Characterisation of the antioxidant effects of Aesculus hippocastanum L. bark extract on the basis of radical scavenging activity, the chemiluminescence of human neutrophil bursts and lipoperoxidation assay.

ABSTRACT

OBJECTIVES: Oxidative stress is increasingly recognised as a pivotal factor that plays a number of roles in the inflammatory response to environmental signals. It has been claimed that Aesculus hippocastanum extracts have antioxidant and anti-inflammatory activity, but these claims are mainly based on the results of chemical reactions and folk-medicine. MATERIALS AND METHODS: The aim of this study was to examine whether a bark extract of Aesculus hippocastanum interferes with reactive oxygen/nitrogen species (ROS/RNS) during the course of human neutrophil respiratory bursts, and to establish the lowest concentration at which it still has antioxidant activity by means of luminol amplified chemiluminescence (LACL). We also studied its ability to counteract lipid peroxidation (LPO) in human cells. Before investigating its antioxidant effects on human cells, we analysed its scavenging activity against ABTS*+, hydroxyl radical, superoxide anion, and Fremy's salt (those last three by means of electron paramagnetic resonance (EPR) spectrometry). RESULTS: The extract of Aesculus hippocastanum exerted its anti-ROS/RNS activity in a concentration-dependent manner with significant effects being observed for even very low concentrations 10 microg/ml without L-Arg, and 5 microg/ml when L-Arg was added to the fMLP test. The LPO assay confirmed these results, which were paralleled by the EPR study. CONCLUSIONS: These findings are interesting for improving the antioxidant network and restoring redox balance in human cells, and extend the possibility of using plant-derived molecules to antagonise the oxidative stress generated in living organisms when the balance is in favour of free radicals as a result of the depletion of cell antioxidants.