Bioengineering / Biyomühendislik

Permanent URI for this collectionhttps://hdl.handle.net/11147/4529

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Author: search.filters.author.Yılmaz, SinemInstitution Author: search.filters.institutionAuthor.Bedir, Erdal

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Now showing 1 - 6 of 6
  • Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Potent Telomerase Activators From a Novel Sapogenin Via Biotransformation Utilizing Camarosporium Laburnicola, an Endophytic Fungus
    (BioMed Central Ltd., 2023) Küçüksolak, Melis; Yılmaz, Sinem; Yılmaz, Sinem; Bedir, Erdal; Ballar Kırmızıbayrak, Petek; Küçüksolak, Melis; Bedir, Erdal; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    BACKGROUND: Cycloartane-type triterpenoids possess important biological activities, including immunostimulant, wound healing, and telomerase activation. Biotransformation is one of the derivatization strategies of natural products to improve their bioactivities. Endophytic fungi have attracted attention in biotransformation studies because of their ability to perform modifications in complex structures with a high degree of stereospecificity. RESULTS: This study focuses on biotransformation studies on cyclocephagenol (1), a novel cycloartane-type sapogenin from Astragalus species, and its 12-hydroxy derivatives (2 and 3) to obtain new telomerase activators. Since the hTERT protein levels of cyclocephagenol (1) and its 12-hydroxy derivatives (2 and 3) on HEKn cells were found to be notable, biotransformation studies were carried out on cyclocephagenol and its 12-hydroxy derivatives using Camarosporium laburnicola, an endophytic fungus isolated from Astragalus angustifolius. Later, immunoblotting and PCR-based ELISA assay were used to screen starting compounds and biotransformation products for their effects on hTERT protein levels and telomerase activation. All compounds showed improved telomerase activation compared to the control group. CONCLUSIONS: As a result of biotransformation studies, seven new metabolites were obtained and characterized, verifying the potential of C. laburnicola as a biocatalyst. Additionally, the bioactivity results showed that this endophytic biocatalyst is unique in transforming the metabolites of its host to afford potent telomerase activators. © 2023. The Author(s).
  • Article
    Citation - WoS: 13
    Citation - Scopus: 15
    The Role of Cycloastragenol at the Intersection of Nrf2/Are, Telomerase, and Proteasome Activity
    (Elsevier, 2022) Yılmaz, Sinem; Bedir, Erdal; Yılmaz, Sinem; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Aging is well-characterized by the gradual decline of cellular functionality. As redox balance, proteostasis, and telomerase systems have been found to be associated with aging and age-related diseases, targeting these systems with small compounds has been considered a promising therapeutic approach. Cycloastragenol (CA), a small molecule telomerase activator obtained from Astragalus species, has been reported to positively affect several age-related pathophysiologies, but the mechanisms underlying CA activity have yet to be reported. Here, we presented that CA increased NRF2 nuclear localization and activity leading to upregulation of cytoprotective enzymes and attenuation of oxidative stress-induced ROS levels. Furthermore, CA-mediated induction of telomerase activity was found to be regulated by NRF2. CA not only increased the expression of hTERT but also its nuclear localization via upregulating the Hsp90-chaperon complex. In addition to modulating nuclear hTERT levels at unstressed conditions, CA alleviated oxidative stress-induced mitochondrial hTERT levels while increasing nuclear hTERT levels. Concomitantly, H2O2-induced mitochondrial ROS level was found to be significantly decreased by CA administration. Our data also revealed that CA strongly enhanced proteasome activity and assembly. More importantly, the proteasome activator effect of CA is dependent on the induction of telomerase activity, which is mediated by NRF2 system. In conclusion, our results not only revealed the cross-talk among NRF2, telomerase, and proteasome systems but also that CA functions at the intersection of these three major aging-related cellular pathways.
  • Article
    Citation - WoS: 24
    Citation - Scopus: 23
    Polyethers Isolated From the Marine Actinobacterium Streptomyces Cacaoi Inhibit Autophagy and Induce Apoptosis in Cancer Cells
    (Elsevier, 2019) Khan, Nasar; Tosun, Çiğdem; Yılmaz, Sinem; Bedir, Erdal; Aksoy, Semiha; Yılmaz, Sinem; Uzel, Ataç; Tosun, Çiğdem; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 04.03. Department of Molecular Biology and Genetics; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Polyether compounds, a large group of biologically active metabolites produced by Streptomyces species have been reported to show a variety of bioactivity such as antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Since some of these compounds target cancer stem cells and multi-drug resistant cancer cells, this family of compounds have become of high interest. In this study, three polyether-type metabolites (1-3), one of which was a new natural product (3), were isolated from the marine derived Streptomyces cacaoi via antimicrobial activity-guided fractionation studies. As several polyether compounds with structural similarity such as monensin have been linked with autophagy and cell death, we first assessed the cytotoxicity of these three compounds. Compounds 2 and 3, but not 1, were found to be cytotoxic in several cell lines with a higher potency towards cancer cells. Furthermore, 2 and 3 caused accumulation of both autophagy flux markers LC3-II and p62 along with cleavage of caspase-3, caspase-9 and poly (ADP-ribose) polymerase 1 (PARP-1). Interestingly, prolonged treatment of the compounds caused a dramatic downregulation of the proteins related to autophagasome formation in a dose dependent manner. Our findings provide insights on the molecular mechanisms of the polyether-type polyketides, and signify their potency as chemotherapeutic agents through inhibiting autophagy and inducing apoptosis.
  • Conference Object
    Bioassay Guided Isolation of Naphthoquinones From Onosma Aksoyii, Investigation of Their Cytotoxic Properties
    (Georg Thieme Verlag, 2019) Kul, Demet; Bedir, Erdal; Karakoyun, Çiğdem; Yılmaz, Sinem; Yılmaz, Sinem; Pirhan, Ademi Fahri; Bedir, Erdal; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The genus Onosma L. (Boraginaceae) includes about 230 species, distributed mainly in the Mediterranean region and Central Asia. Major constituents of Onosma species are alkaloids, naphthoquinones, polyphenols, phytosterols, terpenoids and fatty acids [1], [2]. Naphthoquinones are naturally widespread secondary metabolites deriving from some higher plants, fungi and bacteria. They exhibit significant biological activities such as cytotoxicity, antimalarial, antibacterial, antifungal and wound healing [2], [3]. Recently naphthoquinone derivatives have also been recognized as potent topoisomerase inhibitors [4].
  • Conference Object
    Citation - WoS: 1
    Telomerase Activators Derived From Astragalus Sapogenins Via Biotransformation With the Recently Discovered Endophytic Fungus Camarosporium Laburnicola
    (Georg Thieme Verlag, 2019) Küçüksolak, Melis; Yılmaz, Sinem; Ekiz, Güner; Duman, Seda; Duman, Seda; Bedir, Erdal; Yılmaz, Sinem; Küçüksolak, Melis; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 01.01. Units Affiliated to the Rectorate; 01. Izmir Institute of Technology; 03. Faculty of Engineering
    Telomeres are nucleotide sequences that are located at the end of chromosomes shortening with each cell division. Telomerase is a reverse transcriptase enzyme, and it helps to replenish telomere ends that are truncated by aging and stress factors.
  • Article
    Citation - WoS: 23
    Citation - Scopus: 22
    Microbial Transformation of Cycloastragenol and Astragenol by Endophytic Fungi Isolated From Astragalus Species
    (American Chemical Society, 2019) Ekiz, Güner; Bedir, Erdal; Yılmaz, Sinem; Ballar Kırmızıbayrak, Petek; Bedir, Erdal; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Biotransformation of Astragalus sapogenins (cycloastragenol (1) and astragenol (2)) by Astragalus species originated endophytic fungi resulted in the production of five new metabolites (3, 7, 10, 12, 14) together with 10 known compounds. The structures of the new compounds were established by NMR spectroscopic and HRMS analysis. Oxygenation, oxidation, epoxidation, dehydrogenation, and ring cleavage reactions were observed on the cycloartane (9,19-cyclolanostane) nucleus. The ability of the compounds to increase telomerase activity in neonatal cells was also evaluated. After prescreening studies to define potent telomerase activators, four compounds were selected for subsequent bioassays. These were performed using very low doses ranging from 0.1 to 30 nM compared to the control cells treated with DMSO. The positive control cycloastragenol and 8 were found to be the most active compounds, with 5.2- (2 nM) and 5.1- (0.5 nM) fold activations versus DMSO, respectively. At the lowest dose of 0.1 nM, compounds 4 and 13 provided 3.5- and 3.8-fold activations, respectively, while cycloastragenol showed a limited activation (1.5-fold).