Phytomedicine Plus (Feb 2023)
Anti-MRSA potential of biogenic silver nanoparticles synthesized from hydroponically grown Foeniculum vulgare
Abstract
Background: Antimicrobial-resistant superbugs are rapidly spreading globally. Methicillin-resistant Staphylococcus aureus (MRSA) is one of these superbugs for which effective antibiotics are urgently required. The development of resistance against synthetic compounds has led to the study and utilization of plant based antimicrobial options due to a greater sensitivity against the phytochemcials obtained from them. Fennel (Foeniculum vulgare), a therapeutic, aromatic and nutritionally important herb that grows worldwide has a number of phytochemicals of medicinal importance. These phytochemicals also have the potential to reduce Ag+ to Ag0, thereby, making them available for the green synthesis of silver nanoparticles. Usually, fennel grows under cool environment in well-drained soil. However, it is possible to grow it hydroponically in soilless conditions using water-based mineral nutrient solutions. The technique helps in attaining higher yields of plant biomass and, hence, the phytochemicals. Purpose: This study aimed to prepare a silver nanoparticles based formulation against MRSA-induced skin and soft tissue infections, by using fennel extract (FEHydro) obtained from hydroponically grown plants for better biomass and higher phytochemical content. Methods: Plants grown in hydroponic system were compared with soil grown for growth rate and phytochemical content. Spectrophotometric comparison of total flavonoids, phenols, alkaloids, tannins, carbohydrates, proteins and lipids was carried out between hydroponic fennel extract (FEHydro) and soil grown fennel extract (FESoil). After establishing the efficacy of the hydroponically grown plants, their extract FEHydro was used for AgNPs green synthesis. Fennel extract fabricated AgNPs (FEHydroNP) were tested in vitro against MRSA through disc diffusion, turbidometric and time kill assays. The fennel extract (FEHydro) and AgNPs (FEHydroNP) were, then, formulated in a polyvinyl pyrrolidone and ethylene cellulose (PVP-EC) hydrogel and characterized through in vivo burn model in BALB/c mice. Results: The hydroponic system was found to give efficient plant biomass turnover with phytochemical content comparable to soil cultivated fennel. Hydroponic fennel gained 0.81 inches more height per week and 1.23 more secondary branches per week than soil cultivated fennel. Spherical AgNPs were successfully obtained from the fennel extract of hydroponically grown plants. Moreover, enhanced in vitro anti-MRSA potential of FE NPs was observed with MIC 625 µg/ml and MBC 12,500 µg/ml. In vivo infection elimination in 7 days and skin reepithelization were observed in gross examination and through Hematoxylin & Eosin (H&E) stained slides of treated mouse skin biopsy samples. Conclusion: This study suggests that the green-synthesized silver nanoparticles of Fennel showed a strong antibacterial effect against the clinical isolates of MRSA, both in vitro and in vivo, thereby, suggesting their potential use in plant-based complementary and alternative medicine.
