A new phenolic compound with antioxidant activity from the branches and leaves of Pyrus pashia

The branches and leaves of Pyrus pashia are used to cure abdominal pain and diarrhoea in Chinese folk medicine. A new phenilic compound, 4-O-β-d-glucopyranosylbenzyl-benzoate ester (1), along with 21 known ones (2–22) were isolated from the branches and leaves of this plant. Compounds 2 and 3 displayed remarkable antioxidant activities against 1,1-diphenyl-2-picrylhydrazyl radical (IC₅₀ = 13.26 ± 0.04 μM, 13.28 ± 0.11 μM, respectively), which were at the same grade as positive control rutin. The caffeoyl group in compounds 2 and 3 was supposed to play an important role in the antioxidant activities.     

Enhanced Extraction Efficiency of Flavonoids from Pyrus ussuriensis Leaves with Deep Eutectic Solvents

In this study, deep eutectic solvents (DESs) were synthesized using different ratios of choline chloride (CC) and dicarboxylic acids, and their eutectic temperatures were determined. The DES synthesized using CC and glutaric acid (GA), which showed a higher extraction efficiency than conventional solvents, was used for the extraction of flavonoid components from Pyrus ussuriensis leaves (PUL), and the extraction efficiency was evaluated using the response surface methodology. The flavonoid components rutin, hyperoside, and isoquercitrin were identified through high-performance liquid chromatography (HPLC), equipped with a Waters 2996 PDA detector, and HPLC mass spectrometry (LC-MS/MS) analyses. The optimum extraction was achieved at a temperature of 30 °C using DES in a concentration of 30.85 wt.% at a stirring speed of 1113 rpm and an extraction time of 1 h. The corresponding flavonoid content was 217.56 μg/mL. The results were verified by performing three reproducibility experiments, and a high significance, with a confidence range of 95%, was achieved. In addition, the PUL extracts exhibited appreciable antioxidant activity. The results showed that the extraction process using the DES based on CC and GA in a 1:1 molar ratio could effectively improve the yield of flavonoids from PUL.     

库尔勒香梨(Pyrus bretschneideri Rehd)在不同温度条件下的呼吸和乙烯释放速率的变化

本文对不同温度条件下香梨果实的呼吸及乙烯释放速率进行了研究.实验结果表明,不同温度下香梨的呼吸及乙烯释放速率具有明显的差异;呼吸跃变的发生与乙烯释放速率的增加有密切关系;低温能有效地抑制香梨的呼吸作用,延迟跃变发生的时间,从而延长果实的贮藏寿命.     

苹果梨叶片中IAA氧化酶的测定

本文介绍了用紫外分光光度计测定苹果梨花芽分化各时期叶征中IAA氧化酶活性的方法。该方法使用的样品量少,操作简单,灵敏度高。经回收和重复性实验表明,方法的准确度和精密度均符合要求。     

砂梨糖度近红外光谱波段遗传算法优化

遗传算法不受搜索空间限制性假设的约束,利用简单的编码技术和繁殖机制来解决复杂近红外光谱数据的优化问题。文章采用遗传算法的波段选择法(R-SGA)对砂梨近红外光谱进行了波段优化,得到丰水、圆黄、黄金三种梨的R-SGA最佳因子数分别为10, 12和16,并分别建立了单一品种GA-PLS模型;丰水梨和黄金梨的GA-PLS模型精度高于全谱PLS模型,其模型的RMSEP分别为0.608/0.632和0.524/0.540;圆黄梨GA-PLS模型精度(RMSEP=0.610)与全谱PLS模型(RMSEP=0.595)相当。经波段优化分析表明,使用552个数据点建立多品种砂梨混合模型,具有较高稳健性和预测性(RMSEC=0.627,RMSEP=0.641)。结果表明:基于遗传算法进行波段优化可以提高砂梨糖度模型精度,提高建模效率,同时说明建立多品种砂梨糖度通用模型是可行的。     

Pashinintide A,the first plant cyclopeptide from Rosaceae,included a sucrose,suggests a new natural receptor for saccharide

Pashinintide A (1), a new cyclic hexapeptide, included a saccharose, and a new cyclic heptapeptide named pashinintide B (2) were isolated from the branches and leaves of Pyrus pashia Buch.-Ham. ex D. Don. 1 and 2 present the first two plant cyclopeptides from Rosaceae. And the stable complex of cyclic hexapeptide and sucrose in 1 suggests that cyclic hexapeptide might be a new natural receptor for saccharide.