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    Investigation of Antioxidant, Antimicrobial and In Vitro Cytotoxic Effects on PC-3 Cancer Lines of Alchemilla holotricha Juz. in Different Polarities Extracts
    (2024) Kaya, Bülent; Artuvan, Yekta; Caf, Fatma; Menemen, Yusuf
    The extracts of Alchemilla holotricha Juz. with different polarities were obtained using hexane, dichloromethane, ethyl acetate, methanol, and water. The samples were further analyzed for their overall antioxidant activity, ability to scavenge DPPH free radicals, capacity to chelate metals, total reducing power, ability to scavenging hydrogen peroxide, and hydroxy radical scavenging activity. The ethyl acetate extract exhibited the highest concentration of total phenols (67.63± 0.88 mg GAE/g extract), whereas both the ethyl acetate and dichloromethane extracts demonstrated the highest levels of total flavonoids (14.82±1.02-14.82±0.03 mg CE/g extract). On the other hand, the hexane extract displayed the highest content of phenolic acids (0.72±0.21 mg SAE/g extract). The antimicrobial activity of each extract was assessed using the agar disk diffusion method. The A. holotricha strain's ethyl acetate fraction displayed the most potent antibacterial activity. The Escherichia coli exhibited the greatest antibacterial impact, measuring 17 mm, while the Klebsiella pneumoniae showed a somewhat lower effect of 15 mm. Bacillus subtilis had the highest level of resistance among the microorganisms tested, with a diameter of 8 mm. A. holotricha displayed the most potent antioxidant and antibacterial properties in the ethyl acetate extracts. The study showed that ethyl acetate, a solvent with moderate polarity, is more efficient at dissolving aromatic compounds in the above-ground portion of the plant compared to non-polar solvents like n-hexane and diethyl ether. Moreover, the water and methanol extracts exhibited cytotoxicity towards PC-3 cells at particular concentrations.
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    Magnetite Fe3O4 nanoparticles impregnated on Chlorella vulgaris microalgae: Its role in obtaining hydrogen from the sodium borohydride-hydrolysis
    (Elsevier, 2024) Duman, Sibel; Kaya, Bulent; Caf, Fatma; Kok, Osman; Tuzun, Ilhami
    Recently, the single-celled green freshwater microalgae species Chlorella vulgaris has attracted the attention of researchers due to its different usage areas. In particular, research focuses on the technology of obtaining bio-hydrogen with various techniques. This research involves, for the first time, the use of the microalga Chlorella vulgaris as a bio-supporting material for magnetite Fe3O4 3 O 4 nanoparticles (Fe3O4NPs@Chlorella 3 O 4 NPs@ Chlorella vulgaris) ) and the production of hydrogen through catalytic hydrolysis of NaBH4 4 (sodium borohydride, SB) in the presence of the resulting magnetite nanoparticles. Here, detailed kinetic studies were carried out during the SB-hydrolysis by taking magnetite Fe3O4NPs@Chlorella 3 O 4 NPs@ Chlorella vulgaris and SB in varying amounts and at varying temperatures, and the activation energy and lifetime of magnetite Fe3O4NPs@Chlorella 3 O 4 NPs@ Chlorella vulgaris was found to be 23.49 kJ mol-1- 1 and 93,280 mol H2 2 (mol Fe3O4)-1 , 3 O 4 )- 1 , respectively. No change in the chemical and physical structure of the biocatalyst was observed during the hydrolysis of SB, so only detailed characterization of microalgae and magnetite Fe3O4NPs@Chlorella 3 O 4 NPs@ Chlorella vulgaris was performed, and the particle size of the catalyst was calculated as 10.19 +/- 2.17 nm. The results showed that these Fe3O4NPs@Chlorella 3 O 4 NPs@ Chlorella vulgaris , , which can be easily separated magnetically and have high catalytic activity, are a clean and quite surprising catalyst in terms of hydrogen production.