Chemical composition and antimicrobial activity of essential oils and various extracts of endemic Onosma malatyana (Boraginaceae) from Anatolia.

The chemical contents of the endemic Onosma malatyana roots collected from Malatya/Türkiye were determined using the hydrodistillation and the soxhlet methods and antimicrobial activity analysis of the extracts was also performed. The hydrodistillation method applied to the roots of O.malatyana resulted in identifying 31 compounds according to their retention times in GC-MS analysis. Additionally, crude ethyl acetate and crude oil etheric extracts of O.malatyana roots contained 14 compounds each. This research identified that the main component of the essential oil obtained by the hydrodistillation method was palmitic acid comprising 56.48% of the total composition. Additionally, in the crude petroleum etheric extract, oleic acid methyl ester (31.22%); and palmitic acid (24.69%) were identified as the main components in the crude ethyl acetate extract. The results of the antimicrobial activities indicated that O.malatyana root extracts were particularly effective against Gram-positive bacteria, specifically S. aureus and B. subtilis.

The study, conducted for the first time, sheds detailed light on the chemical composition and antimicrobial activity of Onosma malatyana roots, highlighting the potential pharmacological importance of the plant.The research, carried out using hydrodistillation and Soxhlet extraction methods, emphasizes the chemical diversity of the plant by identifying various organic compounds, particularly prominent ones such as palmitic acid.Antimicrobial tests show strong inhibitory effects, especially against Gram-positive bacteria like S.aureus and B.subtilis. This indicates the potential of crude petroleum etheric extract as a natural antimicrobial agent.The findings allow for a better understanding of the chemical diversity and pharmacological potential of O. malatyana, enabling future research to target the plant's phytochemical profile, antimicrobial compound mechanisms, and optimization of cultivation practices.

Synthesis of Graphene Quantum Dot Magnesium Hydroxide Nanocomposites and Investigation of Their Antioxidant and Antimicrobial Activities.

In this paper, we synthesized graphene quantum dots magnesium hydroxide nanocomposites (GQDs/Mg(OH)2). The synthesized nanocomposites were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Malvern Zetasizer. The antimicrobial and antioxidant properties of the obtained GQDs/Mg(OH)2 nanocomposites were investigated. GQDs/Mg(OH)2 nanocomposites have MIC values of 15.625 µg/mL against fungi (C. metapsilosis and C. parapsilosis) and 62.5 µg/mL against Gram (+) (S. pneumonia and E. faecalis) and Gram (-) (E. coli). The synthesized GQDs/Mg(OH)2 nanocomposites showed moderate antioxidant activity. The results showed that at 100-µg/mL GQDs/Mg(OH)2 nanocomposite concentration, the H2O2 scavenging activity was 62.18%.

Green synthesis of silver nanoparticles using pollen extract: Characterization, assessment of their electrochemical and antioxidant activities.

In the present study, a simple, cheaply and environmental friendly method was evaluated for the synthesis of silver nanoparticle via Cupressus sempervirens L. (CSPE) pollen extract as reducing and stabilizing agent. Various parameters such as volume of CSPE, temperature and reaction time on AgNPs formation were investigated spectrophotometrically to optimize reaction conditions. The electrochemical behavior of the biosynthesized AgNPs were investigated by cyclic voltammetry and square wave voltammetry techniques. An electrosensor based on AgNPs modified glassy carbon electrode were constructed and tested on electro reduction of hydrogen peroxide in phosphate buffer medium. The prepared electrosensor could detect the H2O2 in the range of 5.0 µM - 2.5 mM with a detection limit of 0.23 µM. In addition, the antioxidant activity of biosynthesized AgNPs were evaluated against DPPH free radical. Results obtained from the antioxidant study suggested that CSPE mediated AgNPs exhibit a good antioxidant effect.