Study of plasma antioxidant status in Alzheimer''s disease

To examine the plasma antioxidant status of Alzheimer's disease (AD) patients and to evaluate the influence of apolipoprotein E (APOE) genotype. There are reasons to suspect involvement of the free hydroxyl radical in the pathogenesis of AD. In contrast, studies in plasma of AD patients for the evaluation of levels of biomarkers of oxidation are controversial. Twenty AD patients diagnosed using the National Institute for Neurological Disorders/Alzheimer's Disease and Related Disorders (NINDS/ADRDA) criteria and 22 controls chosen amongst different subjects without cognitive damage. All the subjects--both AD patients and controls--were stratified by their APOE genotype (3/3, 3/4 or 4/4), which was determined by PCR. Plasma total antioxidant capacity (TAC) was determined using two complementary procedures: FRAP, which measures the ferric reduction capacity, and ABTS, which measures the radical scavenging capacity. In addition, 2-amino-adipic semialdehyde (2-AAS), a biomarker of protein oxidation, was evaluated. No significant difference was observed between the AD and control groups regarding plasma TAC. When the subjects were classified by their APOE genotype, significant differences were found in the APOE 4/4 group in the TCA determined by the FRAP method. Subjects with APOE genotype 4/4, which is the group with higher incidence in AD, showed lower antioxidant capacity of plasma. It is the first time that antioxidant capacity in plasma is evaluated in AD patients characterized by their APOE genotypes.     

Sulfur mustard causes oxidative stress and depletion of antioxidants in muscles,livers, and kidneys of Wistar rats

Sulfur mustard (SM) is a chemical warfare agent with cytotoxic effect and a tight link to oxidative stress (OS). Depletion of antioxidants is considered as a cause of detrimental consequence and belongs to the important steps leading to cell death. The oxidative injury appearing after SM exposure is not well understood. Nevertheless, identification of the pathological processes would be a good opportunity to establish an efficient therapy. Here, we focused our effort on an estimation of reactive oxygen species homeostasis and apoptotic processes in Wistar rats exposed to 0–160?mg/kg of SM. We assayed antioxidant activity, thiobarbituric acid reactive substances, reduced glutathione/oxidized glutathione, metallothionein, glutathione reductase, glutathione peroxidase, glutathione S-transferase, caspase 3, and glucose in the livers, kidneys, and muscles of the animals. Significant OS, depletion of low-molecular-mass antioxidants, increase in caspase activity, and some other processes related to SM action were determined. Moreover, we infer a principal role of OS in the tested organs.     

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Ethnopharmacological importance

Gastrointestinal disorders and infections are the major pathoaetiologies of diarrhoea causing many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat infectious diseases including diarrhoea and many other ailments by rural people in Africa and Asia. Much of the work done to date on this genus was on the non-polar or intermediate polarity components. Some parameters that may cause diarrhoea and the evaluation of more polar extracts have apparently not been investigated.

Aims

The polar components were extracted and fractionated by solvent–solvent fractionation to yield fractions with different polarities. The activity of these fractions on different parameters that could be involved in factors associated with diarrhoea was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals.

Materials and methods

Phenolic-enriched leaf extracts of Combretum bracteosum (COB), Combretum padoides (COP), Combretum vendae (COV) and Combretum woodii (COW) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. Acetone was removed from a portion of the 70% acetone extract and it was sequentially treated by solvent–solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures The antioxidant activities were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH); 2,2′-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid (ABTS⁺) radical scavenging, ferric reducing antioxidant power (FRAP) methods and lipid peroxidation inhibitory capacity standard methods. The ferric reducing antioxidant activities of the fractions were also determined. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method. Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.

Result

Some of the fractions had much higher antioxidant activity than the positive controls. The average EC₅₀ values of the extracts for the DPPH and ABTS antioxidant assays were 0.21–12 µg/ml (COP), 0.25–16 µg/ml (COV), 0.33–9.41 µg/ml (COW) and 4.97–85 µg/ml (COB) respectively while the mean EC₅₀ values for the positive controls ascorbic acid and trolox were 1.28–1.51 and 1.02–1.19 µg/ml respectively. All the crude extracts inhibited lipid peroxidation of linoleic acid by more than 80% at a concentration of 64 µg/ml. COP had the highest antibacterial activity with MICs ranging between 19–2500 µg/ml, followed by COV with MICs ranging between 39–625 µg/ml; COW and COB had similar MICs ranging between 39–2500 µg/ml. COP also had the highest antifungal activity with MICs between 19–625 µg/ml. The MIC for COW and COV ranged from 19 to 1250 µg/ml. COB had the lowest antifungal activity (MIC values were between 39 and 625 µg/ml). In general non-polar fractions had a high antimicrobial activity and polar fractions had a high antioxidant activity. The extracts had no activity against COX 1 and 2 enzymes in the anti-inflammatory assay but had good lipoxygenase inhibition. The crude extracts had high concentration of hydrolysable tannin (gallotannin). A good correlation (R²= 0.99) was found between the antioxidant activity and total tannin content indicating that, gallotannins may be responsible for the antioxidant activity.

Conclusion

The results obtained in this study with more polar extracts indicate that the use of extracts of these plant species as antidiarrhoeal agents may have a scientific basis. The extractant used here extracted a much higher percentage of the phytochemicals than acetone. It was better for isolating antioxidant compounds (polar) but not good for isolating antimicrobial compounds (non-polar) from the same species compared to acetone, ethyl acetate, dichloromethane, and hexane.     

Improvement of serum antioxidant status in humans after the acute intake of apple juices

It is hypothesized that apples of 2 Brazilian cultivars with different content of sugars and antioxidant compounds promote similar effects on the antioxidant status and lipid peroxidation in human serum after acute intake. Nine healthy women ingested 300 mL of Golden Delicious or Catarina apple juice (AJ) or water, and blood samples were collected before and 1 hour after intake. After intake of both AJ, a similar and significant increase in serum antioxidant capacity and ascorbic and uric acid levels and a significant decrease in serum lipid peroxidation was observed. The increase in serum antioxidant capacity after consumption of both AJ was correlated directly with the uric acid levels and inversely with serum lipid peroxidation. In summary, the acute intake of AJ of 2 cultivars promoted a similar effect on the antioxidant status and lipid peroxidation in human blood serum.     

5-HT_(1A)受体蛋白在PC12细胞膜转运的动态变化

目的在神经元样PC12活细胞上进行实时、可视和定量研究5-羟色胺1A受体的时空分布、膜转运和信号传导机制。方法运用RT-PCR方法获得小鼠5-HT1A基因,并插入到pEGFP-N1真核表达载体中。采用阳离子脂质体方法将质粒转染至PC12细胞和HEK293细胞中,通过G418筛选出稳定表达5-HT1A-EGFP的PC12细胞系。运用激光共聚焦成像系统观察活细胞中5-HT1A-EGFP的表达情况,利用光漂白荧光恢复(FRAP)技术在PC12细胞膜局部漂白后观察5-HT1A-EGFP荧光蛋白在细胞膜上转运的情况。结果克隆所获得的小鼠5-HT1A基因是准确的。5-HT1A-EGFP蛋白清晰的分布于PC12和HKE293细胞膜上。通过FRAP技术观察到漂白区域的细胞膜在100s内有部分恢复,说明受体在细胞膜上发生转运。结论建立了稳定表达5-HT1A-EGFP融合蛋白的PC12细胞系,并利用活细胞成像和FRAP技术观察分析并证实了5-HT1A受体在PC12细胞的膜表面的表达和转运的动态变化。     

Viral nucleolar localisation signals determine dynamic trafficking within the nucleolus

Localisation of both viral and cellular proteins to the nucleolus is determined by a variety of factors including nucleolar localisation signals (NoLSs), but how these signals operate is not clearly understood. The nucleolar trafficking of wild type viral proteins and chimeric proteins, which contain altered NoLSs, were compared to investigate the role of NoLSs in dynamic nucleolar trafficking. Three viral proteins from diverse viruses were selected which localised to the nucleolus; the coronavirus infectious bronchitis virus nucleocapsid (N) protein, the herpesvirus saimiri ORF57 protein and the HIV-1 Rev protein. The chimeric proteins were N protein and ORF57 protein which had their own NoLS replaced with those from ORF57 and Rev proteins, respectively. By analysing the sub-cellular localisation and trafficking of these viral proteins and their chimeras within and between nucleoli using confocal microscopy and photo-bleaching we show that NoLSs are responsible for different nucleolar localisations and trafficking rates.     

Effects of capsaicin on receptive fields and on inhibitions in rat spinal cord

The dorsal horn of the lumbar enlargement of the spinal cord is somatopically arranged such that the medial half contains cells with receptive fields on the distal parts of the leg and the cells in the lateral half have proximal receptive fields. After chronic sciatic nerve transection that removes input from the distal limb, a substantial number of cells in the medial dorsal horn begin to respond to proximal cutaneous stimulation. We attempted to discover the mechanisms responsible for this expansion of receptive fields following deafferentation. In these series of experiments we used capsaicin, a C-fiber neurotoxin that either destroys C fibers when administered neonatally or produces a functional blockade of C input to the cord when administered topically to a peripheral nerve. After both neonatal or topical capsaicin treatment there was disorganization of the somatopic map of the dorsal horn similar to that produced by nerve transection. Neonatal capsaicin treatment also produced a decrease in primary afferent depolarization and of A-afferent-mediated inhibitions in the dorsal horn, similar to that observed after nerve transection. Local capsaicin treatment, however, did not alter primary afferent depolarization or A-afferent inhibitions. It is unlikely, therefore, that these forms of inhibitions were responsible for controlling receptive field size. The actions of capsaicin, however, did imply some role for C fibers in determining the organization of receptive fields in the dorsal horn.     

Protective effect of aqueous extract of Perilla frutescens on tert-butyl hydroperoxide-induced oxidative hepatotoxicity in rats.

The leaves of perilla [Perilla frutescens (L.) Britt. var. japonica (Hassk.) Hara] are often used in Asian gourmet food. The object of this study was to evaluate the protective effects of an aqueous extract of perilla leaves on the tert-butyl hydroperoxide (t-BHP)-induced oxidative injury observed in rat livers. The treatment of the hepatocytes with the perilla leaf extract (PLE) significantly reversed the t-BHP-induced cell cytotoxicity and lipid peroxidation. In addition, PLE exhibited ferric-reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activities. The in vivo study showed that the pretreatment with PLE (1000 or 3000 mg/kg) for 5 days before a single dose of t-BHP (i.p.; 0.2 mmol/kg) significantly lowered the serum levels of aspartate aminotransferase and alanine aminotransferase, reduced the indicators of oxidative stress in the liver, such as the glutathione disulfide content and lipid peroxidation level in a dose-dependent manner, and remarkably increased the activity of hepatic gamma-glutamylcysteine synthetase. Histopathological examination of the rat livers showed that PLE reduced the incidence of liver lesions induced by t-BHP. Based on the results described above, it is suggested that PLE has the potential to protect liver against t-BHP-induced hepatic damage in rats.     

蝉翼藤抗氧化酮成分研究

目的：研究蝉翼藤抗氧化活性成分。方法：采用活性跟踪，利用各种色谱法分离，运用多种波谱技术(1D-NMR,2D-NMR和MS)鉴定结构。结果：从具有抗氧化活性的蝉翼藤根95%乙醇提取物的氯仿部位得到9个酮类化合物：1,2,5-三羟基-6,8-二甲氧基-酮(1), 1,5-二羟基-2,6,8-甲氧基-酮(2), 3,8-二羟基-1,4-二甲氧基-酮(3), 4,6-二羟基-1,5,7-三甲氧基-酮(4), 7-羟基-1,2,3,8-四甲氧基-酮(5), 1,7-二羟基-酮(6), 4-羟基-3,7-二甲氧基-酮(7), 1,7-二甲氧基-酮(8)和aucuparin(9)。结论：化合物1，2为新化合物,化合物3为新天然产物,化合物4，6为首次从该属中获得；化合物9在ABTS和FRAP模型中显示出显著的抗氧化活性；化合物1清除DPPH自由基能力的IC₅₀为0.31 mg·L^-1。ABTS和FRAP两个模型显示较高相关性(r=0.955 5)。