Antibiotic resistance has become one of the major problems facing humanity. The need for new antimicrobials has been increased dramatically. Plants are considered as one of the most promising sources for new antimicrobials discovery. Despite relatively small area, Armenia has large diversity of flora with many endemic species. In Armenian folk medicine plant materials have been used to treat various microbial diseases since ancient times. The goal of our research was to evaluate antimicrobial efficiency of different parts of five wild plants species which are commonly used in Armenian traditional medicine. Plant crude extracts were obtained with maceration technique using five solvents separately: distilled water, methanol, chloroform, acetone, and hexane. Agar well diffusion assay was used for initial evaluation of antimicrobial properties of plant materials against five bacterial and two yeast strains. Minimum inhibitory concentrations of the most active plant parts were determined by broth microdilution method. Crude extracts of all five tested plants expressed antimicrobial activity against at least four test strains at 500 μg ml−1 concentration. Minimum inhibitory and bactericidal/fungicidal concentrations of selected plant parts were determined. Crude acetone and hexane extracts of Hypericum alpestre and acetone extract of Sanguisorba officinalis inhibited the growth of P. aeruginosa even at 64 μg ml−1 concentration. Chloroform and acetone extracts of Sanguisorba officinalis exhibited cidal activity against P. aeruginosa till 256 μg ml−1. Acetone was the most effective solvent for solubilizing antimicrobial compounds for almost all tested plant materials. Thus, antimicrobial activity of some medicinal plants used in Armenian traditional medicine was evaluated. Some of the plants had rather low minimum bacteriostatic/bactericidal concentrations and therefore they have prospective for further more inclusive studies.

Silver nanoparticles (Ag NPs) represent one of the most widely employed metal-based engineered nanomaterials with a broad range of applications in different areas of science. Plant extracts (PEs) serve as green reducing and coating agents and can be exploited for the generation of Ag NPs. In this study, the phytochemical composition of ethanolic extract of black currant (Ribes nigrum) leaves was determined. The main components of extract include quercetin rutinoside, quercetin hexoside, quercetin glucuronide, quercetin malonylglucoside and quercitrin. The extract was subsequently employed for the green synthesis of Ag NPs. Consequently, R. nigrum leaf extract and Ag NPs were evaluated for potential antibacterial activities against Gram-negative bacteria (Escherichia coli ATCC 25922 and kanamycin-resistant E. coli pARG-25 strains). Intriguingly, the plant extract did not show any antibacterial effect, whilst Ag NPs demonstrated significant activity against tested bacteria. Biogenic Ag NPs affect the ATPase activity and energy-dependent H⁺-fluxes in both strains of E. coli, even in the presence of N,N’-dicyclohexylcarbodiimide (DCCD). Thus, the antibacterial activity of the investigated Ag NPs can be explained by their impact on the membrane-associated properties of bacteria.

This study focuses on the investigation of the antioxidant and anti-inflammatory activities of alcohol extracts from Ribes nigrum leaves on murine BV-2 microglial Wt and Acyl-CoA oxidase 1 deficient (Acox1−/−) cell line models, useful for the investigation of some neurodegenerative disorders. The extract chemical composition was analyzed via LC-Q-Orbitrap HRMS. Various assays, including DPPH, MTT, and H2DCFDA, were used to assess the extract’s antioxidant capacity, cell viability, and reactive oxygen species (ROS) production. Immunoblotting and RT-qPCR techniques were employed to measure protein expression and gene transcription in treated cells. Statistical analysis was conducted using GraphPad Prism, with significance determined at p < 0.05. Investigations showed the presence of phenolic compounds in this extract, among which flavan-3-ols, flavonols, furanocoumarins, hydroxycinnamates were major components, which are known for their biological activity in various test systems. The MTT test revealed a concentration of 0.125 mg/mL of R. nigrum extract as the highest non-toxic. The investigated extract showed high antioxidant activity in chemical-based tests. The antioxidant potential of the R. nigrum leaf extract was furtherly explored using the BV-2 microglial cell line models. Moreover, the extract was found to alter the activity of the main antioxidant enzyme, catalase and fatty acid oxidation enzyme, Acyl-CoA oxidase 1 (ACOX1) as well as the expression of appropriate genes in Wt and Acox1−/− BV-2 microglial cells such as Cat, iNos, Il-1β, Tnf-α, and Abcd1. In Wt cells, after the 24-hour treatment with R. nigrum leaf extract, ACOX1 activity was downregulated, meanwhile the catalase activity remains unchanged. Further treatment led to the downregulation of catalase and the upregulation of ACOX1 activity. However, in Acox1−/− cells, which represent a model of oxidative stress, an increase in catalase activity was observed only after 48 h of treatment. It was also observed the reduced ROS and NO formation in cells, showing the pronounced antioxidant capacity of R. nigrum extract in the investigated cell-models. Our study demonstrated the protective effects of R. nigrum leaf extracts on BV-2 microglial cells by reducing oxidative and nitrosative stress, decreasing pro-inflammatory gene expression, and normalizing peroxisomal function, highlighting the potential of these extracts as therapeutic agents for managing oxidative stress and inflammation.