Silver nanoparticles (AgNPs) biosynthesized using aqueous medical plant extracts as reducing and capping agents show multiple applicability for bacterial problems. The aim of this study was to expand the boundaries on AgNPs using a novel, low-toxicity, and cost-effective alternative and green approach to the biosynthesis of metallic NPs using Calendula officinalis (Calendula) and Hyssopus officinalis (Hyssopus) aqueous extracts. The formation of AgNPs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) techniques. The effectiveness of biosynthesized AgNPs in quenching free radicals and inhibiting the growth of Gram-positive and Gram-negative microorganisms was supported by in vitro antioxidant activity assay methods and using the Kirby–Bauer disk diffusion susceptibility test, respectively. The elucidated antimicrobial and antioxidative activities of medical plant extracts were compared with data from the engineered biosynthetic AgNPs. The antimicrobial effect of engineered AgNPs against selected test cultures was found to be substantially stronger than for plant extracts used for their synthesis. The analysis of AgNPs by TEM revealed the presence of spherical-shaped nano-objects. The size distribution of AgNPs was found to be plant-type-dependent. The smaller AgNPs were obtained with Hyssopus extract (with a size range of 16.8 ± 5.8 nm compared to 35.7 ± 4.8 nm from Calendula AgNPs). The AgNPs’ presumably inherited biological functions of Hyssopus and Calendula medical plants can provide a platform to combat pathogenic bacteria in the era of multi-drug resistance.

All parts of the sea buckthorn (Hippophae rhamnoides L.) plant are considered to contain large amounts of compounds that are believed to have beneficial health effects. Till now, different parts of sea buckthorn plant have been used for the treatment of diseases in traditional medicine in various countries. Nevertheless, sea buckthorn parts would be a good raw material not only for medicinal properties but also for food products with functional properties; therefore, the aim of the research was to determine the concentration of different phenolic compounds and antioxidant activity in various sea buckthorn parts. The study was conducted on parts of female and male sea buckthorn bushes. Phenolic compounds (total phenols, total flavonoids and condensed tannins) and antioxidative activity (ferric reducing antioxidant power (FRAP) free radical scavenging activity (using 2.2-diphenyl-1-picrylhydrazyl, DPPH)) in ethanolic extracts of leaves, shoots, flowers, and berries were determined using various spectrophotometric methods. The study showed that concentration of phenolic compounds differed among parts of sea buckthorn plant and among gender. Leaves of female plants proved to be the most valuable, as they contained the highest total phenol concentration (165.76 mg/g) and antioxidant activity (220.97 mg/g for FRAP and 43.76 mg/g for DPPH), while lowest values were found in young shoots of male plants (84.94 mg/g, 94.24 mg/g and 24.63 mg/g, respectively). The significant differences in chemical composition and biological activity of sea buckthorn leaves, shoots, berries, and buds indicate a need for detailed studies of their extracts, specific fractions and compounds during a whole vegetative season.