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    Bioactivity guided fractionation for investigation of antidiabetic activity on the different Origanum species from the Brevifilamentum section
    (Marmara Univ, Fac Pharmacy, 2025) Tanriverdi, Basak; Sen, Ali; Sadikoglu, Narin; Bitis, Leyla
    The aim of this study was to evaluate antidiabetic activities of Origanum bargyli (OB), Origanum haussknechtii (OH), Origanum rotundifolium (OR) species from Brevifilamentum section of genus Origanum and to investigate their roles in diabetes with the support of their antioxidant effects. Antidiabetic activities on OB, OH, and OR were investigated for the first time in the present study. DPPH and ABTS radicals scavenging, alpha-glucosidase inhibition methods were performed for antioxidant, antidiabetic activities, respectively. OB (12.70 and 32.62 mu g/mL) and OR (10.61 and 32.28 mu g/mL) exhibited strong antioxidant activity against DPPH and ABTS radicals with remarkable IC50 values. The amounts of total phenolic and total flavonoid compounds of OB, OH and OR were 67.55, 68.97, 68.93 mg/g and 48.46, 40.54 and 62.28 mg/g, respectively. Whereas OH and OR showed IC50 values of 259 and 404 mu g/mL for antidiabetic activity, OB was found to be the most antidiabetic active species, showing more significant inhibitory activity against alpha-glucosidase enzyme than the standard with an IC50 value of 204.20 mu g/ml. Therefore, the OB ethanol extract was fractionated with solvents of different polarity (hexane, chloroform and ethyl acetate, respectively). In the fractions of OB species, chloroform fraction(OBC) showed a much higher inhibitory activity against alpha-glucosidase enzyme with an IC50 value of 126.50 mu g/mL compared to the standard acarbose (261.7 mu g/mL) and was found to be the most antidiabetic active fraction. These results suggest that OB species with significant antidiabetic and antioxidant activity may play a good potential role in developing new herbal medicines against diabetes.
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    In vitro screening for antioxidant and antimicrobial properties of five commercial Origanum species from Turkey
    (Natl Inst Science Communication-Niscair, 2017) Taskin, Turgut; Sadikoglu, Narin; Birteksoz-Tan, Seher; Bitis, Leyla
    The present study was conducted to evaluate the antioxidant and antimicrobial properties of methanol extracts of the five Origanum species, which are commercial importance in Turkey. Antioxidant activity was measured employing three methods namely, DPPH free radical scavenging activity, ABTS(+) radical cation scavenging activity and ferric reducing antioxidant/power activity, including total phenolic and total flavonoid contents. In addition, antimicrobial activities of methanol extracts from five Origanum species aerial parts were investigated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Candida albicans test organisms using the disk diffusion and microdilution methods. Antioxidant studies suggested that methanol extracts behaved as a strong DPPH free radical, ABTS radical cation scavenging activity and ferric reducing antioxidant/power activity. The antimicrobial test results showed that the methanol extracts of all Origanum species had great potential of antibacterial activity against Staphylococcus aureus. As a conclusion of this study, the methanol extracts of five Origanum species showed strong antioxidant and antibacterial activity and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry.