Ibrahim Demirtas

Antioxidant, electrochemical, thermal, antimicrobial and alkane oxidation properties of tridentate Schiff base ligands and their metal complexes

In this study, two Schiff base ligands (HL(1) and HL(2)) and their Cu(II), Co(II), Ni(II), Pd(II) and Ru(III) metal complexes were synthesized and characterized by the analytical and spectroscopic methods. Alkane oxidation activities of the metal complexes were studied on cyclohexane as substrate. The ligands and their metal complexes were evaluated for their antimicrobial activity against Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis (as gram-positive bacteria) and Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Klebsiella fragilis, Saccharomyces cerevisiae, and Candida albicans (as gram-negative bacteria). The antioxidant properties of the Schiff base ligands were evaluated in a series of in vitro tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and reducing power activity of superoxide anion radical generated non-enzymatic systems. Electrochemical and thermal properties of the compounds were investigated.

Selective bromination of 1-bromonaphthalene: efficient synthesis of bromonaphthalene derivatives

Abstract Selective and specific preparation methods are described for 1,4-dibromonaphthalene, 1,5-dibromonaphthalene and 1,3,5-tribromonaphthalene. The reaction of 1-bromonaphthalene and naphthalene with stoichometric quantities of bromine by using a minimum amount of solvent (methylene chloride) at −30 and −50°C smoothly affords 1,4-dibromonaphthalene in 90% yield. Photobromination of 1-bromonaphthalene in CCl 4 at −30°C gives 1,2,3,4,5-pentabromo-1,2,3,4-tetrahydronaphthalenes, whereas 1,5-dibromonaphthalene is obtained at reflux (77°C) in 80% yield under the same conditions. Dehydrobromination of the pentabromide by t -BuOK affords 1,3,5-tribromonaphthalene as a sole product (91%). 1,5-Dibromo- and 1,3,5-tribromonaphthalenes were efficiently converted to the corresponding methoxy naphthalene derivatives.

Antioxidant activity and chemical composition of Sideritis libanotica Labill. ssp. linearis (Bentham) Borm. (Lamiaceae)

Sideritis libanotica ssp. linearis was screened for the isolation of new natural antioxidant compounds. The antioxidant activity of flavones obtained from the methanol extract of the plant was evaluated in vitro using total antioxidant, reduction power and free radical scavenging activity. Results were compared with the positive controls of antioxidant standards (α-tocopherol and butylated hydroxytoluene). The results indicate that the flavones possess a higher antioxidant activity when compared to the other components in the plant. The lowest antioxidant activity was observed in fatty acids (FAs) and hydrocarbons. The FAs were methylated with MeOH and KOH and analysed by GC–MS. The structures of the isolated compounds were established based on spectroscopic evidence (NMR, GC–MS, HPLC, IR and UV). In this work, the isolated pure flavone (3′-O-methylhypolaetin 7-O-[6″′-O-acetyl-β-D-allopyranosyl-(1 → 2)]-6″-O-acetyl-β-D-glucopyranoside) was found to possess the highest antioxidant activity.

Synthesis of hydroxy, epoxy, nitrato and methoxy derivatives of tetralins and naphthalenes

Stereoselective syntheses are described for cis,trans,cis-2,3,5-tribromo-1,4-dihydroxytetralin, trans,trans,cis-2,3,5-tribromo-1,4-dihydroxytetralin, trans,trans,trans-1,4-dihydroxy-2,3-dibromotetralin, trans,trans,trans-1-hydroxy-2,3,4-tribromotetralin, cis,cis,cis-1,2-epoxy-3,5-dibromo-4-hydroxytetralin, anti-1,2:3,4-diepoxytetralin, 1-hydroxy-4-bromonaphthalene, trans,trans,trans-1,4-dinitrato-2,3-dibromotetralin, 1-nitrato-2,3,4-tribromotetralin, 2,3-dibromonaphthalene and 1-methoxy-4-nitrato-2,3-dibromonaphthalene. These isomeric arene oxides and disubstituted naphthalenes provide excellent precursors for a number of 1,4- and 2,3-disubstituted naphthalene derivatives that are difficult to prepare using other routes. The structures of the naphthalene and tetralin derivatives were assigned by NMR and other techniques.

Phytochemical Constituents, ChEs and Urease Inhibitions, Antiproliferative and Antioxidant Properties of Elaeagnus umbellata Thunb.

AIM AND OBJECTIVE Due to the common ethnopharmacological used or scientifically examined biochemical properties, Elaeagnaceae family, Elaeagnus umbellate (Thunb.) (EU, Guz yemisi) was worth investigating. MATERIALS AND METHODS In this investigation, we revealed antioxidant, antiproliferative and enzyme inhibition activities of the water, methanol, ethanol, acetone, ethyl acetate and hexane extracts of EU as well as the contents of their phenolic, flavonoid, anthocyanin, ascorbic acid, lycopene and β- carotene. The antioxidant activity was screened by total antioxidant (phosphomolybdenum), inhibition of linoleic acid peroxidation, reducing power, 2-deoxyribose degradation assay, H2O2 scavenging and metal chelating activities of the samples were tested in vitro. Additionally, the scavenging activities of the extracts were determined against 1,1-diphenyl-2-picrylhydrazyl (DPPH˙), 2,2-azino-bis(3-ethylbenzothiazloine-6-sulfonicacid (ABTS˙+), superoxide anion and peroxide radicals. The samples were determined for their inhibitory activities against urease, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). In vitro, antiproliferative activities of six different extracts were tested using the xCELLigence system against HeLa and HT29 cell lines. RESULTS The antioxidant activities of the extracts were found higher than standard antioxidants. The water extracts of fruit and leaf showed the best antioxidant activity. In inhibition assays of urease, AChE and BuChE, all extracts exhibited remarkable inhibition potential. Ethyl acetate extracts, especially, showed better inhibition capacity. It was found that the antioxidant activities of the extracts presented consistently with their chemical contents. The antiproliferative activities of leaf extracts were more effective than the fruit extracts. The chromatographic methods were applied to the different solvents to analyses phenolic secondery metabolites. It was found that fumaric acid, 4- hydroxybenzoic acid, rutin and quercetin-3-β-D-glucoside, neohesperidin, hesperidin determined to have higher contents all the extracts. CONCLUSION EU can be suggested as a potential natural source of antioxidants appropriate for utilization in nutritional/pharmaceutical fields.

Bioactivity-Guided Isolation of Antiproliferative Sesquiterpene Lactones from Centaurea solstitialis L. ssp. solstitialis

Centaurea solstitialis L. ssp. solstitialis (CSS) has been used as medicine for various diseases. In this work, root, stem and flower parts of the plant were separately extracted with methanol to execute bioassay-guided isolation. Antiproliferative activities of each extracts on C6 cells (Rat Brain tumor cells) and HeLa cells (human uterus carcinoma) were investigated in vitro. The methanol extract of stem exhibited the most antiproliferative activity therefore isolation of active compounds was carried out for stem of the plant. Methanol extract of stem was boiled at 97 °C for 2 hours in water and then hexane and ethyl acetate were extracted sequentially. Solstitialin A 1 and 15-dechloro-15-hydroxychlorojanerin 2 were isolated from ethyl acetate extract by column chromatography and identified by spectroscopic techniques. Solstitialin A 1 was isolated from CSS and 15-dechloro-15-hydroxychlorojanerin 2 was isolated from Saussurea lipschitz and Rhaponticum pulchrum previously. These two compounds exhibited very high antiproliferative activity on C6 and HeLa cells. IC50 and IC75 values of compound 1 were obtained as 10.78 and 53.65 against C6 cell and as 48.78 and 68.52 against HeLa, respectively. IC50 and IC75 values of compound 2 were determined as 432.43 and 109.79 against C6 cell.

Synthetic route to 1,3-disubstituted naphthalene derivatives

The preparation of methoxy and cyanonaphthalene derivatives is described. The preparation of 1,3-dimethoxynaphthalene, 1-bromo-3-methoxynaphthalene, 1-methoxy-3-bromonaphthalene and 1,3-dicyanonaphthalene involves the reaction of 1,3-dibromonaphthalene with the corresponding nucleophile.

Chemical constituents and antiproliferative effects of cultured Mougeotia nummuloides and Spirulina major against cancerous cell lines.

Abstract In this study, the effect of Mougeotia nummuloides and Spirulina major on Vero cells (African green monkey kidney), C6 cells (rat brain tumor cells) and HeLa cells (human uterus carcinoma) was investigated in vitro. The antiproliferative effect of the methanol extract of M. nummuloides and S. major compared with 5-fluorourasil (5-FU) and cisplatin was tested at various concentrations using the BrdU Cell Proliferation ELISA. Both M. nummuloides and S. major extracts significantly inhibited the proliferation of Vero, HeLa and C6 cancer cell lines with IC50 and IC75 values. The M. nummuloides extract exhibited higher activity than 5-FU and cisplatin on Vero and C6 cells at high concentrations. The S. major extract revealed better antifproliferative activity than standards against Vero cells at 500 μg/mL. The compounds of methanol extracts were determined by GC-MS after the silylation process. Trehalose, monostearin and 1-monopalmitin were detected as major products in the M. nummuloides extract where as in the S. major extract; monostearin, 1-monopalmitin and hexyl alcohol were the main constituents.

Antioxidant Activity and Chemical Composition of the Lipophilic Fractions from Phryna ortegioides

The genus Phryna, which belongs to the Caryophyllaceae family, is represented in Turkey only by Phryna ortegioides. It is a monotypic and endemic taxon in Turkey [1]. The chemical composition and biological activity have so far not been investigated. Thus, this study seeks to characterize the chemical composition and antioxidant potential of this plant for the first time. The lipophilic fractions of P. ortedioides showed antioxidant activity in a concentration-dependent way, in general with different behaviors for all fractions. The dichloromethane fraction (DF) showed the highest total antioxidant activity with a value of 91.27 2.47%, while the methanol fraction exhibited weak activity (18.07 1.35%). The Phryna crude extract (PCE) from the ethyl acetate fraction (EF) and the butanol fraction (BF) showed meaningful antioxidant activity close to that of butylated hydroxyanisole (BHA) and vitamin E (Vit-E). In conclusion, the DF fraction and its subfractions demonstrated higher antioxidant activity than that of polar fractions. Information about the chemical composition and antioxidant activity of P. ortegioides has not been reported so far. In this study, we aimed to identify the chemical composition of the lipophilic fractions of P. ortegioides, an endemic species growing in Turkey. The volatile components in 17 subfractions of the active dichloromethane fractions were analyzed by gas chromatography-mass spectroscopy (GC-MS). The total antioxidant activity of the polar and nonpolar fractions was determined by the ferric thiocyanate method. A summary of the chemical composition of the lipophilic fractions showing the relative amounts of fatty acids, and their distribution among the subfractions obtained by column chromatography is given in Table 1. Separation by column chromatography of the dichloromethane fraction affected the different chemical compositions and fatty acid proportions as reported in Table 1. To the best of our knowledge, the effect of fractionation on fatty acid and volatile composition is investigated for the first time in P. ortegioides. As can be seen in Table 1, analysis of the fatty acid composition indicated that, of the total of 17 subfractions from the dichloromethane fractions, palmitic acid was the major compound with a value of 39.5% of total fatty acids in all subfractions followed by arachidic, stearic, linoleic, oleic, -linolenic, myristic, and behenic acids, which constitute 15.96, 13.35, 9.86, 9.45, 7.68, 2.65 and 1.55% of total fatty acids, respectively. These results are in agreement with previous reports stating the fatty acid compositions of different higher plants of the same family [2–4]. The total of 17 subfractions from the dichloromethane fraction was characterized by the presence of a high proportion of saturated fatty acids (SFAs) with a value of 73.01%, followed by polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs), representing 17.53 and 7.46%, respectively. Linoleic and linolenic acids were determined as 17.54% of all subfractions. With regard to omega 3, subfraction 3 had the highest amount (23.20 0.51%). The amounts of omega 6 and omega 3 fatty acids in the subfractions are noteworthy because these fatty acids are not synthesized by the human body. Therefore, they must be obtained through the diet. The studied lipophilic fractions, especially subfractions such as F3 (45.12 1.02%), F4 (35.87 0.81%) and F2 (32.74 0.74%), can be considered as a source of essential fatty acids.