Ultrasound-assisted extraction of phenolic compounds from Azolla filiculoides using Taguchi method: Antioxidant and antibacterial capabilities

In the present study, ultrasonication was applied to extract phenolic compounds from Azolla filiculoides. This may due to its ability to combine ultrasonication and the commonly solvent extraction to improve the output and degree of selectivity and quality extract. Three factors consisting of sonication time, solvent and ratio of dry powder to solvent were optimized by the Taguchi experimental design. However, the optimized conditions by the highest extraction yield were an extraction time of 10 min, solvent extraction of water, and dry powder to the solvent ratio (1:10). Moreover, the parametric evaluation showed that sonication time had no significant effect on TPC (p>0.05), while the dry powder to solvent ratio showed a significant effect on TPC (p<0.05). The highest degree of DPPH, ABTS and metal chelating was 14.68±2.05, 74.40±8.50 and 56.74±1.01, respectively. The results of the antibacterial properties of all treatments against two Gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) and two Gram-negative bacteria (Escherichia coli and Salmonella enterica) showed a significant effect on all treatments (p<0.05). These results indicated that the ultrasound method could be used to extract phenolic compounds from A. Filiculoides. Also, A. filiculoides can be applied as a source of antioxidants and antibacterial compounds.