Spectrometric investigation of DPPH and ABTS free radical-scavenging of Ulva lacyuca L. aqueous extracts

The antioxidant activities of Ulva lacyuca L. aqueous extracts against DPPH and ABTS free radicals were evaluated using spectrometric methods. The results showed that the detection wavelength and stable time for ABTS system were 734 nm and 6 min respectively,while those for DPPH system were 515 nm and 30 min,respectively. The extracts effectively and rapidly removed ABTS and DPPH free radicals,and showed a dose- and time-dependent manner,indicating the potent antioxidant activities under both hydrophilic and hydrophobic conditions. Under the optimized systems,the IC50values for Se-PPC,PPC and VC against ABTS free radical were 76.40,54.11 and 60.69 μg/ml,respectively. Se-PPC exhibited significantly higher activities than the VC. For DPPH free radicals,the IC50values of Se-PPC,PPC and VC were 123.29,76.83 and 24.79 μg/ml,respectively. Our results suggest selenium-enrichment cultured U. lacyuca L. has potential value of applications to be functional food with antioxidation.