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    Comparison of antidiabetic and antioxidant activities of sweet and bitter apricot kernels
    (Mattioli 1885, 2021) Kaya, Gulsen; Keskin, Merve
    Fruits and their kernels have important phytochemical components for human health and nutrition. The fruits and their kernels have antioxidant effects by their seconder metabolites. Apricot (Prunus armeniaca L.) is an important fruit because of its functional properties with both its fruits and kernels. Therefore, in this study, total phenolic, flavonoid content, ferric reducing antioxidant power (FRAP) and inhibition properties of a-amylase enzyme of fruit, sweet and bitter apricot kernels were investigated. Methanol extract of each part of this fruit was prepared respectively. Total phenolic content as 241.83 +/- 1.47; 118.15 +/- 2.03 and 60.41 +/- 0.97 mg GAE/100 g, flavonoid content as 177.05 +/- 1.68; 20.08 +/- 0.63 and 32.16 +/- 0.51 mg QE / 100 g; antioxidant capacity as 0.81 +/- 0.02; 0.66 +/- 0.01 and 0.27 +/- 0.02 mM Fe2+/ mL extract were determined respectively. IC50 values for alpha amylase inhibition were calculated as 1.30 +/- 0.02; 0.74 +/- 0.01 and 3.17 +/- 0.01 mg/mL for fruit, sweet and bitter kernel extract respectively. The extracts showed good amylase inhibition properties. It can be concluded that apricot fruit and kernels might be used as a food supplement in Diabetes mellitus.
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    Green Synthesis, Characterization, Antioxidant, Antibacterial and Enzyme Inhibition Effects of Chestnut (Castanea sativa) Honey-Mediated Silver Nanoparticles
    (Mdpi, 2023) Keskin, Merve; Kaya, Gulsen; Bayram, Sinan; Kurek-Gorecka, Anna; Olczyk, Pawel
    In this study, chestnut honey-based silver nanoparticles (CH-AgNPs) were synthesized at different temperatures (30, 60 and 90 degrees C) and these nanoparticles were characterized by different techniques such as UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The DPPH free radical scavenging assay was used to determine the antioxidant activity of the obtained nanoparticles. The inhibition effects of these nanoparticles for some clinically important enzymes such as myeloperoxidase and collagenase were investigated. In addition, the disk diffusion method (DDM), agar well diffusion (AWD), and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) techniques were used to determine the antibacterial activity of CH-AgNPs. In honey-based silver nanoparticle production processes using green synthesis, it was determined that the nanoparticle sizes decreased from 55 to 27 nm with an increase in temperature. In addition, it was determined that the rate of inhibition of myeloperoxidase (36.4% to 34.0%) and collagenase enzymes (74.2% to 68.7%) increased with a decrease in particle size. As a result of the antibacterial activity tests, it was observed that CH-AgNPs have antibacterial activity against all target pathogens including Gram-positive and Gram-negative bacteria. The obtained results show that CH-AgNPs produced using chestnut honey have the potential to be used in fields such as medicine, pharmacy and cosmetic technology.
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    Gundelia Tournefortii L. (Kenger): Determination of in vitro Antidiabetic Activities
    (Mattioli 1885, 2021) Keskin, Merve; Kaya, Gulsen; Keskin, Saban
    Diabetes mellitus is a chronic disease that negatively effects daily life. Synthetic drugs, which are inhibitors of alpha-glucosidase and alpha-amylase enzymes, are used in its treatment. These drugs may have adverse reaction on organs such as the liver. Therefore, it is important to include plants that inhibit these enzymes in the diet in the treatment of Diabetes mellitus. Gundelia tournefortii L. (Kenger) is an edible wild natural plant that is widely used as traditional food. In this study, biochemical characterization of the Gundelia tournefortii L. (Kenger) extracts was performed. The inhibition effect of the extract on alpha-amylase and alpha-glycosidase enzymes was also investigated. Total phenolic content, antioxidant activity and chemical composition of Gundelia tourneforti L. extracts were determined. Chemical composition of extracts was determined by using GC/MS technique. IC50 values of alpha-amylase and alpha-glucosidase enzymes of the Gundelia tournefortii L. ethanolic extracts of stalk were determined as 4.18 +/- 0.08 mg/mL and 9.77 +/- 1.2 mg/mL, respectively. The results showed that Gundelia tournefortii L. could be used as a supplementary food in the treatment of Type 2 diabetes.