Ultrasound-assisted extraction of antimicrobial compounds from Thymus daenensis and Silybum marianum: Antimicrobial activity with and without the presence of natural silver nanoparticles
Mohammad Safarpoor, Mehrorang Ghaedi, Arash Asfaram, Masoumeh Yousefi-Nejad, Hamedreza Javadian, Hossein Zare Khafri, Marzieh Bagherinasab
Department of Chemistry, Yasouj University, Yasouj 75918-74831, Iran.
The present study is devoted to prepare a new antibacterial and antifungal agent based on in situ-synthesized silver nanoparticles at room temperature using Rosmarinus officinalis (R. officinalis) leaf extract. The Ag-NPs characterization by UV-visible, SEM, TEM and XRD revealed that the particles sizes were in the range of 10–33 nm. In this study, hydroalcoholic extracts were used with ultrasonic method. Ultrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. The antimicrobial activities of T. daenensis and S. marianum extracts with and without the presence of Ag-NPs were investigated at concentrations from 12.5 to 50 mg/mL against Staphylococcus aureus (S. aureus, Gram-positive organism) and Escherichia coli (E. coli, Gram-negative organism), and fungal strains were Aspergillus oryzae (A. oryzae) and Candida albicans (C. albicans). Antimicrobial activity determined using agar disc diffusion method revealed that the activities of Ag-NPs/T. daenensis were superior to Ag-NPs/S. marianum and extracts (T. daenensis and S. marianum). The medicinal plant extract can be used to synthesize the Ag-NPs as an eco-friendly and inexpensive method in large scale. The results showed that the prepared Ag-NPs/extracts as good antibacterial and antifungal agents can be potentially applied against rapidly increasing of antibiotic resistance.
Keywords: Ultrasonic-assisted extraction, Antimicrobial activity, Disc diffusion, Green synthesis, Silybum marianum, Thymus daenensis.