Antioxidant Enzyme Biosynthesis Research Articles

Adropin promotes testicular functions by modulating redox homeostasis in adult mouse.

Adropin is an emerging metabolic hormone that has a role in regulating energy homeostasis. The present study aimed to explore the impact of adropin on redox homeostasis and its possible role in testicular functions in adult mouse testis. Western blot, flow-cytometry, and TUNEL assay were performed to explore the impact of intra-testicular treatment of adropin (0.5 μg/testis) on testicular functions of adult mice. Hormonal assay was done by ELISA. Further, antioxidant enzyme activities were measured. Adropin treatment significantly increased the sperm count and testicular testosterone by increasing the expression of GPR19 and steroidogenic proteins. Also, adropin treatment reduced the oxidative/nitrosative stress by facilitating the translocation of NRF2 and inhibiting NF-κB into the nucleus of germ cells. Enhanced nuclear translocation of NRF2 leads to elevated biosynthesis of antioxidant enzymes, evident by increased HO-1, SOD, and catalase activity that ultimately resulted into declined LPO levels in adropin-treated mice testes. Furthermore, adropin decreased nuclear translocation of NF-κB in germ cells, that resulted into decreased NO production leading to decreased nitrosative stress. Adropin/GPR19 signaling significantly increased its differentiation, proliferation, and survival of germ cells by elevating the expression of PCNA and declining caspase 3, cleaved caspase 3 expression, Bax/Bcl2 ratio, and TUNEL-positive cells. FACS analysis revealed that adropin treatment enhances overall turnover of testicular cells leading to rise in production of advanced germ cells, notably spermatids. The present study indicated that adropin improves testicular steroidogenesis, spermatogenesis via modulating redox potential and could be a promising target for treating testicular dysfunctions.

Exploring the antioxidant potential of chalcogen-indolizines throughout in vitro assays.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are highly reactive molecules produced naturally by the body and by external factors. When these species are generated in excessive amounts, they can lead to oxidative stress, which in turn can cause cellular and tissue damage. This damage is known to contribute to the aging process and is associated with age-related conditions, including cardiovascular and neurodegenerative diseases. In recent years, there has been an increased interest in the development of compounds with antioxidant potential to assist in the treatment of disorders related to oxidative stress. In this way, compounds containing sulfur (S) and/or selenium (Se) have been considered promising due to the relevant role of these elements in the biosynthesis of antioxidant enzymes and essential proteins with physiological functions. In this context, studies involving heterocyclic nuclei have significantly increased, notably highlighting the indolizine nucleus, given that compounds containing this nucleus have been demonstrating considerable pharmacological properties. Thus, the objective of this research was to evaluate the in vitro antioxidant activity of eight S- and Se-derivatives containing indolizine nucleus and different substituents. The in vitro assays 1,1-diphenyl-2-picryl-hydrazil (DPPH) scavenger activity, ferric ion (Fe3+) reducing antioxidant power (FRAP), thiobarbituric acid reactive species (TBARS), and protein carbonylation (PC) were used to access the antioxidant profile of the compounds. Our findings demonstrated that all the compounds showed FRAP activity and reduced the levels of TBARS and PC in mouse brains homogenates. Some compounds were also capable of acting as DPPH scavengers. In conclusion, the present study demonstrated that eight novel organochalcogen compounds exhibit antioxidant activity.

Exogenous melatonin mediates radish (Raphanus sativus) and Alternaria brassicae interaction in a dose-dependent manner.

Radish (Raphanus sativus L.) is an economically important vegetable worldwide, but its sustainable production and breeding are highly threatened by blight disease caused by Alternaria brassicae. Melatonin is an important growth regulator that can influence physiological activities in both plants and microbes and stimulate biotic stress resistance in plants. In this study, 0-1500 μM melatonin was exogenously applied to healthy radish seedlings, in vitro incubated A. brassicae, and diseased radish seedlings to determine the effects of melatonin on host, pathogen, and host-pathogen interaction. At sufficient concentrations (0-500 μM), melatonin enhanced growth and immunity of healthy radish seedlings by improving the function of organelles and promoting the biosynthesis of antioxidant enzymes, chitin, organic acid, and defense proteins. Interestingly, melatonin also improved colony growth, development, and virulence of A. brassicae. A strong dosage-dependent effect of melatonin was observed: 50-500 μM promoted host and pathogen vitality and resistance (500 μM was optimal) and 1500 μM inhibited these processes. Significantly less blight was observed on diseased seedlings treated with 500 μM melatonin, indicating that melatonin more strongly enhanced the growth and immunity of radish than it promoted the development and virulence of A. brassicae at this treatment concentration. These effects of MT were mediated by transcriptional changes of key genes as identified by RNA-seq, Dual RNA-seq, and qRT-PCR. The results from this work provide a theoretical basis for the application of melatonin to protect vegetable crops against pathogens.

Exogenous nitric oxide protect garlic plants against oxidative stress induced by salt stress

One of the most important environmental stresses in agriculture is soil salinity. This study was conducted to assess the effects of NaCl level on growth, relative leaf water content, electrolyte leakage, chlorophyll and photosynthetic pigment content, antioxidant activity and antioxidant enzyme activity of marketable Garlic (Allium sativum L.) in a hydroponic greenhouse experiment. Garlic plants were treated with NaCl (0, 30, 60 and 90 mM) and sodium nitroprusside application (0, 75 and 150 μg L−1). The results showed that sodium nitroprusside treatment improved the vegetative characteristics of plants (number of leaves, bulb length and dry weight of bulb) under salinity stress. The highest relative water content of leaves was observed in the treatment of 75 μg L−1 sodium nitroprusside and the level of 30 mM sodium chloride. Application of 75 μg L−1 of sodium nitroprusside could prevent the increase of lipid peroxidation at the level of 60 mM sodium chloride. The simple-effects analysis showed that with increasing the concentration of NaCl and also increasing the concentration of SNP, the amount of chlorophyll a, b and total chlorophyll were decreased. Sodium nitroprusside (75 μg L−1) could improve the damaging effect of salinity stress by increasing the activity of superoxide dismutase, peroxidase, and ascorbate peroxidase enzymes. Application of sodium nitroprusside (75 μg L−1) at level 90 mM NaCl, increased the activity of glutathione reductase enzyme compared to the control at the same level. The results showed that the exogenous application of NO protected garlic plants against salt stress-induced oxidative damage by enhancing the biosynthesis of antioxidant enzymes, thereby improving plant growth under saline stress.

Comparative Morphology and Biochemical Analysis of Nickel Toxicity in Minor Fruit Species (Grewia asiatica L., Syzgium cumini (L.) Skeels and Tamarindus indica L.)

We evaluated the growth potential of three minor fruit species (Grewia asiatica L., Syzgium cummini and Tamarindus indica L.) after exposure to increasing Ni levels (0, 10, 20 and 40 µg kg−1 soil). The growth attributes, lipid peroxidation, photosynthetic machinery, macro nutrients and capacity of enzymatic antioxidants; Superoxide dismutase (SOD), Catalase (CAT) and Peroxidase (POD) in both leaves and roots were investigated under Ni exposure. A significant reduction in the biomass elongation of tissues (root and shoot) and enhanced oxidative damage via malondialdehyde (MDA) were noticed in all three species. Ni exposure triggered an induction of antioxidant enzyme response in a concurrent manner. Simultaneous increases in the antioxidant activities in the roots of G. asiatica and in the leaves of S. cumini suggest the existence of a sequence response against tissue damage. However, the activities of antioxidant enzymes in the tissues of T. indica were insufficient to counteract the elevated MDA levels. G. asiatica exhibited its resilience through the restricted transfer of Ni to aerial tissue, adequate uptake of nutrients, robust chloroplasts with lesser biodegradation of chlorophyll molecules and enhanced capacity of antioxidant enzyme biosynthesis. Thus, lesser modulations of morpho-biochemical expressions and the activity of antioxidants seem to contribute important defense mechanisms against Ni stress in the species.

GCN4 Regulates Secondary Metabolism through Activation of Antioxidant Gene Expression under Nitrogen Limitation Conditions in Ganoderma lucidum.

Nitrogen limitation has been widely reported to affect the growth and development of fungi, and the transcription factor GCN4 (general control nonderepressible 4) is involved in nitrogen restriction. Here, we found that nitrogen limitation highly induced the expression of GCN4 and promoted the synthesis of ganoderic acid (GA), an important secondary metabolite in Ganoderma lucidum. The activated GCN4 is involved in regulating GA biosynthesis. In addition, the accumulation of reactive oxygen species (ROS) also affects the synthesis of GA under nitrogen restrictions. The silencing of the gcn4 gene led to further accumulation of ROS and increased the content of GA. Further studies found that GCN4 activated the transcription of antioxidant enzyme biosynthesis genes gr, gst2, and cat3 (encoding glutathione reductase, glutathione S-transferase, and catalase, respectively) through direct binding to the promoter of these genes to reduce the ROS accumulation. In conclusion, our study found that GCN4 directly interacts with the ROS signaling pathway to negatively regulate GA biosynthesis under nitrogen-limiting conditions. This provides an essential insight into the understanding of GCN4 transcriptional regulation of the ROS signaling pathway and enriches the knowledge of nitrogen regulation mechanisms in fungal secondary metabolism of G. lucidum.IMPORTANCE Nitrogen has been widely reported to regulate secondary metabolism in fungi. Our study assessed the specific nitrogen regulatory mechanisms in Ganoderma lucidum. We found that GCN4 directly interacts with the ROS signaling pathway to negatively regulate GA biosynthesis under nitrogen-limiting conditions. Our research highlights a novel insight that GCN4, the nitrogen utilization regulator, participates in secondary metabolism through ROS signal regulation. In addition, this also provides a theoretical foundation for exploring the regulation of other physiological processes by GCN4 through ROS in fungi.

Ecological and Geochemical Conditions for the Accumulation of Antioxidants in the Leaves of Lathyrus maritimus (L.) Bigel.

The article explores how location affected the dynamics of accumulation of ascorbic acid (AC) and oxidized forms of AC—dehydroascorbic acid (DAA) and diketogulonic acid (DKGA) in beach pea during ontogenetic development. Our analysis focuses on research of the ecological and geochemical conditions growing of the plant on the Curonian Spit. The level of hydrogen peroxide and the activity of enzymes that break it down were analyzed. Antioxidant activity and the total concentration of phenolics were evaluated in the leaves of beach pea on the leeward and windward sides of the foredune. It was established that the level of AC, DAA, and DKGA was higher in the plants growing on the windward side of the foredune. A higher concentration of peroxy compounds, which stimulate the biosynthesis of antioxidant enzymes (catalase, ascorbate peroxidase), polyphenols, and other low molecular antioxidants (AOA) was observed in the leaves of these plants. The plants on the windward side enter phenological stages one or two weeks later than their counterparts on the leeward side of the foredune do. There was a generally negative correlation between the temperature of the soil and the accumulation of ascorbate system acids in the leaves of the studied plants (r = −0.46/(−0.68), p < 0.05). The accumulation of low molecular antioxidants and enzymes in beach pea suggests their adaptation to the adverse conditions of the windward side of the foredune.

Bacillus and Pseudomonas spp. strains induce a response in phenolic profile and enhance biosynthesis of antioxidant enzymes in Agrobacterium tumefaciens infected tomato plants

Some antagonistic bacteria contribute to the management of plant diseases by stimulating the host natural defense and/or by providing direct biocontrol of pathogens. The objective of this study was to evaluate the biocontrol performances and the ability to induce a systemic response to crown gall of four strains belonging to Bacillus and Pseudomonas genera. Evaluation of in vitro antagonistic ability showed that the four bacteria had a different spectrum of activity against the three tested strains of Agrobacterium tumefaciens. A delay in time of appearance and a significant reduction of the tumor size were observed in tomato plants obtained by bio-primed seeds and stem inoculated with A. tumefaciens. Seed priming with antagonistic strains stimulated some systemic defense mechanisms in tomato plants that can be related to the reduction of disease symptoms induced by A. tumefaciens. Both antagonists and A. tumefaciens strains induced variations in phenol content and peroxidase activity while polyphenol oxidase activity was mainly affected by the single A. tumefaciens strain. The response was different in relation to the various combinations of antagonist/pathogen, however Pseudomonas brassicacearum EPR3 strain was the most effective strain.

Antioxidant enzyme activity and microRNA are associated with growth of Poa pratensis callus under salt stress

Kentucky bluegrass (Poa pratensis L.) is an important species of turfgrass that is commonly planted on golf courses and landscapes all over the world. It is sensitive to salt stress; however, details relating to its molecular mechanisms of salt resistance are not available. We, therefore, analyzed the changes in growth, antioxidant enzyme activity, and microRNA expression in the callus 1 week after treatment with 200 mM NaCl for 12 h, 24 h, 48 h, 96 h, and 144 h. The results demonstrated that callus growth declined and thiobarbituric acid-reactive substance production and cell membrane permeability increased. Treatment with salt increased ascorbate peroxidase, glutathione reductase, superoxide dismutase, catalase, peroxidase, and polyphenol oxidase activity. Changes in the expression levels of microRNAs were observed under salt treatment. The expression of miR162, miR173, miR391, miR408, miR773, and miR857 increased by 70% after 24 h of salt treatment, after which it declined to a level similar to that of the control. The expression level of miR775 and miR827 decreased by 20% after 24 h, and then further decreased by 80% after 144 h. The expression level of miR841 increased by 50% after 24 h of salt treatment, and then stabilized. In contrast, salt treatment increased the expression of the auxin response factors ARF6, ARF8, ARF10, and ARF16 in the callus from 12 to 144 h of salt treatment, during which the expression increased twofold. Gene expression analysis indicated that salt-responsive gene families were regulated by microRNAs in the callus under salinity stress. The activity of antioxidant enzymes is also changing. MiR841 is considered to be a positive regulator of antioxidant enzyme biosynthesis. The present investigation elucidates the manner in which P. pratensis responds to salt stress in the callus, and could be used to inform further studies on the molecular mechanisms of stress tolerance.

Exogenous Melatonin Enhances Cold, Salt and Drought Stress Tolerance by Improving Antioxidant Defense in Tea Plant (Camellia sinensis (L.) O. Kuntze).

Melatonin is a biological hormone that plays crucial roles in stress tolerance. In this study, we investigated the effect of exogenous melatonin on abiotic stress in the tea plant. Under cold, salt and drought stress, increasing malondialdehyde levels and decreasing maximum photochemical efficiency of PSII were observed in tea leaves. Meanwhile, the levels of reactive oxygen species (ROS) increased significantly under abiotic stress. Interestingly, pretreatment with melatonin on leaves alleviated ROS burst, decreased malondialdehyde levels and maintain high photosynthetic efficiency. Moreover, 100 μM melatonin-pretreated tea plants showed high levels of glutathione and ascorbic acid and increased the activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase under abiotic stress. Notably, melatonin treatments can positively up-regulate the genes (CsSOD, CsPOD, CsCAT and CsAPX) expression of antioxidant enzyme biosynthesis. Taken together, our results confirmed that melatonin protects tea plants against abiotic stress-induced damages through detoxifying ROS and regulating antioxidant systems.

Low dose X –ray effects on catalase activity in animal tissue

This study was intended to investigate the effect of low-dose X ray-irradiation upon the activity of catalase (CAT) in freshly excised chicken tissues (liver, kidney, brain, muscle). The tissue samples were irradiated with 0.5Gy and 2Gy respectively, in a 6 MV photon beam produced by a clinical linear accelerator (VARIAN CLINAC 2100SC). The dose rate was of 260.88cGy/min. at 100 cm source to sample distance. The catalase level was assayed spectrophotometrically, based on reaction kinetics, using a catalase UV assay kit (SIGMA). Catalase increased activity in various tissue samples exposed to the studied X ray doses (for example with 24 % in the liver cells, p<0.05) suggested the stimulation of the antioxidant enzyme biosynthesis within several hours after exposure at doses of 0.5 Gy and 2 Gy; the putative enzyme inactivation could also occur (due to the injuries on the hydrogen bonds that ensure the specificity of CAT active site) but the resulted balance of the two concurrent processes indicates the cell ability of decomposing the hydrogen peroxide-with benefits for the cell physiology restoration for the chosen low dose radiation.

A influência da intensidade do exercício físico aeróbio no processo aterosclerótico

A aterosclerose é um processo inflamatório crônico e degenerativo que acomete os vasos, sendo caracterizada pelo acúmulo de lipídeos no espaço subendotelial da íntima, acúmulo de células inflamatórias e elementos fibrosos. A oxidação de LDL-c parece ser o principal evento para o início da aterosclerose. O exercício físico aeróbio melhora os sistemas de defesa orgânicos contra aterosclerose, diminuindo o estresse oxidativo e aumentando a síntese de enzimas antioxidantes; aumento da vasodilatação via óxido nítrico (NO) e óxido nítrico sintase endotelial (eNOS) e diminuição da inflamação sistêmica com produção de citocinas pró-inflamatórias e aumento de fatores anti-inflamatórios. Porém, de maneira aguda, o exercício aeróbio de alta intensidade aumenta o risco de desenvolvimento de eventos cardiovasculares e, de forma crônica, pode atuar negativa ou positivamente na prevenção do processo aterosclerótico.

Comparison of antioxidant enzyme biosynthesis by free and immobilized Aspergillus niger cells*

Effect of immobilization on antioxidant enzyme synthesis by growing and non-growing cell culture of Aspergillus niger 26 was studied. Entrapped cells showed a greater than 1.5-fold increase in the superoxide dismutase (SOD) activity and a moderate elevation in catalase activity. The immobilization did not cause changes in the spectrum of SOD isoenzymes. The observed increase in SOD activity required de novo synthesis of this enzyme, because it was suppressed by inhibitors of the transcription and translation. The addition of various viscous substances (agar, Na-alginate and pectin) stimulated the SOD synthesis. Despite these results, it was found that the changes in SOD activity are induced in response to growth in the state of immobilization rather than to presence of alginate. Immobilized A. niger cells exhibited about a 4- to 5-fold higher level of cyanide-resistant respiration. This latter phenomenon might use as an indicator of intracellular oxy-intermediate generation in cell culture growing under stress conditions. The results are discussed relative to association between physiological stress caused by immobilization and oxidative stress.