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Öğe Cultivable sponge-associated actinobacteria: Phylogenetic diversity and antimicrobial activities(Elsevier Science Bv, 2012) Oner, Ozlem; Ekiz, Guner; Hames-Kocabas, E. Esin; Demir, Volkan; Gube, Ozkan; Ozkaya, F. Can; Yokes, M. Baki; Uzel, Atac; Bedir, ErdalÖğe A new 5,6-dihydro-2-pyrone derivative from Phomopsis amygdali, an endophytic fungus isolated from hazelnut (Corylus avellana)(Elsevier, 2014) Akay, Seref; Ekiz, Guner; Kocabas, Fatma; Hames-Kocabas, E. Esin; Korkmaz, Kemal S.; Bedir, ErdalAims of this study were to isolate endophytes from different parts of hazelnut - Corylus avellana L. to obtain bioactive secondary metabolites and search for the presence of gene region of taxadiene synthase (Ts), a key enzyme in taxol biosynthesis, on selected fungi. Fourteen fungal species were isolated and cultured for the screening studies. The cell-free fermentation broths were extracted with chloroform. The chloroform extracts were tested for cytotoxic activity by MTT method. Based on the activity results and chemical profiles, the isolate identified as Phomopsis amygdali by internal transcribed spaces (ITS) sequence analysis using ITS1 primer was selected for further studies. After large-scale fermentation and purification studies, two major compounds, one of which turned out to be a new secondary metabolite, were isolated and characterized. Structure of the new metabolite was elucidated as (S)-4-butoxy-6-((S)-1- hydroxypentyl)-5,6-dihydro-2H-pyran-2-one by the extensive use of 1D and 2D NMR, and HR-MS, whereas the known compound was identified as (-) pestalotin. Additionally, to evaluate taxol-producing potential of the selected isolate, a PCR amplification study followed by gel electrophoresis analysis was carried out revealing no Ts gene region. (C) 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.Öğe Telomerase activators from 20(27)-octanor-cycloastragenol via biotransformation by the fungal endophytes(Academic Press Inc Elsevier Science, 2021) Duman, Seda; Ekiz, Guner; Yilmaz, Sinem; Yusufoglu, Hasan; Kirmizibayrak, Petek Ballar; Bedir, ErdalCycloastragenol [20(R),24(S)-epoxy-3 beta,6 alpha,16 beta,25-tetrahydroxycycloartane] (CA), the principle sapogenol of many cycloartane-type glycosides found in Astragalus genus, is currently the only natural product in the anti-aging market as telomerase activator. Here, we report biotransformation of 20(27)-octanor-cycloastragenol (1), a thermal degradation product of CA, using Astragalus species originated endophytic fungi, viz. Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae and Camarosporium laburnicola. Fifteen new biotransformation products (2-16) were isolated, and their structures were established by NMR and HRESIMS. Endophytic fungi were found to be capable of performing hydroxylation, oxidation, ring cleavage-methyl migration, dehydrogenation and Baeyer-Villiger type oxidation reactions on the starting compound (1), which would be difficult to achieve by conventional synthetic methods. in addition, the ability of the metabolites to increase telomerase activation in Hekn cells was evaluated, which showed from 1.08 to 12.4-fold activation compared to the control cells treated with DMSO. Among the compounds tested, 10, 11 and 12 were found to be the most potent in terms of telomerase activation with 12.40-, 7.89- and 5.43-fold increase, respectively (at 0.1, 2 and 10 nM concentrations, respectively).Öğe Two rare quinone-type metabolites from the fungus Septofusidium berolinense and their biological activities(Japan Antibiotics Research Assoc, 2016) Ekiz, Guner; Hames, Elif Esin; Nalbantsoy, Ayse; Bedir, Erdal
