Flavonoid content and antifungal activity of Celastrus hindsii leaf extract obtained by supercritical carbon dioxide using ethanol as co-solvent

In this study, flavonoids were extracted from Celastrus hindsii (C. hindsii) leaf using the supercritical carbon dioxide (CO2) technique with ethanol as a co-solvent. Accordingly, the experimental results revealed the most appropriate conditions for the extraction process were acquired at an extraction duration of 2 h, an ethanol volume of 10 mL, 300 bar of pressure, and 60 °C of temperature, which provided a flavonoid content of approximately 6.51 mg quercetin equivalents/g of dry matter (mg QUE/g). Furthermore, the efficient extraction scheme was confirmed via alterations of functional components in Fourier-transform infrared spectroscopy, signifying the presence of flavonoids in the extract compared to the raw material. Meanwhile, the differences in the corrupted morphological structure through scanning electron microscope also validated the interaction of the CO2-ethanol flow with the cellulosic matrix of C. hindsii. Besides, the antimicrobial activity of the prepared extract was evaluated against Fusarium oxysporum fungus using the disc diffusion method, which elucidated a potentially good inhibitory zone towards the surveyed strain. Therefore, the aforementioned results show the promising applicability of the CO2-ethanol-assisted extract, particularly in the medicinal sectors.