Investigation of the effect of different extraction techniques on the phytochemical analysis of Astragalus stella

This study explores the phytochemical profiles, antioxidant capacities, and enzyme inhibition activities of methanol extracts from the aerial parts of Astragalus stella using Soxhlet extraction, maceration, and ultrasonic-assisted extraction techniques. The maceration extract exhibited the highest concentrations in terms of both total phenolic content (20.67 mg GAE/g extract) and total flavonoid content (25.49 mg RE/g extract). Phytochemical analysis via LC-ESI-MS/MS revealed the presence of 30 distinct compounds. Hesperidin was identified as the most abundant, present at approximately 1000 µg/g of extract across all extraction methods. Furthermore, hyperoside, apigenin, and apigenin-7-glucoside were significant constituents. Antioxidant properties were assessed using a multifaceted approach, incorporating phosphomolybdenum, DPPH, ABTS, CUPRAC, FRAP, and metal chelating assays. In the majority of these tests, the maceration extract displayed superior antioxidant capacity, with notably high activity observed in phosphomolybdenum, CUPRAC, and FRAP assays, as well as DPPH and ABTS radical scavenging, and metal chelating assays. According to the RACI, the maceration extract exhibited the highest antioxidant activity with a value of 1.24, whereas the Soxhlet and ultrasonic extracts showed negative RACI values of -0.41 and -0.83, respectively. Pearson correlation analyses revealed a strong positive correlation between total phenolics and total flavonoids with various antioxidant test results, suggesting that these compounds are likely major contributors to the antioxidant capacity of the extracts. The enzyme inhibition assays revealed that all extracts exhibited similar acetylcholinesterase (AChE) inhibition, while the maceration extract showed the highest α-amylase inhibition, and the ultrasonic extract displayed the lowest tyrosinase inhibition compared to other extracts, although none of the extracts matched the inhibition capacity of the standards used in this study. The findings suggest thatA. stella extracts, particularly those obtained by maceration, can be evaluated in the pharmaceutical, food, and cosmetics industries due to their high antioxidant properties and α-amylase inhibition activity.