as control, two products of GLP-H (H₂O₂-treated) and GLP-V (Vc-treated) were also produced. These products chemical characteristics (total sugar content, molecular weight, monosaccharide composition, UV spectrum, morphological structure, and hypolipidemic activity in vitro) were assessed. The results showed that the optimal conditions for H₂O₂-Vc degradation were as follows: H₂O₂-Vc concentration was 18.7 mM, reaction time was 0.5 h, and reaction temperature was 56 °C. The total sugar content of GLP and its degradation products (GLP-HV, GLP-H and GLP-V) were more than 97%, and their monosaccharides are mainly glucose and galactose. The SEM analysis demonstrated that H₂O₂-Vc made the structure loose and broken. Moreover, GLP, GLP-HV, GLP-H, and GLP-V had significantly inhibition effect on α-glucosidase, and their IC₅₀ value were 3.957, 0.265, 1.651, and 1.923 mg/mL, respectively. GLP-HV had the best inhibition effect on α-glucosidase in a dose-dependent manner, which was the mixed type of competitive and non-competitive. It had a certain quenching effect on fluorescence of α-glucosidase, which may be dynamic quenching.     

Antioxidant Activity of Gracilaria lemaneiformis Polysaccharide Degradation Based on Nrf-2/Keap-1 Signaling Pathway in HepG2 Cells with Oxidative Stress Induced by H2O2

The objective of this research was to investigate the antioxidant activity of Gracilaria lemaneiformis polysaccharide degradation and its underlying mechanism involved in the Nrf-2/Keap-1 signaling pathway in HepG2 cells with oxidative stress induced by H₂O₂. The result of the scavenging ability of free radicals showed that GLP-HV (polysaccharide degraded by H₂O₂–vitamin C (Vc)) performed a better scavenging ability than GLP (G. lemaneiformis polysaccharide). Moreover, the scavenging ability of polysaccharide to these free radicals from strong to weak was as follows: superoxide radical, ferric ion, ABTS⁺, and DPPH radical, and their IC₅₀ values were 3.56 ± 0.0028, 4.97 ± 0.18, 9.62 ± 0.35, and 23.85 ± 1.78 mg/mL, respectively. Furthermore, GLP-HV obviously relieved oxidative stress in HepG2 cells, which strengthened the activity of T-AOC, CAT, GSH-PX, and SOD, and diminished the intensity of MDA, intracellular ROS, and calcium ion based on the Nrf-2/Keap-1 signaling pathway. The PCR result revealed that polysaccharide upregulated the expression of the genes Nrf-2, HO-1, NQO-1, and ZO-1 and downregulated Keap-1. The correlation between chemical properties and antioxidant mechanism of GLP-HV was evaluated via a heat map. The results illustrated that reducing sugar and active groups presented a positive correlation, and molecular weight and viscosity exhibited a negative relation with antioxidant activity.     

乙酰化蛋黄果多糖及其抗氧化活性研究

蛋黄果（Lucuma nervosa A. DC）乙酰化修饰多糖的抗氧活性优于未修饰多糖,通过分析乙酰化蛋黄果多糖的乙酰化度、红外光谱和形貌特征,阐明引起抗氧活性提升的原因。试验采用超声波辅助法提取蛋黄果果肉粗多糖,用三氯乙酸法除去蛋白质得到多糖。选取3份0.50 g多糖加入20% NaOH溶液溶解,分别加入1、3、5 mL乙酸酐,得到3种取代度（0.237±0.05、0.275±0.07、0.228±0.04）的乙酰化蛋黄果果肉多糖,评价其清除DPPH自由基、OH自由基和ABTS自由基的能力。结果表明,乙酸酐添加量由少到多时,蛋黄果多糖乙酰基取代度先显著升高,后趋于平缓下降。乙酰化蛋黄果多糖的红外光谱显示了3417 cm^-1（-OH）、2950 cm^-1（-CH）处的伸缩振动和1636 cm^-1处的（-OH）转动振动,1738 cm^-1处出现酯基C=O的伸缩振动吸收峰,表明乙酰化已经成功接入。扫描电镜结果显示,未经乙酰化的蛋黄果多糖表面相对光滑平整,呈片状结构;乙酰化修饰多糖分子间交联增强,构象发生了变化,变为表面形状不规则,出现很多空隙且表面粗糙。3种乙酰化蛋黄果多糖中DHG-Ac2（3 mL醋酐）清除效果最好,在浓度1.0 mg/mL时,DPPH清除能力、ABTS自由基清除率、OH自由基清除率分别为91.37%、58.73%、56.36%,分别高于蛋黄果多糖10.0%、43.7%、25.3%。这是引入的乙酰基能活化多糖链中的异头碳,使多糖的供氢能力提升,继而提升乙酰化蛋黄果多糖的抗氧化作用。本研究为海南产蛋黄果多糖的深入开发与抗氧化应用提供了基础研究数据。     

Identification,Characteristics and Function of Phosphoglucomutase (PGM) in the Agar Biosynthesis and Carbon Flux in the Agarophyte Gracilariopsis lemaneiformis (Rhodophyta)

Agar is widely applied across the food, pharmaceutical and biotechnology industries, owing to its various bioactive functions. To better understand the agar biosynthesis in commercial seaweed Gracilariopsis lemaneiformis, the activities of four enzymes participating in the agar biosynthesis were detected, and phosphoglucomutase (PGM) was confirmed as highly correlated with agar accumulation. Three genes of PGM (GlPGM1, GlPGM2 and GlPGM3) were identified from the G. lemaneiformis genome. The subcellular localization analysis validated that GlPGM1 was located in the chloroplast and GlPGM3 was not significantly distributed in the organelles. Both the GlPGM1 and GlPGM3 protein levels showed a remarkable consistency with the agar variations, and GlPGM3 may participate in the carbon flux between (iso)floridoside, floridean starch and agar synthesis. After treatment with the PGM inhibitor, the agar and floridean starch contents and the activities of floridean starch synthase were significantly decreased; products identified in the Calvin cycle, the pentose phosphate pathway, the Embden-Meyerhof-Parnas pathway and the tricarboxylic acid cycle were depressed; however, lipids, phenolic acids and the intermediate metabolites, fructose-1,6-phosphate were upregulated. These findings reveal the essential role of PGM in regulating the carbon flux between agar and other carbohydrates in G. lemaneiformis, providing a guide for the artificial regulation of agar accumulation.     

Sulfated Polysaccharide Extracted from the Green Algae Codium bernabei: Physicochemical Characterization and Antioxidant,Anticoagulant and Antitumor Activity

Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS^•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL⁻¹ concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL⁻¹. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource.     

复合酶法制备澳洲坚果蛋白肽及其抗氧化活性研究

本研究以前期制备的澳洲坚果蛋白为原料,经复合酶（木瓜蛋白酶和中性蛋白酶）酶解制备澳洲坚果蛋白肽,采用水解度为指标,利用单因素试验与正交试验考察各酶解因素对澳洲坚果蛋白水解度的影响,同时通过不同分子量（3、10、30 kDa）的超滤离心管对制备的蛋白肽进行初步的分离,并基于DPPH自由基清除能力对不同分子量的澳洲坚果蛋白肽的抗氧化活性进行评价。结果表明：各酶解因素对复合酶酶解制备澳洲坚果蛋白水解度的影响依次为酶解初始pH>复合酶配比>酶添加量>酶解时间;最佳复合酶酶解条件为复合酶配比1∶5、酶添加量12 000 U/g、酶解液初始pH 9.0、酶解时间360 min,在此条件下澳洲坚果蛋白的水解度为21.88%;同时,通过分析不同分子量的澳洲坚果蛋白肽组分发现,不同分子量的澳洲坚果蛋白肽均具有抗氧化活性,分子量在3~10 kDa的肽段组分具有较强的抗氧化能力,其DPPH自由基清除能力达到80.97%,且随着蛋白肽组分浓度的增加,其抗氧化能力也逐渐增强。     

毒死蜱降解细菌WJl-063的鉴定及酶促降解特性

从海南某农药厂地土壤中分离到1株能很好降解毒死蜱的菌株WJI-063,经形态特征、生理生化及16s rDNA序列分析,将该菌株初步鉴定为蜡状芽孢杆菌(Bacillus cereus).降解酶降解性能研究表明,该菌株能以毒死蜱作为唯一碳源生长,并且对毒死蜱起主要降解作用的是胞内酶,其传代降解代谢活性稳定.以牛血清白蛋白为标准蛋白,测得粗提酶中可溶性蛋白含量为0.044 mg/mL;在pH5.0～8.0范围内,酶活力表现稳定,通过双曲线法认为该酶降解毒死蜱的最适pH值为8.0;毒死蜱降解酶热稳定性差,最适温度为25℃;该酶与毒死蜱底物结合力强,对毒死蜱具有较好的降解效果,米氏常数Km为201.92nmol/L,最大降解速率为399.36nmol/mg·min.     

油松松塔多糖提取工艺及抗氧化活性研究

目的研究油松松塔多糖的最佳提取工艺及其抗氧化活性,为充分开发利用油松松塔多糖提供依据。方法:研究单因素试验,再通过正交实验考察各因素对多糖提取率的影响,以确定油松松塔多糖的最佳提取工艺。采用DPPH、ABTS及还原力法测定油松松塔多糖的抗氧化能力。结果单因素对多糖提取率的影响由大到小依次为:料液比提取温度提取时间,热回流提取油松松塔多糖的最佳条件为:料液比1:30(g/mL),回流时间8h,回流温度100℃,其多糖含量为1.12g/100g。油松松塔多糖对DPPH、ABTS自由基有较好的清除作用,当浓度为10mg/mL时清除率分别为86.2%和83.7%。其还原力也较强。结论得出热回流法提取油松松塔多糖的最佳提取工艺,其抗氧化效果良好。     

辣木籽多糖的超高压辅助提取工艺及其抗氧化活性分析

超高压辅助提取技术是一种天然产物新型绿色高效提取技术,在保证提取效率的同时能最大限度保持天然产物的生物活性。为探究超高压辅助提取技术对辣木籽多糖的提取效果及其抗氧化活性的影响,本研究以辣木籽为原料,通过超高压辅助提取技术提取辣木籽中的水溶性多糖,以多糖得率为考察指标,以提取压力、提取时间、料液比、粉碎度作为单因素,在单因素试验基础上,采用正交试验设计方法优化辣木籽多糖的超高压辅助提取工艺,并通过测定总抗氧化能力、清除DPPH自由基（DPPH•）和羟自由基（•OH）的能力来分析辣木籽水溶性多糖的抗氧化活性。结果表明,辣木籽多糖最佳的超高压辅助提取工艺条件为：提取压力100 MPa、保压时间6 min、料液比（g/mL）1:15、粉碎度100目筛,在最佳提取工艺条件下辣木籽多糖最大提取得率为0.346%;在测试范围内辣木籽多糖清除DPPH自由基能力随多糖浓度的增加而增加,并有较好的线性关系,清除率达到50%时对应的浓度（IC₅₀）为0.0439 g/L,但是其抗氧化能力低于相同浓度的Vc,在测试范围内清除羟自由基能力也随辣木籽多糖浓度的增加而增加,也有较好的线性关系,IC₅₀为0.1666 g/L,其抗氧化能力与同浓度的Vc较接近,辣木籽多糖的总抗氧化能力为0.0482 mmol/L（以硫酸亚铁的当量浓度表示）。与热水提取方法相比,超高压辅助提取方法能够缩短提取时间,提取温度大大降低,提取效率显著提高;而且提取的辣木籽水溶性多糖具有较好的抗氧化能力,可以作为天然抗氧化剂进行开发利用。本研究结果可为天然抗氧化剂的开发、辣木资源的综合开发及高值化利用提供技术支持和参考。     

Extraction and Identification of Three New Urechis unicinctus Visceral Peptides and Their Antioxidant Activity

The viscera of Urechis unicinctus with polypeptides, fatty acids, and amino acids are usually discarded during processing to food. In order to improve the utilization value of the viscera of Urechis unicinctus and avoid resource waste, antioxidant polypeptides were isolated from the viscera of Urechis unicinctus. First, a protein hydrolysate of Urechis unicinctus (UUPH) was prepared by ultrasonic-assisted enzymatic hydrolysis, and the degree of hydrolysis was as high as 79.32%. Subsequently, three new antioxidant peptides (P1, P2, and P3) were purified from UUPH using ultrafiltration and chromatography, and their amino acid sequences were identified as VTSALVGPR, IGLGDEGLRR, TKIRNEISDLNER, respectively. Then, the antioxidant activity of the polypeptide was predicted by the structure–activity relationship and finally verified by experiments on eukaryotic cells. The P1 peptide exhibited the strongest antioxidant activity among these three antioxidant peptides. Furthermore, P1, P2, and P3 have no toxic effect on RAW264.7 cells at the concentration of 0.01~2 mg/mL and can protect RAW264.7 cells from H₂O₂-induced oxidative damage in a concentration-dependent manner. These results suggested that these three new antioxidant peptides were isolated from the viscera of Urechis unicinctus, especially the P1 peptide, which might serve as potential antioxidants applied in health-derived food or beverages. This study further developed a new use of the by-product of Urechis unicinctus, which improved the comprehensive utilization of marine biological resources.     

椰子花序汁液中多糖的抗氧化活性

对椰子花序汁液(Coconut inflorescence sap,CIS)中多糖的抗氧化活性进行研究.结果表明,椰花汁多糖对超氧阴离子自由基(O2-·)、DPPH自由基和羟基自由基(·OH)都有较强的清除能力,对ge2+的络合能力也较强,同时椰花汁多糖还有一定的还原能力.说明椰花汁多糖的抗氧化活性较强,具有很好的保健功效.     

金柑果皮精油超声波辅助提取工艺优化及其抑菌、抗氧化活性

采用响应面法对金柑果皮精油超声波辅助提取提取工艺条件进行优化,并对金柑果皮精油的抑菌和抗氧化活性进行评价。结果表明,金柑果皮精油超声波辅助提取的最佳工艺条件为:液料比27∶1 m L/g、超声时间1.25 h、超声波功率300 W。在此条件下,金柑果皮精油得率为2.24%,与理论预测值基本一致。金柑果皮精油对金黄色葡萄球菌、大肠杆菌、沙门氏菌、黑曲霉、酵母菌均有一定抑制作用,最小抑菌浓度分别为1.0%、0.5%、0.5%、0.5%、0.1%。抗氧化活性结果表明,金柑果皮精油对食用油脂的货架期有一定的延缓作用,具有一定的清除羟自由基、DPPH自由基的能力和总抗氧化能力。     

木瓜籽精油的提取及其抗氧化活性研究

采用水蒸气蒸馏法提取木瓜籽精油(PSO),测定PSO的总抗氧化能力、羟基自由基和DPPH自由基清除能力,并应用GC-MS分析测定PSO的化学组成。结果表明,水蒸气蒸馏法提取木瓜籽精油最佳蒸馏时间是2.5 h,料液比和浸泡时间分别是1∶8(w∶V) 和1 h;与合成抗氧化剂相比,PSO的总抗氧化能力偏低,当PSO浓度达到5×10-5 mg/mL和8 mg/mL时,其清除羟基自由基和DPPH自由基的能力分别达到100%和70%以上;PSO化学成分主要是安息香醛、苯乙醛、苯乙腈和异硫氰酸苄酯,其中异硫氰酸苄酯的相对含量占98.28%。说明该方法可获得高纯度的异硫氰酸苄酯,可为工业上生产异硫氰酸苄酯提供一定的理论依据。     

鱼腥草总黄酮超声-微波辅助提取及其抗氧化活性

在单因素试验基础上,通过响应面法优化鱼腥草总黄酮超声-微波辅助提取最佳工艺条件,并采用清除 DPPH·和·OH 法评价其抗氧化活性。结果表明,最佳提取工艺条件为：乙醇浓度 41%,料液比（g∶mL）1∶40,超声 功率 200 W,超声温度 50 ℃,超声时间 40 min,微波功率 260 W,微波时间 40 s。该工艺条件下,鱼腥草总黄酮提取 率为 5.65%,与模型预测值相符。说明超声-微波辅助提取鱼腥草总黄酮的工艺稳定可靠。鱼腥草总黄酮对 DPPH·和·OH 的清除率具有一定的量效关系,均明显高于同浓度的 BHT 溶液。说明鱼腥草总黄酮具有较强的抗氧化活性。     

辣木叶黄酮苷的分离鉴定及抗氧化活性研究

为研究辣木（Moringa Obleifera Lam.）叶片中的黄酮苷成分及其抗氧化活性,利用MCI凝胶柱、羟丙基葡聚糖凝胶（Sephadex LH-20）柱层析、硅胶柱层析（CC）、半制备高效液相色谱等分离手段对石油醚组分进行分离和纯化,利用LC-MS、1H-NMR、13C-NMR等现代波谱技术对分离得到的化合物进行结构鉴定,采用SRB法和DPPH·清除率对分离得到的化合物进行体外抗肿瘤活性筛选和抗氧化活性的测定。结果表明,从辣木叶的石油醚部分分离得到4个化合物,已鉴定为β-谷甾醇（Ⅰ）、胡萝卜苷（Ⅱ）、槲皮素-3-O-β-D-葡萄糖苷（Ⅲ）、山柰酚-3-O-β-D-葡萄糖苷（Ⅳ）。4种化合物均具有抗氧化活性,但化合物Ⅲ的抗氧化活性极显著强于其他三种化合物;体外抗肿瘤活性表明,化合物Ⅰ和化合物Ⅱ对乳腺癌细胞株（MDA-MB-231）有一定的抑制作用。      

不同茶类特征成分抗氧化特性研究进展

简述近年关于绿茶、红茶、乌龙茶、普洱茶主要茶类特征成分抗氧化特性的研究进展,比较分析其异同点,讨论了有待进一步研究的内容,为开发茶类天然抗氧化剂的研究提供一定的参考。     

金花葵的营养价值与抗氧化活性

本研究以广东地区引种种植的金花葵为试材,检测了其花朵和嫩果荚中氨基酸、矿质元素、总黄酮、总酚和多糖等营养成分含量,并评估了其抗氧化能力。结果表明,金花葵的花朵和嫩果荚中均检测到16种氨基酸（含7种必需氨基酸）,氨基酸总量分别占干重的13.01%和12.56%,氨基酸比值系数分（SRC）分别为70.49和67.83。花朵中总黄酮、总酚、铁和钾含量显著高于嫩果荚,而嫩果荚中多糖、钙和镁含量则显著高于花朵。对DPPH和ABTS自由基的清除试验表明,花朵的抗氧化能力要优于嫩果荚。综合来看,金花葵的花朵和嫩果荚都具有食用和药用价值,且适合在广东地区种植。     

火龙果花中多酚类化合物抗氧化活性研究

对火龙果花中多酚类化合物抗氧化活性进行研究。采用抗氧化能力的体外实验方法,研究火龙果花中多酚类化合物的还原能力、清除·OH、O2-、 DPPH·和ABTS·四种自由基的能力,以评价其抗氧化性,并以BHT作为阳性对照。结果表明,火龙果花中多酚类化合物抗氧化能力与浓度(0.4～0.8 mg/mL)呈量效关系。虽总体抗氧化活性较弱于BHT,但总体趋势与BHT相同,在浓度为0.7 mg/mL时,其羟自由基清除活性甚至略高于对比溶液。因此,火龙果花中多酚类化合物具有较好的抗氧化活性,可进一步研究开发为抗氧化功能性食品。     

普洱茶挥发性成分抗氧化活性研究

用同时蒸馏萃取法（SDE）富集普洱茶挥发性物质,并用GC-MS分析其化学组成,采用DPPH和FRAP法对不同发酵阶段普洱茶挥发性物质的抗氧化活性进行评价,分析抗氧化活性与主要成分含量的关系。结果表明,普洱茶在发酵过程中甲氧基苯类化合物的相对含量大幅增加;挥发性物质的DPPH自由基清除能力和FRAP总抗氧化能力随发酵程度的加深呈显著上升趋势,发酵出堆后分别提高了100%和296%;挥发性物质的DPPH自由基清除能力和FRAP总抗氧化能力与甲氧基苯类化合物和芳樟醇氧化物的相对含量具有显著正相关性。     

原生态椰子油体外抗氧化活性

对原生态椰子油(VCO)的体外抗氧化活性进行了评价,分析了VCO中总酚酸的含量及其对DPPH自由基和ABTS+自由基的清除能力,对Fe~(2+)的络合能力以及对花生油的抗氧化能力.结果表明,VCO中总酚酸的含量为(0.180±0.003)mg/mL;对DPPH自由基的清除率为31.95%.低于Trolox、BHT和没食子酸;对ABTS~+自由基的清除能力为67.49 μmol/L Tmlox当量(TEAC值);对Fe~(2+)的络合能力优于Tmlox和BHT,但显著低于没食子酸;VCO对花生油具有一定的抗氧化能力.