Free radicals produced by the oxidation of gallic acid: An electron paramagnetic resonance study

<p>Abstract</p> <p>Background</p> <p>Gallic acid (3,4,5-trihydroxybenzoic acid) is found in a wide variety of plants; it is extensively used in tanning, ink dyes, as well as in the manufacturing of paper. The gallate moiety is a key component of many functional phytochemicals. In this work electron paramagnetic spectroscopy (EPR) was used to detect the free radicals generated by the air-oxidation of gallic acid.</p> <p>Results</p> <p>We found that gallic acid produces two different radicals as a function of pH. In the pH range between 7-10, the spectrum of the gallate free radical is a doublet of triplets (a^H= 1.00 G, a^H= 0.23 G, a^H= 0.28 G). This is consistent with three hydrogens providing hyperfine splitting. However, in a more alkaline environment, pH >10, the hyperfine splitting pattern transforms into a 1:2:1 pattern (a^H(2) = 1.07 G). Using D₂O as a solvent, we demonstrate that the third hydrogen (<it>i.e</it>. a^H= 0.28 G) at lower pH is a slowly exchanging hydron, participating in hydrogen bonding with two oxygens in <it>ortho </it>position on the gallate ring. The p<it>K</it>_aof this proton has been determined to be 10.</p> <p>Conclusions</p> <p>This simple and novel approach permitted the understanding of the prototropic equilibrium of the semiquinone radicals generated by gallic acid, a ubiquitous compound, allowing new insights into its oxidation and subsequent reactions.</p

IAEA Contribution to Nanosized Targeted Radiopharmaceuticals for Drug Delivery

The rapidly growing interest in the application of nanoscience in the future design of radiopharmaceuticals and the development of nanosized radiopharmaceuticals in the late 2000 ' s, resulted in the creation of a Coordinated Research Project (CRP) by the International Atomic Energy Agency (IAEA) in 2014. This CRP entitled 'Nanosized delivery systems for radiopharmaceuticals' involved a team of expert scientist from various member states. This team of scientists worked on a number of cutting-edge areas of nanoscience with a focus on developing well-defined, highly effective and site-specific delivery systems of radiopharmaceuticals. Specifically, focus areas of various teams of scientists comprised of the development of nanoparticles (NPs) based on metals, polymers, and gels, and their conjugation/encapsulation or decoration with various tumor avid ligands such as peptides, folates, and small molecule phytochemicals. The research and development efforts also comprised of developing optimum radiolabeling methods of various nano vectors using diagnostic and therapeutic radionuclides including Tc-99m, Ga-68, Lu-177 and Au-198. Concerted efforts of teams of scientists within this CRP has resulted in the development of various protocols and guidelines on delivery systems of nanoradiopharmaceuticals, training of numerous graduate students/post-doctoral fellows and publications in peer reviewed journals while establishing numerous productive scientific networks in various participating member states. Some of the innovative nanoconstructs were chosen for further preclinical applications-all aimed at ultimate clinical translation for treating human cancer patients. This review article summarizes outcomes of this major international scientific endeavor

Toxicity studies of six types of carbon nanoparticles in a chicken-embryo model

Natalia Kurantowicz,1 Ewa Sawosz,1 Gabriela Halik,1 Barbara Strojny,1 Anna Hotowy,1 Marta Grodzik,1 Radosław Piast,2 Wanvimol Pasanphan,3 Andr&eacute; Chwalibog4 1Department of Animal Nutrition and Biotechnology, Warsaw University of Life Sciences, 2Faculty of Chemistry, Warsaw University, Warsaw, Poland; 3Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok, Thailand; 4Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Copenhagen, Denmark Abstract: In the present study, the toxicity of six different types of carbon nanoparticles (CNPs) was investigated using a chicken-embryo model. Fertilized chicken eggs were divided into the following treatment groups: placebo, diamond NPs, graphite NPs, pristine graphene, small graphene oxide, large graphene oxide, and reduced graphene oxide. Experimental solutions at a concentration of 500 &micro;g/mL were administrated into the egg albumin. Gross pathology and the rate of survival were examined after 5, 10, 15, and 20 days of incubation. After 20 days of incubation, blood samples were collected and the weight of the body and organs measured. The relative ratio of embryo survival decreased after treatment all treatments except diamond NPs. There was no correlation between the rate of survival and the &zeta;-potential or the surface charge of the CNPs in solution. Body and organ weight, red blood-cell morphology, blood serum biochemical parameters, and oxidative damage in the liver did not differ among the groups. These results indicate that CNPs can remain in blood circulation without any major side effects, suggesting their potential applicability as vehicles for drug delivery or active compounds per&nbsp;se. However, there is a need for further investigation of their properties, which vary depending on production methods and surface functionalization. Keywords: nanoparticles, diamond, graphite, graphene, toxicity, red blood cells, oxidative stress, surface charg