Decrease In Lipoxygenase Activity Research Articles

Effect of oxalic acid on postharvest life of tomato modified with the TomLoxB gene in anti-sense

Oxalic acid is an organic compound found in green leafy vegetables, which has proven to be effective in delaying ripening by inhibiting ethylene synthesis in fruits such as banana, mango, peach, tomato, plum, and others. In this study, the response of oxalic acid application on postharvest physiology was evaluated in transgenic tomatoes (Solanum lycopersicum) variety TA234 with the TomLoxB gene insertion in antisense, at two concentrations of oxalic acid: 3 and 10 mM, during 30 d of storage at 25 ± 1 ºC and a relative humidity of 65 - 70 %. The fruits were harvested at break stage and immersed for 10 minutes in the oxalic acid solution, which was maintained at 25 ºC. Upon treatment, less weight loss, better retention of lightness, delay in the decrease of firmness and hue angle, decrease in lipoxygenase activity, low electrolyte leakage and increase in total phenolics content were observed. The most effective oxalic acid concentration was 3 mM, that extended postharvest life by up to 30 d and reduced deterioration of the genetically modified (GM) tomatoes. In turn, the untreated GM tomatoes showed an acceptable appearance up to day 24 of storage, while the wild type fruits were kept satisfactorily for 15 d.

The Effect of Atmospheric Dielectric Barrier Discharge Cold Plasma Treatment on the Nutritional and Physicochemical Characteristics of Various Legumes.

High activity of lipoxygenase (LOX) has been identified as a primary cause of oxidative rancidity in legumes. In this study, the application of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) (5 W, 10 min) resulted in an obvious decrease in LOX activity in mung bean (MB), kidney bean (KB), and adzuki bean (AB) flours by 36.96%, 32.49%, and 28.57%, respectively. Moreover, DBD-ACP induced significant increases (p < 0.05) in content of soluble dietary fiber, saturated fatty acids, and methionine. The starch digestibility of legumes was changed, evidenced by increased (p < 0.05) slowly digestible starch and rapidly digestible starch, while resistant starch decreased. Furthermore, DBD-ACP treatment significantly affected (p < 0.05) the hydration and thermal characteristics of legume flours, evidenced by the increased water absorption index (WAI) and gelatinization temperature, and the decreased swelling power (SP) and gelatinization enthalpy (ΔH). Microscopic observations confirmed that DBD-ACP treatment caused particle aggregation.

The quality of Gold Queen Hami melons stored under different temperatures

Abstract Low temperature storage prolongs the postharvest life of various fresh fruits and vegetables. However, the actual storage temperature may also significantly influence fruit and vegetable quality. In the present study, we stored Gold Queen Hami melons at three different temperatures [21 °C (control), 3 °C, and 0.5 °C (0 ± 0.5 °C)] for 36 days. The humidity for all three temperatures conditions was between 75% and 85%. The results indicated a correlation between chilling injury in Gold Queen Hami melons and storage temperature and time. Different degrees of chilling injury in Gold Queen Hami melons were observed after storage at 3 °C and 0.5 °C, whereas these were detected later when stored at 3 °C. In addition, the rotting rate, weight loss rate, and chilling injury index at 3 °C were significantly lower compared to that at 0.5 °C storage temperature. Compared to other temperatures, storage at 3 °C was associated with a delay in fruit rotting, sustained high fatty acid desaturase and adenosine triphosphatase (ATPase) activity, a decrease in lipoxygenase activity, enhanced cold resistance, and extended total storage period. At 21 °C, no chilling injury was observed, although extensive weight loss and high rotting rates were detected. Moreover, two highly expressed genes, namely, JhMYB24 and JhMYB48, were screened and selected from the Gold Queen Hami melon transcriptome database. Real-time PCR analysis showed that the expression of JhMYB24 and JhMYB48 continuously increased under cold stress and peaked at the 18th day of cold storage. The expression of JhMYB24 and JhMYB48 at 3 °C was significantly higher than that at 0.5 °C or 21 °C. Together, our results demonstrate that regulating enzyme activity and upregulating the expression of JhMYB24 and JhMYB48 alleviate cold stress in fruits stored at 3 °C, thereby maintaining high fruit quality.

Identification of a novel SPLIT-HULL (SPH) gene associated with hull splitting in rice (Oryza sativa L.).

The split-hull phenotype caused by reduced lemma width and low lignin content is under control of SPH encoding a type-2 13-lipoxygenase and contributes to high dehulling efficiency. Rice hulls consist of two bract-like structures, the lemma and palea. The hull is an important organ that helps to protect seeds from environmental stress, determines seed shape, and ensures grain filling. Achieving optimal hull size and morphology is beneficial for seed development. We characterized the split-hull (sph) mutant in rice, which exhibits hull splitting in the interlocking part between lemma and palea and/or the folded part of the lemma during the grain filling stage. Morphological and chemical analysis revealed that reduction in the width of the lemma and lignin content of the hull in the sph mutant might be the cause of hull splitting. Genetic analysis indicated that the mutant phenotype was controlled by a single recessive gene, sph (Os04g0447100), which encodes a type-2 13-lipoxygenase. SPH knockout and knockdown transgenic plants displayed the same split-hull phenotype as in the mutant. The sph mutant showed significantly higher linoleic and linolenic acid (substrates of lipoxygenase) contents in spikelets compared to the wild type. It is probably due to the genetic defect of SPH and subsequent decrease in lipoxygenase activity. In dehulling experiment, the sph mutant showed high dehulling efficiency even by a weak tearing force in a dehulling machine. Collectively, the results provide a basis for understanding of the functional role of lipoxygenase in structure and maintenance of hulls, and would facilitate breeding of easy-dehulling rice.

MnSOD and 9-LOX gene expression along with antioxidant changes of Capsicum annuum cv. Kulai during postharvest treatment

There is increased interest in the consumption of hot pepper (Capsicum annuum cv. Kulai) due to its high antioxidant content; however, pepper is also highly susceptible to postharvest losses. The goal of this study was to evaluate the combined effect of 1-methylcyclopropene (1-MCP) and modified-atmosphere packaging (MAP) compared to MAP alone in maintaining the quality and antioxidant activity of Kulai pepper during low-temperature storage. The enzymatic activities and expression levels of superoxide dismutase (SOD) and lipoxygenase (LOX) were determined to evaluate the changes in their molecular levels in response to the postharvest treatment. The concentrations of total antioxidants as well as hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) were also determined to evaluate the changes in the antioxidant status during storage. The study revealed that a combination treatment (1-MCP and MAP) had a pronounced effect, extending the shelf life of the fruit up to 25days over MAP treatment alone with the retention of high antioxidant content. The combined treatment greatly suppressed the production of H2O2 and TBARS by 29.3% and 57.6% concomitant with an 8-fold increase in SOD activity and a decrease in LOX activity up to 75.4% relative to the control. The total antioxidant level increased consistently throughout the storage period. The overall results indicated that the combination treatment of MAP and 1-MCP provided a sustained protective effect for Kulai peppers stored at low temperature, with the quality of the pepper maintained throughout handling.

Markers of inflammation and oxidative stress studied in adjuvant-induced arthritis in the rat on systemic and local level affected by pinosylvin and methotrexate and their combination

Oxidative stress (OS) is important in the pathogenesis of autoimmune diseases such as rheumatoid arthritis (RA) and its experimental model – adjuvant arthritis (AA). Antioxidants are scarcely studied in autoimmunity, and future analyses are needed to assess its effects in ameliorating these diseases. Although there are studies about antioxidants effects on the course of RA, their role in combination therapy has not yet been studied in detail, especially on extra-articular manifestations of AA. During the 28-d administration of pinosylvin (PIN) in monotherapy and in combination with methotrexate (MTX) to AA rats, we evaluated the impact of the treatment on selected parameters. The experiment included: healthy controls, untreated AA, AA administered 50 mg/kg b.w. of PIN daily p.o., AA administered 0.4 mg/kg b.w. of MTX twice weekly p.o. and AA treated with a combination of PIN+MTX. AA was monitored using: hind paw volume, C-reactive protein, monocyte chemotactic protein-1 (MCP-1), thiobarbituric acid reactive substances (TBARS) and F2-isoprostanes in plasma, γ-glutamyltransferase activity in spleen, activity of lipoxygenase (LOX) in lung, heme oxygenase-1 (HO-1) and nuclear factor kappa B (NF-κB) in liver and lung. PIN monotherapy significantly improved the activation of NF-κB in liver and lung, HO-1 expression and activity of LOX in the lung, MCP-1 levels in plasma (on 14th d) and plasmatic levels of F2-isoprostanes. An important contribution of PIN to MTX effect was the reduction of OS (an increase of HO-1 expression in lung and reduction of plasmatic TBARS) and decrease of LOX activity in the lung.

Hydrogen sulfide promotes wheat seed germination under osmotic stress

Effects of NaHS, H2S donor, on germination and antioxidant metabolism in wheat (Triticum aestivum L.) seeds under osmotic stress were investigated. With the enhancement of osmotic stress, which was mimicked by PEG-6000, the seed germination dropped gradually. NaHS treatment could promote wheat seed germination against osmotic stress in a dose-dependent manner; while Na+ and other sulfur-containing components, such as S2−, SO42−, SO32−, HSO4− and HSO3−, were not able to improve seed germination as NaHS did, confirming H2S or HS− derived from NaHS contribute to the protective roles. Further experiments showed that NaHS treatment combined with PEG enhanced the activities of amylase and esterase in comparison to PEG treatment alone. Alternatively, NaHS treatment significantly reduced malondialdehyde and hydrogen peroxide accumulation in seeds. Significant enhancement of catalase and ascorbate peroxidase activities and decrease in lipoxygenase activity were observed in NaHS treated seeds, while peroxidase and superoxide dismutase activities were not affected as compared with the control. Furthermore, the H2S donor treatment could retain higher levels of endogenous H2S in wheat seeds under osmotic stress. These data indicated that H2S played a protective role in wheat seed against osmotic stress.

Effect of time and temperature on bioactive compounds in germinated Brazilian soybean cultivar BRS 258

Abstract The objective was to determine the effect of time and temperature on the concentration of bioactive compounds during germination of Brazilian soybean cultivar BRS 258. The concentration of bioactive compounds was optimized using Response Surface Methodology, with a 22 central composite rotational design and germination time and temperature as independent variables. Germination was carried out in a germination chamber, using paper in trays containing 500 g of seeds. Germination temperature and time modified the concentrations of bioactive compounds within the ranges studied. An increase in germination time at 25 °C decreased the concentration of Bowman–Birk inhibitor, lectin and lipoxygenase. After 63 h of germination, a temperature increase from 20 °C to 30 °C resulted in a decrease of lipoxygenase activity by 22.5%. Optimal increases in the concentrations of isoflavone aglycones (daidzein and genistein) and saponin glycosides were observed with a 63 h germination time at 30 °C. Both germination time and temperature had an influence on the composition and concentration of bioactive compounds in germinated soybean flour. Equations determined can be used to predict concentrations of bioactive compounds in germinated soybeans in relation to climate changes and thus optimize their potential use in human health and nutrition.

Exogenous Hematin Alleviates Mercury‐induced Oxidative Damage in the Roots of Medicago sativa

Abstract In the present study, we evaluated the protective effect of exogenous heme oxygenase‐1 (HO‐1 EC 1.14.99.3) inducer hematin against mercury‐induced oxidative damage in the roots of Alfalfa (Medicago sativa L.). Plants exposed to mercury (HgCl2) exhibited a significant increase of lipid peroxidation, as well as inhibition of root elongation. However, hematin (50 μM) supplementation to HgCl2 (100 μmol/L) treated plants effectively reduced the lipid peroxidation and partially increased the root elongation. These responses were mimicked by the application of aqueous solution of carbon monoxide (CO) with 50% saturation. Also, treatment with hematin could result in the potent induction of HO‐1 transcript in the root tissues, as detected 12 h following treatment. Moreover, the activation of anti‐oxidant enzyme, including glutathione reductase, monodehydroascorbate reductase and superoxide dismutase activities, and the decrease of lipoxygenase activity, were induced by hematin at 12 h or 24 h, which was further confirmed by histochemical staining for the detection of lipid peroxidation and loss of membrane integrity. Whereas, ascorbate peroxidase and guaiacol peroxidase isozyme activities or their transcripts were reduced, respectively, indicating that hydrogen peroxide might act as a signal to mediate Hg‐tolerance at the beginning of treatment. The ameliorating effects of hematin were specific, since the CO scavenger hemoglobin differentially reversed the above actions. Taken together, our results suggested that hematin exhibits a vital role in protecting the plant against Hg‐induced oxidative damage.

Enzyme sensitivity towards high pressure at low temperature

The sensitivity of several selected enzymes, e.g. Bacillus subtilis α‐amylase (BSA), peroxidase (POD), pectinmethylesterase (PME), polyphenoloxidase (PPO) and lipoxygenase (LOX) towards the combined action of high pressure (1 up to 4000 bar) and low temperature (‐22°C up to 0°C) was investigated. The effect of a high pressure/low temperature (HP/LT) treatment on the selected enzymes was compared to the effect of a freezing process at atmospheric pressure. It was found that (i) no irreversible inactivation of POD, PPO and BSA occurred after the HP/LT treatments tested, (ii) PME was only slightly irreversibly inactivated in the selected pressure and temperature domain (92% up to 80% of activity retention) and (iii) LOX was irreversibly inactivated to a large extent (3 up to 55% of activity retention) after the selected HP/LT treatments whereas a classical freezing at ‐18°C and atmospheric pressure caused only a 10% decrease in LOX activity. It could be observed that the enzymic activity after the treatment of both PME and LOX slightly decreased during storage in an ice bath.

Developmental changes in lipoxygenase activity in cotyledons of cucumber seedlings

Dry cucumber seeds have no lipoxygenase activity, but the activity in the cotyledons from light-grown seedlings increased rapidly from 3 days after germination, peaking at days 4–6 and declined significantly thereafter. The activity in the cotyledons from dark-grown seedlings increased in the same manner as observed in the light, but the enhanced activity persisted for a longer time. Transfer experiments showed that whether the cotyledons had been illuminated or not till day 6 lipoxygenase activity in the cotyledons degraded rapidly in the light concomitant with greening while it remained at the higher levels in the dark. Immunoblot analyses using antilipoxygenase serum indicate that the increase and decrease of lipoxygenase activity are mostly due to changes in the amount of lipoxygenase protein. The activity in the cotyledons from which the embryonic axis and the testa had been removed increased more rapidly than that in the cotyledons that had developed on the seedlings. Especially in the dark, lipoxygenase activity in the excised cotyledons increased by as much as 3.6-fold compared with the highest value observed with the intact cotyledons. Furthermore, detachment of the cotyledons from hypocotyl and roots at day 4 enhanced lipoxygenase activity. The enhancement was again marked in the dark.

Buckwheat lipoxygenase: Inactivation by gamma-irradiation

Lipoxygenase (LOX) activity was detected in buckwheat extracts, and was shown to have a pH optimum of 6·5. LOX activity was not affected during 6 days of germination. The specific activity increased when ground buckwheat seeds were extracted with 0·01% or 0·1% solutions of calcium chloride or magnesium chloride, compared to extractions with distilled water or 1·0% solutions of either of these salts. Increase in specific activity was greater in the presence of calcium ions compared to magnesium ions. Gamma-irradiation of buckwheat seeds up to 4 kGy resulted in a decrease in LOX activity to a level of approximately 22% of the untreated control, but increased to approximately 43% of the control at a dose of 6 kGy. These results suggest that gamma-irradiation reduces LOX activity, but is not likely to completely prevent lipid oxidation in buckwheat.

Role of oxidative stress in cereal protoplast recalcitrance

Cereal leaf protoplasts are often extremely unstable in culture and usually lyse within 24 hours. Using the thiobarbituric acid test and the ferrous thiocyanate test we have shown that corn (Zea mays L. cv. Market Beauty) and wheat (Triticum aestivum L. cv. Benito) leaf protoplasts accumulate peroxides and peroxide degradation products during culture. This increase correlated with an increase in lipoxygenase activity. On the other hand, enzymes involved in detoxification of peroxides such as catalase and peroxidase decreased during culture. The occurrence of lipid peroxidation in leaf protoplasts is likely to be a consequence of a temporary imbalance in the enzymes involved in oxygen metabolism. It has previously been shown that the lipoxygenase inhibitor n-propyl gallate stabilizes the protoplasts in culture and so peroxidation is likely to be the cause of leaf protoplast instability. Protoplasts obtained from suspension cultures are stable in culture and do not undergo lipid peroxidation. This stability is due to a decrease in lipoxygenase activity and increases in catalase and peroxidase activity after protoplast isolation.

Trends of Plant Breeding of Oilseeds in the World

In Japan, Many oilseeds are imported from various foreign countries. Recent research of plant breeding in the world has been made by means of customary breeding but also such new biotechnology as tissue culture, genetic technology, and so on. Concrete targets of plant breeding has been as follows. As for soybean, those are yield up, increase in oil and protein contents, improvement of fatty acids composition, and decrease in lipoxygenase activity. As for rapeseed, decrease in erucic acid and glucosinolate, and improvement of fatty acids composition. As for palm, improvement of oil quality, and development of lower tree. As for sunflower and safflower, high oleic oils have been commercially developed. In future, research of plant breeding of oilseeds will be more faster and successful by the application of the advanced biotechnology.

Effect of a substituted pyridazinone on the decrease of lipoxygenase activity in soybean cotyledons

Application of San 9785 (4-chloro-5-dimethylamino-2-phenyl-3 (2H) pyridazinone) to soybean and peanut plants results in a significant reduction of lipoxygenase activity in the corresponding seeds. The present study of the effect of San 9785 on the decrease of lipoxygenase activity was conducted on soybean ( Glycine max L. Merr., cv. Century) cotyledons developing in vitro. Lipoxygenase 2 3 activity was more reduced by San 9785 than lipoxygenase 1 activity in the cotyledons cultured in the presence of 100 μM San 9785. Immunoblotting of cotyledon proteins with lipoxygenase antisera revealed that San 9785 accelerated the appearance of possible lipoxygenase degradation products in the treated cotyledons. The incorporation of [ 35S]methionine into lipoxygenase was also reduced in the cotyledons incubated with San 9785, but the levels and translational activity of lipoxygenase RNA in these tissues were not affected. This study indicates that the treatment of soybean cotyledons with San 9785 probably causes an increased post-translational degradation of lipoxygenase.

Alternative Pathway Respiration and Lipoxygenase Activity in Aged Potato Slice Mitochondria

Mitochondrial preparations isolated from aged white potato (Solanum tuberosum L.) slices exhibited classical cyanide-insensitive O(2) uptake which was inhibited by salicylhydroxamic acid and tetraethylthiuram disulfide (disulfiram). These mitochondria also possessed lipoxygenase activity, as determined by O(2) uptake in the presence of 4 millimolar linoleic acid. Purification of the mitochondrial preparation on a continuous Percoll gradient resulted in a large decrease in lipoxygenase activity whereas cyanide-insensitive (disulfiram sensitive) O(2) consumption was still observed. These data indicate that cyanide-insensitive O(2) consumption in mitochondrial preparations isolated from aged white potato slices is of mitochondrial origin and not due to lipoxygenase contamination.