Tayyibe Beyza Yücel

In this study, the chemical compositions of volatile oils obtained via Clevenger distillation from red algae species Laurencia obtusa and Ceramium spp., collected from the coastal areas of Sinop (Black Sea), were analyzed by GC/MS. Additionally, hexane, dichloromethane, chloroform, and methanol extracts were prepared using the Soxhlet extraction method, and their antileishmanial activities were evaluated. As a result, 80.92% and 90.51% of the volatile oil compositions of Laurencia obtusa and Ceramium spp. were identified, respectively, with 20 compounds characterized in each species. Hydrocarbons were the predominant compound class in the essential oils of Laurencia obtusa (79.31%) and Ceramium spp. (72.89%). The leishmanicidal activities of the solvent extracts were tested in vitro against Leishmania infantum promastigotes. The minimum inhibitory concentration (MIC) values for Laurencia obtusa extracts in hexane, dichloromethane, chloroform, and methanol were 5, 2.5, 2.5, and 10 mg/mL, respectively. For Ceramium spp., the MIC values were 2.5, 2.5, 2.5, and 10 mg/mL, respectively. Dichloromethane and chloroform extracts of both species exhibited greater antileishmanial activity compared to methanol and hexane extracts, indicating their higher potential as antileishmanial agents.

A number of new methoxy-substituted 4,6-diaryl-3,4-dihydropyrimidine-2(1H)-thiones (DH-Pyr-S, 17-28) were designed and synthesized by the reaction of methoxy-substituted chalcones (1–14) with thiourea using solid-phase microwave method (MW) in view of the structural requirements as suggested in the pharmacophore model for tyrosinase inhibition (TI). Synthesized compounds were assessed for their in vitro TI potential and compounds 16, 17, and 21 exhibited notable tyrosinase inhibitory properties at the concentrations of 31.86 ± 2.45 µM, 44.58 ± 0.46 µM, and 48.47 ± 0.66 µM, respectively. Compounds (16, 17, and 21) were exhibited experimentally more potent TI than the standard used in terms of the IC50 value (Kojic acid, 55.38 ± 2.30 µM; p<0.0001). Additionally, DPPH activity of 15-28 were evaluated and compound 17 showed the moderate DPPH activity (45.64 ± 0.34%). Binding affinities of synthesized molecules to the tyrosinase catalytic core were further investigated through in silico molecular docking studies using AutoDock Vina (version 1.2.5), discovery studio accelyrs (BIOVIA, Dassault Systèmes) and predicting small-molecule pharmacokinetic properties using graph-based signatures (pkCSM) programs were used for ADMET calculations. Among synthesized compounds 15, 21, and 24 revealed high binding affinity to tyrosinase active site with lowest binding free energy (ΔG) values of -7.9 kcal/mol, thereby outperformed kojic acid affinity. In conclusion most modeling results were in agreement with their experimental data, suggesting the TI potential of lead compounds.

In the present study, the volatile composition of Ulva rigida (U. rigida) was elucidated by two different methods. As a result of the identification process of volatile components using the GC/MS‐FID instrument, 31 compounds were identified by hydrodistillation (HD) method, and 15 compounds were identified by solid‐phase microextraction (SPME) method, elucidating the structure of 99.86 % and 92.65 %, respectively. The most abundant compounds in the essential oil of U. rigida were n‐hexadecanoic acid and pentadecanal, while the most abundant compound according to the SPME analysis was heptadecyne, a hydrocarbon compound. In the next step, hexane, dichloromethane, chloroform and methanol solvent extracts of U. rigida were prepared and the antimicrobial activities of the extracts and the essential oil obtained by hydro‐distillation as well as the scolicidal activities of the solvent extracts were determined. The results of the antimicrobial activity test of the essential oil showed a high level of activity against Bacillus cereus ATCC 10876 and MRSA. The highest activity was found on the microorganism of Pseudomonas aeruginosa ATCC 9027 in chloroform and methanol extracts of U. rigida. Furthermore, viability detection was performed and the scolicidal effects of the extracts on protoscoleces were assessed. The values of lethal concentration doses (LD₅₀, LD₇₅ and LD₉₀) were calculated using probit analysis.

Bu çalışmada, 2-aminoasetofenon bileşiğinden başlanarak 2-,3-,4- bromo substitue azakalkon (1-3) bileşikleri sentezlendi. 1-3 Nolu bileşiklerinin katıfaz ortamında mikrodalga cihazı kullanılarak 2-, 3-, 4-bromo azaflavanon bileşikleri (4-6), sırasıyla %52, %89 ve %77 verimlerle sentezlendi. Sentezlenen bileşikler spektroskopik olarak 1Hidrojen, 13Karbon, Bağlanmış Proton Testi (APT) NMR, Fourier Dönüşümlü Kızılötesi Spektroskopisi (FT-IR) Infrared ve Sıvı kromatografi-kütle spektrometresi/kütle spektrometresi (LC-MS/MS)yöntemleriyle karakterize edildi. Sentezlenen bileşiklerin antimikrobiyal aktiviteleri 12 ayrı mikroorganizmaya (4 adet Gram pozitif, 7 adet Gram negatif ve 1 fungus) karşı disk difüzyon yöntemi kullanılarak test edildi ve minimum inhibisyon konsantrasyonu (MİK) hesaplandı. Sentezlenen azakalkon ve azaflavanon bileşikleri (1-6) test edilen mikroorganizmalar arasında en yüksek etkiyi Candida tropicalis’a karşı gösterdi. 3-Bromo azaflavanon (5) bileşiği Gram pozitif Enterococcus feacalis, Staphylococcus aureus ve fungus Candida tropicalis’a karşı etkili bulundu. Test edilen hiçbir bileşik Gram negatif bakterilere karşı etkinlik göstermedi. Sentezlenen bileşikler arasında en yüksek aktiviteyi 6.25 µg/mL’lik MIC değeri ile 2 numaralı azakalkon bileşiği Candida tropicalis’a karşı gösterdi. Ayrıca sentezlenen 1-6 nolu bileşiklerin antioksidan aktiviteleri plazmanın demir indirgeme yeteneği (FRAP) ve 1,1-Difenil-2-pikrilhidrazil kapasitesi (DPPH) yöntemlerine göre yapıldı. Antioksidant testi sonucunda, 3-bromo kalkon (173,78±1,76 ve 0,48±0,01) ve 3-bromo azaflavanon (279,05±1,77 ve 0,093±0,001) bileşiklerinin en yüksek antioksidan aktiviteye sahip oldukları görüldü.

Bichalcones are obtained naturally from the genus Rhus. Bichalcones have attracted attention not only from a synthetic perspective but also because of their broad-spectrum biological activities. A series of methoxy-substituted chalcones (1–9) yielded...

This study aims to derive an essential oil from Cystoseira crinita Duby, analyze the chemical composition of the essential oil, discover the antimicrobial activities of the oil and the extracts, and investigate the scolicidal activities of the extracts. The volatile organic compounds of Cystoseira crinita Duby were determined by GC/MS-FID using both hydro-distillation (HD) and solid-phase microextraction (SPME) methods. As a result of the essential oil analysis, 97.14% of 17 compounds and 93.13% of 19 compounds were elucidated. The main compounds identified were hexanal (31.802%), n-hexadecanoic acid (12.654%), trans-β-ionone (9.118%), 2E-hexenal (15.955%), heptadecane (15.729%) and tetradecane (13.458%). In addition, hexane, dichloromethane, chloroform, and methanol extracts of the algae sample were prepared. The antimicrobial activities of the essential oil and extracts on gram-positive bacteria, gram-negative bacteria, and fungi microorganisms were studied. The results revealed activity within the zone diameter range of 8-16 mm. It was observed that all extracts and the essential oil itself showed high activity against the Pseudomonas aeruginosa ATCC 27853 microorganism. The chloroform and dichloromethane extracts were also found to demonstrate a high level of efficacy against Bacillus cereus ATCC 10876. Furthermore, viability detection was performed and the scolicidal effects of the extracts on protoscoleces were assessed. All extracts showed a strong scolicidal effect at the dose of 15000 μg/mL. For each solution, the difference between hours at each dose and the difference between doses at every hour were compared by One-Way ANOVA. The values of lethal concentration doses (LD50 and LD90) were calculated using Probit Analysis. This study provides information about the effects of Cystoseira crinita Duby algae extracts and suggests that the experimental studies needed for their use in live cells should be performed.

In this study, in the spring of 2019, algaes of Ulva species were collected from eigh station in Giresun costline (Piraziz port, Bulancak port, Giresun port, Keşap station, Espiye-Opet stations, Tirebolu station, Görele station and Eynesil station in May. They are brought to the laboratory in polyethylene bottles. In general, the amount of seaweed samples to be tested was weighed around 15-20 g. Wet algae samples are extracted by methanol solutions with Soxhlet apparatus for 12 hours. By applying the necessary purification processes to the obtained solution, the concentrations of 16 PAH components were determined with the GC/MS device. The amount of most of the 16 PAH compounds in the Keşap site seaweed samples was the highest. The highest amount compounds are found to fluorene, phenanthrene and antresen, and it is high in Bulancak, Giresun-Liman and Keşap sites. It belongs to seaweed samples collected from Piraziz site, which has the lowest values among eight stations. Since the benzo [g, h, i] perylene is lower than the detection levels in many stations. The main origins of PAHs were found as both pyrolytic and petrogenic at most stations.

The aim of the present study was to determine the chemical analysis, antimicrobial and antioxidant effects of the Eurhynchium angustirete (Broth.) and Isothecium alopecuroides (Lam. Ex Dubois) essential oil obtained by distillation method (Clevenger apparatus hydrodistillation). Obtained volatile oils were identified by gas chromatography-mass spectrometry (GC/MS) which revealed the presence of twenty-two components analyzed in the essential oil of E. angustirete representing 95.7% of the total identified compounds and twenty compounds were determined in the essential oil of I. alopecuroides representing 94.3% of the total identified compounds. Trans-pinocarveol and myrtenal as major constituents were 23.0% and 14.1% in E. angustirete and the main components were: biformene (9.9%), α-pinene (9.1%), bornyl acetate (8.4%) in I. alopecuroides. The essential oils from E. angustirete and I. alopecuroides showed higher metal-ion chelating activities which were 65.93±0.39% and 31.01±2.75, respectively. There was no significant difference results DPPH activity of essential oils 16.8±6.98 and 22.8%±8.91, respectively. The antimicrobial activity was investigated by microdiution method. The isolated essential oils were showed effective antimicrobial activities against Escherichia coli ATCC25922, Enterococcus faecalis ATCC29212, Staphylococcus aureus ATCC25923, Pseudomonas aeruginosa ATCC2785 and Streptococcus mutans. Antimicrobial effect values were found ranging of 90.76-95.38%. According to antimicrobial effect value against to microorganism, essential oil of E. angustirete was higher than I. alopecuroides.

The aim of this study is to analyze the volatile composition and antimicrobial and antioxidant activities of the essential oils of Polytrichum commune and Antitrichia curtipendula. The essential oils obtained by hydro-distillation (HD) from each species were identified by GC-MS/FID. The main components were biformene (13.06%), α-pinene (6.53%), and bornyl acetate (8.10%) in P. commune. Nonanal and tetradecanal as major compounds were 19.96% and 20.23% in A. curtipendula essential oils, respectively. Antioxidant activity of obtained essential oils was evaluated using in-vitro antioxidant models. There was no significant difference within the groups according to DPPH activity. Also, the essential oil from P. commune showed higher metal-ion chelating activities than that of the essential oil of A. curtipendula. Metal-ion chelating activities varied between 4.1% and 67.4% at the 800 µg/mL concentration, respectively. The antimicrobial activity was tested by a minimal inhibition concentration test. Each moss species showed good antimicrobial activity against microorganisms according to the results of minimal inhibition concentration experiments.