Synergistic Bioactivity of Neem and Tulsi Infusions Treated with Plasma-Activated Water

Abstract

The integration of plasma activated water (PAW) with herbal infusions offers a sustainable approach to enhancing the functional bioactivity of plant derived compounds. In this study, neem (Azadirachta indica) and tulsi (Ocimum sanctum) infusions were treated with PAW generated using an atmospheric pressure gliding arc discharge system. The aim was to investigate plasma induced modifications in phytochemicals and their subsequent effects on antimicrobial and antioxidant properties. Spectroscopic (UV Vis, FTIR) and chromatographic (HPLC) analyses demonstrated structural alterations in key polyphenolic constituents, accompanied by mild acidification and changes in redox potential. Total phenolic content (TPC) and flavonoid levels increased significantly following 10 min PAW treatment, while prolonged exposure (15 min) led to partial degradation, suggesting an optimum treatment window. Antioxidant assays (DPPH, ABTS, FRAP) confirmed improved radical scavenging capacity, correlating with enhanced reducing power of modified phytochemicals. Antimicrobial evaluation against Escherichia coli and Staphylococcus aureus revealed synergistic inhibitory effects, with reduced minimum inhibitory concentrations (MIC) for PAW-treated infusions. Collectively, the results highlight the potential of PAW to modulate herbal bioactives, extending their efficacy in natural preservation systems and biomedical formulations. This green plasma-herbal synergy provides a promising pathway toward eco-friendly food safety and healthcare applications.