Antioxidant defense responses: physiological plasticity in higher plants under abiotic constraints

Environmental stresses (salinity, drought, heat/cold, light and other hostile conditions) may trigger in plants oxidative stress, generating the formation of reactive oxygen species (ROS). These species are partially reduced or activated derivatives of oxygen, comprising both free radical and non-radical (H₂O₂) forms, leading to cellular damage, metabolic disorders and senescence processes. In order to overcome oxidative stress, plants have developed two main antioxidants defense mechanisms that can be classified as non-enzymatic and enzymatic systems. The first class (non-enzymatic) consists of small molecules such as vitamin (A, C and E), glutathione, carotenoids and phenolics that can react directly with the ROS by scavenging them. Second class is represented by enzymes among them superoxide dismutase, peroxidase and catalase which have the capacity to eliminate superoxide and hydrogen peroxide. In this review, we have tried to explore the related works, which have revealed the changes in the basic antioxidant metabolism of plants under various abiotic constraints.     

Trends in speciation analysis of some heavy metals in serum of patients with chronic hepatitis C and chronic hepatitis B using differential pulse adsorptive stripping voltammetric measurement and atomic absorption spectrophotometry

The relationships between chronic liver diseases and trace heavy metal contents in blood are debatable and have not been understood clearly. The present study is undertaken to determine Co, Fe, and Ni concentrations in sera from viral hepatitis patients. In all eighty patients with chronic hepatitis (B, C) and 29 healthy individuals were chosen for this study. Donors were selected from different environmental areas, including Aswan, Kom Ombo, and Edfu as polluted areas, and Daraw as an unpolluted area. Co, Fe, and Ni concentrations in patient and healthy blood serum were measured by two different analytical techniques: differential pulse adsorptive stripping voltammetry (DPA_dSV) and atomic absorption spectrophotometer (AAS). The results reveal that Fe is present in higher level in the blood serum of hepatitis patients than in the healthy control, whereas Co and Ni showed the opposite trend. Hepatitis patients from Edfu area exhibited higher Fe level in their serum than those from the other areas, while hepatitis patients and healthy control from Daraw area (free from pollution) exhibited the lowest metal values. Patients with hepatitis C show lower levels of Co, Ni, and Fe in their serum than those with hepatitis B. A comparative study was carried out between the results using DPA_dSV and AAS techniques, which are in very good agreements.     

Safety and efficacy of thrombectomy in patients undergoing primary percutaneous coronary intervention for Acute ST elevation MI: A Meta-Analysis of Randomized Controlled Trials

Background

Clinical trials comparing thrombectomy devices with conventional percutaneous coronary interventions (PCI) in patients with acute ST elevation myocardial infarction (STEMI) have produced conflicting results. The objective of our study was to systematically evaluate currently available data comparing thrombectomy followed by PCI with conventional PCI alone in patients with acute STEMI.

Methods

Seventeen randomized trials (n = 3,909 patients) of thrombectomy versus PCI were included in this meta-analysis. We calculated the summary odds ratios for mortality, stroke, post procedural myocardial blush grade (MBG), thrombolysis in myocardial infarction (TIMI) grade flow, and post procedural ST segment resolution (STR) using random-effects and fixed-effects models.

Results

There was no difference in risk of 30-day mortality (44/1914 vs. 50/1907, OR 0.84, 95% CI 0.54-1.29, P = 0.42) among patients randomized to thrombectomy, compared with conventional PCI. Thrombectomy was associated with a significantly greater likelihood of TIMI 3 flow (1616/1826 vs. 1533/1806, OR 1.41, P = 0.007), MBG 3 (730/1526 vs. 486/1513, OR 2.42, P < 0.001), STR (923/1500 vs. 715/1494, OR 2.30, P < 0.001), and with a higher risk of stroke (14/1403 vs. 3/1413, OR 2.88, 95% CI 1.06-7.85, P = 0.04). Outcomes differed significantly between different device classes with a trend towards lower mortality with manual aspiration thrombectomy (MAT) (21/949 vs.36/953, OR 0.59, 95% CI 0.35-1.01, P = 0.05), whereas mechanical devices showed a trend towards higher mortality (20/416 vs.10/418, OR 2.07, 95% CI 0.95-4.48, P = 0.07).

Conclusions

Thrombectomy devices appear to improve markers of myocardial perfusion in patients undergoing primary PCI, with no difference in overall 30-day mortality but an increased likelihood of stroke. The clinical benefits of thrombectomy appear to be influenced by the device type with a trend towards survival benefit with MAT and worsening outcome with mechanical devices.     

Synthesis of AZT analogues: 7-(3-azido-2-hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-,7-(3-triazolyl-2-hydroxypropyl)theophylline

Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3-p-toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph3P/Py/NH4OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N1-propargyl thymine (6) afforded the regioisomeric triazole 7.     

Trichomanes vamana, a new filmy fern species (Hymenophyllaceae - Pteridophyta) from India

Trichomanes vamana, a new species of filmy fern from South India is described and illustrated. Key to South Indian species of Trichomanes subg. Didymoglossum sect. Microgonium and affinities of this taxon with T.mindorense are discussed     

Possible relation between phytoplankton numbers and Saprolegnioid fungi in Shatt Al-Arab near Basrah,Iraq

This study, carried out in Shatt Al-Arab river near Basrah, Iraq, reports a close negative (inverse) relation between phytoplankton numbers and decomposing fungi belonging to the family Saprolegniaceae (Oomycetes). This relation seems to depend on substrate relationship and antagonism. In addition the role of other physico-chemical factors, pH, temperature and salinity has been discussed.     

Reaction of dehydro-d-erythorbic acid and its aryl analogs with ortho-diamines

Condensation of 3-(d-erythro -2,3,4-trihydroxy-l-oxobutyl)-2-quinoxalinone and its 6-chloro derivative (obtained by the reaction of d-erythro-2,3-hexodiulosono-1,4-lactone with ortho-diamines) with aryl- or aroyl-hydrazines gave 3-[l-(phenylhydrazono)-d-erythro-2,3,4-trihydroxybutyl]-2-quinoxalinone (5) and relatives. Whereas boiling acetic anhydride causes the loss of two molecules of water per molecule of such hydrazones, affording, the 3-[5-(acetoxymethyl)-l-arylpyrazol-3-yl]-2-quinoxalinones, identical with those obtained from the l-threo isomer, alkali causes the loss of only one molecule, affording, the corresponding flavazoles. Periodate oxidation of 5 gave 3-[l-(phenylhydrazono)glyoxal-l-yl]-2-quinoxalinone, which afforded the corresponding mixed bis(hydrazones). A similar sequence of reactions was conducted with the aryl analogs, 4-phenyl-2,3-dioxobutano-1,4-lactone and its p-chlorophenyl derivative, whereby the 3-[2-aryl-l-(arylhydrazono)-2-hydroxyethyl]2-quinoxalinones, were prepared; these were transformed into 3-(α-hydroxybenzyl)-flavazoles that gave monoacetyl derivatives.     

C-(polyacetoxy)alkyloxadiazolines and related compounds

The (phenylacetyl)hydrazones of d-galactose, d-glucose, d-mannose, d-arabinose, l-arabinose, d-xylose, and l-sorbose were prepared. The d-galactose and d-arabinose derivatives were converted into their per-O-acetylated derivatives (8 and 9, respectively). The acyclic structure of 8 was proved from its direct preparation by the condensation of(phenylacetyl)hydrazine with penta-O-acetyl-aldehydo-d-galactose. Cyclization of 2,3,4,5,6-penta-O-acetyl-aldehydo-d-galactose (phenylacetyl)hydrazone with boiling acetic anhydride yielded a mixture of two products that could be separated by fractional recrystallization, to give 3-acetyl-5-benzyl-2-(polyacetoxy)alkyl-1,3,4-oxadiazolines; a mechanism for the reaction was proposed. The n.m.r. and mass spectra of some of these derivatives were discussed.     

Rational design of Striga hermonthica-specific seed germination inhibitors

The obligate hemiparasitic weed Striga hermonthica grows on cereal roots and presents a severe threat to global food security by causing enormous yield losses, particularly in sub-Saharan Africa. The rapidly increasing Striga seed bank in infested soils provides a major obstacle in controlling this weed. Striga seeds require host-derived strigolactones (SLs) for germination, and corresponding antagonists could be used as germination inhibitors. Recently, we demonstrated that the common detergent Triton X-100 is a specific inhibitor of Striga seed germination by binding noncovalently to its receptor, S. hermonthica HYPO-SENSITIVE TO LIGHT 7 (ShHTL7), without blocking the rice (Oryza sativa) SL receptor DWARF14 (OsD14). Moreover, triazole ureas, the potent covalently binding antagonists of rice SL perception with much higher activity toward OsD14, showed inhibition of Striga but were less specific. Considering that Triton X-100 is not suitable for field application and by combining structural elements of Triton and triazole urea, we developed two hybrid compounds, KK023-N1 and KK023-N2, as potential Striga-specific germination inhibitors. Both compounds blocked the hydrolysis activity of ShHTL7 but did not affect that of OsD14. Binding of KK023-N1 diminished ShHTL7 interaction with S. hermonthica MORE AXILLARY BRANCHING 2, a major component in SL signal transduction, and increased ShHTL7 thermal specificity. Docking studies indicate that KK023-N1 binding is not covalent but is caused by hydrophobic interactions. Finally, in vitro and greenhouse tests revealed specific inhibition of Striga seed germination, which led to a 38% reduction in Striga infestation in pot experiments. These findings reveal that KK023-N1 is a potential candidate for combating Striga and a promising basis for rational design and development of further Striga-specific herbicides.

Designed strigolactone antagonists inhibit Striga seed germination.