Evaluation of the antioxidant activity of tetracycline antibiotics in vitro.
Tetracyclines are the second most common antibiotic family in medicine usage. These antibiotics exhibit antioxidant potential; however, the exact mechanism remains unclear. The antiradical activity of the seven tetracyclines (TCs; tetracycline, chlortetracycline, oxytetracycline, doxocycline, methacycline, demeclocycline, minocycline) was determined using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and hydroxyl radicals (HO(•)) generated in a Fenton reaction. Electron spin resonance (ESR), ESR spin-trapping, chemiluminescence and spectrophotometry techniques were applied. It was found that the TCs showed high DPPH antiradical activity in the range 26-96% at 2.5 mmol/L concentration. The second-order rate constants for the reaction between HO(•) and TCs were calculated, in the range (3.6-9.6) × 10(9)  L/mol/s. The tetracycline compounds also exhibited a strong decrease in light emission (range 61-85% at concentration of 1 mmol/L). This study also showed that TCs promote the generation of singlet oxygen in the presence of H(2)O(2) and Fe(II)/Fe(III) ions. Our findings suggest direct scavenging activity of the examined tetracyclines towards free radicals, and may be relevant to therapeutic strategy.
Department of Medical History and Ethics, Pomeranian Medical Academy, ul. Rybacka 1, 70-204, Szczecin, Poland.
Aleksandra
A
Kładna
Teresa
T
Michalska
Paweł
P
Berczyński
Irena
I
Kruk
Hassan Y
HY
Aboul-Enein
D000900:Anti-Bacterial Agents / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D010084:Oxidation-Reduction; D010851:Picrates / Q000737:chemistry; D013752:Tetracycline / Q000737:chemistry*
D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001713:Biphenyl Compounds; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl; D013752:Tetracycline