Green Synthesis of Silver Nanoparticles from Diospyros villosa Extracts and Evaluation of Antioxidant, Antimicrobial and Anti-Quorum Sensing Potential

The biosynthesis of silver nanoparticles (AgNPs) from Diospyros villosa leaves and stem bark extracts is described. The stem bark AgNPs of D. villosa synthesized at 80 °C (S80) showed good scavenging activity with a lower IC(50) value of 8.75 µg·mL(−1) compared to ascorbic acid (9.58 µg·mL(−1)). The total phenol content of the S80 AgNPs was measured and found to be 10.22 ± 0.14 mg.g(−1) gallic acid equivalence (GAE). Bacterial growth inhibition (% GI) and violacein inhibition (% VI) of 10.08% and 58.83%, respectively, was observed against C. subtsugae CV017 with leaf AgNPs synthesized at 80 °C (L80) at 80 μg·mL(−1). Stem bark AgNPs synthesized at room temperature (SRT) also indicated % GI of 13.83% and % VI of 65.97% against C. subtsugae CV017 at 160 μg·mL(−1). Leaf AgNPs of D. villosa synthesized at room temperature (LRT), showed % GI of 29.07% and % VI of 56.53%, respectively, against C. violaceum ATCC 12472 at 320 μg·mL(−1). The L80 and SRT at 160 μg·mL(−1) and LRT at 320 μg·mL(−1) may be considered as potential QS inhibitors following their activity against C. subtsugae CV017 and C. violaceum ATCC 12472, respectively. Therefore, D. villosa represents a potential source of antioxidants as well as an anti-quorum sensing therapeutic candidate for the control of Gram-negative bacterial infections.