Screening and Isolation of Natural Antioxidants from Max by TLC-MS/MS Guided Bioautographic Method.

A rapid and simple method has been developed for the screening and identification of natural antioxidants from the leaves of Maxim (AG). The process is that upon reaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH), the white yellow spots of compounds with potential antioxidant effects will be significantly observed on the thin-layer chromatography (TLC), and possible structures will be presumed by the ESI/MS technique. Using the improved approach, 6 compounds in the AG extract were found to possess a potential antioxidant activity. They were speculated as quercetin-3--(3"-galloyl)-rhamnoside , quercetin-3--(2"-galloyl)-rhamnoside , quercetin-3--(2"-galloyl)-arabinopyranoside , acertannin , gallic acid and methyl gallate . In addition, we were still found that compounds , and had favorable antioxidant activity from the scannogram of the DPPH reaction plate. As a result, the isolated 6 compounds structures were in accordance with the presumed structures. Furthermore, the free radical scavenging capacities of the available identified compounds were also investigated. Compounds , and showed significant DPPHScavenging capacities, with IC values of 2.83 μg/mL, 2.34 μg/mL, and 1.86μg/mL, respectively. The results indicated that this newly improved method could be widely applied for rapid screening and identification of natural antioxidants from Chinese herbal medicines.