<i>In Vitro</i> Antibacterial and Antifungal Studies of <i>Pulicaria undulate</i> and <i>Echinacea purpurea</i> Extracts in Combination with Nanowires (Ni:FeO(OH)) and Nanoparticles (NiS)

Abstract

Background: Due to the presence of many antimicrobial-resistant pathogens, researchers are trying to substitute antibacterial drugs with other nanostructures and medicinal plants. Objectives: This study aimed to assess the antibacterial/antifungal and DNA cleavage characteristics of Pulicaria undulate and Echinacea purpurea extracts with/without Ni:FeO(OH) nanowires and NiS nanoparticles. Methods: The antimicrobial activities of extracts in combination with nanostructures were assessed using MIC, MBC, and disc diffusion methods against Aspergillus oryzae, Candida albicans, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis and DNA electrophoresis methods against E. coli. Also, the chemical constituents of extracts and the structures of nanowires/nanoparticles were analyzed by GC-MS and X-ray/SEM, respectively. Results: The main constituents of Pulicaria undulate and Echinacea purpurea extracts were Nonadecane (13.8%) and phytol (17.7%), respectively, in GC analysis. In the disc diffusion method, Ni:FeO (OH)-NW had more effects on Gram-positive bacteria and NiS-NP showed antibacterial effects on Gram-negative bacteria. Also, the combination of Echinacea purpurea and NiFeO(OH) had the most antibacterial effects on Pseudomonas aeruginosa and Staphylococcus aureus (19 and 20 mm, respectively). The lowest MIC effects were seen for Pulicaria undulate and NiS (0.195 mg/mL) against E. coli. Also, the lowest MBC effects were seen for Echinacea purpurea and Ni-doped FeO(OH) against Staphylococcus aureus (0.195 mg/mL). The combination of NiS-NP and Pulicaria undulate had the most DNA cleavage effect. Conclusions: The combination of Pulicaria undulate and Echinacea purpurea extracts with nanostructures was effective to eliminate the bacteria. Therefore, the synergistic effect of the combination of plant extracts and nanoparticles brings about new options for the treatment of microbial diseases.