Reyhan Çalışkan

Dr. Reyhan Çalışkan


Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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16 December 2022 in Bezmialem Science
Verified
Journal Article
Closed access
RÇReyhan Çalışkan
Reyhan Çalışkan
SSSilva Polat Sarı
Silva Polat Sarı
BABetül Büyükkiliç Altinbaşak
Betül Büyükkiliç Altinbaşak
HDHarika Öykü Dinç
Harika Öykü Dinç
ABAleyna Balekoğlu
Aleyna Balekoğlu
PMPelin Yüksel Mayda
Pelin Yüksel Mayda

1 October 2022 in Bezmialem Science
Verified
Journal Article
Closed access
SSSilva Polat Sarı
Silva Polat Sarı
HDHarika Öykü Di̇nç
Harika Öykü Di̇nç
BABetül Büyükkiliç Altinbaşak
Betül Büyükkiliç Altinbaşak
PMPelin Yüksel Mayda
Pelin Yüksel Mayda
ÖAÖzer Akgül
Özer Akgül
RÇReyhan Çalışkan
Reyhan Çalışkan

1 May 2016 in Travel Medicine and Infectious Disease
Verified
Journal Article
Closed access
BKBekir Kocazeybek
Bekir Kocazeybek
PYPelin Yuksel
Pelin Yuksel
DKDilek Keskin
Dilek Keskin
SSSuhail Sheikh
Suhail Sheikh
ZHZafer Habip
Zafer Habip
HThrisi bahar tokman
hrisi bahar tokman

2 September 2025 in Biology
Verified
Journal Article
Open access
PDF file
SDSerpil Demir Düşünceli Demir Düşünceli
Serpil Demir Düşünceli Demir Düşünceli
KCKübra açıkalın coşkun
Kübra açıkalın coşkun
MKMurat Kaloğlu
Murat Kaloğlu
EÜElvan Üstün
Elvan Üstün
RÇReyhan Çalışkan
Reyhan Çalışkan
YTYusuf Tutar
Yusuf Tutar
Background: Theophylline, which is biologically important and found in tea, coffee, and cocoa beans, can be synthesized chemically or by direct extraction and concentration from natural sources. Theophylline derivatives have garnered attention in recent years for their potential therapeutic effects on Mycobacterium tuberculosis, antihistaminic, anti-inflammatory, and anticancer. Also, trifluoromethyl (CF3) group has also been widely used in drug and agrochemical design. Methods: In this study, a series of new theophylline derivatives containing substituted trifluoromethyl and trifluoromethoxy groups were synthesized. The structures of these new compounds were confirmed by NMR, FT-IR, and elemental analyses. Additionally, the anticancer activities of the molecules were analyzed against VEGFR-2, CYP P450, and estrogen receptor by molecular docking method. Furthermore, in vitro biological effects of the compounds were comprehensively evaluated in cancer (A549 and HeLa) and normal (BEAS-2B) cells. Cell viability was assessed by MTT assay, and selectivity index (SI) values were calculated to determine tumor-specific toxicity. Results: N(7)-substituted theophyllines were prepared by the reaction of 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione (theophylline) and trifluoromethyl substituted benzyl halide compounds. The synthesized N(7)-substituted theophyllines were obtained as white powder in high yield. The structure of synthesized compounds was confirmed by various spectroscopic techniques such as 1H, 13C, 19F NMR, and FT-IR spectroscopy, and elemental analysis. The highest interaction was recorded as −5.69 kcal/mol for 3-CF3 substituted against VEGFR-2 structure while the best binding affinity was determined for 4-OCF3 substituted with −6.69 kcal/mol against Human Cytochrome P450 with in silico analysis. The in vitro anticancer activities of the molecules were also evaluated against A549 and HeLa cells, and displayed considerably higher cytotoxicity with 2-CF3, 3-CF3, and 4-CF3 substituted molecules in Hela and A549 cell line. To elucidate the molecular mechanism, apoptosis-related gene expression changes were analyzed by RT-qPCR in A549 and HeLa cells treated with compound 2-CF3. Significant upregulation of pro-apoptotic markers and downregulation of anti-apoptotic genes were observed. Consistently, ELISA-based quantification confirmed increased protein levels of Caspase-3, BAX, and Cytochrome C, and decreased BCL-2, validating the apoptotic mechanism at the protein level. Also, the antibacterial and antibiofilm activity details of the molecules were evaluated against DNA Gyrase, and SarA crystal structures by molecular docking method. The highest interaction was recorded as −5.56 kcal/mol for 2-CF3 substituted with H-bonds with Asn46, Val71, Asp73, and Thr165 against DNA Gyrase crystal structure while 3-CF3 substituted has the best binding affinity against SarA. The in vitro antimicrobial effects of the molecules were also evaluated. Conclusions: The synthesized molecules may provide insight into the development of potential therapeutic agents to the increasing antimicrobial resistance and biofilm-forming capacity of microorganisms. Additionally, compound 2-CF3 substituted exhibited promising and selective anticancer activity through apoptosis induction, supported by gene and protein level evidence.

7 September 2025 in Journal of Fungi
Verified
Journal Article
Open access
PDF file
ZYZeynep Yazgan
Zeynep Yazgan
RÇReyhan Çalışkan
Reyhan Çalışkan
GAGökhan Aygün
Gökhan Aygün
Azole-resistant mycotic infections pose an escalating global health threat, with an estimated 6.5 million invasive fungal infections (IFIs) annually leading to 3.8 million deaths, 68% directly caused by IFIs. While azole antifungals are the cornerstone of treatment, emerging resistance, mainly due to gene mutations and efflux pump overexpression, is a major concern. This study, spanning 2015–2023, investigated azole resistance in clinical Aspergillus isolates in Turkey, a region lacking comprehensive surveillance. Of 200 causative isolates, A. fumigatus accounted for 45% and respiratory samples 57%. Overall azole resistance was 7%, rising to 11% for A. fumigatus. Findings highlight the persistent challenge of azole resistance, emphasizing the critical need for continued local and global surveillance to inform treatment guidelines and public health interventions. Despite limitations, including a single-center focus, this research provides crucial epidemiological insights into the evolving landscape of antifungal resistance in Turkey.

27 November 2022 in Medicina
Verified
Journal Article
Open access
PDF file
RÇReyhan Çalışkan
Reyhan Çalışkan
SSSilva Polat Sarı
Silva Polat Sarı
BEBahadir ERCAN
Bahadir ERCAN
KPKivanc Derya Peker
Kivanc Derya Peker
MSMehtap Omac Sönmez
Mehtap Omac Sönmez
PMPelin Yuksel Mayda
Pelin Yuksel Mayda
Background and Objectives: Helicobacter pylori infection is associated with chronic gastritis, ulcers, and gastric cancer. The H. pylori Type 4 secretion system (T4SS) translocates the CagA protein into host cells and plays an essential role in initiating gastric carcinogenesis. The CagL protein is a component of the T4SS. CagL amino acid polymorphisms are correlated with clinical outcomes. We aimed to study the association between CagL amino acid polymorphisms and peptic ulcer disease (PUD) and non-ulcer dyspepsia (NUD). Materials and Methods: A total of 99 patients (PUD, 46; NUD, 53) were enrolled and screened for H. pylori by qPCR from antrum biopsy samples. The amino acid polymorphisms of CagL were analyzed using DNA sequencing, followed by the MAFFT sequence alignment program to match the amino acid sequences. Results: Antrum biopsy samples from 70 out of 99 (70.7%) patients were found to be H. pylori DNA-positive. A positive band for cagL was detected in 42 out of 70 samples (PUD, 23; NUD, 19), and following this, these 42 samples were sequenced. In total, 27 different polymorphisms were determined. We determined three CagL amino acid polymorphism combinations, which were determined to be associated with PUD and NUD. Pattern 1 (K35/N122/V134/T175/R194/E210) was only detected in PUD patient samples and was related to a 1.35-fold risk (p = 0.02). Patterns 2 (V41/I134) and 3 (V41/K122/A171/I174) were found only in NUD patient samples and were linked to a 1.26-fold increased risk (p = 0.03). Conclusions: We observed three new patterns associated with PUD and NUD. Pattern 1 is related to PUD, and the other two patterns (Patterns 2 and 3) are related to NUD. The patterns that we identified include the remote polymorphisms of the CagL protein, which is a new approach. These patterns may help to understand the course of H. pylori infection.