Influence of extraction solvents on the chemical constituents and biological activities of Astragalus aduncus from Turkey flora: In vitro and in silico insights

The n-hexane, ethyl acetate, ethanol, ethanol/water (70% ethanol), and water extracts of Astragalus aduncus aerial parts were investigated for their antioxidant potential, enzyme inhibition activity (anti-acetylcholinesterase [AChE], anti-butyrylcholinesterase [BChE], antityrosinase, antiamylase, and antiglucosidase) and antiproliferative effect (against colon adenocarcinoma cell line [HT-29], gastric cancer cell line [HGC-27], prostate carcinoma cell line [DU-145], breast adenocarcinoma cell line [MDA-MB-231], and cervix adenocarcinoma cell line [HeLa]). In addition, the phytochemical profile of the extracts was evaluated using validated spectrophotometric and high-pressure liquid chromatography-electrospray ionization/tandem mass spectroscopy methods. Generally, the 70% ethanol extract demonstrated the strongest antioxidant properties, and it was the richest source of total phenolic constituents. Our findings indicated that the ethyl acetate extract was the most potent BChE inhibitor (11.44 mg galantamine equivalents [GALAE]/g) followed by the ethanol extract (8.51 mg GALAE/g), while the ethanol extract was the most promising AChE inhibitor (3.42 mg GALAE/g) followed by the ethanol/water extract (3.17 mg GALAE/g). Excellent tyrosinase inhibitory activity (66.25 mg kojic acid equivalent/g) was observed in ethanol/water extracts of the aerial part of A. aduncus. Тhese results showed that the most cytotoxic effects were exhibited by the ethyl acetate extract against HGC-27 cells (IC50: 36.76 µg/mL), the ethanol extract against HT-29 cells (IC50: 30.79 µg/mL), and the water extract against DU-145 cells (IC50: 37.01 µg/mL). A strong correlation was observed between the highest total flavonoid content and the highest content of individual compounds in the ethanol extract, including rutin, hyperoside, isoquercitrin, delphinidin-3,5-diglucoside (delphinidin-3,5-O-diglucoside), and kaempferol-3-glucoside (kaempferol-3-O-glucoside). In the present study, the A. aduncus plant was considered a new source of antioxidants, enzyme inhibitors, and anticancer agents and could be used as a future health-benefit natural product.

Laccase Catalyzed Oxidative Polymerization of Phloridzin: Polymer Characterization, Antioxidant Capacity and α-Glucosidase Inhibitory Activity

Phloridzin is a naturally occurring dihydrochalcone with various therapeutic properties. However, its low aqueous solubility and poor enzyme inhibitory capacity have limited its application in functional foods and medicines. Inspections of the properties of natural polymeric flavonoids suggest that these limitations could be mitigated by the polymerization of phloridzin, although to date, no relevant studies have been conducted. Here, oxidative polymerization was used to prepare polymeric phloridzin using laccase as the catalyst, and its structure, antioxidant capacity and α-glucosidase inhibitory activity were characterized. The results showed that laccase catalyzed polymerization via oxidative generation of phenolic radicals in the B ring of phloridzin to achieve the polymerization. The 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity of the polymer (IC50, 0.48 mg/mL) was inferior to that of phloridzin (IC50, 0.20 mg/mL), but the α-glucosidase inhibitory activity of the polymer (IC50, 0.12 mg/mL) was significantly higher than that of phloridzin (IC50, 0.21 mg/mL). These effects could be attributed to the reduction of available phenolic groups and binding of the polymer to the enzyme, respectively.