Microwave Assisted Synthesis and Antimicrobial Study of Schiff Base Vanadium(IV) Complexes of Phenyl Esters of Amino Acids

Eco-Friendly Synthesis of an Oxovanadium(IV)-bis(abietate) Complex with Antimicrobial Action

The search for less expensive and viable products is always one of the challenges for research development. Commonly, the synthesis of coordination compounds involves expensive ligands, through expensive and low-yield routes, in addition to generating toxic and unusable residues. In this work, the organic ligand used is derived from the resin of a reforestation tree, Pinus elliottii var. elliottii. The synthesis method used Pinus resin and an aqueous solution of vanadium(III) chloride at a temperature of 80 °C. The procedure does not involve organic solvents and does not generate toxic residues, thus imparting the complex formation reaction a green chemistry character. The synthesis resulted in an unprecedented oxovanadium(IV)-bis(abietate) complex, which was characterized by mass spectrometry (MS), chemical analysis (CHN), vibrational (FTIR) and electronic spectra (VISIBLE), X-ray diffraction (XRD), and thermal analysis (TG/DTA). Colorimetric studies were performed according to the CIELAB color space. The structural formula found, consisted of a complex containing two abietate ligands, [VO(C20H29O2)2]. The VO(IV)-bis(abietate) complex was applied against microorganisms and showed promising results in antibacterial and antifungal activity. The best result of inhibitory action was against the strains of Gram-positive bacteria S. aureus and L. monocytogenes, with minimum inhibitory concentration (MIC) values of 62.5 and 125 μmol L−1, respectively. For Gram-negative strains the results were 500 μmol L−1 for E. coli; and 1000 μmol L−1 for Salmonella enterica Typhimurium. Antifungal activity was performed against Candida albicans, where the MIC was 15.62 μmol L−1, and for C. tropicalis it was 62.5 μmol L−1. According to the MFC analysis, the complex presented, in addition to the fungistatic action, a fungicidal action, as there was no growth of fungi on the plates tested. The results found for the tests demonstrate that the VO(IV)-bis(abietate) complex has great potential as an antimicrobial and mainly antifungal agent. In this way, the pigmented ink with antimicrobial activity could be used in environments with a potential risk of contamination, preventing the spread of microorganisms harmful to health.

Silicon-mediated metabolic upregulation of ascorbate glutathione (AsA-GSH) and glyoxalase reduces the toxic effects of vanadium in rice

Although beneficial metalloid silicon (Si) has been proven to reduce the toxicity of several heavy metals, there is a lack of understanding regarding Si potential function in mitigating phytotoxicity induced by vanadium (V). In this study, effect of Si (1.5 mM) on growth, biomass production, V uptake, reactive oxygen species (ROS), methylglyoxal (MG) formation, selected antioxidants enzymes activities, glyoxalase enzymes under V stress (35 mg L^-1) was investigated in hydroponic experiment. The results showed that V stress reduced rice growth, caused V accumulation in rice. Addition of Si to the nutritional medium increased plant growth, biomass yield, root length, root diameter, chlorophyll parameters, photosynthetic assimilation, ion leakage, antioxidant enzymes activities under V stress. Notably, Si sustained V-homeostasis and alleviated V caused oxidative stress by boosting ascorbate (AsA) levels and the activity of antioxidant enzymes in V stressed rice plants. Furthermore, Si protected rice seedlings against the harmful effects of methylglyoxal by increasing the activity of glyoxalase enzymes. Additionally, Si increased the expression of numerous genes involved in the detoxification of reactive oxygen species (e.g., OsCuZnSOD1, OsCaTB, OsGPX1, OsAPX1, OsGR2, and OsGSTU37) and methylglyoxal (e.g., OsGLYI-1 and OsGLYII-2). The findings supported that Si can be applied to plants to minimize the V availability to plant, and also induced V stress tolerance.

Melatonin pretreatment improves vanadium stress tolerance of watermelon seedlings by reducing vanadium concentration in the leaves and regulating melatonin biosynthesis and antioxidant-related gene expression

Vanadium (V) is an important heavy metal with ubiquitous presence in the Earth's crust, but limited information is available as to its effect on plants and management strategies. Melatonin is a widely studied biomolecule; it acts as an antioxidant and a signaling molecule that enhances the abiotic stress tolerance of plants. Melatonin improves copper, zinc, and cadmium tolerance in plants. In this study, we investigated the response of watermelon seedlings to V stress and the potential role of melatonin in enhancing V stress tolerance of watermelon seedlings. The results showed that seedlings pretreated with melatonin (0.1μM) exposed to V (50mg/L) had a higher relative chlorophyll content (SPAD index), photosynthetic assimilation, and plant growth compared with non-melatonin pretreated seedlings. Melatonin pretreatment lowered leaf and stem V concentrations by reducing V transport from root to shoot. Melatonin pretreatment enhanced superoxide dismutase (SOD) and catalase (CAT) activities, and reduced the hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) content of watermelon seedlings, by regulating melatonin biosynthesis and gene expression for superoxide dismutase, peroxidase, ascorbate peroxidase, glutathione peroxidase, and glutathione S-transferase. So far as we know, these results are the first evidence that melatonin improves plant growth of watermelon seedlings under vanadium stress conditions. Considering these observations, melatonin can be utilized to reduce the availability of V to plants, and improve plant growth and V stress tolerance.

Comparison of antioxidant enzyme activities and DNA damage in chickpea (Cicer arietinum L.) genotypes exposed to vanadium

The present study was done to elucidate the effects of vanadium (V) on photosynthetic pigments, membrane damage, antioxidant enzymes, protein, and deoxyribonucleic acid (DNA) integrity in the following chickpea genotypes: C-44 (tolerant) and Balkasar (sensitive). Changes in these parameters were strikingly dependent on levels of V, at 60 and 120 mg V L(-1) induced DNA damage in Balkasar only, while photosynthetic pigments and protein were decreased from 15 to 120 mg V L(-1) and membrane was also damaged. It was shown that photosynthetic pigments and protein production declined from 15 to 120 mg V L(-1) and the membrane was also damaged, while DNA damage was not observed at any level of V stress in C-44. Moreover, the antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were increased in both genotypes of chickpea against V stress; however, more activities were observed in C-44 than Balkasar. The results suggest that DNA damage in sensitive genotypes can be triggered due to exposure of higher vanadium.

Vanadium, recent advancements and research prospects: A review

Metal pollution is an important issue worldwide, with various documented cases of metal toxicity in mining areas, industries, coal power plants and agriculture sector. Heavy metal polluted soils pose severe problems to plants, water resources, environment and nutrition. Among all non-essential metals, vanadium (V) is becoming a serious matter of discussion for the scientists who deals with heavy metals. Due to its mobility from soil to plants, it causes adverse effects to human beings. This review article illustrates briefly about V, its role and shows the progress about V research so far done globally in the light of the previous work which may assist in inter-disciplinary studies to evaluate the ecological importance of V toxicity.