Assessment of antioxidant, antimicrobial, antibiofilm, carbonic anhydrase and α-glucosidase inhibitory activities of Alchemilla vulgaris L. extracts

This study was to investigate the biological properties (antioxidant, enzyme inhibitory and antimicrobial activity) of water extract (WE), 50:50% water:ethanol extract (WEE) and ethanol extract (EE) of aerial parts of Alchemilla vulgaris L. which was traditionally used to alleviate and treat many diseases. The WEE extract exhibited the highest total phenolic content (TPC), with a value of 612 µg/mL GAE, while the EE extract demonstrated the highest total flavonoid content (TFC), with a value of 0.086 µg/mL GAE. Also, the data demonstrated that the WEE extract exhibited the highest radical scavenging capacities and antioxidant activities, exhibiting 0.0056, 0.0028 mg/mL SC50 and 267, 0.081 μM TEAC, as determined by the DPPH, ABTS, FRAP and CUPRAC assays, respectively. The WEE extract was found to be an effective bovine carbonic anhydrase (BCA) and α-glucosidase inhibitor with an IC50 values of 0.0628 and 0.0535 mg/mL, respectively. The EE extract showed activity against both Gram-negative and Gram-positive bacteria used in the study. EE extract has the highest activity against Yersinia pseudotuberculosis and the lowest activity against Streptococcus pyogenes. Furthermore, the extracts significantly reduced the biofilm ability of Acinetobacter baumannii isolate, which has strong biofilm ability. EE and WE reduced the biofilm formation capacity of the strain to a weak level, while WEE extract reduced it to a moderate level. The results suggest that EE has a significant effect in combating antibiotic resistance, while WEE has high antioxidant activity and good inhibitory effect against BCA and α-glycosidase enzymes. In addition, the results revealed that solvent extracts with different solvent composition and polarity may have different effects on diverse bioactivity tests.