Activities Of Radical Scavenging Enzymes Research Articles

Maintaining postharvest quality and enhancing shelf-life of bell pepper (Capsicum annuum L.) using brassinosteroids: A novel approach

Bell pepper is a major vegetable crop of global commercial interest, but the postharvest quality is constrained by faster deterioration and senescence. Brassinosteroids (BRs), are an emerging and novel biomolecule that delay ripening and senescence in various vegetables. Freshly harvested bell pepper fruit were immersed in an aqueous solution of BRs concentrations (0, 2, 5, 7 and 10 μM) for 20 min and subsequently stored for 20 d at 10 ± 1°C, 85–90% RH. The bell pepper treated with 10 μM BRs significantly reduced respiration rate (∼2.3 fold), delayed weight loss (∼2.2 fold), and retained higher firmness (∼2.5 fold), total phenolic (∼1.7 fold), flavonoid (∼1.7 fold), proline (∼2 fold) and ascorbic acid content (∼2 fold) over the control fruit at the end of cold storage. Also, it retained higher DPPH radical scavenging (∼1.8 fold) and antioxidant enzyme activity (∼1.5 fold) over the control at the end of cold storage. Moreover, BRs treated bell pepper exhibited reduced malondialdehyde accumulation and delayed capsaicin, and chlorophyll degradation. Remarkably, 10 μM BRs treatment prolonged the shelf-life of bell pepper up to 20 d (10 d extra over control) without compromising quality and sensory acceptability.

Melatonin treatment enhances bioactive compound retention, antioxidant activity and shelf‐life of bell pepper (Capsicum annuum L.) during cold storage

SummaryMelatonin (MT), a natural signalling compound derived from tryptophan, has gained significant attention for delaying postharvest ripening and senescence in various fruits and vegetables. In the present study, the effect of MT treatment was evaluated on the postharvest shelf‐life of bell pepper. Fruits were dipped in various MT concentrations (70, 120, 170, 220 μmol L−1) for 20 min and stored at 10 ± 1 °C for 20 days. The bell pepper treated with 120 μmol L−1 MT significantly suppressed respiration, weight loss and delayed chlorophyll degradation. Additionally, MT (120 μmol L−1) treatment reduced loss of firmness, titratable acidity and retained total phenol, flavonoid and ascorbic acid content. It hindered malondialdehyde accumulation by enhanced DPPH radical scavenging and antioxidant enzyme activity like superoxide dismutase, catalase and peroxidase, over the control. Conclusively, 120 μmol L−1 MT prolongs the postharvest shelf‐life of bell pepper by 20 days with superior sensory quality, surpassing the control by 10 days. Therefore, MT treatment is a commercially useful technology for maintaining quality and prolonging the postharvest shelf‐life of bell pepper.

Evaluation of the antioxidative response of diatoms grown on emerging steroidal contaminants.

With increasing anthropic activities, a myriad of typical contaminants from industries, hospitals, and municipal discharges have been found which fail to be categorized under regulatory standards and are hence considered contaminants of "emerging concern". Since these pollutants are not removed effectively even by the conventional treatment systems, they tend to inflict potential threats to both human and aquatic life. However, microalgae-mediated remediation strategies have recently gained worldwide importance owing to their role in carbon fixation, low operational cost, and production of high-value products. In this study, centric diatom Chaetoceros neogracilis was exposed to different concentrations of estradiol (E2)-induced synthetic media ranging from 0 to 2mg L-1, and its impact on the antioxidative system of algae was investigated. The results demonstrate that the nutrient stress caused a strong oxidative response elevating the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in the 2mg L-1 E2-treated diatom cultures. However, the specific activity of the H2O2 radical scavenging enzymes like catalase (CAT) was inhibited by the E2 treatment, while that of ascorbate peroxidase (APX) remained comparable to the control (0mg L-1 of E2). Thus, the study reveals the scope of diatoms as potential indicators of environmental stress even under the varying concentration of a single contaminant (E2).

Improving anti-hypertensive properties of plant-based alternatives to yogurt fortified with rice protein hydrolysate

In recent years, an increasing demand of plant-based yogurt-like products for partially replacing milk products was related to both health and ethical needs. The objective of this study was to improve the functionality of yogurt-like products relevant for hypertension, using fortification with protein hydrolysate and lactic acid bacteria (LAB) fermentation of soy and Job’s tears beverages. Broken rice was hydrolysed by protease enzymes. Plant-based beverages and yogurt-like products with and without rice protein hydrolysate were prepared by LAB fermentation and evaluated by in-vitro assays for inhibition of free radical scavenging and angiotensin-converting enzyme (ACE) activity. Biochemical changes caused by lactic acid bacteria metabolism were characterized using chemical analysis and 1H NMR. The rice protein hydrolysate obtained using Alcalase® at pH 7.0 for 2 h at 60 °C showed the highest antioxidant activity and ACE inhibition. The ACE inhibition increased by 19.52% and 34.13% in Job’s tears and soy yogurt-like products with hydrolysate, respectively. A strongly significant correlation (R2 = 0.84) between o-phthalic dicarboxaldehyde (OPA) peptides and ACE inhibition was observed. These results indicated the promise of hydrolysate and LAB fermentation as a functional ingredient and process, respectively, for the food industry.

Protective potential of sulfated polysaccharides from tropical seaweeds against alkylating- and oxidizing-induced genotoxicity

Sulfated polysaccharides (SPs) from seaweeds are potential bioactive natural compounds, but their DNA protective activity is poorly explored. This article aimed to evaluate the genotoxic/antigenotoxic potentials of a sulfated heterofucan from brown seaweed Spatoglossum schröederi (Fucan A – FA) and a sulfated galactan from green seaweed Codium isthomocladum (3G4S) using in vitro Comet assay (alkaline and oxidative versions) with HepG2 cells. The antioxidant activity of these SPs was evaluated by total antioxidant capacity, radical scavenging, metal chelating, and antioxidant enzyme activity assays. Both SPs were not genotoxic. FA and 3G4S displayed strong antigenotoxic activity against oxidizing chemical (H2O2) but not against alkylating chemical (MMS). The DNA damage reduction after a pre-treatment of 72 h with these SPs was 81.42% to FA and 81.38% to 3G4S. In simultaneous exposure to FA or 3G4S with H2O2, HepG2 cells presented 48.04% and 55.41% of DNA damage reduction compared with the control, respectively. The antigenotoxicity of these SPs relates to direct antioxidant activity by blockage of the initiation step of the oxidative chain reaction. Therefore, we conclude that FA and 3G4S could be explored as functional natural compounds with antigenotoxic activity due to their great protection against oxidative DNA damage.

Salicylic acid pre-treatment induced physiological and biochemical changes in Solanum lycopersicum L. under salinity stress

Agricultural crop production around the world is adversely affected by excess salt accumulation in the soil. Plants initiate broad range of signal transduction pathways to respond any stress. Salicylic acid (SA) is an endogenous plant growth regulator that acts as a signal molecule to modulate plant response by reducing the effects of abiotic stress on plants. The main objective of this study is to examine whether exogenous salicylic acid pre-treatment may reduce the adverse effects of salt stress and enhance salt tolerance in Solanum lycopersicum. For this experiment, two weeks old seedlings were subjected to salt stress by adding salt water (100 mM NaCl) for three days with or without salicylic acid pre-treatment. After salt stress exposure plant leaves were harvested and the various measures were recorded. Results of this study exhibited that salicylic acid pre-treatment mitigates various advers effects of salt stress on plant growth by stimulating plant biomass, water relations, protein content, chlorophyll pigment, and inorganic osmolytes accumulation. Simultaneously, an increase in activity of antioxidant enzymes of SOD, CAT and POX were also triggered. This current study suggested that pre-treating of Solanum lycopersicum with salicylic acid attenuates the depressive effect of salinity by accelerating the osmolyte accumulation and triggering activity of free radical scavenging enzymes.

IN VITRO SELECTION AND CHARACTERIZATION OF SALVIA OFFICINALIS SALT-TOLERANT CLONES

Salvia officinalis L. is a widest-spread attractive plant in different pharmacopoeias throughout the world. Shoot clumps were regenerated from leaf explants on MS medium enriched with 1 mg/l IAA + 1.5 mg/l TDZ. A 12-week old shoot clumps were subcultured on the same medium supplemented with 100 mM of NaCl. After 12 weeks 4 shoots were recovered from 60 cultured shoot clumps. These shoots were elongated and individually cloned on MS medium enriched with 1 mg/l IAA. Single nodes of the recovered clone, as well as, the control plants were cultured using a single node explants on MS medium enriched with 1 mg/l IAA and 0 or 100 mM NaCl. After a month of growth on this medium statistical analysis showedsignificant difference among the selected clones and the control plants on the base of the ability to develop new growth, plant height, shoot and root fresh and dry weights, as well as, chlorophyll content. Moreover, there were significant differences among the selected colons on proline and total soluble protein content. Also, some regenerated clone showed higher activity of the free radical scavenging enzymes; catalase, peroxidase, and ascorbate peroxidase under salt stress. Therefore, somaclonal variation was used to select a drought tolerant S. officinals clone. Moreover, some physiological mechanisms that are crucial for salt stress tolerance were underlined.

Irradiation Studies of LED Light Spectra on the Growth and Development of Potato (Solanum tuberosum L.)

The study aimed to explore the impacts of distinctive qualities of the LED light (such as to low power consumption, lesser production costs, longer operational lifetime and cool light emission with specific monochromatic wavelength) on potato (Solanum tuberosum L.) growth and development including plant height, number of leaves, root length, fresh and dry weight etc. The accumulation of phyto-pigments, soluble proteins and sugars, free radical scavenging activity and overall tuber yield were also evaluated. Enhanced plant height with increased diameter and branching was observed with the plant growing under the B100 and R30B70 LED light combination. Similarly, total number of leaves, leaf surface area, health index, phyto-pigments and tuber yield of potato was also significantly increased as compared to the plant growing under the W100 as control. Soluble proteins and sugar content and free radical scavenging enzyme activity were also significantly enhanced in the R30B70 LED light combination. Tubers yield per plants were also enhanced under the RB combination of the LED light. The current study indicated that the combination of R and B LED lights proved better for plant growth and development in a controlled environment and the R30B70 is the best combinational spectra for increased growth and tuber yield of potato plants. Therefore, the precise management of the irradiance and wavelength may hold promise in maximizing the economic efficiency of potato production, and quality of this important vegetables grown in controlled environments.

Postharvest gibberellic acid, 6-benzylaminopurine and calcium chloride dipping affect quality, antioxidant compounds, radical scavenging capacity and enzymes activities of ‘Grand Nain’ bananas during shelf life

Effects of GA3 (150 and 300 mg L−1), 6-benzylaminopurine (BAP, 50 and 100 mg L−1) or CaCl2 (2 and 4%) dipping on quality and biochemical changes of ‘Grand Nain’ bananas were studied during 8 days of shelf life (SL) at 20 ± 2 °C and 60–70% RH. Weight loss increased during SL to 9.9% but was not affected by treatments. Firmness and membrane stability index (MSI) decreased during SL and were higher in treated fruit than control. Total soluble solids (TSS)/titratable acidity (TA) ratio increased during SL and was lower in treated fruit than control. GA3 at 150 mg L−1 retained more peel green, darker and less yellow color than control and reduced peel browning that was more apparent after 8 days of SL. However, BAP at 50 mg L−1 retained more peel green color than control only during the first 3 days of SL with little or no effect for CaCl2. Total phenol and flavonoid content in both peel and pulp fluctuated during SL and were higher in treated fruit than control. Vitamin C content decreased during SL and was lower in treated fruit than control. Radical scavenging capacity (RSC) of peel decreased during SL and was higher in treatments than control. While, RSC of pulp decreased, in most treatments, during SL and was higher in all treatments only after 3 days of SL. In both peel and pulp, polygalacturonase (PG), xylanase and α-amylase activities increased with fluctuation during SL and were lower in most treatments than control. Polyphenoloxidase (PPO) activity increased during SL and was lower in treated fruit than control. While, peroxidase (POD) activity increased during SL and was higher in most treatments than control especially after 5 and 8 days of SL. In conclusion, postharvest dipping in either 150 mg L−1 GA3, 50 mg L−1 BAP or 2% CaCl2 retarded ripening and retained quality of ‘Grand Nain’ bananas during SL. However, GA3 was more effective in reducing peel browning and retaining green color than other treatments including control.

Effects of alkaline hydrolysis and storage conditions on the biological activity of ostrich egg white

This study aimed to improve the biological activity of ostrich egg white (OEW) using alkaline hydrolysis (0.25 M NaOH at 40°C for 8 hr), and studied the effects of packing materials and temperature on biological and physical properties of OEW hydrolysate (hOEW). The results show that alkaline hydrolysis clearly enhanced several biological activities, including ABTS radical scavenging (61.35%), anti-microbial (51.66% against Bacillus subtilis and 38.58% against Escherichia coli) and anti-angiotensin converting enzyme activity (39.19%). The hydrolysate maintained biological activities after gastrointestinal digestion and showed non-toxicity toward human red blood cells. In storage study, the best storage conditions were packing hOEW powder in an Al-foil-laminated bag at 4°C, resulting in slightly decreased biological activity after 6 months storage and significantly lower moisture content than plastic zipper bag. Additionally, SEM revealed smooth surfaces of hOEW powder for the best condition, while air pores and bridges were found in the worst conditions. Practical applications The alkaline hydrolysis method (incubation in 0.25 M NaOH at 40°C for 8 hr) used in this study can be used to enhance the antioxidant, antimicrobial, and anti-ACE inhibition activity of egg white protein. This study also reports the optimal packaging and storage conditions for egg white hydrolysate powder, which are beneficial for maintaining the antioxidant, antimicrobial, and anti-angiotensin converting enzyme activity as well as the texture of the egg white hydrolysate powder.

Quality and Biochemical Changes of ‘Grand Nain’ Bananas during Shelf Life

. Quality attributes, antioxidant compounds, free radical scavenging capacity (FRSC, DPPH IC50 value) and enzymes activities of ‘Grand Nain’bananas were investigated during shelf life at 20±2oC and 60-70% RH for 7 days. Weight loss, peel color and browning indices increased while, pulp firmness, titratable acidity (TA), pH and membrane stability index (MSI) decreased during shelf life. Total soluble solid (TSS) concentration increased up to day five then remained stable whereas, vitamin C increased ranged from 5.8 to 8.2 mg 100g-1 fresh weight (FW) during the first two days and then decreased. Total phenols concentration in both peel and pulp increased ranged from 0.19 to 1.64 gkg-1 and 0.17 to 0.59 gkg-1 FW, respectively during shelf life. Total flavonoids firstly increased, remained stable until day five then, decreased in both peel and pulp. It ranged from 0.05 to 0.21 gkg-1 FW and 0.03 to 0.19 gkg-1 FW in peel and pulp, respectively. Both total phenols and flavonoids concentrations were higher in peel than pulp. FRSC in peel remained stable until day five then, sharply decreased (higher DPPH IC50 values) and ranged from 3.83 to 19.43 IC50 values. While, in pulp it decreased (higher DPPH IC50 values) during shelf life and ranged from 4.1 to 13.3 IC50 values. Polyphenoloxidase (PPO), peroxidase (POD), polygalacturornase (PG), xylanase and ?-amylase activities in peel and pulp greatly varied during shelf life.

Postharvest chitosan, trans-resveratrol and glycine betaine dipping affect quality, antioxidant compounds, free radical scavenging capacity and enzymes activities of ‘Sukkari’ bananas during shelf life

Effects of chitosan (0.5 and 1%), trans-resveratrol (1.6×10−5M, 1.6×10−4M and 1.6×10−3M) and glycine betaine (GB) (10, 15 and 20mM) dipping on quality and biochemical changes of ‘Sukkari’ bananas were studied during ripening at shelf life (SL) conditions for 13 days. Weight loss increased during shelf life but was not affected by treatments. Peel color index increased during SL and was lower at both resveratrol and GB treatments than control. Membrane stability index (MSI) of peel decreased during SL and was higher, especially after 6 days, at resveratrol and GB treatments than control. Firmness decreased during SL and was higher, especially after 6 days, at resveratrol and low and moderate rates of GB than control. TSS increased during SL and was lower at all treatments than control. Acidity concentration decreased during SL and was higher, especially after 6 days, at low rate of chitosan, resveratrol and high rate of GB than control. pH increased during SL and was higher at low rate of GB and lower at low and moderate rates of resveratrol than control. Vitamin C concentration decreased during SL but was not affected by treatments. Total phenols concentration decreased during SL and was higher at GB and moderate rate of resveratrol than control. Total flavonoids concentration decreased during SL and was lower at resveratrol and low and high rates of GB than control. FRSC (DPPH IC50) increased during SL and was lower at GB and low and moderate rates of resveratrol than other treatments, especially after 6 days. The relations of such biochemical changes with α-amylase, xylanase, polygalacturonase, peroxidase and polyphenoloxidase activities were discussed. In conclusion, both postharvest trans-resveratrol and GB treatments retained quality of ‘Sukkari’ bananas during SL and being suggested as natural alternatives to synthetic chemicals.

Postharvest chitosan, gallic acid and chitosan gallate treatments effects on shelf life quality, antioxidant compounds, free radical scavenging capacity and enzymes activities of 'Sukkari' bananas.

The effect of postharvest chitosan, gallic acid (GA) and chitosan gallate (CG) dipping treatments at different concentrations on quality parameters, antioxidant compounds, free radical scavenging capacity (FRSC) and enzymes activities of 'Sukkari' bananas were studied during storage (ripening) at 20±2°C and 60-70% RH for 13days. Weight loss and peel color index (the change from green to yellow) increased while, membrane stability index of peel tissues, pulp firmness and acidity decreased during storage. CG and GA treatments slowed down the changes in these parameters compared to control. Total soluble solids (TSS) concentration increased during storage and was lower at CG than other treatments. TSS/acid ratio increased during storage and showed higher value after storage than initial. This ratio was lower at 1% chitosan, 0.075% GA and CG treatments than control. Both vitamin C and total flavonoids concentrations decreased during storage and were not affected by the applied treatments. Total phenols concentration decreased during storage and was higher at acetic acid and the high rate of chitosan, GA and CG treatments than control. FRSC (DPPH IC50 values) of fruit peel ranged from 2.54 to 4.19µg phenolics concentration among the treatments. FRSC was not affected by the applied treatments but increased (lower IC50 value) during shelf life. The possible relations of these biochemical changes with the activities of the enzymes α-amylase, xylanase, polygalacturonase, peroxidase and polyphenoloxidase were discussed. It is concluded that postharvest CG and GA treatments delayed ripening and maintained better quality parameters of 'Sukkari' bananas during 13days of shelf life than control.

Fish Oil Supplementation Ameliorates Long Term Cisplatin Treatment Induced Toxicity and Oxidative Damage in Rat Kidney

Background: Cisplatin (CP) is an effective chemotherapeutic agent widely used against various malignancies. However, CP exerts several side effects through oxidative stress by generating reactive oxygen species (ROS). The major side effect of CP chemotherapy is dose dependent nephrotoxicity that limits its clinical usage. We have previously shown that fish oil (FO) supplementation ameliorated gentamicin induced nephrotoxicity as evident by increase in the activities of brush border membrane (BBM) and free radical scavenging enzymes in rat kidney. In the present study we aimed to investigate whether fish oil (FO) can prevent the long term CP-induced nephrotoxic effects. Methods: Rats were divided into four groups viz. control, CP, CPF and FO alone group. Rats in the groups CPF and FO were fed experimental diet prior to and simultaneously with or without CP treatment (3 mg/kg bwt i.p) respectively. Results: FO supplementation to CP treated significantly mitigated the CP induced increase in serum creatinine (Scr) and blood urea nitrogen (BUN) and decrease in the activities of brush border membrane (BBM) enzymes in renal cortical and medullary homogenates as well as in isolated BBM vesicles (BBMV). FO consumption also reduced CP induced alterations in the activities of carbohydrate metabolism enzymes and in the enzymatic and non-enzymatic antioxidant parameters. Conclusion: These results suggest that FO have potential to abrogate CP induced nephrotoxicity and can be a useful adjuvant in long term CP chemotherapy without any side effects. Moreover, the inherent anti-cancer properties of FO with CP treatment may exhibits synergistic beneficial effects.

Protective effect of Nigella sativa oil on cisplatin induced nephrotoxicity and oxidative damage in rat kidney.

Nephrotoxicity is a severe complication in patients undergoing cisplatin (CP) chemotherapy. Previous studies in our lab have shown that administration of a single dose of CP results in decrease in the activities of brush border membrane (BBM) and free radical scavenging enzymes and induces oxidative stress in rat kidney. Nigella sativa, is one of the most revered medicinal plant known for its numerous health benefits. Nigella sativa seed/oil has been shown to improve kidney functions in animal models of acute kidney injury. The present study was undertaken to investigate whether Nigella sativa oil (NSO) can prevent the CP-induced nephrotoxic effects. The effect of NSO was determined on CP induced alterations in various serum parameters and on enzymes of carbohydrate metabolism, BBM and antioxidant defense system in renal cortex and medulla. Administration of NSO (2ml/kg bwt. orally), prior to and following a single dose CP treatment (6mg/kg bwt. i.p), significantly attenuated the CP induced increase in serum creatinine (Scr) and blood urea nitrogen (BUN) and decrease in the activities of BBM enzymes in renal cortical and medullary homogenates as well as in isolated BBM vesicles (BBMV). NSO administration also precluded CP induced alterations in the activities of carbohydrate metabolism enzymes and in the enzymatic and non-enzymatic antioxidant parameters. Histopathological observations showed extensive kidney damage in CP treated animals and remarkably reduced renal injury in CP and NSO co-treated group. The biochemical and histological data suggest a protective effect of NSO against CP-induced acute kidney injury.

Silver nanoparticles and silver ions: Oxidative stress responses and toxicity in potato (Solanum tuberosum L) grown in vitro

Under in vitro conditions, we examined the effects of silver nanoparticles (AgNPs) and silver (Ag) ions on potato (Solanum tuberosum L.) in terms of silver accumulation, production of reactive oxygen species (ROS), oxidative stress responses, and antioxidative defense systems. At all concentrations (except at 2 mg•L-1), the amount of Ag in the shoots and roots of Ag ion-treated plantlets was significantly higher than in plantlets treated with AgNPs. In both treatments, total ROS and superoxide anions were increased at concentrations greater than 2 mg•L-1. Damage caused by oxidative stress, such as ion leakage and cell death, was significantly higher in plantlets treated with AgNPs than those treated with Ag ions. Significant increases in the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase (GR),were found in both AgNP-treated, and Ag ion-treated plantlets compared to the control. However, in AgNP-treated plantlets, GR activity was significantly decreased at 20 mg•L-1. A significant reduction in glutathione (GSH), ascorbate (ASA), and the ratios of GSH to oxidized glutathione (GSSG) and ASA to oxidized ascorbate (DHA)were observed in plantlets treated with both AgNPs and Ag ions at concentrations higher than 2 mg•L-1. Moreover, a greater decrease in GSH and ASA contents was seen in plantlets treated with AgNPs compared to those treated with Ag ions. The present study indicates that both AgNPs and Ag ion treatments impose oxidative stress on potato plantlets under in vitro conditions. Furthermore, based on plantlets’ responses to oxidative damage, the observed alteration in the activities of radical scavenging enzymes and the depletion of GSH and ASA, AgNPs seem to have higher toxicity than the equivalent mass of Ag ions.

Curcumin Blocks Naproxen-Induced Gastric Antral Ulcerations through Inhibition of Lipid Peroxidation and Activation of Enzymatic Scavengers in Rats.

Curcumin is a polyphenol derived from the plant Curcuma longa, which is used for the treatment of diseases associated with oxidative stress and inflammation. The present study was undertaken to determine the protective effect of curcumin against naproxen-induced gastric antral ulcerations in rats. Different doses (10, 50, and 100 mg/kg) of curcumin or vehicle (curcumin, 0 mg/kg) were pretreated for 3 days by oral gavage, and then gastric mucosal lesions were caused by 80 mg/kg naproxen applied for 3 days. Curcumin significantly inhibited the naproxen-induced gastric antral ulcer area and lipid peroxidation in a dose-dependent manner. In addition, curcumin markedly increased activities of radical scavenging enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase in a dose-dependent manner. Specifically, 100 mg/kg curcumin completely protected the gastric mucosa against the loss in the enzyme, resulting in a drastic increase of activities of radical scavenging enzymes up to more than the level of untreated normal rats. Histological examination obviously showed that curcumin prevents naproxen-induced gastric antral ulceration as a result of direct protection of the gastric mucosa. These results suggest that curcumin blocks naproxen-induced gastric antral ulcerations through prevention of lipid peroxidation and activation of radical scavenging enzymes, and it may offer a potential remedy of gastric antral ulcerations.

Protective Effect of 4-(3,4-Dihydroxyphenyl)-3-Buten-2-One from Phellinus linteus on Naproxen-Induced Gastric Antral Ulcers in Rats.

The present study investigated the protective effect of naturally purified 4-(3,4- dihydroxyphenyl)-3-buten-2-one (DHP) from Phellinus linteus against naproxen-induced gastric antral ulcers in rats. To verify the protective effect of DHP on naproxen-induced gastric antral ulcers, various doses (1, 5, and 10 μg/kg) of DHP were pretreated for 3 days, and then gastric damage was caused by 80 mg/kg naproxen applied for 3 days. DHP prevented naproxen-induced gastric antral ulcers in a dose-dependent manner. In particular, 10 μg/kg DHP showed the best protective effect against naproxen-induced gastric antral ulcers. Moreover, DHP significantly attenuated the naproxen-induced lipid peroxide level in gastric mucosa and increased the activities of radical scavenging enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, in a dose-dependent manner. A histological examination clearly demonstrated that the gastric antral ulcer induced by naproxen nearly disappeared after the pretreatment of DHP. These results suggest that DHP can inhibit naproxen-induced gastric antral ulcers through prevention of lipid peroxidation and activation of radical scavenging enzymes.

Evaluation of O<sub>3</sub> effect on net photosynthetic rate in flag leaves of rice (<i>Oryza sativa</i> L.) by stomatal O<sub>3</sub> flux and radical scavenging enzyme activities

To evaluate the effects of O3 on the net photosynthetic rate in flag leaves of rice (Oryza sativa L.) based on stomatal O3 flux and reactive oxygen species (ROS) scavenging enzyme activities, the Japanese rice cultivar Koshihikari was exposed to O3 for 1 month after heading in O3-exposure chambers. During the exposure period, rice plants were exposed to charcoal-filtered air or O3 at 60 or 100 nl l(ppb) daily (10:00–17:00). Light-saturated net photosynthetic rate (Asat) and ROS scavenging enzyme activities in the flag leaves were periodically measured during the exposure period. The O3 exposure significantly reduced Asat on the 20th and 31st days after the beginning of O3 exposure (DAE). The degree of O3-induced reduction in Asat was explained by the cumulative flux of O3 compared with concentration-based O3 indices. The activities of ROS scavenging enzymes such as ascorbate peroxidase and catalase at 32 DAE were lower than at 1 DAE. During the latter half of the O3 exposure period (21–31 DAE), the daily average stomatal O3 flux was also lower than that during the first half of the period (1–20 DAE), which was mainly caused by lower photosynthetic photon flux density, lower air temperature and leaf senescence. These results suggest that the balance between stomatal O3 flux and leaf cellular detoxification capacity in the flag leaves of rice, which determines the degree of O3 damage, might have been similar between the first half and latter half of the O3 exposure period.

Change of antioxidant enzymes activity of hazel (Corylus avellana L.) cells by AgNPs.

Elicitation effect of silver nano particles (AgNPs) and triggering of defence system by production of hydrogen peroxide (H2O2) as a signaling molecule in the regulation of the activity of stress-related enzymes and production of Taxol was evaluated in suspension- cultured hazel cells (Corylus avellana L.). The cells were treated with different concentrations of AgNPs (0, 2.5, 5, and 10ppm), in their logarithmic growth phase (d7) and were harvested after 1 week. Treatment of hazel cells with AgNPs decreased the viability of the cells. Also the results showed that while the activity of certain radical scavenging enzymes in particular of catalase and peroxidase increased by 2.5 and 5ppm AgNPs, the activity of superoxide dismutase decreased in these treatments. The highest activity of ascorbate peroxidase was observed in 10ppm AgNPs treatments. This treatment also showed the highest contents of H2O2 and phenolic compounds, as well as the highest activity of phenylalanine ammonialyase. According to the results, 5ppm AgNPs was the best concentration for elicitation of hazel cells to produce efficient amounts of H2O2 in order for stimulation of antioxidant defence system, production of Taxol at the highest capacity of the cells, meanwhile reserving their viability.