Ayse Yusufoglu

Synthesis and biological activity of new 1,3-dioxolanes as potential antibacterial and antifungal compounds.

A series of new enantiomerically pure and racemic 1,3-dioxolanes 1-8 was synthesized in good yields and short reaction times by the reaction of salicylaldehyde with commercially available diols using a catalytic amount of Mont K10. Elemental analysis and spectroscopic characterization established the structure of all the newly synthesized compounds. These compounds were tested for their possible antibacterial and antifungal activity. Biological screening showed that all the tested compounds, except 1, show excellent antifungal activity against C. albicans, while most of the compounds have also shown significant antibacterial activity against S. aureus, S. epidermidis, E. faecalis and P. aeruginosa.

Asymmetric synthesis of new chiral 1,2- and 1,3-diols

Seven chiral 1,2-diols and six chiral 1,3-diols were synthesized by the asymmetric reduction of the corresponding 1,2-diketones and 1,3-diketones using oxazaborolidine–BH3 catalyst. The 13 corresponding racemic 1,2- and 1,3-diols were synthesized by reducing the diketones with NaBH4 and they were used for determining the ee values through their chiral resolution on HPLC and GC. Five starting diketones, four racemic 1,2-diols, five chiral 1,2-diols, and two chiral 1,3-diols are novel compounds. The new chiral compounds were characterized by IR, 1H and 13C NMR, MS, and elemental analysis. The asymmetric reduction method, oxazaborolidine–BH3, was applied to these diketones for the first time in this study. The relationship between the structure of the diketone and the yield, diastereoselectivity, and enantiomeric excess was discussed.Graphical abstract

Some Monohydroxy Tetradecanoic Acid Isomers as Novel Urease and Elastase Inhibitors and as New Antioxidants

A series of some 3-,6-,7-,9-,12- monohydroxy tetradecanoic acids were evaluated for their antiurease, antielastase and antioxidant activities for the first time in this study. All the test compounds exhibited antioxidant, antielastase and antiurease activities. The relationship between the position of the hydroxy group and the enzyme inhibition effect is studied in this work. The mentioned biological activities are depending on the position of hydroxy group of tetradecanoic acid isomers. The results obtained in this work are indicating that 3-,6-,7-,9-,12-monohydroxy tetradecanoic acid isomers can be used in agriculture, pharmacy and cosmetic industries due to their excellent antielastase, antiurease and antioxidant activities.

Different bio/Lewis acid-catalyzed stereoselective aldol reactions in various mediums

In this work eight different crude biocatalysts together with six Lewis and three Brønsted acids were used for asymmetric aldol reactions of aromatic, heteroaromatic, cyclic, and acyclic six ketones and eleven aldehydes. Optimum reaction conditions were determined by changing temperature and enzyme, ketone, aldehyde, solvent, cofactors types, amounts, and ratios. PPL (porcine pancreatic lipase) of animal and AL-AN (amano lipase A from Aspergillus niger) of fungal origins were the best ones and compared with each other. CoCl2 was the best cofactor and catalyzed the enzymatic aldol reaction better than without cofactor. CoCl2 was not used before for enzymatic aldol reactions. The method in this study, using crude biocatalysts (PPL or AL-AN) and CoCl2 in acetonitrile–water was found as an conventionally useful biocatalytic way for asymmetric aldol reaction and has given better ee values than in the literature.Graphical abstract

Chemical Composition of the Essential Oil of Mentha pulegium L. from Bodrum, Turkey

Abstract The aim of this study was to investigate the chemical composition of Mentha pulegium L.’s essential oils from Bodrum, Turkey and to compare it with the literature values. The essential oils in this study were prepared by two different methods, by Clevenger and Steam Distillation. The yields of the essential oils, obtained by Clevenger and steam distillation were 1.6 % and 1.1 %, respectively. The composition of the essential oils were analysed by GC and GC-MS using Carbowax-20M as polar and DB-5 as apolar columns. The headspace analysis of this plant was examined, too. The basic components of steam distillation method on apolar DB-5 column, were isomenthone (42.1 %), pulegone (28.9 %), piperitenone (11.8 %) and piperitone (11.6 %). Analysis of Clevenger type method on the same column gave pulegone (34.6 %), piperitenone (31.4 %), isomenthone (17.9 %) and piperitone (9.7 %) as main components. The major components of headspace analysis of Mentha pulegium L. on DB5 column were isomenthone (52.6 %), pulegone (29.5 %) and menthol (3.6 %).

Synthesis and elastase inhibition activities of novel aryl, substituted aryl, and heteroaryl oxime ester derivatives

Fifteen novel aryl, substituted aryl and heteroaryl γ‐hydroxy‐ (2a–e), γ‐methoxyimino‐ (3a–e), and γ‐benzyloxyimino‐ (4a–e) butyric acid methyl esters were investigated for their enzyme inhibition, and the synthesis of 10 compounds (3a–e, 4a–e) is given in this study. The other five compounds (2a–e) were synthesized before in another study. Compounds 3a–e and 4a–e were synthesized in this work as original compounds and characterized by 1H and 13C NMR, IR, mass, and elemental analyses. Their (E/Z)‐isomerisation ratios were analyzed by 1H and 13C NMR. All of them are of pure (E)‐configuration. Due to the literature survey, the elastase inhibition activity was not studied for these compounds. Elastase inhibition ability was investigated in this work for five γ‐hydroxy‐ (2a–e), five γ‐methoxy‐ (3a–e), and five γ‐benzyloxyimino‐ (4a–e) butyric acid methyl esters. All these 15 compounds showed elastase inhibition activity. Compound 2b was the best one and exhibited a better activity than the standard ursolic acid whereas compound 2a worked like the standard. All these compounds can be novel elastase inhibitor agents in the pharmaceutical and cosmetic industries.

Detailed studies on the reduction of aliphatic 3-, 4-, 6-, and 13-oximino esters: Synthesis of novel isomeric amino esters, oximino alcohols, and amino alcohols

ABSTRACT The preparation of novel 3-, 4-, 6-, and 13-amino-tetradecanoic acid methyl esters (2a–d) obtained by the reduction of 3-, 4-, 6-, and 13-oximino-tetradecanoic acid methyl esters (1a–d), was investigated. Oximino esters were reduced to afford the corresponding amino esters using NaBH4–ZrCl4 reducing system with good yields (58–82%). However, the reduction of oximino esters with LiAlH4 and BH3. Tetrahydrofuran gave the corresponding novel 3-, 4-, 6-, and 13-oximino alcohols (3a–d), and 3-, 4-, 6-, and 13-amino alcohols (4a–d) respectively with good chemical yields. GRAPHICAL ABSTRACT