Renewable Resources and Enzymatic Processes to Create Functional Polymers: Adapting Materials and Reactions from Food Processing

We are exploiting materials and concepts from food science to create functionalized, environmentally friendly derivatives of the biopolymer chitosan, a byproduct of seafood processing. Functional groups are grafted onto chitosan using tyrosinase, the enzyme responsible for food browning. The functionalizing groups studied include low-molecular-weight phenols derived from natural sources and high-molecular-weight proteins. The approach of using low-molecular-weight phenols to functionalize chitosan is illustrated with arbutin, a natural phenol found in pears. Results demonstrate that tyrosinase initiates reactions that lead to the conversion of arbutin–chitosan solutions into gels. These gels can be rapidly broken by treatment with the chitosan-hydrolyzing enzyme chitosanase, demonstrating that the chitosan derivatives remain biodegradable. We briefly review other studies in which low-molecular-weight natural phenols are enzymatically grafted onto chitosan to confer functional properties. The creation of co-polymers is illustrated by results in which tyrosinase is used to couple gelatin onto chitosan. Gelatin is a proteinaceous byproduct of meat production. The tyrosinase-generated gelatin–chitosan conjugates have been observed to offer interesting rheological and thermal properties. These results demonstrate the potential for using renewable resources and enzymatic processing to create environmentally friendly polymers with useful functional properties.     

镧对UV-B胁迫下大豆幼苗类黄酮含量与抗氧化能力影响

为进一步认识La(Ⅲ)提高类黄酮含量及减轻UV-B辐射伤害植物机制,以大豆幼苗为材料,采用水培实验的方法研究了La(Ⅲ)对UV-B辐射胁迫下大豆幼苗类黄酮抗氧化能力的动态影响.结果表明, UV-B辐射(T1:0.15W·m-2和T2:0.45W·m-2)胁迫下,大豆幼苗类黄酮含量在胁迫期和恢复期均先升后降,质膜透性、MDA含量先升(1～5d)后降(6～11d),类黄酮对O·-2和·OH的清除率与其含量变化趋势近同.各处理组类黄酮含量La(Ⅲ) UV-B>UV-B>La(Ⅲ)>CK, La(Ⅲ) T1>La(Ⅲ) T2;质膜透性、MDA含量UV-B>La(Ⅲ) UV-B>CK>La(Ⅲ), La(Ⅲ) T2>La(Ⅲ) T1;类黄酮对O-2和·OH清除率La(Ⅲ) UV-B>UV-B>La(Ⅲ)>CK, La(Ⅲ) T1, La(Ⅲ) T2,表明La(Ⅲ)对类黄酮的调控作用,提高了清除活性氧自由基的运行效率,降低了MDA浓度,维持了质膜正常透性,且对低剂量(T1)的防护效果优于高剂量(T2),进而在防御系统层面实现了La(Ⅲ)对UV-B辐射伤害大豆幼苗的防护效应.     

响应面法优化西兰花总黄酮提取工艺的研究

利用响应面法优化西兰花总黄酮的提取工艺条件。在预试验的基础上,以乙醇为溶剂,提取西兰花总黄酮。选取提取温度、提取时间及液固比、乙醇浓度4个因素进行Box-Benhnken中心组合设计,利用响应面分析法对提取工艺参数进行优化。结果表明,西兰花总黄酮的提取工艺为:乙醇浓度90%,液固比30∶1,提取温度85.28℃,提取时间1.82h;预测值为0.887%,实际得率为0.853%,两者较接近,说明Box-Behnken设计结合响应面分析法可很好地对西兰花总黄酮提取工艺进行优化。     

The relationship between metal composition,phenolic acid and flavonoid content in Imleria badia from non-polluted and polluted areas

ABSTRACT

The aim of this study was to determine the elemental composition, phenolic content and composition and antioxidant properties of Imleria badia (Fr.) Vizzini (former names Boletus badius (Fr.) Fr., and Xerocomus badius (Fr.) E.-J. Gilbert) fruiting bodies collected from sites with different levels of pollution. Imleria badia was relatively tolerant to soil contamination with toxic elements and was able to grow in As, Cd, Hg and Pb concentrations exceeding 15, 2.9, 0.4 and 77 mg kg^?1, respectively. The concentration of elements in soil was reflected in the element content in I. badia. The fruiting bodies from polluted sites exhibited significantly higher content of all the analyzed elements. Among 21 individual phenolic compounds only protocatechiuc and caffeic acids, and quercetin were determined in fruiting bodies of I. badia. The differences between the concentration of the quantified phenolic compounds and the total flavonoid content in fruiting bodies of I. badia from unpolluted and polluted sites were not significant. However, the greatest total phenolic content was found in fruiting bodies from the polluted areas. The antioxidative capacity of mushrooms collected from heavily polluted sites was lower than those growing in unpolluted areas. The concentrations of some metals in soil and fruiting soil were positively correlated with phenolic content and IC₅₀.     

Biologically active antimicrobial and antioxidant substances in the Helianthus annuus L. bee pollen

The objective of this study was to measure the content of flavonoids, polyphenols, and carotenoids in the Helianthus annuus L. bee pollen. It was also to evaluate the ability of the dried, frozen, and freeze-dried extracts of sunflower (H. annuus) pollen, its scavenged free radicals and reducing action. Another aim of this study was to investigate the antimicrobial in vitro action of the H. annuus pollen extracts against the Gram-positive and Gram-negative bacteria and fungi. All pollen extracts showed medium antiradical activity and reductive ability. The most effective was the freeze-dried extract in both evaluation systems. The evaluation of the protective effects of DNA using a biosensor showed an opposite trending—frozen ? dried ? freeze-dried pollen. For the evaluation of antiradical activity, the DPPH method was used, and reductive ability was assessed by means of phosphomolybdic complex formation. The comparison of the polyphenols content shows higher values in freeze-dried bee pollen than in the dried and frozen pollen. The highest content of flavonoids was found in the frozen samples and the most carotenoids were present in the dried samples. In our study, the best antibacterial effects of the dried sunflower bee pollen extracts were found against Paenibacillus larvae, Pseudomonas aeruginosa, and Enterococcus raffinosus. The best inhibitory properties of the frozen sunflower bee pollen extracts were found against Escherichia coli, Pseudomonas aeruginosa, and Paenibacillus larvae. Very good inhibitory effects of freeze-dried sunflower bee pollen were found against Paenibacillus larvae, Brochotrix thermosphacta, and Enterococcus raffinosus. The best antifungal activity of the sunflower bee pollen was found in the frozen bee pollen extracts against Aspergillus ochraceus and freeze-dried bee pollen extracts against Aspergillus niger.     

攀援型和矮生型四棱豆苯丙氨酸解氨酶活性和黄酮含量的研究

以攀援和矮生型四棱豆为研究对象,对不同部位苯丙氨酸解氨酶活性和总黄酮含量进行比较,结果表明：除嫩豆荚外,矮生型四棱豆不同部位的PAL活性均高于攀援型,其总黄酮含量亦高于攀援型。攀援型和矮生型四棱豆PAL活性均为种子最高,嫩豆荚最低;两者总黄酮含量均为叶最高,储藏器官块根最低。攀援型和矮生型的PAL活性和总黄酮含量之间均呈显著正相关。矮生型四棱豆不同部位的组织或器官PAL活性受外源因子影响小,类黄酮合成能力高于攀援型,具有更高的抗逆性。     

Flavonoids of 17 species of Euphorbia (Euphorbiaceae) in Iran

Euphorbia is one of the largest genus in Euphorbiaceae with more than 2000 species in the world and about 100 species in Iran. Flavonoids characters of 17 collected Euphorbia species from different parts of Markazi Province, Iran area were studied. Aqueous-ethanolic extracts of leaves were examined to practice flavonoid detection, isolation, and identification by 2-Dimensional Paper Chromatography (2-DPC), Thin Layer Chromatography (TLC), and available standard flavonoids. Voucher specimens of each sample were prepared for reference as herbarium vouchers. Studies of leaf flavonoids showed some phytochemical characters such as total number of flavonoids, kaempferol, quercetin, myricetin, flavone, and dihydroflavonol glycoside are valuable for chemotaxonomy and their usage.     

增强UV-B辐射对小麦叶片黄酮类化合物日变化的影响

通过温室盆栽试验,初步研究了UV-B辐射对灌浆期小麦叶片中黄酮类化合物含量日变化的影响.结果发现,UV-B胁迫条件下,黄酮类化合物含量明显上升,而胁迫解除后,其含量下降,与对照组间差异逐渐减小.合成黄酮类化合物的关键性酶--苯丙氨酸解氨酶活性的变化也表现出大致相同的趋势.同时,UV-B辐射对小麦叶片净光合速率没有影响,但使其夜闯呼吸速率显著加强 .这些结果表明,小麦在UV-B胁迫解除前后黄酮类化合物的持续波动可能是植物在UV-B辐射条件下光合能力未受影响而生物量明显下降的一个重要原因.     

蜈蚣草总黄酮体外抗氧化作用的研究

通过回流法提取蜈蚣草黄酮类化合物,利用分光光度法测定总黄酮的含量,并分析了它对羟基自由基、超氧阴离子自由基的清除作用和总抗氧化能力。结果表明,蜈蚣草总黄酮含量为6.15%,且具有较好的抗氧化能力。     

乳苣总黄酮的提取及抗氧化作用研究

通过乙醇回流提取乳苣中的黄酮类化合物,利用分光光度法测定总黄酮的含量,并分析了对羟基自由基的清除作用和总抗氧化能力。结果表明,乳苣中总黄酮含量为16.8%,具有较好的抗氧化能力。