苹果多酚的超声波提取及抗氧化作用研究

苹果中富含维生素、矿物质、黄酮类、酚类等多种生物活性物质,具有预防多种疾病的作用,其中原花青素和绿原酸为苹果中主要的酚类物质,且具有很强的抗氧化作用. 该文以国光苹果为试验材料,通过对苹果多酚超声波提取条件的研究,确立了提取的最佳工艺参数,并对苹果多酚的体外抗氧化性进行了研究,采用DPPH法和2-脱氧-D-核糖法研究了苹果多酚对DPPH自由基和·OH自由基的抑制效果. 结果表明,乙醇可作为苹果多酚的良性提取溶剂,其超声波提取的最佳工艺条件:乙醇浓度为60％,料液比为1∶6,提取时间为20 min,提取温度为60℃,提取一次. 苹果多酚清除DPPH自由基速度快,其抗氧化能力可与葡萄籽多酚相媲美. 通过2-脱氧D－核糖法可以看出:在一定浓度范围内,苹果提取物有很强的抗氧化能力,其最佳浓度范围为8～10 mg/mL,此外,苹果提取物及葡萄籽提取物清除羟基自由基（5OH）的效果远远高于茶多酚.      

不同溶剂提取燕麦油的脂肪酸分析及抗氧化性能研究

为进一步增加燕麦油的利用价值,用石油醚、正己烷、异丙醇、乙酸乙酯和乙醇五种溶剂分别提取燕麦油,精炼后测定其脂肪酸组成、DPPH·清除及还原力,同时与大豆油进行比较研究。提取结果显示,溶剂极性越强,对燕麦油提取率越高。GC-MS的结果表明,随着提取溶剂极性的提高,燕麦油中不饱和脂肪酸和反油酸的含量呈现降低趋势;且燕麦油中的亚油酸、反油酸、硬脂酸和α-亚麻酸含量均明显低于大豆油,但其他多不饱和脂肪酸的种类和含量高于大豆油。燕麦油的DPPH·清除能力及还原力高于大豆油,且随着极性的增强,大致呈现上升趋势。     

DPPH检测碱提香菇菌丝体多糖的抗氧化性能研究

[目的]探讨碱提香菇菌丝体粗多糖抗氧化能力的影响因素。[方法]按Sevag法去除粗多糖中蛋白质,以考马斯亮蓝法、苯酚-硫酸法和DPPH法分别测定碱提香菇菌丝体粗多糖在脱蛋白过程中多糖含量、蛋白含量和清除自由基能力的变化。[结果]碱提香菇菌丝体水溶性多糖经Sevag洗脱后,多糖含量降低了33.10%;蛋白含量降低了97.08%;自由基清除率降低了74.38%。[结论]碱提香菇菌丝体多糖具有较高的抗氧化能力,并与其糖蛋白浓度成正相关,过分脱除香菇菌丝体多糖提取物结合态蛋白会降低其抗氧化活性。     

Antioxidant Properties of Protein Hydrolysate Obtained from Oyster Saccostrea cucullata (Born, 1778)

The antioxidant activities of enzymatically hydrolyzed (protease from Bacillus cereus SU12) oyster (Saccostrea cucullata) protein were studied. The hydrolysate exhibited a strong antioxidant potential in 1, 1-diphenyl-2-picrylhydrazyl (DPPH, 85.7 ± 0.37%), followed by hydrogen peroxide radical scavenging activity (81.6 ± 0.3%), hydroxyl radical scavenging activity (79.32 ± 0.6%), and reducing power assay (2.63 ± 0.2 OD at 700 nm) at a concentration of 1 mg/mL. Due to the high antioxidant potential, the hydrolysate was purified in Sephadex G-25 gel filtration chromatography. The active peptide fraction was identified by DPPH and reducing power assay. The amino acid content of the purified active peptide fraction was analyzed by high performance liquid chromatography. The active fraction contained a good quantity of both essential and nonessential amino acids. The present study revealed that oyster (S. cucullata) protein hydrolysate is a potential source for natural antioxidants.     

紫甘薯乳酸发酵醪体外抗氧化性研究

测定5种乳酸发酵醪和紫甘薯醋的总抗氧化能力和对二苯代苦昧酰基（DPPH）自由基清除率,结果表明紫：甘薯乳酸发酵后抗氧化能力轻微增强,总抗氧化能力达200．18mg／mL,添加量为100μL时对DPPH自由基清除率达96．99％,与紫甘薯醋抗氧化能力相当。5种乳酸发酵醪中,紫甘薯乳酸发酵醪抗氧化能力最强。     

Antioxidant,Anti-Nephrolithe Activities and in Vitro Digestibility Studies of Three Different Cyanobacterial Pigment Extracts

Phycobiliprotein-containing water and carotenoid-containing methanolic extracts of three different cyanobacteria, Pseudanabaena sp., Spirulina sp. and Lyngbya sp., were studied for their DPPH scavenging, iso-bolographic studies, and anti-nephrolithe activities. The best EC₅₀ values for DPPH scavenging were in Lyngbya water (LW, 18.78 ± 1.57 mg·mg⁻¹ DPPH) and Lyngbya methanol (LM, 59.56 ± 37.38 mg·mg⁻¹ DPPH) extracts. Iso-bolographic analysis revealed most of the combinations of extracts were antagonistic to each other, although LM—Spirulina methanol (SM) 1:1 had the highest synergistic rate of 86.65%. In vitro digestion studies showed that DPPH scavenging activity was considerably decreased in all extracts except for Pseudanabaena methanol (PM) and LM after the simulated digestion. All of the extracts were effective in reducing the calcium oxalate crystal size by nearly 60%–65% compared to negative control, while PM and Spirulina water (SW) extracts could inhibit both nucleation and aggregation of calcium oxalate by nearly 60%–80%.     

地肤子总黄酮含量测定及其抗氧化活性

研究地肤(Kochia scoparia)子不同溶剂提取物的总黄酮含量及其抗氧化活性。用冷浸法得到地肤子乙醇、丙酮和乙酸乙酯提取物。测定了三种提取物的总黄酮含量,并通过测定其对DPPH自由基的清除能力和还原能力来研究其抗氧化能力。地肤子不同溶剂提取物均表现出很强的抗氧化性能,其抗氧化能力随提取物浓度增大而增强。地肤子提取物具有作为天然抗氧化剂的潜力。     

桉叶抗氧化物分离纯化及其抗氧化活性的研究

本文以DPPH自由基清除能力为指标,采用Diaion HP-20大孔吸附树脂、Toyopearl HW-40凝聚树脂柱层析、HPLC液相及核磁共振等技术对桉叶中抗氧化活性成分进行分离纯化及鉴定,得到1,2,3,6-四没食子酰葡萄糖和5-甲氧基糠醛,其中后者为首次在桉叶中分离得到.与抗氧化剂Trolox相比,两者具有更强的DPPH自由基清除能力,尤其是1,2,3,6-四没食子酰葡萄糖.     

Antioxidant flavonoids from Epimedium wushanense

Two new flavonoids, wushanicaritin (1) and wushankaempferol (2), along with 24 known flavonoids were isolated from the whole herb of Epimedium wushanense T.S. Ying (Berberidaceae). On the basis of NMR and ESI-MS spectroscopic analysis, structures of compounds 1 and 2 were elucidated as 8-γ-hydroxy-γ,γ-dimethylpropyl-3,5,7-trihydroxy-4′- methoxyflavone and kaempferol 3-O-α-l-[2,3-di-O-β-d-(6-E-p-coumaroyl) glucopyranosyl]-rhamnopyranosyl-7-O-α-l-rhamnopyranoside, respectively. DPPH radical scavenging activity tests indicated that 1 (IC₅₀ 35.3 μM) exhibited antioxidant activity comparable to Vitamin C (IC₅₀ 32.0 μM), while 2 (IC₅₀ 443.7 μM) showed weak activity.     

北京野生软枣猕猴桃果实品质综合评价体系

为评价北京野生软枣猕猴桃资源的驯化栽培价值,构建野生软枣猕猴桃品质综合评价体系,采集怀柔地区野生软枣猕猴桃11个样本的果实,以市售的栽培猕猴桃果实为对照,测定了单果重、果形指数、可溶性固形物含量、可滴定酸含量、固酸比、Vc含量、总酚含量和黄酮含量8个果实品质指标,利用隶属函数值法对测定的8个指标进行主成分分析;测定果实的DPPH抗氧化活性,探究其与果实的Vc、总酚和黄酮类物质含量的相关性。结果表明:主成分分析将8个品质指标综合成3个主成分因子,前3个主成分的累计贡献率为84.71%,样本S9和S6的果实品质综合评价为优。DPPH自由基清除率与果实的Vc含量、总酚黄酮类物质含量的相关指数分别为0.783 5、0.897 2和0.004,说明野生软枣猕猴桃的DPPH抗氧化作用与Vc和总酚含量相关性高,与黄酮类物质含量不相关。野生软枣猕猴桃个体间果实品质差异大,评价果实品质的重要指标是果实的总酚含量、Vc含量、固酸比、平均单果重、可溶性固形物和可滴定酸。