Rapid screening and evaluation of antioxidants in alkaloid natural products by capillary electrophoresis with chemiluminescence detection

Abstract

A capillary electrophoresis (CE) incorporating chemiluminescence (CL) detection method was applied to on-line screening and evaluation of antioxidants in alkaloid natural products. Constant and stable CL intensity was derived from the reaction of luminol with reactive oxygen species (ROS) which were generated from a sodium hypochlorite–hydrogen peroxide system, and the inhibited peaks were then acquired as the quenching effects of antioxidants against ROS. The relationship between the inhibited extent of CL and scavenging efficiency for the ROS of antioxidants was discovered. The curvilinear equations between concentrations and scavenging ratios of matrine and oxymatrine as model samples were obtained, and the IC₅₀s were calculated and validated by fluorospectrophotometry. Under optimized conditions, antioxidants in five alkaloid natural products were on-line screened. Each quantitative decrease in CL corresponded to different antioxidative potentials; the distribution and activity of constituents in congener natural products were consequently obtained. This applied CE–CL combination was found to be an efficient method for the assessment of antioxidants in complex samples.