Characterization of astragaloside I-IV based on the separation of HPTLC from Pleurotus ostreatus cultivated with Astragalus

Abstract

In this study, total saponins were extracted from Pleurotus ostreatus cultivated with Astragalus as one of organic culture substrates. High Performance Thin Layer Chromatography (HPTLC) assay showed total saponins could be separated effectively, and four kinds of spots were identified as AG I, AG II, AG III, and AG IV, respectively. FTIR spectra based on HPTLC separation assay showed the saponin characteristic groups including -OH, C-H, C=O, and the glycoside linkaged to sapogenin group C-O-C, suggesting the four kinds of spots belonged to cycloartane-type triterpene saponins. The primary mass spectra of precursor ion (HPTLC-ESI-MS) assay further proved the main composition of four kinds of spots was AG I-IV, respectively. Physical properties, including the detection of specific rotation and melting point, revealed the separation of high-purity saponin monomer by HPTLC. HPTLC-dual wavelength spectrodensitometric method detection showed that content of astragaloside I-IV was ranged from 0.2 to 0.5 mg/g, and the total astragalosides contents attained to 1.397 mg/g, indicating P. ostreatus could bioaccumulate astragalosides from Astragalus. These results demonstrated the characterization of astragalosides based on the separation of HPTLC was effective, and supported to consider astragalosides-enriched P. ostreatus as functional edible fungus for food and medical applications. PRACTICAL APPLICATION: Currently, the consumption of enriched foods has become common and continues to increase due to urgent demanding for foods with high nutritional value. Pleurotus ostreatus is a functional edible fungus, which not only can produce secondary metabolites, but can enrich bioactive ingredients. Astragalosides have a wide range of biological activities, especially currently being tested as cardioprotective agent. In this study, P. ostreatus was cultivated through adding Astragalus into culture substrates, which realized massive enrichment of astragalosides. Astragalosides-enriched P. ostreatus as functional edible fungus could be extensively used in food and medical areas, especially for the prevention of cardiovascular diseases.

Keywords: Astragalus, HPTLC; HPTLC-ESI-MS, Pleurotus ostreatus.