Oxygen Species Scavenging Activity Research Articles

GABA Metabolism, Transport and Their Roles and Mechanisms in the Regulation of Abiotic Stress (Hypoxia, Salt, Drought) Resistance in Plants

γ- Aminobutyric acid (GABA) is a ubiquitous four-carbon non-protein amino acid. In plants, GABA is found in different cell compartments and performs different metabolic functions. As a signalling molecule, GABA participates in the regulation of tolerance to various abiotic stresses. Many research studies have found that GABA accumulates in large amounts when plants are subjected to abiotic stress, which have been demonstrated through the Web of Science, PubMed, Elsevier and other databases. GABA enhances the tolerance of plants to abiotic stress by regulating intracellular pH, ion transport, activating antioxidant systems and scavenging active oxygen species. In the process of GABA playing its role, transport is very important for the accumulation and metabolism pathway of GABA in cells. Therefore, the research on the transport of GABA across the cell membrane and the organelle membrane by transport proteins is a direction worthy of attention. This paper describes the distribution, biosynthesis and catabolism of GABA in plants. In addition, we focus on the latest progress in research on the transport of exogenous GABA and on the function and mechanism in the regulation of the abiotic stress response. Based on this summary of the role of GABA in the resistance to various abiotic stresses, we conclude that GABA has become an effective compound for improving plant abiotic tolerance.

Effect of Different Nano-NPK Fertilizers on Vegetative Growth Parameter and Soil Microbial Activity of Fig Crop under Different Irrigation Regims

World face several challenges the most decisive climatic changes , freshwater poverty and poor usage efficiency for natural resources (soil & water) particularly in developing countries.
 Applying Nanotechnology may represent a smart mechanism toward sustainable agricultural. Much efforts have been exerted to utilizing nano-technology and producing agro-chemicals in nano-form i.e, nano-fertilizers and nano-pesticides.
 Current work that carried out in greenhouse belong pomology department , National Research Centre, Cairo, Egypt during 2020/2021, aims to assessing impact of nano-fertilizers on growth performance and soil microbial activity under different drought stress levels. NPK-nano-fetrilizer was applied on uniform one-year old fig seedlings, as foliar application at two levels (200 and 400ppm) compared with traditional NPK fertilizer, under three levels of water regimes (once, twice and three times irrigation weekly. Obtained results indicated that under drought stress nano-fertilizers enhanced fig seedlings growth performance and nutrient content. Moreover, nano-fertilizer raised antioxidant enzyme activity that work on scavenging active oxygen species and thereby reinforce drought stress tolerance in plants. Besides, nano-fertilizer had a positive impact on soil microbial under low soil moisture. This study came in chain of studies which proved the efficiency of nano-fertilizer under drought stress with no negative impact on environments under this study conditions. This study concluded that nano-fertilizer has a bright future particularly under challenges that face the world (climatic changes, poverty of water resources, soil degradation and global food famine risk with fast growing of population) toward sustainable agriculture with low risk on environment.

Ultradurable fluorinated V2AlC for peroxymonosulfate activation in organic pollutant degradation processes

Vanadium-based catalysts are considered the most promising materials to replace cobalt-based catalysts for the activation of peroxymonosulfate (PMS) to degrade organic pollutants. However, these traditional vanadium species easily leak out metal ions that can affect the environment, even though the of vanadium is much less than that of cobalt. Compared to other vanadium-based catalysts, e.g., V 2 O 3 , fluorinated V 2 AlC shows a high and constant activity and reusability regarding PMS activation. Furthermore, it features extremely low ion leakage. Active oxygen species scavenging and electron spin resonance measurements reveal that the main reactive oxygen species was 1 O 2 , which was induced by a two-dimensional confinement effect. More importantly, for the real-life application of tetracycline (TC) degradation, the introduction of fluorine changed the adsorption mode of TC over the catalyst, thereby changing the degradation path. The intermediate products were detected by liquid-chromatography mass spectroscopy (LC-MS), and a possible degradation path was proposed. The environmental impact test of the decomposition products showed that the toxicity of the degradation intermediates was greatly reduced. Therefore, the investigated ultradurable catalyst material provides a basis for the practical application of advanced PMS oxidation technology. F-V 2 AlC showed higher activity and better reusability than V 2 O 3 for PMS activation with extremely low ion leakage. And mechanism investigation showed that the main reactive oxygen specie was 1 O 2 , which induced by the two-dimensional confinement effect. In addition, the introduction of F changed the adsorption mode of TC over catalyst, thereby changing the degradation path.

Pinus thunbergii Parl. Extracts Reduce Acute Inflammation by Targeting Oxidative Stress

Pinus thunbergii Parl. (PTP) has traditionally been used for edible and medicinal purposes to treat several disorders, including diabetes and neuralgia. Therefore, this study sought to evaluate the inhibitory effects of PTP leaf ethanol extracts on acute inflammation. Moreover, the reactive oxygen species (ROS) scavenging activity, superoxide dismutase (SOD) activity, lipopolysaccharide (LPS)-induced nitric oxide (NO) generation, and H2O2-induced lipid peroxidation capacity of PTP were assessed in vitro in RAW 264.7 macrophages. Our results suggest that PTP prevents cell damage caused by oxidative free radicals and downregulates the expression of LPS-induced inflammation-associated factors including inducible nitric oxidase synthetase (iNOS), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PGE2). PTP inhibited NO production by 53.5% (P < 0.05) and iNOS expression by 71.5% (P < 0.01) at 100 µg/mL. PTP at 100 µg/mL also inhibited ROS generation by 58.2% (P < 0.01) and SOD activity by 29.3%, as well as COX-2 expression by 83.3% (P < 0.01) and PGE2 expression by 98.6% (P < 0.01). The anti-inflammatory effects of PTP were confirmed in vivo using an arachidonic acid (AA)-induced ear edema mouse model. Ear thickness and myeloperoxidase (MPO) activity were evaluated as indicators of inflammation. PTP inhibited edema formation by 64.5% (P < 0.05) at 1.0 mg/ear. A total of 16 metabolites were identified in PTP extracts and categorized into subgroups, including two phenolic acids (mainly quinic acid), seven flavonoids, five lignans, one sesquiterpenoid, and one long-chain fatty acid. Therefore, our results suggest that PTP possesses anti-inflammatory properties.

The Alleviative Effects of Salicylic Acid on Physiological Indices and Defense Mechanisms of Maize (Zea Mays L. Giza 2) Stressed with Cadmium

The present study evaluated the physiological and biochemical mechanisms through which exogenous salicylic acid (SA) mitigates cadmium (Cd) stress in maize. The different concentrations of Cd included 0, 5, 10 µM CdCl2.3H2O. Half of plants received salicylic acid as a soil drench. Results showed that Cd exposure reduced chlorophyll contents, chlorophyll fluorescence, photosynthetic rate and activity of catalase (CAT). However, Cd stress enhanced non-photochemical quenching (NPQ), the production of malondialdehyde (MDA) and activities of key antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (POD). The increased activities of antioxidant enzymes and concentration of MDA were reduced by exogenous application of SA as a soil drench. Our research proves that SA, as a novel endogenous plant hormone exerts beneficial physiological effects on plants as it has a dual role in scavenging active oxygen species (AOS) and modulating redox balance to enhance photosynthetic performance in cadmium-stressed maize plants. It was concluded that SA improved plant tolerance under Cd contamination and may have alleviated the inhibitory effect of Cd on photosynthesis by protecting maize plants against oxidative damage as indicated by the marked decline in net photosynthetic rates, quantum yield and chlorophyll content as well as alteration of antioxidants activity and accumulation of MDA. Collectively, results of the present study provide an insight into the alleviative role of SA in Cd-stressed maize and propose SA as a potential candidate in mitigating Cd toxicity.

Physiological and molecular mechanisms of cobalt and copper interaction in causing phyto-toxicity to two barley genotypes differing in Co tolerance

The combined effects of cobalt (Co) and copper (Cu) in their toxicity to plants is poorly studied although these two metals co-exist commonly in soil. In this study, a hydroponic experiment was carried out to investigate the effect of longer exposure of two barley genotypes differing in Co tolerance to the combined Co and Cu stress. The results confirmed the previous findings that Co accumulation in plant tissues was reduced by Cu presence, while Cu accumulation was stimulated by Co presence. Moreover, both single and combined treatments of Co and Cu reduced the mineral (Mn, Zn and K) uptake. Co and Cu applied alone or in combination at rate of 50 μM resulted in the significant reduction of plant growth and increase of oxidative stress (ROS and MDA), and meanwhile the capacity of scavenging active oxygen species (AOS) was enhanced, reflected by increased phytochelatin (PC) and glutathione (GSH and GSSG) content, as well as expression of the related genes (HvPCS1 and HvGR1). Yan66, a Co tolerant genotype was less affected in oxidative stress, and had higher AOS scavenging capacity in comparison with Ea52, a Co sensitive one. Among three HvSOD isoforms, only HvFeSOD expression was up-regulated in the combined treatment relative to control as well as the treatment of Co or Cu alone, while HvCuZnSOD and HvMnSOD were down-regulated and unaffected, respectively. In addition, the expressions of metal transporter genes (HvHMA2, HvHMA3 and HvHMA5) varied with genotype and metal treatments, with the extent being greater in Yan66 on the whole. The results suggest that upon longer exposure to the combined stress of Co and Cu, the greater phyto-toxicity than each element alone is associated with more Cu accumulation stimulated by Co and that, the higher regulation of transporter genes observed in Yan66 could in part explain for its higher metal tolerance ability.

Synthesis of Defense Enzymes in Potato in Induced Resistance against Late Blight using Inorganic Chemicals as Inducer

Differences in physiological and biochemical responses between sensitive and tolerant rice cultivars to ozone were investigated to develop reliable indications of early ozone damage. Three Korean local rice cultivars -sen-sitive cultivar Dongjin (DJ), moderately tolerant cultivar Hwayeong (HY) and tolerant cultivar Ilmee (IM) were exposed to ozone at the concentrations of 100 nl or 200 nl , 8 h per day for 10 days in a controlled-environment fumigation chamber. The rice cultivars seemed to be endurable to ozone stress at the concentration of 100 nl which is frequently monitored during the growing season in summer. However, severe damage was induced and differential sensitivity was clearly noted among the rice cultivars at the higher ozone concentration. Activation of the glutathion (GR) -ascorbate peroxidase (APX) cycle was likely to be responsible for protection of rice plants against ozone exposure, relating difference in sensitivity of rice cultivars to ozone. Photosynthetic activity appeared to be one of sensitive responses, for which chlorophyll fluorescence and leaf greenness can together provide a very reliable index, a degree of photosynthetic damages by ozone. Formation of malondialdehyde (MDA) was also considered as an indication that can differentiate cultivars sensitivity to ozone. However, the changes in polyamines and total phenolics were not consistent with exposed ozone concentrations and/or ozone sensitivity of the cultivars. The behavior of polyamines and phenolics in the damaged plants at high ozone levels could be interpreted as an indication of ozone injury rather than activation of additional protection mechanisms scavenging active oxygen species formed by ozone. Several responses triggered by ozone could explain the differential sensitivity of the rice cultivars and be used as reliable indications of relative ozone damage to rice plant.

Anti-inflammatory, analgesic and antioxidant activities of 3,4-oxo-isopropylidene-shikimic acid

Context 3,4-Oxo-isopropylidene-shikimic acid (ISA) is an analog of shikimic acid (SA). SA is extracted from the dry fruit of Illicium verum Hook. f. (Magnoliaceae), which has been used for treating stomachaches, skin inflammation and rheumatic pain.Objective To investigate the anti-inflammatory, analgesic and antioxidant activities of ISA.Materials and methods Analgesic and anti-inflammatory activities of ISA were evaluated using writhing, hot plate, xylene-induced ear oedema, carrageenan-induced paw oedema and cotton pellets-induced granuloma test, meanwhile the prostaglandin E2 (PGE2) and malondialdehyde (MDA) levels were assessed in the oedema paw tissue. ISA (60, 120 and 240 mg/kg in mice model and 50, 120 and 200 mg/kg in rat model) was administered orally, 30 min before induction of inflammation/pain. Additionally, ISA was administered for 12 d in rats from the day of cotton pellet implantation. The active oxygen species scavenging potencies of ISA (10−3–10−5 M) were evaluated by the electron spin resonance spin-trapping technique.Results ISA caused a reduction of inflammation induced by xylene (18.1–31.4%), carrageenan (7.8–51.0%) and cotton pellets (11.4–24.0%). Furthermore, ISA decreased the production of PGE2 and MDA in the rat paw tissue by 1.0–15.6% and 6.3–27.6%, respectively. ISA also reduced pain induced by acetic acid (15.6–48.9%) and hot plate (10.5–28.5%). Finally, ISA exhibited moderate antioxidant activity by scavenging the superoxide radical and hydroxyl radical with IC50 values of 0.214 and 0.450 μg/mL, respectively.Discussion and conclusion Our findings confirmed the anti-inflammatory, analgesic and antioxidant activities of ISA.

Drought stress tolerance mediated by zinc-induced antioxidative defense and osmotic adjustment in cotton (Gossypium Hirsutum)

Zinc, as one of the essential microelements in crop plant, plays a crucial role in resistance to drought stress. To acquire a comprehensive of the physiological mechanism of resistance to drought stress enhanced by supplemental Zn in cotton, a hydroponic trial was conducted to investigate the changes in antioxidants and osmoregulation substances under zinc def icient and zinc sufficient conditions after 0, 3, 6 and 48 h of polyethylene glycol 6000-simulated drought stress. The present research showed that supplemental Zn significantly enhanced photosynthetic rate, chlorophyll a, chlorophyll b and dry matter of cotton under polyethylene glycol 6000 simulated drought stress, indicating that supplemental zinc improved the cotton growth. The antioxidant enzymes activities such as catalase, ascorbate peroxidase and superoxide dismutase, and non-enzymatic antioxidants such as carotenoid, reduced glutathione and ascorbic acid were all significantly enhanced and malonaldehyde content was remarkably reduced by supplemental zinc under polyethylene glycol 6000 simulated drought stress, indicating that the capacity of scavenging active oxygen species was improved by supplemental zinc in cotton. The osmoregulation substances such as soluble sugar, proline and soluble protein were all enhanced by supplemental zinc under Polyethylene glycol 6000 simulated drought stress, suggesting that zinc enhanced the osmotic adjustment capacity of cotton. It is implied that supplemental zinc could enhance the resistance to drought stress by inducing the buildup of antioxidative defences and osmotic adjustment ability in cotton.

Effects of molybdenum on water utilization, antioxidative defense system and osmotic-adjustment ability in winter wheat (Triticum aestivum) under drought stress

Molybdenum (Mo), as an essential trace element in plants, plays an essential role in abiotic stress tolerance of plants. To obtain a better understanding of drought tolerance enhanced by Mo, a hydroponic trial was conducted to investigate the effects of Mo on water utilization, antioxidant enzymes, non-enzymatic antioxidants, and osmotic-adjustment products in the Mo-efficient ‘97003’ and Mo-inefficient ‘97014’ under PEG simulated drought stress. Our results indicate that Mo application significantly enhanced Pn, chlorophyll, dry matter, grain yield, biomass, RWC and WUE and decreased Tr, Gs and water loss of wheat under drought stress, suggesting that Mo application improved the water utilization capacity in wheat. The activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and the contents of non-enzymatic antioxidants content such as ascorbic acid, reduced glutathione, carotenoid were significantly increased and malonaldehyde contents were decreased by Mo application under PEG simulated drought stress, suggesting that Mo application enhanced the ability of scavenging active oxygen species. The osmotic-adjustment products such as soluble protein, proline and soluble sugar were also increased by Mo application under PEG simulated drought stress, indicating that Mo improved the osmotic adjustment ability in wheat. It is hypothesized that Mo application might improve the drought tolerance of wheat by enhancing water utilization capability and the abilities of antioxidative defense and osmotic adjustment. Similarities and differences between the Mo-efficient and Mo-inefficient cultivars wheat in response to Mo under drought stress are discussed.

Physicochemical Characteristics of Saudi Arabian Locally Produced Raw and Diluted Honeys and Their Relations to Antimicrobial Activity

The physicochemical characteristics and antibacterial activity of Saudi Arabia honeys were studied for the first time. The levels of free and total acidity, pH, ash and moisture content were in the range 1.6 ±0.17 - 15.1 ±0.1 meq/kg, 2.77 ± 0.06 - 5.37 ±0.04, 1.1 ±0.02 – 1.7 ±0.03 % and &lt; 18.0 %, respectively. Lovibond comparator color scale (P, mm) of samples was ranged from water white (P=0.0-1.3), extra light Amber (P=38.14-46.57), light Amber (P=60.39-75.54), Amber (P=86.72-110.08), dark (P=142.39-348.44) and very dark shade (P= 541.84). Dark honeys showed excellent inhibitory effects against bacterial growth. Excellent correlation between color of raw and diluted (&gt;10.0%m/v) honey and antimicrobial activity was noticed. Honey species from different floral sources posses’ strong antioxidant and anti bacterial activities and are scavengers of active oxygen species.

Novel biotransformation processes of artemisinic acid to their hydroxylated derivatives 3β-hydroxyartemisinic acid and 3β, 15-dihydroxyartemisinic by fungus Trichothecium roseum CIMAPN1and their biological evaluation

The biotransformation of artemisinic acid (1) by endophytic fungus Trichothecium roseum CIMAPN1 is reported here for the first time. The major biotransformed products appeared as a grayish color spot on thin-layer chromatography (TLC) with transparent crystal-like texture. Based on their infrared (IR) and 1H nuclear magnetic resonance (NMR) spectra, the products were characterized as a 3β-hydroxyartemisinic acid (2) and 3β, 15-dihydroxyartemisinic acid (3) and were obtained in 51.1% and 37.3% yields, respectively. The highest conversion efficiencies were obtained respectively when 2-day-old cultures of T. roseum were fed with 20 mg of compound 1 in 50 ml of medium per culture and the mycelia were harvested after 14 days of incubation. Metabolite 3 is a new compound and metabolite 2 is reported here for the first time from artemisinic acid. Compound 3 was acetylated to the product diacetate derivative 4. All these compounds were evaluated for their antimicrobial and in vitro antioxidant activities. Further, for pharmaceutical utility these compounds were analyzed in vivo using well established animal model Caenorhabditis elegans for antioxidant/reactive oxygen species scavenging activity. The results clearly showed that the novel derivatives performed well in comparison to the parent compound both in-vitro and in-vivo studies. The presence of hydroxyl groups in metabolites 2 and 3 could make them interesting synthones for further modification into new clinically potent molecules. Thus, the study suggested a new aisle towards better drug development through the utilization of micro engineers.

Antioxidative, and Inhibitory Activities on Melanogenesis of Vitex negundo L. Leaf Extract

The aim of this study was to evaluate various aspects of Vitex negundo L. leaf extract, such as the antioxidative activity, tyrosinase inhibitory effects, and inhibitory activities on -MSH induced melanogenesis, and active component analysis. The DPPH (1, 1-diphenyl-2-picrylhydrazyl) scavenging activities () of the ethyl acetate fraction and aglycone fraction of V. negundo L. leaf extract were and , respectively. A luminol-dependent chemiluminescence assay revealed that the reactive oxygen species (ROS) scavenging activity () of the aglycone fraction of V. negundo L. leaf extract on ROS generated in an - system was the most prominent at . The protective effects of the extracts fractions of V. negundo L. leaf against the rose-bengal sensitized photohemolysis of human erythrocytes were increased in a concentration dependent manner (). In particular, there were greater protective effects of the aglycone fraction on the cellular membrane than that of the fat-soluble antioxidant (+)--tocopherol. The inhibitory effects () on mushroom tyrosinase were the highest for the ethyl acetate fraction ( = ). The inhibitory effect on -MSH induced melanogenesis in B16 melanoma cells was 41.80% at of ethyl acetate fraction. Active component analyses by TLC, HPLC and LC/ESI-MS revealed luteolin and isoorientin. These results indicate that V. negundo L. leaf extract can be used as an antioxidant for ROS scavenging. Particularly, the luteolin and isoorientin of the ethyl acetate fraction may be applicable to new whitening cosmetics because of its inhibitory effect on mushroom tyrosinase and -MSH induced melanogenesis in B16 melanoma cells.

Heat-induced oxidative stress and changes in protein profile in wheat cultivars

Wheat (Triticum aestivum L.) occupies an important place among cereals and it serves as a staple food for about 35% of the world population. Crop plants experience various stresses during their life cycle under high or low temperature, drought, and salinity conditions. Among these stresses, heat stress is getting alarming as a result of global warming. Therefore, research on the mechanism of high temperature stress in plants has the importance for future generations. The present investigation was aimed at studying the effect of heat stress and revival on antioxidative system and polypeptide pattern in the leaves of wheat seedlings. Four wheat genotypes, i.e., two tolerant (HW-2045 and WH-1021) and two susceptible (HS-277 and WH-147) were selected and the enzymes of antioxidant system, levels of antioxidant metabolites and pattern of polypeptide were observed. The production of H2O2 was higher in the leaves of susceptible and tolerant genotypes under heat stress conditions. However, its level was significantly higher in susceptible as compared to tolerant genotypes. There was enhancement in the activities of antioxidative enzymes, viz. CAT, POX, GR and APX in the leaves of tolerant and susceptible genotypes under heat stress. However, higher per cent increase was observed in tolerant genotypes. Heat stress increased the SOD activity in tolerant genotypes but activity declined in susceptible genotypes. On revival, the activities of the CAT, POX and GR declined in comparison to stressed seedlings but remained higher as compared to control. Accumulation of H2O2, which is a strong oxidant, led to disruption of cellular membrane integrity as obvious from increase in MDA content and an indicator of lipid peroxidation. Higher increase of H2O2 and MDA content was observed in susceptible genotypes which indicate more oxidative stress in the heat susceptible genotypes as compared to heat tolerant genotypes. On revival, accumulation of H2O2 and MDA content was reduced in all the genotypes but their level remained higher than their respective controls. A large number of studies have revealed a positive correlation between induction of HSPs and acquisition of thermotolerance. The most studied effect of heat shock treatment was on the induction of protective heat shock proteins which disappeared on removal of heat stress. In tolerant genotype WH-1021 under stressed conditions five polypeptide bands of MW 103.7, 92.2, 83, 65 and 26 kDa appeared in comparison to unstressed seedlings, while HW-2045 showed five bands of MW 103.7, 98.5, 79, 62 and 26 kDa under heat stress. Both the susceptible genotypes showed similar polypeptide bands of MW 80, 57.9, 45.7 and 34.4 kDa in response to high temperature. The better tolerance character of HW-2045 and WH-1021 during present investigation might be due to the induction of protective heat shock proteins and much higher activities of the enzymes involved in scavenging active oxygen species.

Synthesis and in vitro studies of pyrone derivatives as scavengers of active oxygen species.

The antioxidant properties of eleven alpha-pyrones and four gamma-pyrones were evaluated by means of three different tests: reduction of the stable free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion scavenging assay and lipid peroxidation assay. In the DPPH test, 6-aryl-5,6-dihydro-4-hydroxypyran-2-ones (3) and 4-hydroxypyran-2-one (5f) were the most active derivatives with IC50 values ranging from 36.7 to 394 mumol/l. Potent superoxide anion scavenging properties appeared in derivatives possessing phenol moieties. Thus phenolic pyrones 5e and 5f exhibited a noteworthy activity (IC50 = 0.180 and 0.488 mmol/l, respectively) when reference compound, ascorbic acid, demonstrated only 24% inhibition at a concentration of 1 mg/ml. In addition derivative 5f significantly inhibited the Fe2+/ADP/ascorbate-induced lipid peroxidation of rat liver microsomes with an IC50 value of 0.069 mmol/l. Due to its multiple mechanism of protective action, compound 5f may be useful for the treatment of oxidative tissue injury in human disease.

Protective effect of Perilla frutescens cv. Chookyoupjaso mutant water extract against oxidative injury in vitro and in vivo

The aim of this study was to elucidate the protective ability of the Perilla frutescens cv. Chookyoupjaso mutant water extract (PFWE) against oxidative injury in vitro and in vivo. In in vitro experiments, our results showed that PFWE indicated the intracellular reactive oxygen species (ROS) scavenging activity as well as cytoprotective effect in SIN-1-treated HepG2 cells. The intracellular ROS scavenging activity of PFWE was 44% at 50 μg/mL, 50% at 100 μg/mL, and 56% at 200 μg/mL. Furthermore, in vivo results showed that treatment with PFWE attenuated the activity of serum alkaline phosphatase (ALP) and lipid peroxidation increased by carbon tetrachloride (CCl4) and also markedly recovered the activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) decreased by CCl4 in BALB/c mice. GPx activity was elevated almost 3-fold compared to control group at 50 mg/kg of PFWE. The present study suggests that PFWE possesses significant protective effects against oxidative injury.

Effect of high-temperature stress on the activity of key enzymes in the AsA-GSH cycle in ‘Yali’ pears

Through treating fruits at higher temperatures, choosing natural fruits on different exposures on a tree canopy and collecting exclusively both sunburn and normal fruits, the metabolic patterns were studied by comparing the activity of key enzymes in the ascorbate-glutathione (AsA-GSH) cycle including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR). The results indicated that the activity of three enzymes increased under around less than 35°C acclimating conditions, with no significant changes in membrane electrolyte leakage. The activity of APX, MDAR, and GR rose during the initial stage when fruits were treated at 45°C but decreased significantly as treating time extended. A time response existed in APX, MDAR, and GR to high temperature. For example, APX activity reached the maximum when fruits were treated for 1 h, however, MDAR and GR showed the peak when fruits were treated for 3 h and 5 h, respectively, implying the possible acting sequence relationship of three enzymes in the AsA-GSH cycle. In view of the whole cycle, APX served as the first enzyme directly scavenging active oxygen species, followed by a series of chain reactions to regenerate ascorbic acid (AsA), and GR served as the last post in the cycle. Because various ecological conditions existed in a tree canopy, there was a significant difference in the enzymatic activity among fruits bearing on either exterior or interior canopy. A significantly higher activity of APX and MDAR was found with exterior fruits, compared with interior ones, which may be regarded as a frequent acclimation to high temperature and excessive sunlight.

Differential cytoprotective effect of copper- and iron-containing chlorophyllins against oxidative stress-mediated cell death

Chlorophyllin (CHL), a copper-containing chlorophyll derivative, was previously reported to possess reactive oxygen species (ROS) scavenging activity. However, the antioxidant property of iron-containing chlorophyllin, iron chlorin e6 (FeCe6), has not been explored in detail. This study systematically investigated the antioxidant capacity of two chlorophyllins, CHL and FeCe6, and their cytoprotective effects against ROS toxicity in human Jurkat T-cells. Both CHL and FeCe6 exhibited a wide range of antioxidant activities to ABTS radical, singlet oxygen, peroxynitrite, and peroxyl radical. Notably, FeCe6 exerted a significant suppressive effect on hydrogen peroxide-dependent cytotoxicity and apoptosis in Jurkat T-cells, while negligible or much weaker inhibition was observed by CHL. This differential cytoprotective effect is likely due to the different hydrogen peroxide scavenging capacity of two chlorophyllins. Moreover, FeCe6 attenuated menadione-induced cell death and tumour necrosis factor (TNF)-α-induced IκB phosphorylation via scavenging of intracellular ROS. Taken together, the results suggest that FeCe6 is a promising cytoprotective antioxidant against oxidative stress-mediated cellular toxicity.

Photochemistry of anthocyanins and their biological role in plant tissues

Abstract Anthocyanins, the major red, purple, and blue pigments of plants, absorb visible as well as UV radiation and are effective antioxidants and scavengers of active oxygen species. In plant leaves, one of the functional roles proposed for anthocyanins is protection of the photosynthetic apparatus from the effects of excess incident visible or UV-B radiation and photooxidative stress. In essence, a photoprotective role requires that the excited singlet states of both complexed and uncomplexed anthocyanins deactivate back to the ground state so quickly that intersystem crossing, photoreaction, and diffusion-controlled quenching processes cannot compete. Studies of the photochemical properties of synthetic analogs of anthocyanins and of several naturally occurring anthocyanins show that this is indeed the case, uncomplexed anthocyanins decaying back to the ground state via fast (subnanosecond) excited-state proton transfer (ESPT) and anthocyanin-copigment complexes by fast (subpicosecond) charge-transfer-mediated internal conversion.

Chemical composition, botanical evaluation and screening of radical scavenging activity of collected pollen by the stingless bees Melipona rufiventris (Uruçu-amarela)

Stingless bees in Brazil are indigenous and found all over the country. Bee pollen is used for its nutritional value in the human diet. It is made up of natural flower pollen mixed with nectar and bee secretions. In order to evaluate the chemical composition, free radical scavenging activity, and botanical origin, sample of pollen loads from stingless bee, Melipona rufiventris (Uruçu amarela) was studied. The EtOAc extract of pollen of Melipona rufiventris yielded the following compounds: p-hydroxycinnamic acid, dihydroquercetin, isorhamnetin, isorhamnetin3-O-(6'-O-E-p-coumaroyl)-beta-D-glucopyranoside, luteolin, and quercetin. This is the first report of the isolation of isorhamnetin3-O-(6'O-E-p-coumaroyl)beta-D-glucopyranoside from pollen. The free radicalscavenging activities of different solvent extracts of pollen were determined using DPPH assay. This activity decreases in the order: EtOAc>EtOH>Hexane extract. It appears that the EtOAc extract of the pollen is a good scavenger of active oxygen species. The botanical evaluation of pollen loads showed the composition by two pollen types, with the dominant type (97.3%) being Scopariadulcis (L.) (Scrophulariaceae) and the minor one Senna obtusifolia (L.) Irwin & Barneby (Fabaceae). This suggests a specific foraging behavior in Melipona rufiventris bees, even in an environment with such a rich botanical diversity as the Northeastern Brazil.