Variation of phenolic composition and biological activities in Limoniastrum monopetalum L. organs

Changes in phenolic composition and biological activities were investigated in different Limoniastrum monopetalum L. organs. For that, 80% aqueous acetone extracts were used to estimate total phenolic contents and their antioxidant activities were evaluated using DPPH· and O₂^·− radical scavenging activities and reducing power. The efficiency of organ extracts was tested against human pathogen strains. Ultimately, acid hydrolysis of all organs was subjected to RP-HPLC for phenolic identification. Results showed that flower extracts exhibited the highest polyphenol (65.42 GAE/g DW) and flavonoid (35.36 CE/g DW) contents. Stems were enriched in condensed tannin content (21.4 mg CE/g DW) and displayed the best antiradical activities and the highest reducing power. Besides, stem and gall extracts showed the highest efficiency against pathogenic bacteria as compared with those of flower. Concerning the antifungal test, a slight activity was found in gall extracts. The RP-HPLC showed a difference in phenolic compounds that varied as function of organ. In fact, the major phenolic compound varied as function of organ. Results suggest that L. monopetalum could be a promising source of biomolecules for therapeutic and nutraceutical industries and the difference between organs may be related to their physiological role.     

Partial purification and characterization of a copper-induced anionic peroxidase of sunflower roots

Treatment of 14-day-old sunflower seedlings with a toxic amount of copper (50 μM of CuSO₄) during 5 days caused significant increase in peroxidase activity in roots. Qualitative analysis of soluble proteins using native anionic PAGE followed by detection of peroxidase activity with guaïacol as electron donor in the presence of H₂O₂ revealed five stimulated peroxidases, named A1, A2, A3, A4, and A5. These peroxidases had differential behavior during the period of treatment. A1, A2, A3 and A4 were stimulated in the first period of stress, but rapidly suppressed at 72 h. A5 showed a progressive stimulation which was even increased at 120 h. A1 was partially purified, identified using liquid chromatography coupled to mass spectrometry (LC-MS/MS), and characterized. Effects of pH and temperature on its activity were determined with guaïacol as electron donor. Optima were obtained at pH 8 and at 40 °C. Analysis of substrate specificity showed that A1 was active on coniferyl alcohol but not on IAA. Enzymatic activity was inhibited by a high concentration of H₂O₂.     

Phenolic composition of Cynara cardunculus L. organs, and their biological activities

Polyphenols are bioactive molecules exhibiting a lot of scientific attention due to their multiple biological activities. This study compared phenolic contents and antioxidant activity in Cynara cardunculus L. organs and focus on leaf phenolic compounds identification by RP-HPLC and their antibacterial activity. The analyzed organs exhibited different total polyphenol contents (7-14.8 mg GAE g(-1) DW). Leaf and seed phenolic contents were similar and two times higher than those in flowers. The same tendency was observed for the amount of flavonoids and tannins. However, seed extracts displayed the highest DPPH. scavenging ability with the lowest IC50 value (23 microg ml(-1)), followed by leaves and flowers (over 50 microg ml(-1)). In contrast, leaves showed the highest capacity to quench superoxide (IC50: 1 microg ml(-1)) as compared to seeds (6 microg ml(-1)). In addition, cardoon leaves were efficient to inhibit growth of pathogenic bacteria mainly against Staphylococcus aureus and Escherichia coli. The identification of phenolic compounds from leaves revealed that syringic and trans-cinnamic acids were the major molecules.     

Phenolic composition and biological activities of Tunisian Nigella sativa L. shoots and roots

In the present investigation, methanolic extracts from shoots and roots of Tunisian Nigella sativa were assayed for their antioxidant and antimutagenic activities. The phenolic composition of the methanolic extracts was determined by RP-HPLC. The predominant phenolic compound was vanillic acid with a mean concentration of 143.21 and 89.94 mg per 100 g dry weight of shoots and roots, respectively. Shoots and roots showed comparable and strong superoxide scavenger activity; however, shoots exhibited higher DPPH radical scavenging, reducing and chelating activities than roots. Mutagenic and antimutagenic activities were determined by using the Ames test. Shoots and roots demonstrated important antimutagenic effects. Roots exhibited stronger activity than shoots with an inhibition percentage of 71.32%.     

Heavy metal-induced oxidative damage is reduced by β-estradiol application in lentil seedlings

The protective effect of β-estradiol (E) application against heavy metal (HM) toxicity in lentil (Lens culinaris) seedlings was investigated. Seeds were treated with distilled water (control) or aqueous solutions of 100 μM CdCl₂, 200 μM CuCl₂ and 1 μM E singly or in combinations (1 μM E+100 μM CdCl₂ and 1 μM E+200 μM CuCl₂). HM treatments resulted in increase in the activities of antioxidative enzymes, including superoxide dismutase (SOD), catalase (CAT), guaicol peroxidase and ascorbate peroxidase. In a similar manner, Cd and Cu affected significantly oxidative injury indicators measured as electrolyte leakage (electrical conductivity of germination medium), lipoxygenase (LOX) activity and contents of malondialdehyde (MDA; lipoperoxidation marker), carbonyl groups (protein oxidation marker) and hydrogen peroxide (a reactive oxygen species). However, E was effective in reducing HM-induced toxicity. The steroid (1) alleviated HM-induced increase in the electrolyte leakage, LOX activity and contents of MDA, carbonyl and H₂O₂ and (2) improved the activities of SOD and CAT, but not the peroxidase ones, as compared to treatments with HM singly. In addition, E application prevented HM-induced decrease in dry weight production, but did not reduce the accumulation of Cd and Cu in tissues. Results of the present study suggest that E is able to protect lentil from HM-induced oxidative damage most likely by avoidance of H₂O₂ generation and improving antioxidative enzyme activities and, thereby, decreasing oxidative stress injury, but not by reducing Cd and Cu uptake.     

Association of BANK1 and cytokine gene polymorphisms with type 1 diabetes in Tunisia

Type 1 diabetes (T1D) is an autoimmune disease (AID) with both genetic and environmental components. We aimed to investigate the genetic association of polymorphisms in genes previously linked with other AIDs, namely BANK1, IL15 and IL2/IL21 region.     

A direct interaction with calponin inhibits the actin-nucleating activity of gelsolin

Gelsolin and calponin are well-characterized cytoskeletal proteins that are abundant and widely expressed in vertebrate tissues. It is also becoming apparent, however, that they are involved in cell signalling. In the present study, we show that gelsolin and calponin interact directly to form a high-affinity (K(d)=16 nM) 1:1 complex, by the use of fluorescent probes attached to both proteins, by affinity chromatography and by immunoprecipitation. These methods show that gelsolin can form high-affinity complexes with two calponin isoforms (basic h1 and acidic h3). They also show that gelsolin binds calponin through regions that have been identified previously as being calponin's actin-binding sites. Moreover, gelsolin does not interact with calponin while calponin is bound to F-actin. Reciprocal experiments to find calponin-binding sites on gelsolin show that these are in both the N- and C-terminal halves of gelsolin. Calponin has minimal effects on actin severing by gelsolin. In contrast, calponin markedly affects the nucleation activity of gelsolin. The maximum inhibition of nucleation by gelsolin was 50%, which was achieved with a ratio of two calponins for every gelsolin. Thus the interaction of calponin with gelsolin may play a regulatory role in the formation of actin filaments through modulation of gelsolin's actin-binding function and through the prevention of calponin's actin-binding activities.     

Cadmium induced mitochondrial redox changes in germinating pea seed

Mitochondria play an essential role in producing the energy required for seedling growth following imbibition. Heavy metals, such as cadmium impair mitochondrial functioning in part by altering redox regulation. The activities of two protein redox systems present in mitochondria, thioredoxin (Trx) and glutaredoxin (Grx), were analysed in the cotyledons and embryo of pea (Pisum sativum L.) germinating seeds exposed to toxic Cd concentration. Compared to controls, Cd-treated germinating seeds showed a decrease in total soluble protein content, but an increase in –SH content. Under Cd stress conditions, Grx and glutathione reductase (GR) activities as well as glutathione (GSH) concentrations decreased both in cotyledons and the embryo. Similar results were obtained with the Trx system: Trx and NADPH-dependent thioredoxin reductase (NTR) activities were not stimulated, whereas total NAD(P) contents diminished in the embryo. However, Cd enhanced the levels of all components of the Trx system in the cotyledons. On the other hand, Cd caused a significant increase in oxidative stress parameters such as the redox ratio of coenzymes (oxidized to reduced forms) and NAD(P)H oxidase activities. These results indicate that Cd induces differential redox responses on different seed tissues. We suggest that neither Grx system nor Trx one may improve the redox status of mitochondrial thiols in the embryo of germinating pea seeds exposed to Cd toxicity, but in the cotyledons the contribution of Trx/NTR/NADPH can be established in despite the vulnerability of the coenzyme pools due to enzymatic oxidation.     

OPTIMIZATION OF SALT CONCENTRATIONS FOR A HIGHER CAROTENOID PRODUCTION IN DUNALIELLA SALINA (CHLOROPHYCEAE)1

Dunaliella salina (Dunal) Teodor, when treated over 25 d with a wide range of NaCl salinities (0.6–4.5 M), showed its maximal growth potentialities at 1.5–3.0 M NaCl and was able to survive even at 4.5 M NaCl. Sodium concentrations increased significantly at the supraoptimal salinities, reaching up to 5 mmol · g^?1 dry weight (dwt) at 4.5 M NaCl. Interestingly, ability of D. salina to take up essential mineral nutrients was not impaired by increased salinity. As for growth, chl concentrations were maximal in the 1.5–3.0 M NaCl range. Interestingly, carotenoid concentrations increased with the increasing salinity. The highest values of total antioxidant activity (5.2–6.9 mg gallic acid equivalents [GAE] · g^?1 dwt), antiradical activity, and reducing power were measured at 1.5–3.0 M NaCl. As a whole, these results showed that at 1.5–3.0 M NaCl, D. salina produce appreciable antioxidant level. But, once it reaches its growth maximum, a salt addition up to 4.5 M could enhance its carotenoid yield.