Valorisation of waste fractions from autohydrolysis of selected lignocellulosic materials

Non‐isothermal processing of lignocellulosic materials in aqueous media (autohydrolysis reaction) under mild conditions leads to solutions containing valuable chemicals (oligosaccharides, sugars and acetic acid) and other, undesired, compounds (belonging to the extractive and acid‐soluble lignin fractions) which have to be removed in further purification treatments. Liquors obtained by non‐isothermal autohydrolysis of Eucalyptus globulus wood and corncobs under a variety of operational conditions were extracted with ethyl acetate in order to remove non‐saccharide components, and the suitability of the fraction dissolved in the organic phase was assayed for possible utilisation as an antioxidant. The yield and antioxidant activity of ethyl acetate extracts (measured by the α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) radical scavenging capacity) showed a strong dependence on the autohydrolysis conditions. The antioxidant activity of extracts obtained under selected operational conditions compared well with synthetic antioxidants. © 2003 Society of Chemical Industry     

Category Learning in Rhesus Monkeys: A Study of the Shepard, Hovland, and Jenkins (1961) Tasks.

In influential research, R. N. Shepard, C. I. Hovland, and H. M. Jenkins (1961) surveyed humans' categorization abilities using tasks based in rules, exclusive-or (XOR) relations, and exemplar memorization. Humans' performance was poorly predicted by cue-conditioning or stimulus-generalization theories, causing Shepard et al. to describe it in terms of hypothesis selection and rule application that were possibly supported by verbal mediation. The authors of the current article surveyed monkeys' categorization abilities similarly. Monkeys, like humans, found category tasks with a single relevant dimension the easiest and perceptually chaotic tasks requiring exemplar memorization the most difficult. Monkeys, unlike humans, found tasks based in XOR relations very difficult. The authors discuss the character and basis of the species difference in categorization and consider whether monkeys are the generalization-based cognitive system that humans are not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

抗氧剂KY-60的精制研究

KY-60即4,4,-亚甲撑双(2,6-二叔丁基苯酚),是多种合成树脂的优异的抗氧剂,其相容性好,抗氧效能高,挥发性小,对制品无污染,无毒,不着色,对热、氧、龟裂老化有极好的防护作用;尤其是对日光下的橡胶制品老化起了最大的防护效能,对硫化和可塑度均无影响,使用方便,可以与多种辅助抗氧剂、稳定剂配用,具有明显的增效作用。目前国内对KY-60的研究工作已完成了实验室合成,针对KY60生产中产品粒度小、分布不均匀、纯度低、用户使用不便等问题,重结晶作为整个工作的关键一步,为此对KY60结晶过程进行了大量的研究。     

Modulation of the antioxidant/pro-oxidant balance,cytotoxicity and antiviral actions of grape seed extracts

Grape seed extracts (GSEs) were investigated in yeast cells harbouring defects in their antioxidant system (regarding the cellular growth and growth recovery from H₂O₂ insult). GSEs antioxidant activity was detected in wild-type and mutant strains Δcta1, Δgsh1 and Δoye2glr1, while pro-oxidant activity in Δsod1 cells was seen. Assessment of proliferation of prostate cancer PC3 and HBV-replicating HepG2 2.2.15 cells treated with GSEs has shown higher cytotoxicity of red grape seed extract (RW) than white grape seed extract (WW) subjective to dose and period of administration. No antiviral effect was detected by measuring the secreted virion particles in HepG2 2.2.15 cells treated with GSEs. The GSEs play a dual antioxidant/pro-oxidant role in vivo according with the cellular antioxidant system deficiencies and exhibit cytotoxic properties in PC3 and HepG2 2.2.15 cell lines, but no antiviral action against HBV.     

Effect of microwave‐assisted extraction on the release of polyphenols from ginger (Zingiber officinale)

The significance of different variables viz. temperature, time and solvent at constant power in microwave‐assisted extraction (MAE) process of ginger was studied and compared with conventional method. Aqueous ethanol (50%) provided higher yields of extract as well as the highest release of total polyphenols (TPP) than alcoholic solvents. The reason could be the high dielectric constant of aqueous ethanol as compared to alcohols. Microwave heating being a volumetric process, an exposure time of 1 min was found to be sufficient. The better penetration of microwaves and greater solubility at higher temperature resulted in higher yield of TPP and [6]‐gingerol. The resultant extract showed higher radical scavenging activity (RSA) values. Thus, MAE allowed higher recoveries compared to conventional extraction process, with improvement in the quantity and quality of extract in very short period of time.     

脂溶性茶多酚的制备与表征

茶多酚(Teapolyphenols,TP)是一种天然抗氧化剂,但其易溶于水,难溶于油的特性使其应用受到了限制。实验通过月桂酰氯酰化制备了脂溶性茶多酚。结果表明,制备脂溶性茶多酚最佳反应条件为:在氮气气氛中,反应温度控制在75￣78℃,用乙酸乙酯作溶剂,将月桂酰氯与茶多酚以n(月桂酰氯)∶n(TP)=5∶1反应而得到。     

In vitro gastrointestinal digestion of polyphenols from different molasses (pekmez) and leather (pestil) varieties

In this study, to evaluate the in vitro bioaccessibility of eight different pekmez and pestil samples, total phenolics, flavonoids, proanthocyanidins, anthocyanins and antioxidant capacity were determined at different phases of simulated gastrointestinal (GI) digestion. For the analysis of antioxidant activity, four different methods were used including 2,2‐azinobis(3‐ethylbenzothiazoline)‐6‐sulfonic acid, 1,1‐diphenyl‐2‐picrylhydrazil, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. The results revealed that the dialysed fraction (IN) represented 12–50%, 3–17% and 3–72% of the total phenolics, flavonoids and proanthocyanidins, respectively. Moreover, total antioxidant capacity of IN fraction was 2–57% of the initial values obtained for pekmez and pestil samples. To identify the influence of simulated in vitro GI digestion on total anthocyanins, only black mulberry molasses (pekmez) and plum leather (pestil) were analysed and according to the results no anthocyanins were detected in the IN fraction for both samples. The present study presented a detailed insight of bioaccessibility of polyphenols in various pekmez and pestil samples.     

马蹄皮总提取物多组分的协同抗氧化能力研究

利用不同溶剂提取获得马蹄皮多种总提取物,研究不同提取物的总还原能力及对DPPH和羟自由基的清除能力。结果表明,乙醇总提取物清除自由基的作用最强,不同溶剂提取物清除能力具有量效关系,同时多种组分间存在着一定的相互协同作用,并利用薄层层析初步分析了总提取物中的黄酮种类。     

桦褐孔菌富锗培养及其总黄酮抗氧化活性

以菌落直径为指标考察桦褐孔菌富锗培养的适宜加锗量,采用L9(34)正交优选的提取条件微波提取富锗培养后的桦褐孔菌总黄酮(简称Ge-TFIO),并运用活性氧(ROS)试剂盒、DPPH·法、H2O2诱导小鼠氧化溶血抑制实验评价Ge-TFIO的抗氧化能力。结果表明:桦褐孔菌富锗培养的适宜加锗量为40mg/L;富锗培养的桦褐孔菌总黄酮微波提取优化工艺条件为乙醇浓度80%、料液比1:40、处理时间180s、微波功率352W,此条件下,Ge-TFIO提取率为4.59%;2mg/mLGe-TFIO的抗活性氧单位为25.85U/mL,DPPH·自由基清除率为91.39%,H2O2诱导红细胞氧化溶血抑制率约为29.13%,可见,富锗培养后的桦褐孔菌总黄酮含量较高,具有较强的抗氧化活性。