Abstract: [Objective] To study the main antioxidants in common buckwheat and tartary buckwheat . [Method] It takes the buckwheat ethanol extraction subtracts with the DPPH free radicals reaction, identify the antioxidants in the extrcats with HPLC, study the structure character of antioxidation compositions by Electro Spray Ionization-Mass Spectrometry (ESI-MS), and determine the antioxidation compositions of buckwheat ethanol extracts. [Result] Both the common buckwheat and the tartary buckwheat ethanol extracts can scavenge free radical. From the HPLC figure there were two main peaks, which included two kinds of antioxidants in the extracts. Meanwhile, the corresponding chromatograph retention time was the same as the spectrum information. The ESI-MS indicated that, the molecular weights and MS fragmentation pattern of antioxidants in the extracts were similar to the reference material of rutin and quercetin. [Conclusion] The method of HPLC-MS/MS can be used to screen the antioxidants in the extraction quickly; the main antioxidants of the buckwheat extracts were rutin and quercetin, while the activity of antioxidant activity of quercetin was higher than rutin.

Key words: Buckwheat, Antioxidant, HPLC, MS/MS