Immune adjuvants are added to vaccines in order to enhance the immune response to an antigen. Muramyl dipeptide, N-acetylmuramyl-L-alanyl-D-isoglutamine, is the smallest structural unit of peptidoglycans showing the immunostimulating activity. Muramyl dipeptide analogues without the hydrophilic N-acetylmuramyl moiety are called desmuramyl peptides. Here, we provide review of desmuramyl peptides which were synthesized in order to improve the pharmacological properties of parent muramyl dipeptide, including our results regarding adamantane containing derivatives. Approach for future design of novel immunostimulators based on multiple pathogen recognition receptor activation was also considered.
在疫苗中加入免疫佐剂是为了增强对抗原的免疫反应。Muramyl二肽，n -乙酰Muramyl - l- alanyl- d -异谷氨酰胺，是具有免疫刺激活性的肽聚糖中最小的结构单元。没有亲水性n -乙酰基Muramyl部分的Muramyl二肽类似物被称为去乳酰肽。在此，我们综述了为改善亲本二肽的药理特性而合成的金刚烷酰肽，包括我们在含金刚烷衍生物方面的研究结果。展望了基于多病原体识别受体激活的新型免疫刺激剂的设计思路。
{"title":"Advances in Desmuramyl Peptide Research","authors":"R. Ribić, Marija Paurević, S. Tomić","doi":"10.5562/cca3556","DOIUrl":"https://doi.org/10.5562/cca3556","url":null,"abstract":"Immune adjuvants are added to vaccines in order to enhance the immune response to an antigen. Muramyl dipeptide, N-acetylmuramyl-L-alanyl-D-isoglutamine, is the smallest structural unit of peptidoglycans showing the immunostimulating activity. Muramyl dipeptide analogues without the hydrophilic N-acetylmuramyl moiety are called desmuramyl peptides. Here, we provide review of desmuramyl peptides which were synthesized in order to improve the pharmacological properties of parent muramyl dipeptide, including our results regarding adamantane containing derivatives. Approach for future design of novel immunostimulators based on multiple pathogen recognition receptor activation was also considered.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3556","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46993816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Lučić, Jadranko Batista, V. Bojović, M. Lovrić, Ana Sovic Krzic, D. Bešlo, Damir Nadramija, D. Vikić-Topić
Shortcomings of the correlation coefficient (Pearson's) as a measure for estimating and calculating the accuracy of predictive model properties are analysed. Here we discuss two such cases that can often occur in the application of the model in predicting properties of a new external set of compounds. The first problem in using the correlation coefficient is its insensitivity to the systemic error that must be expected in predicting properties of a novel external set of compounds, which is not a random sample selected from the training set. The second problem is that an external set can be arbitrarily large or small and have an arbitrary and uneven distribution of the measured value of the target variable, whose values are not known in advance. In these conditions, the correlation coefficient can be an overoptimistic measure of agreement of predicted values with the corresponding experimental values and can lead to a highly optimistic conclusion about the predictive ability of the model. Due to these shortcomings of the correlation coefficient, the use of standard error (root-mean-square-error) of prediction is suggested as a better quality measure of predictive capabilities of a model. In the case of classification models, the use of the difference between the real accuracy and the most probable random accuracy of the model shows very good characteristics in ranking different models according to predictive quality, having at the same time an obvious interpretation.
{"title":"Estimation of Random Accuracy and its Use in Validation of Predictive Quality of Classification Models within Predictive Challenges","authors":"B. Lučić, Jadranko Batista, V. Bojović, M. Lovrić, Ana Sovic Krzic, D. Bešlo, Damir Nadramija, D. Vikić-Topić","doi":"10.5562/cca3551","DOIUrl":"https://doi.org/10.5562/cca3551","url":null,"abstract":"Shortcomings of the correlation coefficient (Pearson's) as a measure for estimating and calculating the accuracy of predictive model properties are analysed. Here we discuss two such cases that can often occur in the application of the model in predicting properties of a new external set of compounds. The first problem in using the correlation coefficient is its insensitivity to the systemic error that must be expected in predicting properties of a novel external set of compounds, which is not a random sample selected from the training set. The second problem is that an external set can be arbitrarily large or small and have an arbitrary and uneven distribution of the measured value of the target variable, whose values are not known in advance. In these conditions, the correlation coefficient can be an overoptimistic measure of agreement of predicted values with the corresponding experimental values and can lead to a highly optimistic conclusion about the predictive ability of the model. Due to these shortcomings of the correlation coefficient, the use of standard error (root-mean-square-error) of prediction is suggested as a better quality measure of predictive capabilities of a model. In the case of classification models, the use of the difference between the real accuracy and the most probable random accuracy of the model shows very good characteristics in ranking different models according to predictive quality, having at the same time an obvious interpretation.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3551","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42254070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antonija Erben, J. Matić, N. Basarić, I. Piantanida
Dipeptide 4 containing two unnatural amino acids, a modified tyrosine and a phenanthridine derivative, was synthesized. Binding of the dipeptide to a series of polynucleotides including ct-DNA, poly A - poly U, poly (dAdT)2, poly dG - poly dC and poly (dGdC)2 was investigated by thermal denaturation experiments, fluorescence spectroscopy and circular dichroism. Thermal denaturation experiments indicated that dipeptide 4 at pH 5.0, when phenanthridine is protonated, stabilizes ds-DNA, whereas it destabilizes ds-RNA. At pH 7.0, when the phenanthridine is not protonated, effects of 4 to the polynucleotide melting temperatures are negligible. At pH 5.0, dipeptide 4 stabilized DNA double helices, and the changes in the CD spectra suggest different modes of binding to ds-DNA, most likely the intercalation to poly dG- poly dC and non-specific binding in grooves of other DNA polynucleotides. At variance to ds-DNA, addition of 4 destabilized ds-RNA against thermal denaturation and CD results suggest that addition of 4 probably induced dissociation of ds-RNA into ss-RNA strands due to preferred binding to ss-RNA. Thus, 4 is among very rare small molecules that stabilize ds-DNA but destabilize ds-RNA. However, fluorescence titrations with all polynucleotides at both pH values gave similar binding affinity (log Ka ≈ 5), indicating nonselective binding. Preliminary photochemical experiments suggest that dipeptide 4 reacts in the photochemical reaction, which affects polynucleotides chirality, presumably via quinone methide intermediates that alkylate DNA.
{"title":"The Phenanthridine-modified Tyrosine Dipeptide","authors":"Antonija Erben, J. Matić, N. Basarić, I. Piantanida","doi":"10.5562/CCA3542","DOIUrl":"https://doi.org/10.5562/CCA3542","url":null,"abstract":"Dipeptide 4 containing two unnatural amino acids, a modified tyrosine and a phenanthridine derivative, was synthesized. Binding of the dipeptide to a series of polynucleotides including ct-DNA, poly A - poly U, poly (dAdT)2, poly dG - poly dC and poly (dGdC)2 was investigated by thermal denaturation experiments, fluorescence spectroscopy and circular dichroism. Thermal denaturation experiments indicated that dipeptide 4 at pH 5.0, when phenanthridine is protonated, stabilizes ds-DNA, whereas it destabilizes ds-RNA. At pH 7.0, when the phenanthridine is not protonated, effects of 4 to the polynucleotide melting temperatures are negligible. At pH 5.0, dipeptide 4 stabilized DNA double helices, and the changes in the CD spectra suggest different modes of binding to ds-DNA, most likely the intercalation to poly dG- poly dC and non-specific binding in grooves of other DNA polynucleotides. At variance to ds-DNA, addition of 4 destabilized ds-RNA against thermal denaturation and CD results suggest that addition of 4 probably induced dissociation of ds-RNA into ss-RNA strands due to preferred binding to ss-RNA. Thus, 4 is among very rare small molecules that stabilize ds-DNA but destabilize ds-RNA. However, fluorescence titrations with all polynucleotides at both pH values gave similar binding affinity (log Ka ≈ 5), indicating nonselective binding. Preliminary photochemical experiments suggest that dipeptide 4 reacts in the photochemical reaction, which affects polynucleotides chirality, presumably via quinone methide intermediates that alkylate DNA.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3542","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42312677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Amuthavalli, B. Prakash, D. Edison, R. Velmurugan
A new series of specifically substituted cyclohepta[b]indole derivatives from the precursor thiophen-2-ylmethylene has been synthesized. The structures of synthesized derivatives were established by spectral and elemental analyses. The docking studies with protein kinase CK2 was performed, derivative 6c exhibited the most excellent glide and E model score of –7.61 and –58.27, respectively. In-vitro anticancer activity against cervical cancer cell line (HeLa) was studied. The IC50 values were compared with the standard drug Ellipticine. Compounds 5c, 6c and 6d showed better IC50 value when compared to the other molecules. The derivatives were evaluated for their antibacterial activity against the reference drugs Sparfloxacin and Norfloxacin using agar dilution method. The derivatives 4a–d exhibited better MIC values against Gram-positive bacteria and Gram-negative bacteria when compared with remaining derivatives. Structure activity relationship (SAR) analyses established that the derivatives are potential lead compounds for future drug development studies.
{"title":"Synthesis, Spectral Analysis, Molecular Docking and Biological Evaluation of Cyclohepta[b]indole Derivatives","authors":"A. Amuthavalli, B. Prakash, D. Edison, R. Velmurugan","doi":"10.5562/cca3375","DOIUrl":"https://doi.org/10.5562/cca3375","url":null,"abstract":"A new series of specifically substituted cyclohepta[b]indole derivatives from the precursor thiophen-2-ylmethylene has been synthesized. The structures of synthesized derivatives were established by spectral and elemental analyses. The docking studies with protein kinase CK2 was performed, derivative 6c exhibited the most excellent glide and E model score of –7.61 and –58.27, respectively. In-vitro anticancer activity against cervical cancer cell line (HeLa) was studied. The IC50 values were compared with the standard drug Ellipticine. Compounds 5c, 6c and 6d showed better IC50 value when compared to the other molecules. The derivatives were evaluated for their antibacterial activity against the reference drugs Sparfloxacin and Norfloxacin using agar dilution method. The derivatives 4a–d exhibited better MIC values against Gram-positive bacteria and Gram-negative bacteria when compared with remaining derivatives. Structure activity relationship (SAR) analyses established that the derivatives are potential lead compounds for future drug development studies.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3375","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42570916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kristina Mlinac-Jerković, V. Damjanović, S. Kalanj-Bognar, J. Lovrić
In 2018 the Department of Chemistry and Biochemistry at Zagreb School of Medicine celebrated 100 years since it was established by professor Fran Bubanović. This essay is focused on his successors, outstanding teachers and scientists, professors Tomislav Pinter and Mihovil Proštenik, members of Yugoslavian (today Croatian) Academy of Sciences and Arts. Tomislav Pinter was a prominent physical chemist who had an original approach and gave novel interpretation of van der Waals and Wohl’s equations. He also served as the president of Croatian Chemical Society. Neurobiochemist Mihovil Proštenik started as an organic chemist at “Prelog’s Zagreb School of Organic Chemistry”. He collaborated with two Croatian Nobel prize winners in chemistry: his PhD thesis supervisor Vladimir Prelog and Lavoslav Ružička. He was the founder of “Zagreb School of Lipidology”, discovered a new sphingoid base C20-sphingosine, and had a major role in the establishment of Ruđer Bošković Institute. Herein we honor their contributions to Croatian science and beyond, and share so far unpublished valuable material from the Department archive.
2018年，萨格勒布医学院化学和生物化学系庆祝了Fran Bubanović教授成立100周年。这篇文章的重点是他的继任者，杰出的教师和科学家，南斯拉夫（今天的克罗地亚）科学与艺术学院的Tomislav Pinter和Mihovil Proštenik教授。Tomislav Pinter是一位杰出的物理化学家，他有着独创的方法，并对范德华和沃尔方程做出了新颖的解释。他还担任过克罗地亚化学学会主席。神经生物化学家Mihovil Proštenik最初是“Prelog’s Zagreb School of organic Chemistry”的有机化学家。他与两位克罗地亚诺贝尔化学奖得主合作：他的博士论文导师Vladimir Prelog和Lavoslav Ružička。他是“萨格勒布脂质体学院”的创始人，发现了一种新的鞘氨醇碱C20-sphingosine，并在RuŞer Bošković研究所的建立中发挥了重要作用。在此，我们向他们对克罗地亚科学及其他领域的贡献表示敬意，并分享迄今为止国防部档案中未发表的宝贵材料。
{"title":"Marking a Century of the Department of Chemistry and Biochemistry at School of Medicine in Zagreb","authors":"Kristina Mlinac-Jerković, V. Damjanović, S. Kalanj-Bognar, J. Lovrić","doi":"10.5562/cca3554","DOIUrl":"https://doi.org/10.5562/cca3554","url":null,"abstract":"In 2018 the Department of Chemistry and Biochemistry at Zagreb School of Medicine celebrated 100 years since it was established by professor Fran Bubanović. This essay is focused on his successors, outstanding teachers and scientists, professors Tomislav Pinter and Mihovil Proštenik, members of Yugoslavian (today Croatian) Academy of Sciences and Arts. Tomislav Pinter was a prominent physical chemist who had an original approach and gave novel interpretation of van der Waals and Wohl’s equations. He also served as the president of Croatian Chemical Society. Neurobiochemist Mihovil Proštenik started as an organic chemist at “Prelog’s Zagreb School of Organic Chemistry”. He collaborated with two Croatian Nobel prize winners in chemistry: his PhD thesis supervisor Vladimir Prelog and Lavoslav Ružička. He was the founder of “Zagreb School of Lipidology”, discovered a new sphingoid base C20-sphingosine, and had a major role in the establishment of Ruđer Bošković Institute. Herein we honor their contributions to Croatian science and beyond, and share so far unpublished valuable material from the Department archive.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3554","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44806409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The antioxidant properties of six flavonols -fisetin, galangin, gossipetin, kaempferol, morin and myricetin- have been investigated at HF/6-311G+(d,p) level of theory, using ethanol as solvent. Three known antioxidant mechanisms, namely HAT (hydrogen atom transfer), SET-PT (single electron transfer followed by proton transfer) and SPLET (sequential proton loss electron transfer) have been employed in order to evaluate the radical scavenging abilities of the investigated compounds. Thermodynamic parameters like bond dissociation energy (BDE), proton affinity (PA), electron transfer enthalpy (ETE), ionization potential (IP) and proton dissociation enthalpy (PDE) were calculated and the results were associated with the number and the positions of the hydroxyl groups, the geometry of the parent molecule and of the corresponding radicals, as well as with the electron spin distribution. Also, computations of global reactivity descriptors like HOMO-LUMO gap showed that an increased reactivity is related to the presence of the catechol moiety (gossipetin, myricetin, fisetin). The influence of the catecholic OH groups is also outlined by the HOMO energies, highest electron-donor ability being obtained for gossipetin, the flavonol with two catecholic moieties on rings A and B. According to the HAT mechanism, it has been outlined an enhanced antioxidant character of the 3-OH groups, followed by the hydroxyl groups attached to the phenyl ring B. The calculated values of the condensed Fukui functions, computed for a radical attack, are in good agreement with the above-mentioned results.
{"title":"Evaluation of the Radical-Scavenging Properties of Various Flavonols in Ethanol Environment: an ab initio Study","authors":"Raluca Pop","doi":"10.5562/cca3449","DOIUrl":"https://doi.org/10.5562/cca3449","url":null,"abstract":"The antioxidant properties of six flavonols -fisetin, galangin, gossipetin, kaempferol, morin and myricetin- have been investigated at HF/6-311G+(d,p) level of theory, using ethanol as solvent. Three known antioxidant mechanisms, namely HAT (hydrogen atom transfer), SET-PT (single electron transfer followed by proton transfer) and SPLET (sequential proton loss electron transfer) have been employed in order to evaluate the radical scavenging abilities of the investigated compounds. Thermodynamic parameters like bond dissociation energy (BDE), proton affinity (PA), electron transfer enthalpy (ETE), ionization potential (IP) and proton dissociation enthalpy (PDE) were calculated and the results were associated with the number and the positions of the hydroxyl groups, the geometry of the parent molecule and of the corresponding radicals, as well as with the electron spin distribution. Also, computations of global reactivity descriptors like HOMO-LUMO gap showed that an increased reactivity is related to the presence of the catechol moiety (gossipetin, myricetin, fisetin). The influence of the catecholic OH groups is also outlined by the HOMO energies, highest electron-donor ability being obtained for gossipetin, the flavonol with two catecholic moieties on rings A and B. According to the HAT mechanism, it has been outlined an enhanced antioxidant character of the 3-OH groups, followed by the hydroxyl groups attached to the phenyl ring B. The calculated values of the condensed Fukui functions, computed for a radical attack, are in good agreement with the above-mentioned results.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42732113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Barbara Soldo, N. Nikolov, Ivana Generalić Mekinić, I. Ljubenkov, Vida Šimat, Danijela Skroza, I. Anđelić
The aim of this study was to investigate the effect of different herb extracts on the oxidative stability of hemp, flax, sesame and sunflower seed oils by means of Rancimat test. The dominant phenolic acids in herb extracts were detected by HPLC, while fatty acid profiles of oils, before and after oxidation, were determined by GC-FID. As expected, autoxidation increased the content of saturated fatty acids. The sesame oil showed the longest oxidative stability (3.43 h), while the shortest induction period was obtained for the flax oil. Lemon balm and oregano extracts accelerated the oxidation of hemp and flax oil, while in all other cases the addition of extracts had a positive effect on oil oxidative stability. The best results were obtained for lemon balm extract added to sesame and sunflower oil which resulted with OSI values of 1.33 and 1.48, respectively, while extremely prooxidative activity was obtained for lemon balm extract added to the hemp oil.
{"title":"The Effect of Selected Herb Extracts on Oxidative Stability of Vegetable Oils","authors":"Barbara Soldo, N. Nikolov, Ivana Generalić Mekinić, I. Ljubenkov, Vida Šimat, Danijela Skroza, I. Anđelić","doi":"10.5562/cca3479","DOIUrl":"https://doi.org/10.5562/cca3479","url":null,"abstract":"The aim of this study was to investigate the effect of different herb extracts on the oxidative stability of hemp, flax, sesame and sunflower seed oils by means of Rancimat test. The dominant phenolic acids in herb extracts were detected by HPLC, while fatty acid profiles of oils, before and after oxidation, were determined by GC-FID. As expected, autoxidation increased the content of saturated fatty acids. The sesame oil showed the longest oxidative stability (3.43 h), while the shortest induction period was obtained for the flax oil. Lemon balm and oregano extracts accelerated the oxidation of hemp and flax oil, while in all other cases the addition of extracts had a positive effect on oil oxidative stability. The best results were obtained for lemon balm extract added to sesame and sunflower oil which resulted with OSI values of 1.33 and 1.48, respectively, while extremely prooxidative activity was obtained for lemon balm extract added to the hemp oil.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3479","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43545159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The synthesis and liquid-crystalline properties are reported for novel naphthyl-based diketones incorporating variant terminal chains and lateral fluoro- substitution. Newly prepared materials exhibit a broad temperature range of the nematic phase. The study demonstrates how subtle structural modifications can be exploited to alter the efficiency of molecular packing and consequently the thermal behaviour.
{"title":"Synthesis and Mesomorphic Properties of Novel Bent-shaped Naphthyl Diketones","authors":"Anđela Buljan, A. Knežević, I. Dokli, A. Lesac","doi":"10.5562/cca3541","DOIUrl":"https://doi.org/10.5562/cca3541","url":null,"abstract":"The synthesis and liquid-crystalline properties are reported for novel naphthyl-based diketones incorporating variant terminal chains and lateral fluoro- substitution. Newly prepared materials exhibit a broad temperature range of the nematic phase. The study demonstrates how subtle structural modifications can be exploited to alter the efficiency of molecular packing and consequently the thermal behaviour.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3541","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43806483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrofugality scale has been extended with new substituted ferrocenylphenylmethyl cations 1-4. Ef values were determined by applying the linear free energy relationship (LFER): log k = sf (Ef + Nf). Due to ability of the ferrocene moiety to efficiently stabilize the positive charge, ferrocenylphenylmethyl cations constitute a group of very powerful electrofuges (Ef > 1). Impact of the phenyl group in ferrocenylphenylmethyl derivatives on stabilization of the positive charge is considerably leveled by the ferrocenyl group, so the rate effect of the alkyl substituents (methyl, ethyl and tert-butyl) on the phenyl ring is suppressed, causing narrow range of Ef parameters. Lack of breakdown of Hammett-Brown plot if the rates for the complete set of substrates 1–5 have been correlated, indicates that the ferrocenyl group in α-position diminishes the stabilizing effects of electron-donating substituents as well.
{"title":"Electrofugality of Some Ferrocenylphenylmethyl Cations","authors":"S. Jurić, M. Marijan, O. Kronja","doi":"10.5562/cca3553","DOIUrl":"https://doi.org/10.5562/cca3553","url":null,"abstract":"The electrofugality scale has been extended with new substituted ferrocenylphenylmethyl cations 1-4. Ef values were determined by applying the linear free energy relationship (LFER): log k = sf (Ef + Nf). Due to ability of the ferrocene moiety to efficiently stabilize the positive charge, ferrocenylphenylmethyl cations constitute a group of very powerful electrofuges (Ef > 1). Impact of the phenyl group in ferrocenylphenylmethyl derivatives on stabilization of the positive charge is considerably leveled by the ferrocenyl group, so the rate effect of the alkyl substituents (methyl, ethyl and tert-butyl) on the phenyl ring is suppressed, causing narrow range of Ef parameters. Lack of breakdown of Hammett-Brown plot if the rates for the complete set of substrates 1–5 have been correlated, indicates that the ferrocenyl group in α-position diminishes the stabilizing effects of electron-donating substituents as well.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2019-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/cca3553","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49244227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hamit Ismaili, Željka Ban, J. Matić, D. Saftić, Marijana Jukić, L. Glavaš‐Obrovac, B. Žinić
Efficient synthesis of 5-aminosulfonyl uracil derivatives 2-9 and results of their antiproliferative activity are provided. Sulfonylation of the amino group in 5-aminouracil 1 with selected arylsulfonyl chlorides occurs regioselectively when the reaction is carried out in pyridine at room temperature. Simple isolation of the products by recrystallization of the crude product mixture from aqueous methanol provides good to excellent yields. The prepared 5-aminosulfonyl uracil derivatives 2-9 were tested for the antiproliferative activity on a panel of seven tumor cell lines of different histological origin (HeLa, Caco-2, NCI-H358, Raji, HuT78, Jurkat, K562) and normal MDCK I cells. Derivatives 2-9 were found more efficient to lymphoma and leukemia cells compared to solid tumor and normal cells.
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