A New Antioxidant with Natural Origin Characterized by Electron Paramagnetic Resonance Spectroscopy Methods

ABSTRACT

Formerly, naturally isolated SQGD exhibited good in vitro radical scavenging capacity towards 1, 1-diphenyl-2-picrylhydrazyl (DPPH). By the present research using EPR in vitro and ex vivomethods we report our further studies on the antioxidant and free radical properties of SQGD. SQGD in powder or in solution form was studied before and after 2 h of UV irradiation by direct EPR in vitro spectroscopy. A single almost symmetrical EPR signal with a g value of 2.0056±0.0002 was registered for the powder form and g=2.0044±0.0002 for the solution form. Based on the calculated g values and the strong EPR signal stability we accept that the radical recorded can be safely ascribed to a semiquinone radical. To study in vivo antioxidant properties of SQGD, white laboratory mice were inoculated i.p.: first group with SQGD (20mg/kg), second with anticancer drug N'-cyclohexyl-N-(2-chloroethyl)-N-nitrosourea (CCNU, 80 mg/kg), third with SQGD plus CCNU and the controls were inoculated with the solvent only. At the 3rd h after treatment mice livers were isolated and homogenates in DMSO solution of the spin trap n-tert-butyl-alpha-phenylnitrone (PBN) were prepared and their EPR spectra were recorded. Statistical significant increased level of ROS production was found in liver homogenates of mice treated by CCNU comparing to those of the controls. ROS production in livers of mice treated by SQGD, or by the combination of SQGD plus CCNU was slightly decreased comparing to the controls.

In conclusion, obviously SQGD does not cause oxidative stress in the livers of mice for the followed period and behaves in vivo as an excellent antioxidant and hepatoprotector.

Keywords:

• EPR spin trapping technique
• anticancer drug
• semiquinone radical
• antioxidants