Ayse Ercan

Mitochondrial complex I and IV activities in leukocytes from patients with parkin mutations

The parkin protein functions as a RING‐type ubiquitin protein ligase. Considering the possibility that impaired ubiquitin‐proteosomal system activity may impair antioxidant defenses and enhance oxidative stress, we have investigated the activity of mitochondrial respiratory enzymes in patients with parkin gene mutations. A significant decrease in the leukocyte complex I activity was found both in patients with parkin mutations (62.5%) and idiopathic PD (64.5%) compared with age‐matched controls (P < 0.001). Complex IV activity was also decreased significantly in idiopathic PD patients (60%), but no difference was detected between controls and patients with parkin mutations.

Pyrazoline-based mycobactin analogues as MAO-inhibitors

3,5-Diaryl carbothioamide pyrazolines designed as mycobactin analogs (mycobacterial siderophore) were reported to be potent antitubercular agents under iron limiting condition in our earlier study. Clinical complications of newly introduced antibiotic Linezolid, due its MAO inhibitory activity, prompted us to evaluate our compounds for their MAO-inhibitory activity against rat liver MAO-A and MAO-B as pyrazolines were reported to be antidepressants and MAO inhibitors. The present study carried out with this pilot library of 32 compounds will provide us with necessary information for designing antitubercular molecules with reduced MAO-inhibitory activity and also help us in identifying a selective MAO-B inhibitor which has potential clinical utility in neurodegenerative disorders. Thirty-two compounds analyzed has shown spectrum of activity from selective to nonselective against two isoforms of rat liver MAO-A and MAO-B and also as competitive, reversible to non-competitive, irreversible. It is also interesting to note that anti-tubercular compound 11, 14 and 16 were also found to be selective inhibitors of rat liver MAO-B. Docking studies with human MAO shows that compound 11 interacts with the catalytic site of both the isoforms, suggesting compound 11 as nonselective inhibitor of human MAO isoforms.

Pyrazoline based MAO inhibitors: Synthesis, biological evaluation and SAR studies

Twenty-two pyrazoline derivatives were synthesized and tested for their human MAO (hMAO) inhibitory activity. Twelve molecules with unsubstituted ring A and substituted ring C (5-16) were found to be potent inhibitors of hMAO-A isoform with SI(MAO-A) in the order 10(3) and 10(4). Ten molecules with unsubstituted ring A and without ring C (21-30), in which eight molecules (21, 23-26, and 28-30) were selective for hMAO-A, one for hMAO-B (22) and the other one non-selective (27). Presence of ring C increases potency as well as SI towards hMAO-A; however its absence decreases both potency and SI towards hMAO-A and hMAO-B.

Synthesis and molecular modeling of some novel hexahydroindazole derivatives as potent monoamine oxidase inhibitors.

A novel series of 2-thiocarbamoyl-2,3,4,5,6,7-hexahydro-1H-indazole and 2-substituted thiocarbamoyl-3,3a,4,5,6,7-hexahydro-2H-indazoles derivatives were synthesized and investigated for the ability to inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). The target molecules were identified on the basis of satisfactory analytical and spectra data (IR, (1)H NMR, (13)C NMR, (2)D NMR, DEPT, EI-MASS techniques and elemental analysis). Synthesized compounds showed high activity against both the MAO-A (compounds 1d, 1e, 2c, 2d, 2e) and the MAO-B (compounds 1a, 1b, 1c, 2a, 2b) isoforms. In the discussion of the results, the influence of the structure on the biological activity of the prepared compounds was delineated. It was suggested that non-substituted and N-methyl/ethyl bearing compounds (except 2c) increased the inhibitory effect and selectivity toward MAO-B. The rest of the compounds, carrying N-allyl and N-phenyl, appeared to select the MAO-A isoform. The inhibition profile was found to be competitive and reversible for all compounds. A series of experimentally tested (1a-2e) compounds was docked computationally to the active site of the MAO-A and MAO-B isoenzyme. The autodock 4.01 program was employed to perform automated molecular docking. In order to see the detailed interactions of the docked poses of the model inhibitors compounds 1a, 1d, 1e and 2e were chosen because of their ability to reversibly inhibit the MAO-B and MAO-A and the availability of experimental inhibition data. The differences in the intermolecular hydrophobic and H-bonding of ligands to the active site of each MAO isoform were correlated to their biological data. Observation of the docked positions of these ligands revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. Excellent to good correlations between the calculated and experimental K(i) values were obtained. In the docking of the MAO-A complex, the trans configuration of compound 1e made various very close interactions with the residues lining the active site cavity these interactions were much better than those of the other compounds tested in this study. This tight binding observation may be responsible for the nanomolar inhibition of form of MAOA. However, it binds slightly weaker (experimental K(i)=1.23 microM) to MAO-B than to MAO-A (experimental K(i)=4.22 nM).

Simple, high-yield purification of xanthine oxidase from bovine milk.

Xanthine oxidase, a commercially important enzyme with a wide area of application, was extracted from fresh milk, without added preservatives, using toluene and heat. The short purification procedure, with high yield, consisted of extraction, ammonium sulfate fractionation, and DEAE-Sepharose (fast flow) column chromatography. Xanthine oxidase was eluted as a single activity peak from the column using a buffer gradient. The purification fold, specific activity and yield for the purified xanthine oxidase were 328, 10.161 U/mg and 69%, respectively. The enzyme was concentrated by ultrafiltration, although 31% of the activity was lost during concentration, no change in specific activity was observed. Activity and protein gave coincident staining bands on native polyacrylamide gels. The intensity and the number of bands were dependent on the oxidative state(s) of the enzyme; reduction by 2-mercaptoethanol decreased the intensity of the slow-moving bands and increased the intensity of the fastest-moving band. Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two major bands (molecular masses of 152 and 131 kDa) were observed, accounting for > or = 95% of xanthine oxidase. Native- and SDS-PAGE showed that the purified xanthine oxidase becomes a heterodimer due to endogenous proteases.

Evaluation of selective human MAO inhibitory activities of some novel pyrazoline derivatives.

A series of 1-[2-((5-methyl/chloro)-2-benzoxazolinone-3-yl)acetyl]-3,5-diaryl-4,5-dihydro-1H-pyrazole derivatives were prepared by reacting 2-((5-methyl/chloro)-2-benzoxazolinone-3-yl)acetylhydrazine with appropriate chalcones. The chemical structures of all compounds were confirmed by elemental analyses, IR, 1H NMR and ESI–MS. All the compounds were investigated for their ability to selectively inhibit monoamine oxidase (MAO) by in vitro tests. MAO activities of the compounds were compared with moclobemide and selegiline and all the compounds were found to inhibit human MAO-A selectively. The inhibition profile was found to be competitive and reversible for all compounds by in vitro tests. Among the compounds examined, compounds 5ae, 5af and 5ag were more selective than moclobemide, with respect to the Ki values experimentally found. In addition, the compound 5bg showed MAO-A inhibitor activity as well as moclobemide. A series of experimentally tested compounds (5ae–5ch) were docked computationally to the active site of the MAO-A and MAO-B isoenzyme. The AUTODOCK 4.01 program was employed to perform automated molecular docking.

The determination of matrix metalloproteinase 9 activity and gene expression levels in Behcet’s disease patients with aneurysmal complications

The information concerning aneurysmal progress in Behcet’s disease is still insufficient, while researches in the role of matrix metalloproteinases (MMPs) in aneurysmal formation are rapidly expanding. The goal of the present study is to investigate the role of metalloproteinase 9 (MMP-9) in vascular complications which is observed in 10% of Behcet’s disease patients. Three groups have been studied; patients with Behcet’s disease, patients with Behcet’s disease who have vascular problems (vasculo-Behcet’s), and patients with abdominal aortic aneurysm (AAA). The third group was used as a control. The activity and gene expression levels of MMP-9 in plasma have been determined. We showed that compared to AAA patients there was no difference in the MMP-9 activity in Behcet’s disease patients (vascular and non-vascular). We also evaluated the gene expression level and activity of MMP-9 for every patient. The increase in the gene expression level for MMP-9 could only be detected at two patients. One of them was Behcet’s, the other was AAA patient. It is surprising that MMP levels of these patients were different. While the patient with Behcet’s had low protein level, another patient with AAA had high of MMP-9 level. This result suggested to us that the relationship between gene expression and active protein level is not correlated. It is not sufficient alone to determine MMPs levels for evaluating the pathogenesis. At the same time gene expression and the level of active protein should be assessed together.

Global omics strategies to investigate the effect of cyclodextrin nanoparticles on MCF-7 breast cancer cells

ABSTRACT Cyclodextrins (CD) are natural macrocyclic oligosaccharides linked by &agr;(1,4) glycosidic bonds. Hydrophobic cavity of CDs are able to incorporate small molecules, ions, macromolecules which makes them excellent delegates for forming nanoparticulate carriers upon chemical modification to render amphiphilicity to CDs. In this study, blank 6OCapro&bgr;CD nanoparticle was prepared and administered to MCF‐7 breast cancer cells. The effects of these nanoparticles on the cells were investigated in depth through biochemical and proteomic tests following 48 h of incubation. Proteomics studies revealed that apoptosis‐related protein levels of hnRNP and CBX1 were increased while HDGF was not affected supporting the idea that 6OCapro&bgr;CD nanoparticles prevent cell proliferation. Gene expression studies were generally in correlation with protein levels since gene expression was significantly stimulated while protein levels were lower compared to the control group suggesting that a post‐transcriptional modification must have occurred. Furthermore, 6OCapro&bgr;CD was observed to not trigger multidrug resistance as proved with RT‐PCR that effectuates another exquisite characteristic of 6OCapro&bgr;CD nanoparticle as carrier of chemotherapeutic drugs. Metabolomic pathways of CD effect on MCF7 cells were elucidated with HMDB as serine biosynthesis, transmembrane transport of small molecules, metabolism of steroid hormones, estrogen biosynthesis and phospholipid biosynthesis. In conclusion, 6OCapro&bgr;CD is a promising nanoparticulate carrier for chemotherapeutic drugs with intrinsic apoptotic effect to be employed in treatment of breast cancer and further studies should be conducted in order to comprehend the exact mechanism of action. Graphical abstract Figure. No Caption available.

Synthesis and Cytotoxic Evaluation of Kojic Acid Derivatives with Inhibitory Activity on Melanogenesis in Human Melanoma Cells

BACKGROUND Malignant melanoma is an agressive tumour related to the overproduction of melanin, which provides colors of skin, eyes and hair. In addition contributing to the risk of malignant melanoma, abnormal production of melanin has many drawbacks, including hyperpigmentation, post-inflammatory pigmentation, melasma and skin aging. Kojic acid is currently employed in order to lighten skin pigmentation and provide depigmentation. OBJECTIVE Mannich bases of kojic acid with the structure of 2-substituted-3-hydroxy-6-hyroxymethyl/chloromethyl/ methyl/morpholinomethyl/piperidinylmethyl/pyrrolidinylmethyl-4H-pyran-4-one (compounds 1-23) were synthesized by the reaction of kojic acid/chlorokojic acid/allomaltol and substituted benzylpiperazine derivatives in the presence of formaline. To obtain the cyclic amine (morpholine, piperidine and pyrrolidine) derivatives, nucleophilic substitutions were carried out. METHOD Cytotoxic effects on A375 human malignant melanoma, HGF-1 human gingival fibroblasts, and MRC-5 human lung cell lines were investigated by sulphorhodamine B assay. Control agents were vemurafenib, dacarbazine, temozolomide, and lenalidomide, which are the commercially available drugs for the treatment of malignant melanoma. RESULTS Cytotoxic action against melanoma cells was significantly more efficacious (IC50: 11.26-68.58 μM) than the FDA-approved drugs except for vemurafenib. Fourteen of the compounds were proven to have higher IC50 values for the non-cancerous cell lines, HGF-1, and MRC-5 cells. Melanogenesis inhibition assay was performed to observe the ability of the drugs to inhibit melanin production and certain compounds were shown to be capable of actively inhibiting melanin production in melanoma cells. CONCLUSION Mannich bases of kojic acid derivatives may be promising therapeutic agents, since some have more potent effects on melanoma cells than previously FDA-approved drugs for the treatment of malignant melanoma.