11 research outputs found
Istraživanje mehanizma toksiÄnosti anilina u eritrocitima
Strategies for the use of bio-indicators in the prediction of environmental damage should include mechanistic research. This study involves the relationship between the chemical structure and hemotoxic markers of aniline and its halogenated analogs. Aniline-induced methemoglobinemia, loss of circulating blood cells, blood stability, glutathione depletion and membrane cytoskeletal changes were assessed following exposure to phenylhydroxylamine (PHA), para-fluoro-, para-bromo-, and para-iodo in male Sprague-Dawley rats. Methemoglobin was determined spectrophotometrically at 635 nm. Erythrocyte depletion was investigated by loss of radioactivity in chromium-labeled red blood cells in vivo. Membrane proteins were analyzed by SDS-PAGE using red blood ghost cells treated with various aniline analogs. Results showed dose- and time-dependent changes in the induction of methemoglobin of up to 78 % with para-bromo PHA and 75 % with para-iodo PHA compared to 3 % to 5 % in control. Treated animals lost up to three times more blood from circulation compared to control within 14 days after treatment. Erythrocytes were more stable in buffer solution than in para-iodo-treated cells. Depletion of reduced glutathione in PHA and para-iodo-PHA treated red cells was also observed. Analysis of red cell skeletal membrane treated with para-iodo-PHA showed that protein band 2.1 became broader and band 2.2 diminished completely in some treatments. Dose- and time-dependent changes suggested the use of hemotoxic endpoints as potential biomarkers for assessing chemical and drug safetyStrategije primjene biopokazatelja za predviÄanje Å”tete u okoliÅ”u trebaju u obzir uzeti istraživanja mehanizama djelovanja. Ovo istraživanje propituje odnos izmeÄu kemijske strukture i hemotoksiÄnih pokazatelja djelovanja anilina i njegovh halogeniranih analoga. Nakon izlaganja mužjaka Å”takora soja Sprague-Dawley para-fluoro-, para-bromo- i para-jodofenilhidroksilaminu, utvrÄena je methemoglobinemija uzrokovana anilinom te pad broja krvnih stanica u krvotoku i stabilnosti krvi, gubitak glutationa i promjene na membrani stanice. Methemoglobin je odreÄivan spektrofotometrijski na 635 nm. Pad broja eritrocita mjeren je in vivo s pomoÄu eritrocita obilježenih radioaktivnim kromom. Membranske su bjelanÄevine analizirane s pomoÄu SDS-PAGE, rabeÄi eritrocite bez hemoglobina (engl. ghost cells) kojima su dodani razliÄiti analozi anilina. Nalazi upuÄuju na promjene indukcije methemoglobina ovisno o dozi i vremenu djelovanja do 78 % s para-bromo-fenilhidroksilaminom te do 75 % s para-jodofenilhidroksilaminom u usporedbi s 3 % do 5 % u kontrolnih uzoraka. U razdoblju od 14 dana nakon tretiranja izložene životinje izgubile su tri puta viÅ”e krvi iz krvotoka od kontrolnih. Eritrociti su bili stabilniji u puferskoj otopini negoli u stanicama kojima je dodan para-jodofenilhidroksilamin. ZamijeÄen je i pad glutationa u eritrocitima kojima je dodan fenilhidroksilamin odnosno para-jodofenilhidroksilamin. Analizom membrane eritrocita kojima je dodan para-jodofenilhidroksilamin zamijeÄeno je da se u pojedinih obrada raÅ”irila proteinska vrpca 2.1, a potpuno smanjila proteinska vrpca 2.2. ZamijeÄene promjene uvjetovane dozom i vremenom upuÄuju na primjenu hemotoksiÄnih parametara kao moguÄih biopokazatelja u procjeni sigurnosti lijeka odnosno kemikalije
8āAminoquinolines with an Aminoxyalkyl Side Chain Exert in vitro DualāStage Antiplasmodial Activity
Computational Study on the Effect of Exocyclic Substituents on the Ionization Potential of Primaquine: Insights into the Design of Primaquine-Based Antimalarial Drugs with Less Methemoglobin Generation
Methemoglobin Generation by 8-Aminoquinolines: Effect of Substitution at 5-Position of Primaquine
CYP450 phenotyping and accurate mass identification of metabolites of the 8-aminoquinoline, anti-malarial drug primaquine
<p>Abstract</p> <p>Background</p> <p>The 8-aminoquinoline (8AQ) drug primaquine (PQ) is currently the only approved drug effective against the persistent liver stage of the hypnozoite forming strains <it>Plasmodium vivax</it> and <it>Plasmodium ovale</it> as well as Stage V gametocytes of <it>Plasmodium falciparum</it>. To date, several groups have investigated the toxicity observed in the 8AQ class, however, exact mechanisms and/or metabolic species responsible for PQās haemotoxic and anti-malarial properties are not fully understood.</p> <p>Methods</p> <p>In the present study, the metabolism of PQ was evaluated using <it>in vitro</it> recombinant metabolic enzymes from the cytochrome P450 (CYP) and mono-amine oxidase (MAO) families. Based on this information, metabolite identification experiments were performed using nominal and accurate mass measurements.</p> <p>Results</p> <p>Relative activity factor (RAF)-weighted intrinsic clearance values show the relative role of each enzyme to be MAO-A, 2C19, 3A4, and 2D6, with 76.1, 17.0, 5.2, and 1.7% contributions to PQ metabolism, respectively. CYP 2D6 was shown to produce at least six different oxidative metabolites along with demethylations, while MAO-A products derived from the PQ aldehyde, a pre-cursor to carboxy PQ. CYPs 2C19 and 3A4 produced only trace levels of hydroxylated species.</p> <p>Conclusions</p> <p>As a result of this work, CYP 2D6 and MAO-A have been implicated as the key enzymes associated with PQ metabolism, and metabolites previously identified as potentially playing a role in efficacy and haemolytic toxicity have been attributed to production via CYP 2D6 mediated pathways.</p