New Method For Rapid Screening Of Antioxidants From Nature Products

It is important to establish a practical approach for rapid antioxidant screening from complicated natural products for the development of new drugs. In this thesis, an on-line HPLC approach to rapid screening for radical scavenging components was proposed. In this method, the activity of antioxidants was evaluated by the scavenging ratio of antioxidants (SRA). The detail is as follows.1. An on-line HPLC method for rapid screening of antioxidants against DPPH from natural products was developed. With this method, the antioxidant activity of the six flavonoids was investigated rapidly both in pure and mixed form. Based on the result, the structure-activity relationship and synergy effect were analyzed for these flavones. The successful application to the extracts of A. altilis indicated that it is a practical way for the rapid screening of antioxidants from mixture. This screening method is high sensitive, practical, easy to operate, which could be used for bioactivity-guided fractionation.2. An on-line HPLC method for screening of antioxidants against superoxide anion radical from complex mixtures was developed. With this method, the antioxidant activity of the seven flavonoids was investigated rapidly both in pure and mixed form. This method solved the large error caused by the stability of superoxide anions and detecting time. It was successfully applied to the isolation of eight active compounds from the extracts of black tea.3. A new method for rapid screening, isolating, and analyzing potential antioxidants against hydroxyl radicals (HO·) was developed. With this method, the antioxidant activity of the six flavonoids was investigated in their pure and mixed form, and the structure-activity relationship was discussed. This method could be applied to the screening antioxidants from natural and synthesized compounds.