Diagnostic product ions-based chemical characterization and antioxidative activity evaluation of solid fermentation for Astragali radix produced by Paecilomyces cicadae

Abstract

Studies on herbal medicines and fermentation products have become increasingly essential with the development of modern industry and technology. In order to verify that fermentation can bring about changes, Paecilomyces cicadae [Paecilomyces cicadae (Miquel.) Samson] was used to ferment Astragali radix [Astragalus membranaceus (Fisch.) Bge. var. mongho-licus (Bge.) Hsiao]. After solid fermentation for Astragali radix produced by Paecilomyces cicadae (SF-AP) was established, an efficient strategy based on ultra-high performance liquid chromatography-linear ion trap-Orbitrap mass spectrometry (UHPLC-LTQ-Orbitrap MS) was developed to screen and identify the chemical transformations in SF-AP and Astragali radix according to the acquired diagnostic product ions (DPIs). As a result, 114 compounds including 45 saponins and 69 flavonoids were finally identified and validated. Moreover, two kinds of antioxidative tests corresponding to the scavenging of DPPH· and ABTS·+ were applied to evaluate the antioxidative activity of Astragali radix before and after fermentation. The results demonstrated that some significant chemical transformations such as relative content fluctuations and structural isomerism owing to the occurrence of hydrolysis and conversion reactions and the antioxidative activity of SF-AP was much higher than that of the Astragali radix. This study could provide a new method for the utilization of Astragali radix and constructive guidance for the further research of fermented herbal medicines.