Synergistic Antimicrobial and Antioxidant Activity of Saponins-Rich Extracts from Paronychia argentea and Spergularia marginata

Abstract

Aims: The crude saponins extracted from the aerial parts of Paronychia argentea and the roots of Spergularia marginata were tested for their antioxidant, antimicrobial and synergistic effects with antibiotics. Methodology: Antioxidant activity was evaluated using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical, β-carotene-linoleic acid and reducing power assays. However, the antibacterial activity was assessed by the agar disc diffusion method, whereas the MIC determination and the synergistic interaction with antibiotics were evaluated using microdilution method. Results: Saponins-rich extract from Paronychia argentea showed a higher antioxidant activity than that from Spergularia marginata. Using DPPH assay, the IC50 values for saponins-rich extracts from P. argentea and S. marginata were 19.08 and 29.65 µg/ml, respectively. For β-carotene-linoleic acid assay, IC50 values were 98.24 and 614 µg/ml respectively for P. argentea and S. marginata. However, for reducing power assays, the IC50 values for saponins-rich extracts from P. argentea and S. marginata were respectively 27.22 and 61.44 µg/ml. The result of MIC assay showed that both saponins-rich extracts was found to be active against the majority of Candida strains and Gram-positive bacteria. However, crude saponins extracted from S. marginata was more active on microorganisms than that from P. argentea. In fact, the in vitro association of saponin extracts and some commercial antibiotics showed a synergistic effect. For bacteria strains, 30 combinations were studied, 17 (56.66%) combinations had total synergism, 7 (23.33%) had partial synergism, 4 (13.33%) had no effect and 2 (6.66%) had antagonism effect. For Candida strains, 8 combinations of saponins extracts and fluconazol are tested. All of these combinations (100%) exhibited a total synergism with FICi ranging from 0,31 to 0,50. Conclusion: The results founded suggested that further work should be performed on the isolation and identification of the antioxidative and antimicrobial components of these saponins-rich extracts.