ABSTRACT
Green synthesis and biological activity of silver nanoparticles mediated by Hypericum perforatumL. and the endemic H. malatyanum Pesmen

Elif Özbey1*
 
Plant-mediated green synthesis of nanoparticles has gained increasing attention as an environmentally friendly alternative to conventional chemical synthesis. In this study, the phytochemical properties and antioxidant capacities of Hypericum perforatum L. and the endemic H. malatyanum Pesmen were determined, and their potential for the biosynthesis of Ag nanoparticles (AgNPs) was comparatively evaluated. Hypericum malatyanum exhibited higher total phenolic content (231.4 ± 5.8 vs. 216.9 ± 4.4 mg GAE g-¹), DPPH radical scavenging activity (79.9 ± 0.9% vs. 73.8 ± 1.6%), and FRAP values (315.5 ± 8.6 vs. 269.6 ± 7.7 µmol Fe²+ g-¹) than H. perforatum, whereas H. perforatum contained higher total flavonoid content and ABTS radical scavenging activity. The biosynthesized AgNPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy analyses. The SEM images revealed predominantly spherical nanoparticles with sizes ranging from 1 to 80 nm. Antimicrobial activity was evaluated using disk diffusion and minimum inhibitory concentration (MIC) assays. The AgNPs synthesized using H. malatyanum generally exhibited stronger antimicrobial activity and lower MIC values than those synthesized using H. perforatum. The highest antimicrobial activity was observed against Bacillus spizizenii, with an inhibition zone of 7.45 ± 0.087 mm and a MIC value of 6.25 mg mL-¹. The lowest MIC value (6.25 mg mL-¹) was also recorded against Streptococcus pyogenes, Enterococcus faecalis, and Klebsiella pneumoniae for H. malatyanum-derived AgNPs. These findings demonstrate that differences in phytochemical composition among Hypericum species influence AgNP formation and biological performance and highlight endemic species as promising biological resources for the sustainable production of antimicrobial nanomaterials.
Key words: Antimicrobial activity, green synthesis, Hypericum malatyanum, Hypericum perforatum, phytochemicals, silver nanoparticles.
1Malatya Turgut Ozal University, Battalgazi Vocational School, Department of Park and Horticultural Crops Malatya, Türkiye.
*Corresponding author (elif.ozbey@ozal.edu.tr)
Received: 26 March 2026; Accepted: 15 July 2026, Available online: 8 September 2026.