Chemical profiling and biological screening of Thymus lotocephalus extracts obtained by supercritical fluid extraction and hydrodistillation

Essential oil and extracts from the aerial parts of Thymus lotocephalus were obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE) in two different collectors, respectively. SFE was conducted at 40 °C and a working pressure of 12 or 18 MPa. The chemical profiles were determined using GC-FID and GC-IT-MS. Oxygen-containing monoterpenes were the primary constituents in the essential oil and SFE extracts collected in the second separator, while the extracts obtained in the first separator were predominantly oxygen-containing sesquiterpenes. A large number of compounds were identified by hydrodistillation and, in contrast, the highest extraction yields were obtained using SFE. Linalool (10.43 ± 1.63%) was the main component in essential oil, whereas camphor (7.91 ± 0.84%) and cis-linalool oxide (7.25 ± 1.45%) were the major compounds in the extracts-2nd separator obtained at pressures of 12 and 18 MPa, respectively. Caryophyllene oxide was the primary constituent identified in the extracts-1st separator (4.34 ± 0.51 and 4.41 ± 1.25% obtained at 12 and 18 MPa, respectively). The antioxidant activity was assessed by ORAC and DPPH assays, and the anti-cholinesterase activity was evaluated in vitro using Ellman's method. The essential oil and SFE extracts (first separator) of T. lotocephalus possessed antioxidant activity and strongly inhibited cholinesterases. We also demonstrated that the acetylcholinesterase and butyrylcholinesterase inhibitory activities of the essential oil could be attributed to 1,8-cineole and caryophyllene oxide, respectively.     

Characterization and mapping of a novel light-dependent lesion mimic mutant lmm6 in rice(Oryza sativa L.)

A novel rice lesion mimic mutant(LMM) was isolated from an ethane methyl sulfonate(EMS)-induced 02428 mutant bank. The mutant, tentatively designated as lmm6, develops necrotic lesions in the whole growth period along with changes in several important agronomic traits. We found that the initiation of the lesions was induced by light and cell death occurred in lmm6 accompanied with accumulation of reactive oxygen species(ROS). The lower chlorophyll content, soluble protein content and superoxide dismutase(SOD) activity, the higher malondialdehyde(MDA) content were detected in lmm6 than in the wild type(WT). Moreover, the observation by transmission electronic microscope(TEM) demonstrated that some organelles were damaged and the stroma lamella of chloroplast was irregular and loose in mesophyll cell of lmm6. In addition, lmm6 was more resistant than WT to rice blast fungus Magnaporthe grisea infection, which was consistent with increased expression of four genes involved in the defense-related reaction. Genetic analysis showed that mutant trait of lmm6 is inherited as a monogenic recessive nuclear gene located on the long arm of chromosome 6. Using simple sequence repeat(SSR) markers, the target gene was finally delimited to an interval of 80.8 kb between markers MM2359 and MM2370, containing 7 annotated genes. Taken together, our results provide the information to identify a new gene involved in rice lesion mimic, which will be helpful in clarifying the mechanism of cell death and disease resistance in rice.     

The role of seasonality on the inhibitory effect of Brazilian green propolis on the oxidative metabolism of neutrophils

The reactive oxygen species (ROS) produced by neutrophils are involved in the pathogenesis of several diseases, for which the intake of antioxidants could benefit patients either as a prophylactic or therapeutic treatment. Propolis is among the known antioxidants, and its chemical composition may vary under the influence of seasonality, which may interfere in its biological properties. This work evaluates the role of seasonality on the production of some important compounds of propolis samples produced monthly from November 2001 through October 2002 as well as the effect of these samples on the oxidative metabolism of stimulated neutrophils, by using both luminol and lucigenin to produce chemiluminescence (CLlum and CLluc, respectively). The cytotoxicity of the most active extracts to neutrophils was also investigated. The inhibitory effect of the propolis samples varied significantly during the studied period for both assays (3.4 ± 1.1 to 16.0 ± 1.1 μg/mL for CLlum and 6.2 ± 2.0 to 30.0 ± 5.0 μg/mL for CLluc), which was also observed in the quantitative profile of the main analyzed compounds (aromadendrin-4′-methyl ether, artepillin C, and baccharin). This effect started to become more prominent during the fall and, among all the studied extracts, the one obtained in May displayed the highest inhibitory effect on CL production (3.4 ± 1.1 μg/mL for CLlum and 6.2 ± 2.0 μg/mL for CLluc). The HPLC qualitative profiles of the extracts of propolis samples were quite similar, but there was a huge variation in terms of quantitative profile. It seems that aromadendrin-4′-methyl ether and baccharin play an essential role in the antioxidant activity, while artepillin C is not very important for this effect. The extracts presenting the highest antioxidant activity were produced in May, June, and August, and they did not display cytotoxicity at 25 μg/mL; quercetin, used as control, was not toxic to neutrophils at 8.5 μg/mL.     

乙烯在Tm-2~2抗ToMV反应中激发ROS发生并导致细胞死亡(英文)

番茄的抗病基因Tm-22对Tobamoviruses属病毒有持续抗性.鉴于Tm-22基因在烟草(Nicotianatabaccum)上能够功能表达,我们可以应用这一体系来了解Tm-22抗ToMV反应中氧离子自由基(ROS)的产生机制.瞬间表达的研究结果表明,ROS能够被外源的乙烯和ACC诱导,持续的乙烯刺激和应用高浓度的ACC能够导致细胞坏死并伴随着ROS的产生.     

多胺参与植物逆境响应过程的作用机理研究进展

多胺是植物的一类生理活性物质,与植物生长发育和逆境胁迫抗性密切相关,强化多胺代谢活动可显著提高植物的综合逆境抗性。在简要介绍多胺组成成分及合成途径的基础上,概括了近年来多胺在植物逆境抗性响应机理中的研究进展。     

N-乙酰半胱氨酸对玻璃化冻存小鼠GV期卵母细胞成熟和后续胚胎发育能力影响

冷冻保存后的GV期卵母细胞内大量积累ROS,影响胚胎发育。NAC作为一种抗氧化剂,可缓解氧应激造成的损伤。但NAC对冷冻GV期卵母细胞是否存在维持作用尚待研究。为探究NAC在冷冻、解冻后小鼠GV期卵母细胞发育中作用,检测冷冻保存后小鼠GV期卵母细胞在添加不同浓度NAC成熟培养液后成熟情况,观察其卵裂率与囊胚率、线粒体分布、ROS水平和受精后胚胎发育等。结果表明,添加1.5 mmol·L~(-1)NAC,冷冻保存后,小鼠GV期卵母细胞,线粒体排布均匀,卵母细胞比例显著提高,ROS水平降低。NAC可改善小鼠GV期卵母细胞经冷冻保存后复苏和体外成熟水平,提高其发育能力。     

T-2毒素激活活性氧/核转录因子-κB信号通路诱导猪空肠上皮细胞发生炎性反应

本试验以猪空肠上皮细胞(IPEC-J2)为模型细胞,探讨T-2毒素诱导IPEC-J2炎性反应的影响及相关作用机制.通过四甲基偶氮唑盐(MTT)方法测定细胞活力,选择适宜的T-2毒素和N-乙酰-L-半胱氨酸(NAC)浓度.试验分为4个组,分别为对照组、NAC组(4.0 mmol/L NAC)、T-2组(4.0 ng/mL...     

人工老化对沙葱种子中活性氧与超微弱发光的影响

以人工老化和Ce^3+浸种后再人工老化的沙葱种子为试材,对种子活力、电导率、呼吸速率、活性氧和超微弱发光等指标进行了研究,探讨Ce3+浸种对沙葱老化种子活性氧与超微弱发光的影响。结果表明,Ce^3+1处理下,沙葱种子的发芽率、活力指数和胚根长分别比ck1高4%、0.042和1.64cm,表明Ce^3+有助于提高种子活力及促进胚根的伸长;在老化程度较低的情况下,Ce^3+前处理对沙葱种子电解质外渗有一定缓解作用;活性氧在老化15h前,Ce^3+处理的超氧阴离子产生速率低于ck;Ce^3+比ck的超微弱发光强度高,Ce^3+1和Ce^3+0的超微弱发光强度差异不显著,Ce^3+0显著高于Ce^3+2、Ce^3+3和Ce^3+4的超微弱发光强度。超微弱发光与胚根长、超氧阴离子产生速率和过氧化氢含量呈极显著正相关,表明超微弱发光强度随活性氧的变化而变化。在种子的加速老化过程中,Ce3+处理可调控活性氧的增加,减缓老化对细胞损伤,维持细胞功能稳定性。     

Exogenous paraquat changes antioxidant enzyme activities and lipid peroxidation in drought-stressed cucumber leaves

In order to examine whether paraquat modifies the functioning of antioxidants and oxidative stress levels in drought-stressed plants, a cucumber cultivar (Cucumis sativus cv. Yuexiu no. 3) was grown hydroponically for 2 days. Drought stress, which was induced by polyethylene glycol (PEG), increased the contents of malonaldehyde (MDA), superoxide radical (O₂⁻) and hydrogen peroxide (H₂O₂) in cucumber leaves, while pretreatment of paraquat decreased them. Under drought stress induced by PEG, we observed the decreased contents of MDA, H₂O₂ and O₂⁻ in paraquat-pretreated plants in comparison to unpretreated stressed plants. Drought stress and paraquat both increased the activities of antioxidants such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1), monodehydroascorbate reducatase (MDHAR, EC 1.6.5.4), glutathione reductase (GR, EC 1.6.4.2), reduced glutathione (GSH) and reduced ascorbate (AsA). But the combined effect of paraquat application and drought stress resulted in the highest activities of antioxidants. So paraquat is able to moderate the activities of scavenging system enzymes and to influence oxidative stress intensity under drought stress induced by PEG.     

Mechanism of Cd<Superscript>2+</Superscript> on DNA cleavage and Ca<Superscript>2+</Superscript> on DNA repair in liver of silver crucian carp

The subject of acute injury, apoptosis and canceration of animals induced by heavy metal ions has been one of the hotspots studied worldwide. However, the exact molecular mechanism of Cd-induced carcinogenicity remains largely unclear, and how to relieve the toxicity in vivo has rarely been reported. For this paper, we have investigated the mechanism of Cd²⁺ on DNA cleavage and Ca²⁺ on DNA repair in the liver of silver crucian carp (Carassius auratus gibelio) by agarose gel electrophoresis methods and by estimating biochemical indexes. Our results show that Cd²⁺ induces the classical laddering degradation of DNA in vivo and that DNA cleavage is repaired after injection with Ca²⁺ under various Cd²⁺ concentrations. DNA cleavage caused by Cd²⁺ is due to the activation of deoxyribonuclease (DNase) and the accumulation of reactive oxygen species (ROS). Furthermore, Cd²⁺ destroys the antioxidant system, which diminishes the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), causing an increase of the lipid peroxidation (LPO) level, respectively. However, after the liver is injected with Ca²⁺ under various Cd²⁺ concentrations, the DNase activity, the ROS generating rate and the LPO level are obviously reduced, the activities of SOD, CAT, and POD are greatly increased. At the same time, ROS production and removal recoves its balance. The results show that Ca²⁺ can relieve the toxicity of Cd²⁺ in silver crucian carp.