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    Antibacterial and Antioxidant Activity Evaluation of Bis-Substituted İsovanillin Derivatives
    (Turkish Chemical Society, 2023) Tekin Z.; Tekeli Y.; Küçükbay Z.; Lolak N.; Yapar G.; Akocak S.
    Herein, a series of twelve bis-hydrazone substituted isovanilline derivatives 3(a-l), were freshly re-synthesized by the reaction of bis-aldehydes with substituted hydrazide derivatives since these compounds previously showed potent aldose reductase inhibition properties. The obtained compounds were tested for their potential antibacterial and antioxidant activities. In the present study, four different bacterial strains were used, including Gram-positive (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and Gram-negative (Pseudomonas aeruginosa ATCC 10231, Escherichia coli ATCC 25912). On the other hand, the antioxidant capacities of freshly re-synthesized bis-hydrazone substituted isovanilline derivatives were determined by using several antioxidant methods, including DPPH free radical scanvenging, TEAC cupric reducing (CUPRAC) and metal chelating activity methods. Several lead molecules were discovered as a potential bacterial inhibitors against S. aureus and E. coli bacterial strains. More specifically, compounds 3g (R=-H) and 3j (R=-4Cl) showed great inhibition properties against E. coli bacterial strains by having MIC values of 1.56 and 6.25 µg/mL, respectively. Moreover, none of the compounds showed potent antioxidant activity against tested methods with respect to compared standards. © 2023, Turkish Chemical Society. All rights reserved.
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    In vitro antioxidant activities of methanol extracts of three achillea species from Turkey
    (Turkish Chemical Society, 2021) Tekin Z.; Küçükbay F.Z.; Dikme A.
    In this study, total phenolics and flavonoid compounds of methanolic extract concentrations of three medicinal plant, Asteraceae (Compositae) L. genus that are grown in Turkey and belong to the genus Achillea, were determined with the goal of measuring their antioxidant activities. Antioxidant capacity was measured by widely used iron reducing power, DPPH radical scavenging activity and metal chelating capacity. The antioxidant activities of the achillea extracts used in the study were compared with the standard antioxidants (BHA, BHT and ?-tocopherol), which were frequently used as antioxidant food additives. According to the free radical scavenging activity antioxidant results, all the extracts exhibited higher DPPH radical scavenging activity than the standards used. The extract from A.boissieri showed remarkable 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (68.51% at 37.5 ?g/mL) comparable with synthetic antioxidants. The ferric reducing antioxidant power was found to be moderate in methanolic extract of Achillea species, whereas the chelating capacity of the extracts were found to be lower as compared to the standards. In addition, total phenolic, flavonoid and flavonol content of all extracts were measured spectrophotometrically and the results were expressed as "gallic acid equivalent" or "quercetin equivalent". The total phenolic content was expressed as equivalents of gallic acid and the results were observed to range from 11.86 to 23.63 mg/g dry extract weight. The total flavonoid concentrations of Achillea extracts were expressed as quercetin equivalent. Flavonoid content ranged from 15.05 to 29.70 mg/g. Total flavonol concentrations of the extracts were determined to be between 5.92 and 7.20 mg/g in terms of quercetin equivalent. This study showed that Achillea L. species, which has been used for treatment in Anatolia for years, can be used as a potential natural antioxidant source. © 2021, Turkish Chemical Society. All rights reserved.