Microwave-Induced Enhancement of Antimicrobial and Antioxidant Activities in Six Traditional Medicinal Plant Extracts

Background: The growing threat of antimicrobial resistance (AMR) and oxidative stress-related diseases underscores the need for sustainable therapeutic alternatives. This study evaluates the antimicrobial and antioxidant properties of six medicinal plant extracts and examines the enhancement of their bioactivities through microwave-assisted treatment. Methods: Aqueous extracts were prepared from Punica granatum, Juglans regia, Matricaria chamomilla, Glycyrrhiza glabra, Pterocarpus santalinus, and Albizia lebbeck (commonly known as shrein). After extraction, samples were irradiated using microwave energy (1–5 minutes at 800 W). Antimicrobial activity was assessed against Escherichia coli and Staphylococcus aureus using the agar well diffusion method. Antioxidant activity was measured using the DPPH radical scavenging assay at 25, 50, and 100 µL extract concentrations. Statistical analysis included one-way ANOVA and factorial regression. Results: Microwave irradiation significantly enhanced both antimicrobial and antioxidant activities across all extracts. For instance, chamomile's zone of inhibition against E. coli increased from 11 mm to 14 mm, while pomegranate's DPPH inhibition improved from 72.00% to 93.00%. Pterocarpus santalinus, initially inactive, displayed a 30.00% antioxidant gain post-irradiation. Factorial regression confirmed that both microwave exposure time and extract concentration were significant predictors of antioxidant response (p < 0.05). Conclusions: Microwave irradiation provides a green, scalable method to boost the bioactivity of plant-based therapeutics. These findings support the potential of microwave-assisted phytochemicals in combating AMR and oxidative stress-related conditions.