Reactive oxygen species (ROS) can attack a diverse range of targets to exert antimicrobial activity, which accounts for their versatility in mediating host defense against a broad range of pathogens. Most ROS are formed by the partial reduction in molecular oxygen. Four major ROS are recognized comprising superoxide (O2•-), hydrogen peroxide (H2O2), hydroxyl radical (•OH), and singlet oxygen ((1)O2), but they display very different kinetics and levels of activity. The effects of O2•- and H2O2 are less acute than those of •OH and (1)O2, because the former are much less reactive and can be detoxified by endogenous antioxidants (both enzymatic and nonenzymatic) that are induced by oxidative stress. In contrast, no enzyme can detoxify •OH or (1)O2, making them extremely toxic and acutely lethal. The present review will highlight the various methods of ROS formation and their mechanism of action. Antioxidant defenses against ROS in microbial cells and the use of ROS by antimicrobial host defense systems are covered. Antimicrobial approaches primarily utilizing ROS comprise both bactericidal antibiotics and nonpharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma, and medicinal honey. A brief final section covers reactive nitrogen species and related therapeutics, such as acidified nitrite and nitric oxide-releasing nanoparticles.

Antimicrobial strategies centered around reactive oxygen species - bactericidal antibiotics, photodynamic therapy and beyond

Photodynamic therapy for localized infections--state of the art.

Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen induced systemic acquired resistance Rhizobacteria mediated induced systemic resistance has been demonstrated against fungi,bacteria,and viruses in Arabidopis,bean,camation,cucumber,radish,tobacco and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated Bacteria induce plants to produce the JA and ethylene to develop the ISR And ISR is effective under field conditions and offers a natural mechanism for biological control of plant disease

Systemic resistance induced by rhizosphere bacteria

Plant growth promotion in cereal and leguminous agricultural important plants: from microorganism capacities to crop production.

Triazole compounds containing three nitrogen atoms in the five-membered aromatic azole ring are readily able to bind with a variety of enzymes and receptors in biological system via diverse non-covalent interactions, and thus display versatile biological activities. The related researches in triazole-based derivatives as medicinal drugs have been an extremely active topic, and numerous excellent achievements have been acquired. Noticeably, a large number of triazole compounds as clinical drugs or candidates have been frequently employed for the treatment of various types of diseases, which have shown their large development value and wide potential as medicinal agents. This work systematically reviewed the recent researches and developments of the whole range of triazole compounds as medicinal drugs, including antifungal, anticancer, antibacterial, antitubercular, antiviral, anti-inflammatory and analgesic, anticonvulsant, antiparasitic, antidiabetic, anti-obesitic, antihistaminic, anti-neuropathic, antihypertensive as well as other biological activities. The perspectives of the foreseeable future in the research and development of triazole-based compounds as medicinal drugs are also presented. It is hoped that this review will serve as a stimulant for new thoughts in the quest for rational designs of more active and less toxic triazole medicinal drugs.

Recent researches in triazole compounds as medicinal drugs.

Photodynamic inactivation of Candida albicans sensitized by tri- and tetra-cationic porphyrin derivatives.

Allfalfa and soybean are the most important leguminous plants in the agricultural system of the semiarid pampas of Argentina. The possible action of phosphate solubilizing bacteria on the leguminous-rhizobia symbiosis was studied since in this region the available phosphorus distribution is not uniform. The strains used were Sinorhizobium meliloti 3DOh13, a good solubilizer of iron and phosphorus for alfalfa, Bradyrhizobium japonicum TIIIB for soybean and two phosphorus-solubilizing strains of Pseudomonas putida (SP21 and SP22) for growth promotion treatments. Modification of shoot and root system dry weights occured in soybean but not in alfalfa in presence of Pseudomonas strains.

Phosphate-solubilizing Pseudomonas putida can influence the rhizobia-legume symbiosis

Wheat ( Triticum aestivum L.), rice ( Oryza sativa ) and maize ( Zea mays L.) are the most important cereals worldwide. However, in the last few years, soil has been submitted to both use and handling pressures due to the increase in agricultural practices, which are leading to its degradation. The use of plant growth-promoting rhizobacteria (PGPR) as inoculants constitutes a biological alternative for sustainable production. Pseudomonas aurantiaca SR1 was formulated as an inoculant in order to evaluate its growth promotion effect in the field when applied on maize and wheat seeds at the sowing time. P and N fertilization treatments were also included in the assays. P. aurantiaca SR1 colonized the root system of both crops and it persisted at appropriate population densities. It also showed a significant plant growth-promoting effect that was reflected in the yield. Another relevant finding was that both crops, when inoculated with P. aurantiaca SR1, presented higher yields with fertilization doses lower than those conventionally applied. This indicated its potential use as a reasonable alternative for crop production, with a minimization of the ecological impact.

Root colonization and growth promotion of wheat and maize by Pseudomonas aurantiaca SR1.

The photodynamic activities of novel asymmetrically meso-substituted cationic porphyrins, 5,10-di(4-methylphenyl)-15,20-di(4-trimethylammoniumphenyl)porphyrin iodide 1 and 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide 2 and its metal complex with Pd(II) 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram-negative bacterium Escherichia coli. The amphiphilic character of porphyrin 2 was increased by the presence of a high-lipophilic trifluoromethyl group and its photophysical properties changed by forming a complex with Pd(II). Absorption and fluorescence spectroscopic studies were compared in different media. Fluorescence quantum yields (phi(F)) of 0.16 for 1 in tetrahydrofuran and 0.08 for 2 in N, N-dimethylformamide (DMF) were calculated, whereas no significant emission was detected for Pd(II) porphyrin 3. The singlet molecular oxygen, O(2)((1)Delta(g)), production was evaluated using 9,10-dimethylanthracene in DMF yielding relative values of 1, 0.55 and 0.47 for porphyrins 3, 2 and 1, respectively. A faster decomposition of l-tryptophan was obtained using Pd(II) porphyrin 3 as sensitizer with respect to the free-base porphyrins 1 and 2. In biological medium, the behavior of cationic porphyrins 1-3 were compared with that of 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl)porphyrin 4, which was used as a noncationic sensitizer. These porphyrins are rapidly bound to E. coli cells in 5 min and the amount of cell-bound sensitizer is not appreciably changed incubating the cultures for longer times. The recovered porphyrin 2 after one washing step reaches a value of approximately 2.9 nmol/10(6) cells and this amount remains high even after three washes, indicating that this sensitizer is tightly bound to cells. Photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. In both cases, a higher photoinactivation of cells was found for tricationic porphyrin 2 and 3, causing a approximately 5.5 log (99.999%) decrease of cell survival, when treated with 10 microM of sensitizer. Under these conditions, a lower effect was found for porphyrin 1 (approximately 4 log) whereas sensitizer 4 did not produce appreciable photodamage. The results were also confirmed by growth delay experiments. These studies show that the amphiphilic tricationic porphyrin 2 and 3 bearing a trifluoromethyl group can be a promising model for phototherapeutic agents with potential applications in inactivation of bacteria by photodynamic therapy.

Photodynamic Studies and Photoinactivation of Escherichia coli Using meso-Substituted Cationic Porphyrin Derivatives with Asymmetric Charge Distribution¶

The antiviral activity of alcoholic extracts of several species belonging to the Asteraceae, Labiatae, Plantaginaceae, Schizaceae, Umbelliferae, Usneaceae and Verbenaceae families has been studied. The tests were carried out in Vero celis-pseudorabies virus strain RC/79 (herpes suis virus) system. Eight plant extracts (Achyrocline satureioides, Ambrossia tenuifolia, Baccharis articulata, Eupatorium buniifolium, Mynthostachys verticillata, Plantago brasiliensis, Plantago mayor L and Verbascum thapsus) were able to inhibit at least 2 log, the viral infectivity.

Marisa Rovera

Papers

Photodynamic inactivation of Candida albicans sensitized by tri- and tetra-cationic porphyrin derivatives.

Phosphate-solubilizing Pseudomonas putida can influence the rhizobia-legume symbiosis

Root colonization and growth promotion of wheat and maize by Pseudomonas aurantiaca SR1.

Photodynamic Studies and Photoinactivation of Escherichia coli Using meso-Substituted Cationic Porphyrin Derivatives with Asymmetric Charge Distribution¶

Search for antiviral activity of certain medicinal plants from Córdoba, Argentina