The new compounds 7a–k, 8a–k, and 9a–k were synthesized from flavonones 4–6, which can be considered new precursors for quinoline synthesis through a one-step reaction. All the target compounds (7a–k, 8a–k, and 9a–k) were evaluated for their in vitro antimicrobial activity against nine test microorganisms. They showed the most activity against Mycobacterium smegmatis with minimum inhibitory concentrations (MIC) of 62.5–500 µg/mL, indicating their potential uses as antituberculosis agents. Among them 8a–k (m-fluoride) were the most active compounds against M. smegmatis (MIC, 62.5–125 µg/mL).
Turk J Chem (2015) 39: 850 866 ă ITAK ˙ c TUB ⃝ Turkish Journal of Chemistry http://journals.tubitak.gov.tr/chem/ doi:10.3906/kim-1501-112 Research Article Synthesis and biological evaluation of a new series of 4-alkoxy-2-arylquinoline derivatives as potential antituberculosis agents ă UK ă 1,3 , Gonca TOSUN1 , Tayfun ARSLAN2 , Zeynep ISKEF IYEL I˙ , Murat KUC 5, S engă ul ALPAY KARAOGLU , Nurettin YAYLI Department of Chemistry, Faculty of Science, Karadeniz Technical University, Trabzon, Turkey Department of Chemistry, Faculty of Science, Giresun University, Giresun, Turkey Faculty of Engineering and Natural Sciences, Gă umă uáshane University, Gă umă uáshane, Turkey Department of Biology, Faculty of Arts and Sciences, Recep Tayyip Erdo˘ gan University, Rize, Turkey Faculty of Pharmacy, Karadeniz Technical University, Trabzon, Turkey Received: 26.01.2015 • Accepted/Published Online: 09.05.2015 • Printed: 28.08.2015 Abstract: Three new series of 33 quinolone compounds, 2-(2-, 3-, and 4-fluorophenyl)-4-O-alkyl(C 5−15 ) quinolines (7a– k, 8a–k, and 9a–k), were synthesized from 2-(2-, 3-, and 4-fluorophenyl)-2,3-dihydroquinolin-4(1H )-one (4, 5, and 6) by the reaction of alkyl halides under basic conditions in DMF The new compounds 7a–k, 8a–k, and 9a–k were synthesized from flavonones 4–6, which can be considered new precursors for quinoline synthesis through a one-step reaction All the target compounds (7a–k, 8a–k, and 9a–k) were evaluated for their in vitro antimicrobial activity against nine test microorganisms They showed the most activity against Mycobacterium smegmatis with minimum inhibitory concentrations (MIC) of 62.5–500 µ g/mL, indicating their potential uses as antituberculosis agents Among them 8a–k (m-fluoride) were the most active compounds against M smegmatis (MIC, 62.5–125 µ g/mL) The newly synthesized title compounds were also evaluated for their in vitro antioxidant activities using DPPH• radical scavenging and FRAP tests They showed at a low concentration (mg/mL) a range of SC 50 values of 0.03–12.48 mg/mL (DPPH•) and 0–722 µ M (FRAP), respectively The antioxidant results of compounds 7a–k, 8a–k, and 9a–k revealed that the length of the alkyl chain was negatively correlated with antioxidant capacity Key words: Quinoline derivatives, flavonones, air oxidation, antimicrobial activity, antituberculosis activity, antioxidant activity Introduction Natural, synthetic, semisynthetic, or natural product-derived alkaloid compounds are important sources of new drugs and have a variety of biological activities in clinical trials Naturally occurring quinolines have been identified and reported to possess a high degree of various biological activities 1,2 Graveoline and chimanine 4,5 are alkaloids isolated from Ruta graveolens L and Galipea longiflora, respectively, and showed comprehensive pharmacological activities such as antibacterial and antitumor activities 6−11 Tumor angiogenesis is a promising target of cancer therapy A series of graveoline derivatives has been synthesized and tested for their antiangiogenesis activities The quinoline core has been synthesized previously by various conventional strategies such as Skraup, 12 ∗ Correspondence: 850 yayli@ktu.edu.tr TOSUN et al./Turk J Chem Friedlander, 13,14 Pfitzinger, 15 and Pavarov 16 These classical synthetic methods are still frequently used for the preparation of quinolines However, in this work, a new and practical method was used for the synthesis of substituted quinoline derivatives The reaction sequence consists of an initial Aldol condensation (1–3) and then intramolecular Michael addition of amines to an α ,β -unsaturated carbonyl group using K-10 clay under solvent-free conditions using a microwave to give compounds 4–6, and finally air oxidation of compounds 4–6 with alkyl halide under basic conditions afforded the target compounds 7a–k, 8a–k, and 9a–k Heterocyclic systems with a quinoline are widely used in medicinal chemistry 17 and display many different biological activities such as antiparasitic, 18 antibacterial, cytotoxic and antineoplastic, 19 antimycobacterial, 20 and antiinflammatory activities 21 The biological activities of quinolin-4(1H)-one moiety depend on the bicyclic heteroaromatic pharmacophore as well as on the peripheral substituents and their spatial relationship A number of 2-phenylquinolone derivatives with a phenyl group attached to the C-2 position of quinolin-4(1H)one have expressed antimitotic activity 22 In spite of their wide range of pharmacological activities, very few activity studies have been reported against tuberculosis for these group of compounds in comparison with other classes 23 Tuberculosis is one of the most important diseases worldwide, with approximately three million deaths per year 24 Tuberculosis is a problematic disease especially with respect to the ease of the spread of HIV infection and the increases in the prevalence of drug resistance as well as multidrug-resistant strains 25 New synthetic compounds are certainly required for the long-term control of tuberculosis On the basis of these observations and as a part of our continued research for new antimicrobial and antioxidant agents, we report an efficient and simple method for the synthesis of 33 new series of quinolines derivatives 2-(2-, 3-, 4-fluorophenyl)-4-O-alkyl quinolines with an increasing number of carbons (C –C 15 ) in the side chain Thus, we wanted to determine the influence of the length of the carbon chain in the O-alkyl substituent of the synthetic compounds 7a–k, 8a–k, and 9a–k The antimicrobial (antibacterial, antifungal, and antituberculosis) and antioxidant activities were also evaluated for the synthetic compounds 4–9 Results and discussion 2.1 Chemistry Many synthetic methods for quinoline synthesis have been used in the literature 12−16,26,27 However, many of these classical synthetic approaches suffer from a limited source of precursors, harsh reaction conditions, and low yields and selectivity We first synthesized substituted quinoline starting from flavonone and alkyl halide at room temperature, which was a single step process and which was a practical method for the synthesis of substituted quinoline derivatives This method can be used for naturally occurring or synthetically prepared substituted quinolines starting from flavonones The reaction sequences used for the synthesis of the target compounds (7a–k, 8a–k, 9a–k) are outlined in the Scheme Flavonones of 2-(2fluorophenyl),2,3-dihydroquinolin-4(1H )-one (4), 2-(3-fluorophenyl),2,3-dihydroquinolin-4(1H )-one (5), and 2(4-fluorophenyl),2,3-dihydroquinolin-4(1H )-one (6) were synthesized through the cyclization of the corresponding (2E )-1-(2-aminophenyl)-3-(2-fluorophenyl)prop-2-en-1-one (1), (2E )-1-(2-aminophenyl)-3-(3-fluorophenyl)prop2-en-1-one (2), and (2E )-1-(2-aminophenyl)-3-(4-fluorophenyl)prop-2-en-1-one (3), respectively, using K-10 clay under solvent-free conditions using a microwave at 85 ◦ C (Scheme) Then compounds 4, 5, and were dis- solved in DMF and treated with KOH and alkyl halides (C -C 15 -Br) The reaction mixture was stirred at room temperature overnight and then was treated with 20 mL of distilled water and extracted with CH Cl The crude residue was purified by silica gel column chromatography to afford compounds 7a–k, 8a–k, and 9a–k in 851 TOSUN et al./Turk J Chem moderate yields (27%–51%) The reaction progress was monitored using thin layer chromatography In order to improve the yield, the reactions were carried out at higher temperatures, but the flavonone ring was opened and N-alkyl derivatives of compounds 1, 2, and occurred Scheme Synthesis of the 4-alkoxy-2-arylquinoline derivatives (7a–k, 8a–k, and 9a–k) The structures of the newly synthesized compounds 7a–k, 8a–k, and 9a–k were identified by spectroscopic data such as H NMR, 13 C/APT NMR, H- H COSY, UV-Vis, FT-IR, LC-MS/MS, and elemental analyses (Tables 1–9) The mass spectra of these compounds (7a–k, 8a–k, and 9a–k) showed molecular ion peaks at the appropriate m/ z values and the results are listed in Tables 1, 4, and 7, respectively In the H 13 and C NMR spectra of compounds 7a–k, 8a–k, and 9a–k, in particular, H showed peaks at δH 7.2 (1H, s) and C at δC 98.2–102.1 ppm, which are an indication of quinoline ring systems Moreover, the alkoxy moiety of products 7a–k, 8a–k, and 9a–k exhibited characteristic signals at δH 4.2 (2H, t, J = 6.6) and δC 68.4 ppm for –OCH – in the H (Tables 2, 5, and 8) and 13 C NMR (Tables 3, 6, and 9) data, 28,29 respectively 2.2 Biological activities Quinolines, 4(1H)-quinolines, and their hydroderivatives are the most biologically active natural and synthetic compounds Quinine, cinchonine, graveoline, and chimanine alkaloid derivatives are well known bioac852 IR C=N– 1592 1592 1593 1592 1592 1592 1593 1593 1593 1593 1594 =C–F 1210 1210 1212 1212 1212 1211 1215 1213 1212 1212 1213 C20 H20 FNO C21 H22 FNO C22 H24 FNO C23 H26 FNO C24 H28 FNO C25 H30 FNO C26 H32 FNO C27 H34 FNO C28 H36 FNO C29 H38 FNO C30 H40 FNO Formula 310 324 338 352 366 380 394 408 422 436 450 (100) (100) (100) (87) (89) (100) (100) (100) (100) (100) (100) LC-MS/MS Yield (%) 41 33 29 30 27 28 51 24 32 33 28 mp (◦ C) 36–40 55–60 46–51 44–49 44–48 oily 33–36 38–42 42–44 48–51 43–47 392 403 402 426 402 391 402 399 389 430 399 (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) 291 296 298 299 298 294 296 297 294 300 301 H6 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, dd dd dd dd dd dd dd dd dd dd dd H7 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, t t t t t t t t t t t H8 8.0, 8.0, 8.0, 8.0, 8.0, 8.0, 8.0, 8.0, 8.1, 8.1, 8.1, d d d d d d d d d d d H3′ 7.2, 7.2, 7.2, 7.2, 7.2, 7.2, 7.1, 7.2, 7.2, 7.2, 7.2, d d d d d d d d d d d H4′ 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, 7.4, dd dd dd dd dd dd dd dd dd dd dd H5′ 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, 7.3, t t t t t t t t t t t H6′ 8.1, 8.1, 8.1, 8.1, 8.1, 8.2, 8.1, 8.1, 8.1, 8.1, 8.1, H NMR data of compounds 7a–k d d d d d d d d d d d (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) O–(CH2 )– 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 4.2, t 251 251 252 250 252 251 252 251 252 252 253 –(CH2 )n – n: 2–14 1.2–1.9, 6H 1.2–1.9, 8H 1.3–1.9, 10H 1.3–1.9, 12H 1.2–2.2, 14H 1.3–2.0, 16H 1.3–1.9, 18H 1.3–2.0, 20H 1.3–2.0, 22H 1.3–2.3, 24H 1.3–2.0, 26H Elemental analyses data C H 77.64/77.55 6.52/6.51 77.99/77.92 6.86/6.79 78.31/78.43 7.17/7.19 78.60/78.64 7.46/7.42 78.87/78.80 7.72/7.65 79.12/79.16 7.97/7.94 79.35/79.38 8.20/8.27 79.57/79.47 8.41/8.44 79.77/79.79 8.61/8.65 79.96/79.91 8.79/8.81 80.13/80.09 8.97/8.93 –CH3 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t (%)a N 4.53/4.49 4.33/4.36 4.15/4.19 3.99/3.89 3.83/3.88 3.69/3.72 3.56/3.51 3.44/3.40 3.32/3.30 3.22/3.24 3.12/3.18 a J7a−k (Hz): H , d ( ∼ 8.2); H , dd ( ∼ 7.4, 7.2); H , t ( ∼ 7.4); H , d ( ∼ 8.2); H 3′ , d ( ∼ 7.8); H 4′ , dd ( ∼ 6.6, 6.2); H 5′ , t ( ∼ 7.8); H 6′ , d ( ∼ 8.2); O–(CH ) –, t ( ∼ 6.2); –(CH )n –, m; –CH , t ( ∼ 6.0) H NMR, δ ppm (CDCl3 ),J a , (Hz) Comp H1 H2 H3 H5 7a 7.2, s 8.2, d 7b 7.2, s 8.2, d 7c 7.2, s 8.2, d 7d 7.2, s 8.2, d 7e 7.2, s 8.2, d 7f 7.2, s 8.2, d 7g 7.2, s 8.2, d 7h 7.2, s 8.2, d 7i 7.2, s 8.2, d 7j 7.2, s 8.2, d 7k 7.2, s 8.2, d Table (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) UV-vis λ nm (log ε) IR: cm −1 ; LC-MS/MS: [M + H] + or [M – H] + ; R f : (0.72–0.8), n-hexane–diethyl ether (8:2) a First number is calculated value and second number is found value for C, H, and N 7a 7b 7c 7d 7e 7f 7g 7h 7i 7j 7k Comp Table Physicochemical data of compounds 7a–k TOSUN et al./Turk J Chem 853 854 IR C=N– 1590 1589 1590 1589 1590 1591 1591 1589 1590 1590 1591 =C–F 1235 1234 1234 1233 1234 1235 1235 1234 1234 1234 1234 7d 155.0 102.1/101.9 161.6 121.7 129.0 129.8 125.5 150.0 120.5 128.5/128.3 162.9/158.0 116.3/115.8 130.7/130.5 131.4/131.3 124.6/124.5 68.4 31.8–22.6 (6C) 14.1 (100) (100) (100) (100) (100) (100) (100) (100) (100) (100) (100) LC-MS/MS 310 324 338 352 366 380 394 408 422 436 450 7f 155.0 102.0/101.9 161.6 121.7 128.9 129.9 125.5 148.9 120.4 128.5/128.3 162.9/158.0 116.3/115.8 130.7/130.6 131.4/131.3 124.6/124.5 68.5 31.9–22.67 (8C) 14.1 7g 155.0 102.0/101.9 161.5 121.7 129.0 129.7 125.4 148.9 120.4 128.5/128.3 162.9/158.0 116.3/115.8 130.6/130.5 131.4/131.3 124.6/124.5 68.4 31.8–22.6 (9C) 14.1 Yield (%) 33 31 35 29 27 32 30 28 31 34 29 mp (◦ C) 58–63 47–50 55–60 56–61 66–71 58–60 44–49 42–45 43–46 42–47 42–44 396 426 399 404 393 394 417 397 398 430 395 (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) (4.6) 298 305 308 300 294 295 309 300 306 301 297 (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) (4.5) UV-vis λ nm(log ε) 7i 155.0 102.1/101.9 161.6 121.7 129.0 129.8 125.5 148.9 120.5 128.5/128.3 162.9/158.0 116.3/115.8 130.7/130.5 131.4/131.3 124.6/124.5 68.4 31.9–22.7 (11C) 14.1 (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) (4.4) 7k 155.0 102.1/102.0 161.7 121.8 129.0 129.9 125.5 148.9 120.5 128.5/128.3 162.9/158.0 116.3/115.9 130.7/130.6 131.4/131.3 124.6/124.5 68.5 31.9–22.67 (13C) 14.1 (%)a N 4.53/4.50 4.33/4.30 4.15/4.13 3.99/3.91 3.83/3.89 3.69/3.76 3.56/3.60 3.44/3.51 3.32/3.36 3.22/3.27 3.12/3.15 J CF ( ∼ 3.3); C 5′ : J CF 7j 155.0 102.0/101.9 161.6 121.7 129.0 129.8 125.5 149.0 120.5 128.5/128.3 162.9/158.0 116.3/115.8 130.7/130.5 131.4/131.3 124.6/124.5 68.5 31.9–22.7 (12C) 14.1 Elemental analyses data C H 77.64/77.25 6.52/6.58 77.99/77.90 6.86/6.83 78.31/78.61 7.17/7.12 78.60/78.72 7.46/7.50 78.87/78.85 7.72/7.80 79.12/79.29 7.97/7.89 79.35/79.42 8.20/8.30 79.57/79.53 8.41/8.47 79.77/79.82 8.61/8.75 79.96/79.90 8.79/8.88 80.13/80.19 8.97/8.96 J CF ( ∼ 8.4); C 6′ : 256 256 255 256 256 255 256 255 255 255 255 7h 155.0 102.1/101.9 161.6 121.7 129.0 129.8 125.5 148.9 120.4 128.5/128.3 162.9/158.0 116.3/115.8 130.6/130.5 131.4/131.3 124.6/124.5 68.4 31.9–22.6 (10C) 14.1 J CF ( ∼ 23.1); C 1′ : J CF ( ∼ 11.7);C 4′ : 7e 155.0 102.1/102.0 161.7 121.8 129.0 129.9 125.5 150.0 120.5 128.5/128.3 162.9/158.0 116.3/115.9 130.7/130.5 131.4/131.3 124.6/124.5 68.5 31.9–22.7 (7C) 14.1 C NMR data of compounds 7a–k a Table Physicochemical data of compounds 8a–k J CF ( ∼ 247.8); C 3′ : C20 H20 FNO C21 H22 FNO C22 H24 FNO C23 H26 FNO C24 H28 FNO C25 H30 FNO C26 H32 FNO C27 H34 FNO C28 H36 FNO C29 H38 FNO C30 H40 FNO Formula 7c 155.1 102.1/102.0 161.6 121.7 129.0 129.8 125.5 148.9 120.5 128.5/128.3 162.9/158.0 116.3/115.9 130.7/130.5 131.4/131.3 124.6/124.5 68.4 31.7–22.6 (5C) 14.1 J CF ( ∼ 8.0); C 2′ : 7b 155.0 102.1/101.9 161.5 121.7 129.0 129.7 125.4 148.9 120.4 128.5/128.3 162.9/158.0 116.3/115.8 130.6/130.5 131.4/131.3 124.6/124.5 68.4 31.5–22.5 (4C) 14.0 13 IR: cm −1 ; LC-MS/MS: [M + H] + or [M – H] + ; R f : (0.72–0.8), n-hexane–diethyl ether (8:2) a First number is calculated value and second number is found value for C, H, and N 8a 8b 8c 8d 8e 8f 8g 8h 8i 8j 8k Comp 7a 155.1 102.1/101.9 161.6 121.7 129.0 129.8 125.5 148.9 120.4 128.5/128.3 162.9/158.0 116.3/115.8 130.7/130.5 131.4/131.3 124.6/124.5 68.4 28.5–22.4 (3C) 14.0 a J7a−k (Hz): C : ( ∼ 2.9) C No C2 C3 C4 C5 C6 C7 C8 C9 C10 C1 ’ C2′ C3′ C4′ C5′ C6′ O–(CH2 )– –(CH2 )n – n: 2–14 –CH3 Table TOSUN et al./Turk J Chem a H6 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.7, 7.8, dd dd dd dd dd dd dd dd dd dd dd H7 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, t t t t t t t t t t t d d d d d d d d d d d H2′ 7.8, 7.9, 7.8, 7.9, 7.9, 7.8, 7.8, 7.9, 7.9, 7.8, 7.9, s s s s s s s s s s s H4′ 7.2, 7.3, 7.2, 7.3, 7.3, 7.2, 7.2, 7.2, 7.2, 7.2, 7.2, d d d d d d d d d d d H5′ 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, 7.5, t t t t t t t t t t t H6′ 8.2, 8.3, 8.3, 8.3, 8.3, 8.2, 8.3, 8.2, 8.3, 8.3, 8.3, H NMR data of compounds 8a–k H8 7.9, 7.9, 7.9, 7.9, 7.9, 7.8, 7.9, 7.9, 7.9, 7.9, 8.1, d d d d d d d d d d d O–(CH2 )– 4.2, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t –(CH2 )n – n: 2–14 1.3–2.0, 6H 1.3–2.0, 8H 1.2–2.0, 10H 1.3–2.0, 12H 1.3–2.0, 14H 1.3–2.0, 16H 1.3–2.0, 18H 1.3–2.0, 20H 1.3–2.0, 22H 1.3–2.0, 24H 1.3–2.0, 26H –CH3 1.0, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t a J8a−k : C 3′ : C No C2 C3 C4 C5 C6 C7 C8 C9 C10 C1 ’ C2′ C3′ C4′ C5′ C6′ O–(CH2 )– –(CH2 )n – n: 2–14 –CH3 8b 157.1 98.4 162.6 121.7 125.6 130.1 128.8 148.6 120.5 142.6/142.5 114.8/114.3 165.6/160.7 116.4/115.9 130.4/130.2 123.2/123.1 68.6 31.5–22.5 (4C) 14.0 J CF ( ∼ 244.5); C 2′ : 8a 157.1 98.2 162.3 121.7 125.5 130.0 129.0 148.9 120.5 142.6/142.5 114.6/114.2 165.5/160.7 116.1/115.7 130.2/130.0 123.0/123.0 68.4 28.5–22.4 (3C) 14.0 2 8f 156.9 98.6 163.1 121.8 125.9 130.7 128.1 147.6 120.4 142.6/142.5 115.0/114.6 165.5/160.6 116.7/116.3 130.3/129.8 123.0/122.9 69.0 31.8–22.6 (8C) 14.1 8g 157.4 98.9 163.5 122.1 126.3 131.0 128.3 147.9 122.1 142.6/142.5 115.3/114.8 165.8/160.9 117.1/116.7 130.7/130.6 123.0/122.9 69.2 31.2–22.9 (9C) 14.4 C NMR data of compounds 8a–k a 8e 157.0 98.6 163.1 121.8 125.9 130.7 128.0 147.8 120.4 142.6/142.5 115.0/114.5 165.5/160.6 116.8/116.3 130.4/130.2 123.0/122.9 69.9 31.8–22.6 (7C) 14.1 13 8h 157.1 98.2 162.4 121.7 125.5 130.0 129.1 148.9 120.5 142.6/142.5 114.7/114.2 165.6/160.7 116.2/115.7 130.2/129.9 123.0/122.9 68.4 31.8–22.6 (10C) 14.1 8j 157.0 98.5 162.9 121.8 125.8 130.5 128.4 148.1 120.5 142.6/142.5 114.9/114.4 165.5/160.6 116.6/116.1 130.3/130.2 123.0/122.9 68.8 31.9–22.7 (12C) 14.1 J CF ( ∼ 2.9) 8i 157.0 98.6 163.5 121.8 125.9 130.7 128.2 147.9 120.7 142.6/142.5 115.0/114.5 165.6/160.7 116.7/116.3 130.4/130.2 123.0/122.9 68.9 31.9–22.6 (11C) 14.1 J CF ( ∼ 21.8); C 5′ : J CF ( ∼ 8.1); C 1′ : J CF ( ∼ 7.7); C 6′ : 8d 157.0 98.6 163.1 121.8 125.9 130.6 128.1 147.8 120.4 142.6/142.5 114.9/114.5 165.5/160.6 116.7/116.3 130.4/130.2 123.0/122.9 68.9 31.8–22.6 (6C) 14.1 J CF ( ∼ 22.7); C 4′ : 8c 157.3 98.9 163.5 122.1 126.3 131.0 128.3 147.9 120.7 142.6/142.5 115.3/114.8 165.8/160.9 117.1/116.7 130.7/130.5 123.0/122.9 69.3 32.0–22.5 (5C) 14.4 Table 8k 156.9 98.6 163.1 121.8 125.9 130.6 128.1 147.7 120.4 142.6/142.5 114.9/114.5 165.5/160.6 116.7/116.2 130.7/130.5 123.0/122.9 68.9 34.1–22.6 (13C) 14.2 a J8a−k (Hz): H , d ( ∼ 8.2); H , dd ( ∼ 7.6, 8.2); H , t ( ∼ 8.2); H , d ( ∼ 7.6); H 4′ , d ( ∼ 8.2); H 5′ , t ( ∼ 7.8); H 6′ , d ( ∼ 8.2); O–(CH ) –, t ( ∼ 6.4); –(CH )n –, m; –CH , t ( ∼ 6.2) H NMR, δ ppm (CDCl3 ),J , (Hz) Comp H1 H2 H3 H5 8a 7.1, s 8.1, d 8b 7.1, s 8.2, d 8c 7.1, s 8.2, d 8d 7.1, s 8.2, d 8e 7.1, s 8.2, d 8f 7.1, s 8.2, d 8g 7.1, s 8.2, d 8h 7.1, s 8.1, d 8i 7.1, s 8.2, d 8j 7.1, s 8.2, d 8k 7.1, s 8.2, d Table TOSUN et al./Turk J Chem 855 856 1590 1590 1590 1591 1590 1590 1590 1590 1590 1590 1590 9a 9b 9c 9d 9e 9f 9g 9h 9i 9j 9k 1222 1222 1222 1222 1223 1222 1222 1223 1222 1221 1222 =C–F + C30 H40 FNO C29 H38 FNO C28 H36 FNO C27 H34 FNO C26 H32 FNO C25 H30 FNO C24 H28 FNO C23 H26 FNO C22 H24 FNO C21 H22 FNO C20 H20 FNO Formula + 450 (5) 436 (10) 422 (25) 408 (5) 394 (30) 380 (10) 366 (13) 352 (5) 338 (10) 324 (14) 310 (32) LC-MS/MS 28 29 34 30 33 27 32 26 31 28 30 Yield (%) 67–68 52–53.5 63–63.5 38–39 46–47 38–39.5 42–43.5 42–43 46–47 62–62.5 59–60 mp (◦ C) 336 (4.5) 346 (4.5) 333 (4.5) 310 (4.5) 320 (4.5) 323 (4.5) 322 (4.5) 326 (4.5) 326 (4.5) 326 (4.5) 326 (4.5) H6 7.5, 7.5, 7.5, 7.5, 7.5, 7.4, 7.5, 7.5, 7.5, 7.5, 7.5, dd dd dd dd dd dd dd dd dd dd dd H7 7.7, 7.7, 7.7, 7.7, 7.7, 7.6, 7.7, 7.7, 7.7, 7.7, 7.7, dd dd dd dd dd dd dd dd dd dd dd H8 8.1, 8.1, 8.1, 8.1, 8.1, 8.0, 8.0, 8.1, 8.1, 8.1, 8.1, d d d d d d d d d d d H2′ ,6′ 8.1, d 8.1, d 8.1, d 8.1, d 8.1, d 8.0, d 8.1, d 8.2, d 8.1, d 8.1, d 8.1, d H3′ , 5′ 7.2, dd 7.2, dd 7.2, dd 7.2, dd 7.2, dd 7.1, dd 7.2, dd 7.2, dd 7.2, dd 7.2, dd 7.2, dd O–(CH2 )– 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t 4.2, t 4.3, t 4.3, t 4.3, t 4.3, t 4.3, t H NMR data of compounds 9a–k 8.97/8.99 8.79/8.81 8.61/8.69 8.41/8.51 8.20/8.24 7.97/7.95 7.72/7.79 7.46/7.53 7.17/7.18 6.86/6.90 6.52/6.61 –CH3 1.0, t 0.9, t 0.9, t 0.9, t 0.9, t 0.8, t 0.9, t 0.9, t 0.9, t 0.9, t 0.9, t 80.13/80.16 79.96/79.98 79.77/79.90 79.57/79.61 79.35/79.37 79.12/79.21 78.87/78.90 78.60/78.71 78.31/78.31 77.99/77.87 77.64/77.71 –(CH2 )n – n: 2–14 1.3–2.0, 6H 1.3–2.0, 8H 1.3–2.0, 10H 1.3–2.0, 12H 1.3–2.0, 14H 1.2–2.0, 16H 1.3–2.0, 18H 1.3–2.0, 20H 1.3–2.0, 22H 1.3–2.0, 24H 1.3–2.0, 26H 258 (4.4) 267 (4.4) 256 (4.4) 258 (4.4) 256 (4.4) 254 (4.4) 244 (4.4) 256 (4.4) 256 (4.4) 256 (4.4) 256 (4.4) a 3.12/3.14 3.22/3.29 3.32/3.40 3.44/3.48 3.56/3.58 3.69/3.71 3.83/3.87 3.99/3.96 4.15/4.17 4.33/4.34 4.53/4.60 Elemental analyses data (%)a C H N J9a−k (Hz): H , d ( ∼ 8.2); H , dd ( ∼ 7.4, 7.4); H , dd ( ∼ 6.7, 8.1); H , d ( ∼ 6.4); H 2′ ,6′ , d ( ∼ 7.8); H 3′ , 5′ , dd ( ∼ 8.3, 8.4); O–(CH ) –, t ( ∼ 6.6); –(CH )n –, m; –CH , t ( ∼ 7.2) H NMR, δ ppm (CDCI3 ),J a , (Hz) Comp H1 H2 H3 H5 9a 7.1, s 8.2, d 9b 7.1, s 8.2, d 9c 7.1, s 8.2, d 9d 7.1, s 8.2, d 9e 7.1, s 8.2, d 9f 7.0, s 8.1, d 9g 7.1, s 8.2, d 9h 7.1, s 8.2, d 9i 7.1, s 8.2, d 9j 7.1, s 8.2, d 9k 7.1, s 8.2, d Table 288 (4.5) 297 (4.5) 283 (4.4) 278 (4.4) 280 (4.4) 277 (4.4) 256 (4.4) 276 (4.4) 276 (4.4) 278 (4.4) 278 (4.4) UV-vis λ nm(log ε) IR: cm ; LC-MS/MS: [M + H] or [M – H] ; R f : (0.72–0.8), n-hexane–diethyl ether (8:2) a First number is calculated value and second number is found value for C, H, and N −1 IR C=N– Comp Table Physicochemical data of compounds 9a–k TOSUN et al./Turk J Chem a J9a−k : C 4′ : C No C2 C3 C4 C5 C6 C7 C8 C9 C10 C1 ’ C2′ , 6′ C3′ , 5′ C4′ O–(CH2 )– –(CH2 )n – n: 2–14 –CH3 9b 157.7 98.5 162.3 125.3 129.0 129.9 121.7 149.1 120.4 136.4/136.5 129.4/129.2 115.8/115.4 166.1/161.1 68.4 31.5–22.6 (4C) 14.0 J CF ( ∼ 247.0); C 3′ , 5′ : 9a 157.7 98.2 162.3 125.3 128.9 130.0 121.7 149.1 120.4 136.6/136.5 129.5/129.3 115.8/115.4 166.1/161.1 68.4 28.6–22.4 (3C) 14.0 9d 157.7 98.2 162.3 125.3 128.9 129.9 121.7 149.0 120.4 136.4/136.4 129.4/129.2 115.8/115.3 166.1/161.1 68.4 31.7–22.6 (6C) 14.1 9g 157.8 98.3 162.3 125.3 128.7 130.0 121.7 148.9 120.3 136.5/136.4 129.4/129.3 115.8/115.3 166.0/161.1 68.4 31.8–22.6 (9C) 14.0 J CF ( ∼ 3.0) 9f 157.6 98.1 162.3 125.2 128.9 139.9 121.7 149.0 120.3 136.4/136.4 129.4/129.2 115.8/115.3 166.1/161.1 68.4 31.8–22.6 (8C) 14.1 C NMR data of compounds 9a–k a 9e 157.7 98.1 162.3 125.2 129.0 129.9 121.7 149.1 120.3 136.5/136.4 129.4/129.2 115.8/115.4 166.1/161.1 68.4 31.8–22.1 (7C) 14.1 13 J CF ( ∼ 21.4); C 2′ , 6′ : J CF ( ∼ 8.3); C 1′ : 9c 157.7 98.2 162.3 125.3 128.9 130.0 121.7 149.0 120.4 136.5/136.5 129.5/129.3 115.8/115.4 166.1/161.1 68.4 31.7–22.6 (5C) 14.1 Table 9h 157.6 98.1 162.3 125.2 129.0 129.9 121.7 149.0 120.3 136.5/136.4 129.4/129.2 115.8/115.3 166.1/161.1 68.4 29.6–22.6 (10C) 14.1 9i 157.7 98.1 162.3 125.2 129.0 130.0 121.7 149.1 120.3 136.5/136.4 129.4/129.2 115.8/115.4 166.1/161.2 68.4 34.6–22.7 (11C) 14.1 9j 157.7 98.1 162.3 125.3 129.0 130.0 121.7 149.1 120.4 136.5/136.4 129.4/129.3 115.8/115.4 166.1/161.1 68.4 31.9–22.6 (12C) 14.1 9k 157.6 98.1 162.3 125.2 128.9 129.9 121.7 149.0 120.3 136.5/136.4 129.4/129.2 115.8/115.3 166.0/161.1 68.4 31.9–22.6 (13C) 14.1 TOSUN et al./Turk J Chem 857 TOSUN et al./Turk J Chem tive agents Various antiparasitic, 18 antibacterial, cytotoxic and antineoplastic, 19 antimycobacterial, 20 and antiinflammatory 21 biological activity studies of quinolone derivatives have been conducted and are still needed for new quinolone derivatives 2.2.1 In vitro antibacterial screening The antimicrobial activities of three new series of 33 quinolone compounds 2-(2-, 3-, and 4-fluorophenyl)4-O-alkyl(C 5−15 )quinolines (7a–k, 8a–k, and 9a–k) were tested against gram-negative, gram-positive, and antifungal bacteria The experimental results showed that antimicrobial activity was more effective on the gram-positive bacteria than the others that were used Additionally, the length of the alkyl chain on the quinolone ring increases and the antimicrobial activity decreases as its interaction with the membrane lowers In the literature, quinolines including fluorine substitution showed antituberculosis activity against Myosotis tuberculosis bacteria type 30 The compounds 4–6, 7a–k, 8a–k, and 9a–k were prescreened with an agar well diffusion assay at 500 µ g/mL concentration, and those that showed activity were further tested to determine their minimal inhibition concentration (MIC) values (Table 10) The MIC values of tested compounds 7a–k, 8a–k, and 9a–k decreased slightly with the number of carbon atoms in the alkyl chain as shown in Figure It was difficult to attribute decreasing MIC values with the length of the carbon chain in the O-alkyl substituents The antimicrobial activity of compounds 4, 5, and showed that there was no adverse activity against grampositive and antifungal bacteria apart from compound out of nine different bacteria types in total examined as gram-positive, acido-resistant, and antifungal bacteria The antimicrobial results revealed that compounds 9d, 9e, and 9f only have higher activities against the gram-positive bacterium Enterococcus faecalis at a high concentration (500 µ g/mL) among other bacteria used in this work Furthermore, it was observed that initial compounds 4, 5, and and apart from 7b and 7c out of synthesized compounds and all other compounds have activities against tuberculosis bacteria type Mycobacterium smegmatis The experimental results showed that the longer the alkyl chain gets, the lower activity is for the tested compounds 7a–k, 8a–k, and 9a–k 31 Antimicrobial activities of these three series of title compounds showed that 8a–k is the most active (MIC, 62.5–125 µ g/mL), 9a–k is the second (MIC, 125–250 µ g/mL, except 9h), and 7a–k is the least active (MIC, 125–500 µ g/mL) against tuberculosis bacteria (M smegmatis) When the fluoride was substituted at the m-position of the target compounds 8a–k showed higher antituberculosis activity (MIC, 62.5–125 µ g/mL) than the other o-, and p-fluoride substituted compounds 7a–k (MIC, 250–500 µ g/mL, except compound 7a) and 9a–k (MIC, 125–250 µ g/mL, except compound 9h) (Table 10), respectively 2.3 In vitro antioxidant activity Two or more antioxidant test methods with different strategies were generally utilized in antioxidant activity determinations Antioxidant activity differences appear in many cases between the results of different assays due to different reaction mechanisms with varying effects of solvents and temperature, existence of sterical issues, pH, and the matrix components In the current study, two widely used antioxidant test methods were used for the determination of antioxidant capacities of the synthesized compounds 7a–k, 8a–k, and 9a–k The DPPH• radical scavenging test has been used extensively for various types of samples including synthetic compounds (Figure 2) 32 The ferric reducing/antioxidant power (FRAP) method has also been utilized in many investigations with synthetic organics (Figure 3) To overcome solubility issues of the compounds when the solutions are mixed with FRAP reagent, the original method 33,34 has been modified to contain methanol in 3:2 ratio in water instead of using water as solvent in the preparation of FRAP reagent 858 TOSUN et al./Turk J Chem Table 10 Screening for antimicrobial activity of the compounds (4, 5, 6, 7a–k, 8a–k, 9a–k) Compounda a b c d e f g h i j k Ampicillin Streptomycin Fluconazole a b Microorganisms and minimum inhibition concentration (MIC, µg/mL) Gram (–) Gram (+) Mycobacterium Fungi Ec Yp Pa Ef Sa Bc Ms Ca Sc 125 62.5 250 125 125 125 125 125 125 62.5 250 b 500 500 62.5 250 500b 500 62.5 125 500b 500 125 250 500 62.5 250 500 125 500 250 125 250 500 125 250 250 125 250 32 > 128 2 < nt nt nt nt nt nt nt nt nt nt nt nt nt nt nt nt nt nt