Salt-Induced Changes in Antioxidative Enzyme Activities in Shoot Tissues of Two Atriplex Varieties

  This study examined the influence of salt levels on antioxidant activity and content of carotenoids and anthocyanins of the A. hortensis leaves using two varieties: green orach (var. purpurea ) and red orach (var. rubra). Seeds of Atriplex were exposed to 0, 90, 180 and 260 mM NaCl for 3 months and seeds were sown in an earthen pot. Overall levels of ascorbate peroxidase (APX) and glutathione reductase (GR) activity were significantly elevated. Salt stress caused a significant decline in tissue concentrations of catalase (CAT) and superoxide dismutase (SOD). However, 90 mM NaCl did not modify these parameters, which remains similar to control values. Activities of APX and CAT were increase whether the shoots of A. hortensis var. purpurea were grown in the presence of 180 mM NaCl. Thus although some indications of oxidative stress accompany exposure of this salt-tolerant Atriplex varieties to salinity, mechanisms appear to exist within its shoot tissue to permit the tolerance of such oxidative stress. High salt concentration in the culture medium provokes oxidative damage in Atriplex leaves and induces a general increase in antioxidant enzyme activity. In particular, NaCl toxicity decreased content of carotenoids. It also decreased the concentration of anthocyanin pigments in leaves of Atriplex. This work therefore provides a starting point towards a better understanding of the role of antioxidant enzyme in the plant response against salt stress.</p

Does Lycium europaeum leaf have antihyperglycemic, antihyperlipidemic and antioxidant effects

The purpose of the present investigation is to assess, for the first time, the antidiabetic, antihyperlipidemic and antioxidant activities of Lycium europaeum extract in alloxan-induced diabetic rats. Diabetes was induced in adult male Wistar rats via a single subcutaneous alloxan injection (120 mg/kg). Lycium europaeum aqueous extract was orally administered at a dose of 20 mg/kg for 28 consecutive days. Serum concentrations of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were assayed at the end of the experimental period in all investigated groups. Antioxidant enzymes such as glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) were sought in the serum and pancreas. Lycium europaeum extract significantly increased HDL-C and reduced blood glucose, TC, LDL-C and TG as compared to the alloxan-control group. Lycium europaeum extract was also efficient in reducing oxidative stress in diabetic rats by increasing SOD, CAT and GPx activities both in the pancreas and the plasma of the animals. Moreover, Lycium europaeum extract contained considerable levels of polyphenols and flavonoids. It also exhibited an important antioxidant capacity and a remarkable ability to quench DPPH radicals and reduce irons. The obtained results highlight potentially relevant health beneficial effects of Lycium europaeum extract, reversing hyperglycemic, hyperlipidemic and oxidative stress effects in rats with alloxan-induced diabetes. Therefore, it may be considered as a promising alternative or complementary agent to diabetes treatment

Physiological responses of Arabidopsis thaliana to the interaction of iron deficiency and nitrogen form

Physiological responses of Arabidopsis thaliana to the interaction of iron deficiency and nitrogen form were studied using plants grown in hydroponics. Thirty-three-day-old seedlings were submitted to four treatments for 7 days : NO3 + 5 µM Fe; NO3 + 0.1 µM Fe; NH4 + 5 µM Fe and NH4 + 0.1 µM Fe. Leaf growth and chlorophyll content were highest in NO3-fed, Fe sufficient plants, but were strongly diminished by Fe deficiency under nitric nutrition, and by ammoniacal nutrition independently of Fe regime. However, the leaves of NH4-fed plants presented a higher Fe content than those of Fe sufficient, NO3-fed plants. Thus, leaf chlorosis of NH4-fed in plant did not depend on Fe availability, and seemed to be due to another factor. Root acidification capacity and Fe-chelate reductase (FCR) activity were also dependent on N form. The medium was acidified under ammoniacal regime and alkalinized under nitric regime regardless of Fe level. FCR activity stimulation in response to Fe deficiency was observed only in NO3- fed plants. In addition, both N form and Fe level induced antioxidant responses in rosette leaves. Ammoniacal regime increased both peroxidase expression and anthocyanin accumulation, whereas Fe deficiency enhanced superoxide dismutase expression

Physiological and molecular characterization of salt response of Arabidopsis thaliana NOK2 ecotype.

International audienceArabidopsis thaliana is a glycophyte capable to tolerate mild salinity. Although salt sensitivity of this species, a variability of this characteristic was revealed between different ecotypes. This study presents the physiological and molecular characteristics of salt response of two ecotypes, NOK2 and Columbia (Col). Seedlings were cultivated in hydroponics in the presence of 0 or 50 mM NaCl during 25 days. Rosette leaf samples were collected after 19, 22, and 25 days for determination of physiological parameters, and after 18 days for study of DNA polymorphism. Salt treatment decreased rosette dry matter, leaf number, leaf hydration, and leaf surface area. All these effects were significantly more visible in Col than in NOK2. Moreover, the NOK2 leaves accumulated less Na+ and more K+ than those of Col. DNA polymorphism between the two ecotypes was analyzed with codominant molecular markers based on PCR amplification, namely, microsatellites, cleaved amplified polymorphism sequence (CAPS), and single nucleotide polymorphism markers (SNP). Among the 35 tested markers, 17 showed a clear polymorphism and were distributed on the five Arabidopsis chromosomes ending with a genetic map construction. These results could play an important role in the future establishment of cartography of candidate gene controlling the K+/Na+ selectivity of ion transport in leaves, a component of plant salt tolerance

Salt-Induced Changes in Antioxidative Enzyme Activities in Shoot Tissues of Two Atriplex Varieties

  This study examined the influence of salt levels on antioxidant activity and content of carotenoids and anthocyanins of the A. hortensis leaves using two varieties: green orach (var. purpurea ) and red orach (var. rubra). Seeds of Atriplex were exposed to 0, 90, 180 and 260 mM NaCl for 3 months and seeds were sown in an earthen pot. Overall levels of ascorbate peroxidase (APX) and glutathione reductase (GR) activity were significantly elevated. Salt stress caused a significant decline in tissue concentrations of catalase (CAT) and superoxide dismutase (SOD). However, 90 mM NaCl did not modify these parameters, which remains similar to control values. Activities of APX and CAT were increase whether the shoots of A. hortensis var. purpurea were grown in the presence of 180 mM NaCl. Thus although some indications of oxidative stress accompany exposure of this salt-tolerant Atriplex varieties to salinity, mechanisms appear to exist within its shoot tissue to permit the tolerance of such oxidative stress. High salt concentration in the culture medium provokes oxidative damage in Atriplex leaves and induces a general increase in antioxidant enzyme activity. In particular, NaCl toxicity decreased content of carotenoids. It also decreased the concentration of anthocyanin pigments in leaves of Atriplex. This work therefore provides a starting point towards a better understanding of the role of antioxidant enzyme in the plant response against salt stress.</p

Effects of 2,4-dichlorophenoxyacetic acid combined to 6-Benzylaminopurine on callus induction, total phenolic and ascorbic acid production, and antioxidant activities in leaf tissue cultures of Crataegus azarolus L. var. aronia

peer reviewedThe present research work describes the effects of 2,4-dichlorophenoxyacetic acid (2,4-D)/6-Benzylamino-purine (BAP) ratio on callus induction, total phenols and ascorbic acid production and antioxidant activities in leaf-derived calli of Crataegus azarolus (hawthorn). The supplementation of 1.0 mg/L 2,4-D and 1.0 mg/L BAP to MS medium was found to be the most efficient for callus induction (as percentage and fresh weigh). The results of biochemical analysis showed that the highest total phenols contents were obtained in callus cultured on MS medium supplemented with 2.0 mg/L 2,4-D and 1.0 mg/L BAP (52 ± 0.56 mg GAE/g DM) and were significantly lower than those of intact leaves (76 ± 1.72 mg GAE/g DM). However, the highest ascorbic acid contents were found in callus cultured on MS supplemented with 1.0 mg/L 2,4-D and 0.5 mg/L BAP (0.96 ± 0.13 mg AAE/g DM) and these amounts were statistically similar to those found in leaves tissues (0.74 ± 0.07 mg AAE/g DM). Antioxidant activities of callus extracts were determined using two TEAC assays and results showed that extract of callus cultured on MS medium supplemented with 2.0 mg/L 2,4-D and 1.0 mg/L BAP have the greatest antiradical activities against DPPH (124 ± 2.92 mg TE/g DM) and ABTS (0.19 ± 0.02 mg TE/g DM) compared to the leaves of field-grown plant. Thus, the use of high level of 2,4-D over BAP can be suitable to enhance the quality more than the quantity of bioactive compounds in leaf callus culture of hawthorn

Effects of environment and development stage on phenolic content and antioxidant activities of <em>Mentha Pulegium</em> L.

International audienceWe investigated the relative contributions of the environment and development stage on total polyphenols, flavonoids and condensed tannins contents, as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide scavenging activities in four Tunisian Mentha pulegium. Shoot total phenolics and antioxidant capacities were significantly dependent on environment, development stage and their interaction. Environment effects were considerably larger than development stage effects for total phenolics, flavonoids, DPPH and superoxide scavenging capacities, whereas development stage was much stronger than environment for tannin content and, although small, interaction effects of the two factors (environment and development stage) were significant for all antioxidant properties analyzed. The highest antioxidant activities were related to high phenolic contents. Three behaviors were revealed; the best antioxidant capacities in Soliman at floral bud stage, followed by Takelsa and the lowest potentialities (Bouarada and Jdeida). These findings indicate that antioxidant properties of M. pulegium were respectively influenced by environment, development stage and their interaction

Phytochemical Profile and In Vitro Bioactivities of Wild <i>Asparagus stipularis</i>

In this study, Asparagus stipularis was characterized concerning its phytochemical composition, antioxidant potential, cytotoxicity, and pancreatic lipase inhibitory activities. Twenty-seven compounds were identified and quantified by HPLC-DAD-MS in the leaf, stem, pericarp, and rhizome of ethanolic extracts. Seven steroidal saponins were detected, and the highest content was quantified in rhizome and pericap. A. stipularis also contained significant amounts of flavonoids in the aerial part. Isorhamnetin tetra-glycoside, quercetin-3-glucosyl-rutinoside, and rutin were the main flavonoid derivatives in leaf, stem, and pericarp extracts, respectively. In addition, eleven phenolic acids were also detected; among them, caffeic acid, protocatechuic acid, p-hydroxybenzoic acid, and ferulic acid were the predominant phenolics, with these having the highest amounts quantified in the rhizome extracts. All the tested extracts possessed antioxidant capacities, with pericarp and rhizome extracts exhibiting the highest activity in DPPH, ABTS, and FRAP assays. The extracts from pericarp and rhizome were revealed to also be the strongest inhibitors of pancreatic lipase. The rhizome extracts exhibited potent cytotoxic activity against HCT-116 and HepG2 with IC50 values of 30 and 54 µg/mL after 48 h of treatment. The present study demonstrated that A. stipularis can be used as a new source of natural antioxidants and potential anticancer and antiobesity compounds

Enterococcus spp.: Is It a Bad Choice for a Good Use—A Conundrum to Solve?

International audienceSince antiquity, the ubiquitous lactic acid bacteria (LAB) Enterococci, which are just as predominant in both human and animal intestinal commensal flora, have been used (and still are) as probiotics in food and feed production. Their qualities encounter several hurdles, particularly in terms of the array of virulence determinants, reflecting a notorious reputation that nearly prevents their use as probiotics. Additionally, representatives of the Enterococcus spp. genus showed intrinsic resistance to several antimicrobial agents, and flexibility to acquire resistance determinants encoded on a broad array of conjugative plasmids, transposons, and bacteriophages. The presence of such pathogenic aspects among some species represents a critical barrier compromising their use as probiotics in food. Thus, the genus neither has Generally Recognized as Safe (GRAS) status nor has it been included in the Qualified Presumption of Safety (QPS) list implying drastic legislation towards these microorganisms. To date, the knowledge of the virulence factors and the genetic structure of foodborne enterococcal strains is rather limited. Although enterococcal infections originating from food have never been reported, the consumption of food carrying virulence enterococci seems to be a risky path of transfer, and hence, it renders them poor choices as probiotics. Auspiciously, enterococcal virulence factors seem to be strain specific suggesting that clinical isolates carry much more determinants that food isolates. The latter remain widely susceptible to clinically relevant antibiotics and subsequently, have a lower potential for pathogenicity. In terms of the ideal enterococcal candidate, selected strains deemed for use in foods should not possess any virulence genes and should be susceptible to clinically relevant antibiotics. Overall, implementation of an appropriate risk/benefit analysis, in addition to the case-by-case assessment, the establishment of a strain’s innocuity, and consideration for relevant guidelines, legislation, and regulatory aspects surrounding functional food development seem to be the crucial elements for industries, health-staff and consumers to accept enterococci, like other LAB, as important candidates for useful and beneficial applications in food industry and food biotechnology. The present review aims at shedding light on the world of hurdles and limitations that hampers the Enterococcus spp. genus and its representatives from being used or proposed for use as probiotics. The future of enterococci use as probiotics and legislation in this field are also discussed