Phytochemical Screening and In vitro Antioxidant, Antibacterial, and Antihemolytic Activities of Putoria calabrica Leaf Extracts

Background: Putoria calabrica is a common Mediterranean plant used topically in folk medicine for medical purposes. The aim of this study is to evaluate the in vitro antioxidant, antibacterial, and antihemolytic properties of Putoria calabrica leaf extracts. Methods: Total phenol content (TPC), total flavonoid content (TFC), and condensed tannins content (CTC) were determined spectrophotometrically. The antioxidant activity was tested using TAC, DPPH, ABTS, and FRAP assays. Agar diffusion method was used to determine the antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. Anti-hemolytic activity was evaluated by the measurement of erythrocytes turbidity and extracellular hemoglobin concentration using the AAPH method. Results: Methanol was the optimal solvent to extract the bioactive components with the highest extraction yield (30.11 ± 0.42%), TPC (142.11 ± 4.04 mg GAE/g dry extract) and TFC (29.16 ± 0.99 mg QrE/g dry extract). In terms of antioxidant activity, methanol extract was the most effective against ABTS free radical (IC50 = 5.02 ± 0.13 mg/ml) and FRAP (A0.5 = 2.91 ± 0.09 mg/ml). While, acetone extract showed the highest TAC (214.05 ± 8.74 mg GAE/g dry extract) and DPPH scavenging activity (IC50 = 1.94 ± 0.02 mg/ml). The strongest antimicrobial effect at a concentration of 10.24 mg/well was observed with acetone extract against P. aeruginosa (22.52 ± 0.60 mm) and C. albicans (17.33 ± 0.41 mm). While, methanol extract was the most active against S. aureus (17.31 ± 0.98 mm). Aqueous extract showed a good capacity to protect erythrocytes from oxidative damage by preventing their hemolysis and the oxidation of hemoglobin induced by AAPH. Conclusion: P. calabrica leaves hold great importance as a source of therapeutic bioactive compounds.