Alzheimer's disease and related neurodegenerative disorders: implication and counteracting of melatonin

Multi-targeted anti-Alzheimer's agents: Synthesis, biological evaluation, and molecular modeling study of some pyrazolopyridine hybrids

A new series of compounds bearing a pyrazolopyridine scaffold was synthesized as integrated anti-Alzheimer's disease (AD) multi-targeted ligands. Compounds 49 and 51 showed remarkable activity as hAChE inhibitors with IC50 values of 0.17 and 0.16 μM, respectively; and proved to be active hBuChE inhibitors with IC50 values 0.17 and 0.69 μM, eight and two-fold more active than the reference compound rivastigmine, respectively. Compounds 49 and 51 showed potent GSK3β inhibition with IC50 values of 0.21 and 0.26 μM, respectively compared to L807mts. Also, 49 and 51 showed 66.0 and 60.0% as tau protein aggregation inhibitors; and Aβ1-42 self-aggregation inhibitors with 79.0 and 75.0% respectively. Furthermore, 49 and 51 could bind virtually with the PAS affecting Aβ aggregation, thus preventing Aβ-dependent neurotoxicity. They proved to have the ability to chelate bio-metals such as Fe2+, Cu2+, and Zn2+ preventing their oxidative damage in the brain of AD patients, in addition to their safety upon WI-38 cell line. Both compounds could virtually penetrate BBB and obeyed Lipinski's rule of five. Compounds 49 and 51 could be considered as MTDLs for AD patients and the obtained model and pattern of substitution could be used for further development of new multi-targeted anti-Alzheimer's agents.

Association between the plasma concentration of melatonin and behavioral temperament in horses

Aggression in horses may cause serious accidents during riding and non-riding activities. Hence, predicting the temperament of horses is essential for selecting suitable horses and ensuring safety during the activity. In certain animals, such as hamsters, plasma melatonin concentrations have been correlated with aggressive behavior. However, whether this relationship applies to horses remains unclear. To address this research gap, this study aimed to evaluate differences in the plasma melatonin concentrations among horses of different breeds, ages, and sexes and examine the correlation between plasma melatonin concentrations and the temperament of the horses, including docility, affinity, dominance, and trainability. Blood samples from 32 horses were collected from the Horse Industry Complex Center of Jeonju Kijeon College. The docility, affinity, dominance, and trainability of the horses were assessed by three professional trainers who were well-acquainted with the horses. Plasma melatonin concentrations were measured using an enzyme-linked immunosorbent assay. The consequent values were compared between the horses of different breeds, ages, and sexes using a three-way analysis of variance and least significant difference post hoc test. Linear regression analysis was employed to identify the relationship between plasma melatonin concentrations and docility, affinity, dominance, and trainability. The results showed that the plasma melatonin concentrations significantly differed with breeds in Thoroughbred and cold-blooded horses. However, there were no differences in the plasma melatonin concentrations between the horse ages and sexes. Furthermore, plasma melatonin concentrations did not exhibit a significant correlation with the ranking of docility, affinity, dominance, and trainability.

Biochemical and histopathological investigation of the protective effects of melatonin and vitamin E against the damage caused by acetamiprid in Balb-c mouse testicles at light and electron microscopic level

The protective effects of melatonin (Mel) and vitamin E (Vit E) against the negative effects of acetamiprid (Acmp) on testicles, reproductive hormones, and oxidative stress parameters were investigated in the present study. A total of 50 Balb-c male mice were used in 7 groups; 6 mice in the control groups (distilled water, corn oil, ethanol), and 8 in other groups (Acmp, Acmp + Mel, Acmp + Vit E, Acmp + Vit E + Mel). After the experiment, which lasted 21 days, hematoxylin eosin (H&E), periodic acid Schiff (PAS), and caspase-3 immunohistochemical (IHC) staining was performed on the testicular tissues. Also, the tissues were examined ultrastructurally with the transmission electron microscopy (TEM). In the Acmp group, there were decreased seminiferous tubule diameter and epithelial thickness, epithelial degeneration, decreased spermatozoa in the lumen, decreased PAS-positive staining in the seminiferous epithelial basement membrane, edema in the interstitial area, and hydropic degeneration in Leydig cells. Caspase-3 immunoreactivity was higher than in the other groups. TEM examination showed degeneration in tubule cells, lysosomal accumulation in cells of the spermatogenic line, vacuolizations with myelin figures, and necrosis. Hydropic degeneration, electron-dense lipid vacuoles, and chromatolysis were evident in the Leydig cell cytoplasm. In Sertoli cells, electron-dense lysosomal deposits were noted. In biochemical terms, there were decreased tissue glutathione (GSH) and total antioxidant status (TAS), and increased malondialdehyde (MDA) and total oxidant status (TOS). Plasma luteinizing hormone (LH), follicular stimulating hormone (FSH), and testosterone levels were decreased. In the groups with melatonin, vitamin E, and both were applied together, tissue damage, and apoptotic cell death were reduced at both light microscopic and ultrastructural levels. In biochemical terms, there were decreased oxidative parameters and increased hormonal parameters. It was found that vitamin E was more effective in decreasing oxidative parameters and increasing antioxidative parameters when compared to melatonin, and hormonal parameters increased at a higher level in the Acmp + Vit E group than in all groups. As a result, it was found that exposure to Acmp caused damage to testicular tissue, induced oxidative stress in testicles, and decreased plasma LH, FSH, and testosterone levels, and although vitamin E is more effective than melatonin in preventing this damage, both are effective.

Synthesis of Melatonin Derivatives and the Neuroprotective Effects on Parkinson's Disease Models of Caenorhabditis elegans

Melatonin (MT) is a hormone with antioxidant activity secreted by the pineal gland in the human brain, which is highly efficient in scavenging free radicals and plays an important role in the neuro-immuno-endocrine system. Emerging evidence showed that MT supplementation was a potential therapeutic strategy for Parkinson’s disease (PD), which inhibits pathways associated with oxidative stress in PD. In this study, we reported a C7-selective olefination of melatonin under rhodium catalysis with the aid of P^III-directing groups and synthesized 10 new melatonin-C7-cinnamic acid derivatives (6a–6j). The antioxidant potential of the compounds was evaluated both by ABTS and ORAC methods. Among these newly synthesized melatonin derivatives, 6a showed significantly higher activity than MT at 10⁻⁵ M. In the transgenic Caenorhabditis elegans model of PD, 6a significantly reduces alpha-synuclein aggregation and dopaminergic neuronal damage in nematodes while reducing intracellular ROS levels and recovers behavioral dysfunction induced by dopaminergic neurodegeneration. Further study of the mechanism of action of this compound can provide new therapeutic ideas and treatment strategies for PD.

Ameliorating Effect on Aβ-Induced Alzheimer's Mice by Litsea cubeba Persoon Powder

Alzheimer’s disease (AD) is caused by excessive oxidative damage and aging. The objective of this study was to investigate the anti-dementia effect of LCP fruit powder on amyloid β (Aβ)-induced Alzheimer’s mice. The composition of LCP essential oil was determined by gas chromatography/mass spectrometry. In addition, the water maze was used to evaluate the learning and memorizing abilities of the mice. The concentrations of malondialdehyde (MDA), protein carbonyl, phosphorylated τ-protein, and the deposition of Aβ plaques in mouse brains were also assessed. The results showed that the main components of essential oils in LCP and d-limonene, neral, and geranial contents were 14.15%, 30.94%, and 31.74%, respectively. Furthermore, oral administration with different dosages of LCP significantly decreased the escape time (21.25~33.62 s) and distance (3.23~5.07 m) in the reference memory test, and increased the duration time (26.14~28.90 s) and crossing frequency (7.00~7.88 times) in the target zone of probe test (p < 0.05). LCP also inhibited the contents of MDA and the phosphor-τ-protein from oxidative stress, reduced the brain atrophy by about 3~8%, and decreased the percentage of Aβ plaques from 0.44 to 0.05%. Finally, it was observed that the minimum dosage of LCP fruit powder (LLCP, 30.2 mg/day) could prevent oxidative stress induced by Aβ and subsequently facilitate memory and learning deficits in Aβ-induced neurotoxicity and cognitively impaired mice.

Protective effects of melatonin and vitamin E in acetamiprid-induced nephrotoxicity

Investigation of probable toxic effects of acetamiprid (ACMP) on kidney and comparative analysis of the probable protective effects of vitamin E and melatonin were conducted in the present study. The ethics committee approval was obtained from Inonu University Medical Faculty Ethics Committee. Fifty Balb-c mice were randomly assigned to control, corn oil, ethyl alcohol, ACMP, ACMP + melatonin, ACMP + vitamin E, and ACMP + melatonin + vitamin E groups. At the end of the experiments, rat kidney tissues were incised under anesthesia. Blood samples and kidney tissues were examined. After 21 days of ACMP administration, it was observed that malondialdehyde (MDA), total oxidant status (TOS), BUN, creatinine, IL-6, IL-1β, and TNF-α levels, histopathological damage, and Caspase-3 immunoreactivity scores increased, and glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and total antioxidant status (TAS) levels decreased, and histopathological damages were observed. Melatonin and vitamin E administration led to improvements in oxidative stress parameters, renal functions, inflammatory markers, and histopathological findings. ACMP administration led to nephrotoxicity in rat kidney tissues. Although melatonin and vitamin E administrations were effective on ACMP nephrotoxicity separately, co-administration of both was quite effective. Concomitant use of melatonin and vitamin E could be effective on prevention of toxicity.

Neural Network Modeling of AChE Inhibition by New Carbazole-Bearing Oxazolones

Acetylcholine esterase (AChE) is one of the targeted enzymes in the therapy of important neurodegenerative diseases such as Alzheimer's disease. Many studies on carbazole- and oxazolone-based compounds have been conducted in the last decade due to the importance of these compounds. New carbazole-bearing oxazolones were synthesized from several carbazole aldehydes and p-nitrobenzoyl glycine as AChE inhibitors by the Erlenmeyer reaction in the present study. The inhibitory effects of three carbazole-bearing oxazolone derivatives on AChE were studied in vitro and the experimental results were modeled using artificial neural network (ANN). The developed ANN provided sufficient correlation between several dependent systems, including enzyme inhibition. The inhibition data for AChE were modeled by a two-layered ANN architecture. High correlation coefficients were observed between the experimental and predicted ANN results. Synthesized carbazole-bearing oxazolone derivatives inhibited AChE under in vitro conditions, and further research involving in vivo studies is recommended. An ANN may be a useful alternative modeling approach for enzyme inhibition.

Anti-Parkinson Drug Biperiden Inhibits Enzyme Acetylcholinesterase

Biperiden is a drug used in Parkinson disease treatment and it serves also as an antiseizures compound in organophosphates poisoning. It acts as antagonist of muscarinic receptor activated by acetylcholine while the enzyme acetylcholinesterase (AChE) cleaves acetylcholine in synaptic junction into choline and acetic acid. This enzyme is inhibited by various compounds; however there has not been proposed evidence about interaction with biperiden molecule. We investigated this interaction using standard Ellman's assay and experimental findings were critically completed with an in silico prediction by SwissDock docking software. Uncompetitive mechanism of action was revealed from Dixon plot and inhibition constant (K_i) was calculated to be 1.11 mmol/l. The lowest predicted binding energy was −7.84 kcal/mol corresponding to H-bond between biperiden molecule and Tyr 341 residuum in protein structure of AChE. This interaction seems to be further stabilized by π-π interaction with Tyr 72, Trp 286, and Tyr 341. In conclusion, biperiden appears as a very weak inhibitor but it can serve as a lead structure in a pharmacological research.

Decreased melatonin levels and increased levels of advanced oxidation protein products in the seminal plasma are related to male infertility

Melatonin, an indolamine secreted by the pineal gland, is known as a powerful free-radical scavenger and wide-spectrum antioxidant. Therefore, the aim of this study was to correlate markers of oxidative protein damage (advanced oxidation protein products, AOPPs) and the total antioxidant capacity (TAC) with melatonin levels in the seminal plasma of men with azoospermia (n=37), theratozoospermia (n=29) and fertile controls (normozoospermia, n=37). Melatonin concentration was measured by radioimmunoassay. The levels of AOPP as well as TAC efficiency (determined by the ferric reducing antioxidant power, FRAP) were estimated by spectrophotometric methods. The concentration of melatonin and AOPP significantly differed in azoospermic (P<0.0001) and theratozoospermic (P<0.0001) patients versus fertile men, and correlated negatively (r=-0.33, P=0.0016). The TAC levels were significantly higher in azoospermia than in theratozoospermia (P=0.0022) and the control group (P=0.00016). In azoospermia, the AOPP concentration was also significantly higher than that observed in theratozoospermia (P=0.00029). Decreased levels of melatonin together with elevated AOPP altered the oxidative-antioxidative balance in the ejaculate, thereby reducing fertility. Therefore, melatonin and AOPP levels may serve as additional diagnostic markers of semen quality and male reproductive potential.

Development and Validation of New Ultra-High-Performance Liquid Chromatography-Hybrid Quadrupole-Orbitrap Mass Spectrometry Method for Determination of Melatonin in Fruits

A new reliable analytical method based on ultra-high-performance liquid chromatography coupled with hybrid quadrupole-Orbitrap mass spectrometry was developed for the analysis of melatonin (MEL) in food products. In-house validation was performed using deuterated melatonin (MEL-d4) as an internal standard to ensure method selectivity and accuracy and to evaluate the efficiency of a robust ethyl acetate extraction technique used for sample preparation. The analysis of 18 tart cherry varieties and 28 tomato varieties was performed at optimized conditions. The method was linear (R(2)> 0.99) over the concentration range of 5-200 pg/g. A very low limit of quantification (10 pg/g) was provided for both analyzed matrices. The determined average recoveries (102 and 110%) and the values of intraday repeatability (6.30 and 10.9%) for cherry and tomato matrices, respectively, indicated a good accuracy and precision. The elaborated procedure proved the absence of MEL in any of tart cherries (<10 pg/g), whereas the concentration levels in tomatoes were found to be in the range of <10-149 pg/g, where the highest concentrations were determined in "Cherry," "Cherry Red" and "Rome" tomatoes grown in the Netherlands.

Antioxidant potential, total phenolic and total flavonoid contents of Rhododendron anthopogonoides and its protective effect on hypoxia-induced injury in PC12 cells

BACKGROUND

Rhododendron anthopogonoides Maxim, a kind of traditional Tibetan medicine, has been used to remove body heat, body detoxification, cough, asthma, stomachic and swelling, eliminate abundant phlegm and inflammatory for a long time. In the present study, the total phenols and total flavonoid contents as well as antioxidative properties of the crude extract and solvent fractions of R. anthopogonoides were determined using seven antioxidant assays. Additionally, the protective effect of the extracts on hypoxia-induced injury in PC12 cells was also investigated.

METHODS

The content of total flavonoid and total phenolic was determined by the aluminum colorimetric method and Folin-Ciocalteu assay, respectively. In vitro antioxidant study, the effect of the crude extract and solvent fractions on total antioxidant activity, reducing power, DPPH radical scavenging, ABTS radical scavenging, superoxide radical scavenging, hydroxyl radical scavenging and nitric oxide radical scavenging were examined. The correlation between the phenolic and flavonoid content of the extracts and their antioxidant properties also analyzed. Furthermore, the protective effect of extracts on hypoxia-induced damage on PC12 cells was investigated by cell viability, lactate dehydrogenase (LDH) release, malondialdehyde (MDA) production and the activities of antioxidant enzymes.

RESULTS

Our results showed that ethyl acetate and n-butanol fractions had higher content of phenolics and flavonoid compounds than other fractions. Except ABTS radical assay, n-butanol fraction exhibited the strongest antioxidant activity. While the hexane fraction showed the lowest antioxidant activity. Ethyl acetate also presented excellent antioxidant activity, which was just lower than n-butanol fraction. Significant correlation between the phenolic, flavonoid content of the extract and fractions with antioxidant assay excluding ABTS, OH scavenging assay was observed. Moreover, ethyl acetate and n-butanol fractions showed protective effect in PC12 cell under hypoxia condition, while crude extract and water fraction had no protective effect. In contrast, hexane fraction exhibited strong cytoprotective effect. Further study indicated that pretreatment of PC12 cells with ethyl acetate and n-butanol fractions, prior to hypoxia exposure, significantly increased the survival of cells and the activities of SOD, CAT, GSH-Px and T-AOC, as well as reduced the level of LDH and MDA. The gathered data demonstrated that ethyl acetate and n-butanol fractions were able to protect PC12 cells against hypoxia induced injury through direct free radical scavenging and modulation of endogenous antioxidant enzymes.

CONCLUSION

These findings suggested that ethyl acetate and n-butanol fractions of R. anthopogonoides had significant antioxidant activity and could prevent PC12 cells against hypoxia-induced injury. So it might be regarded as an excellent source of antioxidants and had great potential to explore as therapeutic agent for preventing hypoxia related sickness in future.

Melatonin Regulates Oxidative Stress Initiated by Freund’s Complete Adjuvant

Melatonin is a hormone with strong antioxidant properties. In this experiment, Freund’s complete adjuvant was used as a stressogenic substance given to laboratory outbred mice, whereas melatonin was investigated as a protectant against the stressogenic effect. Levels of low molecular weight antioxidants, thiobarbituric acid reactive substances, and tumor necrosis factor α and activity of glutathione reductase were determined in blood from the animals. Surprisingly, melatonin was not involved in direct regulation of antioxidants, thiobarbituric acid reactive substances and tumor necrosis factor α. On the other hand, melatonin regulated glutathione reductase activity. We can conclude on regulation of metabolism caused by melatonin in the model. The effect was more important than the expected regulation of immunity and basal oxidative homeostasis.

Folates and aging: Role in mild cognitive impairment, dementia and depression

In almost all tissues, including the brain, folates are required for one-carbon transfer reactions, which are essential for the synthesis of DNA and RNA nucleotides, the metabolism of amino acids and the occurrence of methylation reactions. The aim of this paper is to review the impact of folate status on the risk of development of neuropsychiatric disorders in older individuals. The prevalence of folate deficiency is high among individuals aged ≥ 65 years mainly due to reduced dietary intake and intestinal malabsorption. Population-based studies have demonstrated that a low folate status is associated with mild cognitive impairment, dementia (particularly Alzheimer's disease) and depression in healthy and neuropsychiatric diseased older individuals. The proposed mechanisms underlying that association include hyperhomocysteinemia, lower methylation reactions and tetrahydrobiopterin levels, and excessive misincorporation of uracil into DNA. However, currently, there is no consistent evidence demonstrating that folic acid supplementation improves cognitive function or slows cognitive decline in healthy or cognitively impaired older individuals. In conclusion, folate deficiency seems to be an important contributor for the onset and progression of neuropsychiatric diseases in the geriatric population but additional studies are needed in order to increase the knowledge of this promising, but still largely unexplored, area of research.

Toxicology and the biological role of methanol and ethanol: Current view

BACKGROUND

Alcohol variants such as ethanol and methanol are simple organic compounds widely used in foods, pharmaceuticals, chemical synthesis, etc. Both are becoming an emerging health problem; abuse of ethanol containing beverages can lead to disparate health problems and methanol is highly toxic and unfit for consumption.

METHODS AND RESULTS

This review summarizes the basic knowledge about ethanol and methanol toxicity, the effect mechanism on the body, the current care of poisoned individuals and the implication of alcohols in the development of diseases. Alcohol related dementia, stroke, metabolic syndrome and hepatitis are discussed as well. Besides ethanol, methanol toxicity and its biodegradation pathways are addressed.

CONCLUSIONS

The impact of ethanol and methanol on the body is shown as case reports, along with a discussion on the possible implication of alcohol in Alzheimer's disease and antidotal therapy for methanol poisoning. The role of ethanol in cancer and degenerative disorders seems to be underestimated given the current knowledge. Treatment in case of poisoning is another issue that remains unresolved even though effective protocols and drugs exist.

Biosensors containing acetylcholinesterase and butyrylcholinesterase as recognition tools for detection of various compounds

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes expressed in the human body under physiological conditions. AChE is an important part of the cholinergic nerves where it hydrolyses neurotransmitter acetylcholine. Both cholinesterases are sensitive to inhibitors acting as neurotoxic compounds. In analytical applications, the enzymes can serve as a biorecognition element in biosensors as well as simple disposable sensors (dipsticks) and be used for assaying the neurotoxic compounds. In the present review, the mechanism of AChE and BChE inhibition by disparate compounds is explained and methods for assaying the enzymes activity are shown. Optical, electrochemical, and piezoelectric biosensors are described. Attention is also given to the application of sol-gel techniques and quantum dots in the biosensors’ construction. Examples of the biosensors are provided and the pros and cons are discussed.

'Melatonin isomer' in wine is not an isomer of the melatonin but tryptophan-ethylester

Melatonin is a neurohormone, chronobiotic, and antioxidant compound found in wine and deriving directly from grapes and/or synthesized by yeast during alcoholic fermentation. In addition, a melatonin isomer has been detected in different foods, wine among them. The special interest for melatonin isomer related to the fact that it was found in greater quantities than melatonin and probably shares some of its biological properties. Despite this, its chemical structure has not yet been defined; although some researchers hypothesize, it could be melatonin with the ethylacetamide group shifted into position N1. Thus, the aim of our study was to identify the structures of the melatonin isomer. For this purpose, melatonin and melatonin isomer in Syrah wine were separated chromatographically by a sub-2 μm particle column and detected by tandem mass spectrometry. The sample was then purified and concentrated by solid-phase extraction, hydrolyzed with alkali or esterase, and substrates and products quantified by UPLC-MS/MS. Moreover, melatonin, melatonin isomer, and their product ions were evaluated by high-resolution mass spectrometry. The amount of melatonin isomer and melatonin in the wine was 84 ± 4 and 3 ± 0 ng/mL, respectively. In the solutions, containing diluted alkali or esterase, melatonin isomer was hydrolyzed in about 8 min. Correspondingly, tryptophan was detected, and its amount increased and reached the maximum concentration in about 8 min. Melatonin concentration was not affected by diluted alkali or esterase. The fragmentation pattern of melatonin isomer was different from that of melatonin but comparable to that of tryptophan-ethylester. Finally, the so-called melatonin isomer identity was verified by cochromatography with authentic standard of tryptophan-ethylester.

Bioactive compounds derived from the yeast metabolism of aromatic amino acids during alcoholic fermentation

Metabolites resulting from nitrogen metabolism in yeast are currently found in some fermented beverages such as wine and beer. Their study has recently attracted the attention of researchers. Some metabolites derived from aromatic amino acids are bioactive compounds that can behave as hormones or even mimic their role in humans and may also act as regulators in yeast. Although the metabolic pathways for their formation are well known, the physiological significance is still far from being understood. The understanding of this relevance will be a key element in managing the production of these compounds under controlled conditions, to offer fermented food with specific enrichment in these compounds or even to use the yeast as nutritional complements.

Impact of melatonin on immunity: a review

Melatonin is a hormone produced by the pineal gland. In addition to its hormonal effect, it has strong antioxidant properties. Melatonin is probably best known for its ability to control circadian rhythm; it is sold in many countries as a supplement or drug for improving of sleep quality. However, melatonin’s effect is not limited to control of circadian rhythm:. it is involved in other effects, including cell cycle control and regulation of several important enzymes, including inhibition of inducible nitric oxide synthase. Melatonin affects immunity as well. It can modulate the immune response on disparate levels with a significant effect on inflammation. The role of melatonin in body regulatory process is not well understood; only limited conclusions can be drawn from known data. The current review attempts to summarize both basic facts about melatonin’s effects and propose research on the lesser known issues in the future.

Caffeine inhibits acetylcholinesterase, but not butyrylcholinesterase

Caffeine is an alkaloid with a stimulant effect in the body. It can interfere in transmissions based on acetylcholine, epinephrine, norepinephrine, serotonin, dopamine and glutamate. Clinical studies indicate that it can be involved in the slowing of Alzheimer disease pathology and some other effects. The effects are not well understood. In the present work, we focused on the question whether caffeine can inhibit acetylcholinesterase (AChE) and/or, butyrylcholinesterase (BChE), the two enzymes participating in cholinergic neurotransmission. A standard Ellman test with human AChE and BChE was done for altering concentrations of caffeine. The test was supported by an in silico examination as well. Donepezil and tacrine were used as standards. In compliance with Dixon’s plot, caffeine was proved to be a non-competitive inhibitor of AChE and BChE. However, inhibition of BChE was quite weak, as the inhibition constant, K_i, was 13.9 ± 7.4 mol/L. Inhibition of AChE was more relevant, as K_i was found to be 175 ± 9 μmol/L. The predicted free energy of binding was −6.7 kcal/mol. The proposed binding orientation of caffeine can interact with Trp86, and it can be stabilize by Tyr337 in comparison to the smaller Ala328 in the case of human BChE; thus, it can explain the lower binding affinity of caffeine for BChE with reference to AChE. The biological relevance of the findings is discussed.

Role of oxidative stress in infectious diseases. A review

Oxidative stress plays a dual role in infections. Free radicals protect against invading microorganisms, and they can also cause tissue damage during the resulting inflammation. In the process of infection, there is generation of reactive species by myeloperoxidase, NADPH oxidase, and nitric oxide synthase. On the other hand, reactive species can be generated among others, by cytochrome P450, some metals, and xanthine oxidase. Some pathologies arising during infection can be attributed to oxidative stress and generation of reactive species in infection can even have fatal consequences. This article reviews the basic pathways in which reactive species can accumulate during infectious diseases and discusses the related health consequences.

Effect of selenium in organic and inorganic form on liver, kidney, brain and muscle of Wistar rats

Selenium is a micronutrient, localized in the active sites of enzymes such as glutathione peroxidase and thioredoxin reductase, and participating together with these enzymes in an antioxidant defence system of organisms against free radicals. Administration of selenium is necessary for maintaining oxidative homeostasis. The present experiment is aimed at investigation of selenium impact on basal metabolic processes and selected antioxidants in a Wistar rat model, fed selenium in organic and inorganic forms. Liver, kidney, brain and muscle were sampled during a month-long feeding with four different doses of selenium (0.075 mg or 1.5 mg of inorganic and/or organic selenium per kg of feed). We found a significant reduction in glutathione level in liver tissue regardless of the form of the administered selenium. On the other hand, selenium caused a decreased glutathione reductase level in the liver and metallothionein level in the liver, kidney and muscle.

Toxicological scoring of Alzheimer's disease drug huperzine in a guinea pig model

Huperzine is a secondary metabolite in lycopods Huprzia and an inhibitor of acetylcholinesterase and antagonist of N-methyl-D-apartate receptor. Huperine is a suitable drug for the treatment of Alzheimer's disease as it is a part of traditional Chinese medicine. Currently, it undergoes clinical trials in the European Union and United States. The toxicological data about huperzine are missing and link between huperzine and oxidative stress has not been extensively investigated. For the above mentioned reasons, we organized experiment on a guinea pig model aimed at the investigation of adverse effects caused by huperzine. Guinea pigs were exposed to (-)-huperzine A in doses 5-625 µg/kg. Animals were sacrificed one day after exposure. Ferric reducing antioxidant power, thiobarbituric acid reactive substances, glutathione reductase, caspase 3 activity and selected biochemical markers (e.g. transaminases, blood urea nitrogen and glucose) were assayed. In frontal, parietal, temporal lobes and cerebellum, we found increase of antioxidants, glutathione reductase and oxidative stress markers in a dose dependent manner. Effects on liver, kidney and spleen were milder. We discuss ambivalent action of huperzine in the body and judge the huperzine action owing to recently reported experiments.