肉桂精油及其主要成分的羟自由基清除能力、抗脂质过氧化活性及抑菌效果研究

为了探究肉桂精油中主要的活性成分,试验分析了肉桂精油的化学成分,并对肉桂精油及其主要成分(肉桂醛、邻甲氧基肉桂醛、乙酸桂酯、苯甲醛)的羟自由基清除能力[羟自由基清除率和羟自由基半数清除浓度(IC_(50))]、抗脂质过氧化活性[脂质过氧化抑制率和脂质半数抑制浓度(IC_(50))]及抑菌效果[对志贺氏菌、沙门氏菌、金黄色葡萄球菌的抑菌圈直径、最小抑菌浓度(MIC)和最小杀菌浓度(MBC)]进行测定。结果表明:在肉桂精油中共鉴定出34种成分,占精油总含量的98.02%。其中烯类化合物最多,有16种;醛类化合物有7种,醇类化合物有6种,酮类化合物有3种,腈类化合物和酸类化合物各有1种。肉桂精油、肉桂醛、邻甲氧基肉桂醛、苯甲醛对羟自由基均有一定的清除作用,且羟自由基清除率均随浓度增加而升高,当浓度一致时,羟自由基清除率从大到小依次为肉桂醛、肉桂精油、苯甲醛、邻甲氧基肉桂醛,均小于抗坏血酸(对照);肉桂精油及其主要成分羟自由基半数清除浓度(IC_(50))从小到大依次为肉桂醛(18.01 mg/mL)、肉桂精油(35.76 mg/mL)、苯甲醛(45.52 mg/mL)和邻甲氧基肉桂醛(73.73 mg/mL)。肉桂精油及其主要成分均有一定的抗脂质体过氧化活性,当样品浓度为5 mg/mL时,肉桂精油、肉桂醛、邻甲氧基肉桂醛、乙酸桂酯和苯甲醛的脂质过氧化抑制率分别为71.67%、69.81%、55.44%、10.46%和31.48%,其中肉桂精油和肉桂醛的脂质过氧化抑制率大于二丁基羟基甲苯(BHT,对照,67.84%);肉桂精油及其主要成分的脂质过氧化抑制浓度(IC_(50))从小到大依次为肉桂精油(2.15 mg/mL)、肉桂醛(2.54 mg/mL)、邻甲氧基肉桂醛(5.71 mg/mL)、苯甲醛(10.33 mg/mL)、乙酸桂酯(26.08 mg/mL)。肉桂精油、肉桂醛、乙酸桂酯、邻甲氧基肉桂醛、苯甲醛对志贺氏菌、沙门氏菌、大肠杆菌和金黄色葡萄球菌表现不同程度的抑制效果,其中肉桂醛对革兰氏阴性菌(志贺氏菌、沙门氏菌和大肠杆菌)的抑菌圈直径均大于20 mm(等级划分均属极度敏感);同时肉桂醛的MIC和MBC在肉桂精油主要成分中均最低。说明肉桂醛为肉桂精油的主要活性成分,且肉桂精油的抑菌效果是肉桂醛与多种抑菌活性成分共同作用的结果。

栓皮栎虫瘿的酚性成分及其生物活性

从栓皮栎(Quercus variabilis Bl.)虫瘿中分离了2对平衡互变异构体和4个单体化合物,通过光谱数据和化学方法鉴定为:G-1为1-O-(3′-没食子酰基)没食子酰基-β-D-葡萄吡喃糖和1-O-(4′-没食子酰基)没食子酰基-β-D-葡萄吡喃糖的平衡互变异构体,G-2为3-O-没食子酰基-没食子酸和4-O-没食子酰基-没食子酸的平衡互变异构体,G-3为1,6-二-O-没食子酰基-β-D-葡萄吡喃糖,G-4为1,2,3,6-四-O-没食子酰基-β-D-葡萄吡喃糖,G-5为1-O-没食子酰基-β-D-葡萄吡喃糖,G-6为没食子酸甲酯。对G-1、G-3和G-4进行了初步的抗肿瘤、抗脂质过氧化和抗血小板聚集活性实验。

Novel Stilbene Glycosides from Polygonum multiflorum

Two new stilbene glycosides (1 and 2), together with nine known compounds (3-11), were isolated from the water extract of Polygonum multiflorum Thunb. The structures of the new compounds were elucidated by their chemical properties and spectroscopic analyses, including extensive 2D NMR experiments. Compound 2 showed strong DNA cleavage activity, and compounds 1, 2 and 10 (2, 3, 4′, 5_tetrahydroxy_ trans _stilbene_2_O_β_ D _glucopyranoside) exhibited significant inhibition of lipid peroxidation.

Effects of chilled storage and cryopreservation on sperm characteristics, antioxidant enzyme activities, and lipid peroxidation in Pacific cod Gadus macrocephalus

The present study evaluated the ef fects of chilled storage and cryopreservation on sperm motion characteristics, antioxidant enzyme activities, and lipid peroxidation in the Pacific cod Gadus macrocephalus. Sperm motility and the activities of superoxide dismutase(SOD), catalase(CAT), glutathione peroxidase(GPx), glutathione reductase(Gr), and lipid peroxidation(measured via malondialdehyde(MDA) content) were determined after the milt was stored at 4°C for 12 h, cryopreserved without cryoprotectant in 12% propylene glycol(PG), cryopreserved in 12% PG+0.1 mol/L trehalose, or cryopreserved in 12% PG spermatozoa but centrifuged to decant the supernatant prior to cryopreservation(only sperm cells were cryopreserved). After chilled storage or cryopreservation, the SOD, CAT and GPx activities were reduced in sperm cells and increased in seminal plasma in almost all treatments; sperm motility parameters were also decreased. However, the addition of trehalose into the cryoprotectant could signifi cantly improve the postthaw sperm quality as revealed by the sperm average path velocity. This improvement might be attributed to the function of trehalose in scavenging reactive oxygen species. Chilled storage and cryopreservation had signifi cant eff ects on sperm motion characteristics, antioxidant enzyme activities, and lipid peroxidation in the Pacific cod.

Alterations of Antioxidative Enzymes Activities and Induction of Lipid Peroxidation in Germinating Wheat Seeds Subjected to Cadmium Stress

Germinating wheat （Triticum aestivum L.） seeds were exposed to CdCI2 （50, 100 and 200 μM） for 48 h and some aspects of oxidative metabolism was assessed in the embryonic tissues. The germination percentage and the soluble protein content of the embryonic tissues were found to decrease with increasing of Cd concentration. There was elevation in superoxide dismutase （SOD） and decline in catalase （CAT） and peroxidase （POX） activities. The increasing of lipid peroxidation levels indicated the prevalence of oxidative stress in the tissues which was probably due to the alteration of antioxidative enzymes activities. The adding of ascorbate, along with CdCl2, has resulted in restoration of the Cd induced decline in CAT activity. Weakening in H2O2 detoxification system seems to be the principal reason behind Cd induced oxidative stress in germinating seeds. Thus, imposition of oxidative stress might be the consequence of cadmium stress and this finding may help in elucidating the mechanisms underlying cadmium mediated toxicity in germinating seeds.

Studies on the Antioxidant Potential of Extracts from Unripe Fruit of Carica papaya

The antioxidant activities of the ethyl acetate fraction and aqueous extract of unripe fruit of Carica papaya were compared and investigated in vitro using thiobarbituric reactive species （TBARS） assay, total phenol content, evaluation of reactive oxygen species （ROS） in liver mitochondria, Fe2＋ chelating and 2,2-diphenyl-lpicrylhydrazyl （DPPH） scavenging activities. Both extracts had high antioxidant properties and could inhibit FeE＋ and sodium nitroprusside lipid peroxidation in the liver. Total phenol content of ethyl acetate fraction and aqueous extract were 4.50 ±2.26 and 1.21±3.12 mg/g, respectively. Both extracts had a maximal effect at the lowest concentrations tested （15 μg/mL for ethyl acetate and 150 μg/mL for the aqueous）. Ethyl acetate fraction showed that the highest values of antioxidant activity is probably associated with its high phenolic content, Fe2＋ chelating and DPPH scavenging activities. It is therefore concluded that ethyl acetate fraction and to a less extent the aqueous fractions are potent inhibitor of lipid peroxidation.