Cyclic hydroxycarboxylic acids. III. Tosylation studies on Mono- and Di-hydroxycyclopentanecarboxylates and Mono- and Di-hydroxyprolines

1977 ◽  
Vol 30 (1) ◽  
pp. 131 ◽  
Author(s):  
RP Philp ◽  
AV Robertson
Keyword(s):  
Free Amino ◽  
Heterogeneous System ◽  
Methyl Esters ◽  
Hydroxyl Groups ◽  
Large Excess ◽  
Molar Ratios ◽  
Tosyl Chloride ◽  
Hydroxycarboxylic Acids ◽  
Hydroxy Proline ◽  
Cis And Trans

A large excess of reagent is needed for satisfactory ditosylation of methyl c-2,t-3- and t-2,c-3-di-hydroxycyclopentane-r-1-carboxylates using tosyl chloride-pyridine at 5° overnight. With less reagent, mixtures are produced from which one monotosyl derivative of the t-2,c- 3-series was isolated and its structure proved. By contrast, the methyl cis- and trans-2-hydroxycyclopentanecarboxylates readily tosylate with normal molar ratios of reagent. In the proline series ditosylation of 2,3-trans- 3,4-cis-3,4-dihydroxy-N-tosylproline methyl ester occurs normally in tosyl chloride-pyridine, and so does tosylation of both cis- and trans-4-hydroxy-N-tosylproline methyl esters. On the other hand tosylation of the 3-hydroxy counterparts is very slow, although acetylation of these 3-hydroxyl groups proceeds normally. The O-tosylation results are striking for the lack of pattern. A comparison is also made of O-tosylation accompanying N-tosylation of the free amino acids cis- and trans-3-hydroxy-proline, cis- and trans- 4- hydroxyproline, and the two cis-glycols of 3,4-dihydroxyproline in the heterogeneous system tosyl chloride-ether-aqueous NaOH. Significant O- tosylation occurs in some cases but not in others. This correlation permits assignment of structure to a mono-O-tosyl derivative of a 3,4- dihydroxy-N-tosylproline obtained previously by us.

Cyclic hydroxycarboxylic acids. I. Synthesis, stereochemistry and reactivity of 2,3-trans-2,3-Dihydroxycyclopentanecarboxylic acids

1976 ◽  
Vol 29 (7) ◽  
pp. 1493 ◽  
Author(s):  
RP Philp ◽  
AV Robertson
Keyword(s):  
Proton Magnetic Resonance ◽  
Methyl Esters ◽  
Performic Acid ◽  
Hydroxy Acids ◽  
Dihydroxy Acid ◽  
Tosyl Chloride ◽  
Hydroxycarboxylic Acids ◽  
Derivatives Of ◽  
Acidic Methanolysis ◽  
Infrared Data

Cyclopent-2-enecarboxylic acid and performic acid give a mixture of approximately equal amounts of the corresponding c-2,t-3- and t-2,c-3-dihydroxycyclopentane-r-1-carboxylic acids. The mixture was separated by chromatography of the methyl esters. Relative configurations were assigned from the action of tosyl chloride-pyridine on the separate acids. The c-2,t-3-dihydroxy acid yields a t-3-tosyloxy ,β-lactone and the t-2,c-3-dihydroxy acid yields a r-2-tosyloxy γ-lactone. Structures of the lactones were proved by correlating the products of acidic methanolysis and of alkaline hydrolysis with various derivatives of the acids. Proton magnetic resonance spectra are reported for 21 compounds from the two stereochemical families, including acetate, trifluoroacetate, tosylate and mesylate derivatives. Infrared data for relded lactones are tabulated. Formation of β-lactones from β-hydroxy acids by tosyl chloride appears to be unprecedented.

scholarly journals Reaction of cis- and trans-Dichlorotetra(Dimethylsulfoxide)Ruthenium(II) With the Antiviral Drug Acyclovir

2000 ◽  
Vol 7 (6) ◽  
pp. 325-334 ◽  
Author(s):  
Aglaia Koutsodimou ◽  
Giovanni Natile
Keyword(s):  
Trans Isomer ◽  
Early Stage ◽  
Antiviral Drug ◽  
Metallic Substrate ◽  
Purine Base ◽  
Coordination Environment ◽  
Molar Ratios ◽  
Discrete Amount ◽  
Cis And Trans ◽  
Cis Isomer

NMR was used to investigate the reaction of cis- and trans-[RuCl2(DMSO)4] with the antiviral drug acyclovir, a guanine derivative containing the acyclic (2-hydroxo) ethoxymethyl pendant linked to N(9). Studies were performed in aqueous solutions at ambient temperature and at 37 °C, and at various molar ratios. Both isomers yielded two compounds, a monoadduct and a bisadduct, the relative yields being dependent upon the metal to ligand concentration ratios. The products derived from the two Ru isomers displayed identical NMR spectra, suggesting that they have the same coordination environment, however the rate of formation of the monoadduct was higher in the case of the trans isomer than in the case of the cis isomer, while the rate of conversion of the monoadduct into the bisadduct appeared to be similar in both cases. As a consequence in the case of the trans isomer there is accumulation of monoadduct in the early stage of the reaction, whose concentration afterwards decreases with the progress of the reaction. As for platinum, also for ruthenium the preferred binding site is N(7) of the purine base, however, in the case of ruthenium a discrete amount of bisadduct is formed even in the presence of an excess of metallic substrate with respect to the acyclovir ligand; under similar conditions a platinum substrate would have given, nearly exclusively, the monoadduct.

scholarly journals THE LOCATION OF THE XANTHATE GROUPS IN PARTLY SUBSTITUTED CELLULOSE XANTHATES

1957 ◽  
Vol 35 (12) ◽  
pp. 1522-1533 ◽  
Author(s):  
E. P. Swan ◽  
C. B. Purves
Keyword(s):  
Cellulose Acetate ◽  
Chlorine Dioxide ◽  
Methyl Esters ◽  
Lead Tetraacetate ◽  
Degree Of Substitution ◽  
Hydroxyl Groups ◽  
Primary Position ◽  
Standard Methods ◽  
The Third ◽  
Almost All

Cellulose sodium xanthates of degree of substitution (D.S.) 0.4 to 0.66 were methylated to xanthate S-methyl esters which were then acetylated completely, the final xanthate D.S. remaining close to the original value. Dexanthation with aqueous chlorine dioxide near pH 4.5 and −5° removed almost all of the S-methyl xanthate groups, but the loss of a few acetyl groups from, and the retention of 1 to 2% of sulphur in, the resulting cellulose acetate could not be avoided. The original xanthate groups were presumably represented in this acetate as unsubstituted hydroxyl groups, and these were located by standard methods involving tosylation–iodination, tritylation, and oxidations with lead tetraacetate. Xanthate groups appeared to occupy the third and sixth, but not the second, position in the cellulose, and 53 to 61% of the substituent was in the sixth or primary position; one sample of viscose was "ripened" before the cellulose sodium xanthate was isolated, and the value was 81%. The results were of a preliminary nature, because severe technical difficulties reduced their reliability.

scholarly journals Hydrophilic Polyhedral Oligomeric Silsesquioxane, POSS(OH)32, as a Complexing Nanocarrier for Doxorubicin and Daunorubicin

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5512 ◽  
Author(s):  
Kinga Piorecka ◽  
Anna Janaszewska ◽  
Marta Majkowska ◽  
Monika Marcinkowska ◽  
Jan Kurjata ◽  
...  
Keyword(s):  
Drug Carrier ◽  
Correlation Spectroscopy ◽  
Hydroxyl Group ◽  
Cancer Drug ◽  
Breast Adenocarcinoma ◽  
Hydroxyl Groups ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Molar Ratios ◽  
Anti Cancer ◽  
Mcf 7

A novel strategy, recently developed by us, to use polyhedral oligomeric silsesquioxanes (POSS) as an anti-cancer drug carrier is presented. Anthracycline:POSS complexes were prepared by simple co-addition of doxorubicin (DOX) or daunorubicin (DAU) with hydrophilic POSS(OH)32. Co-delivery of POSS and anthracyclines led to higher anti-cancer activity towards HeLa (cervical cancer endothelial) and MCF-7 (human breast adenocarcinoma) cell lines. The obtained supramolecular hybrid complexes were characterised by nuclear magnetic resonance (NMR) spectroscopy (nuclear Overhauser effect spectroscopy [NOESY] and homonuclear correlation spectroscopy [COSY]), Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The two-dimensional (2D) NOESY spectra of the complexes showed the cross-correlation peaks for hydroxyl groups of POSS (~4.3–4.8 ppm) with OH groups of DOX and DAU. FTIR showed that hydroxyl group of POSS can interact with amine and hydroxyl groups of DOX and DAU. The viability of HeLa and MCF-7 was analysed with the MTT assay to evaluate the cytotoxicity of free DOX and DAU and the relevant complexes with POSS at different molar ratios. At a low DOX concentration (2.5 µM), for molar ratios 1:1, 1:4, and 1:8 (POSS:DOX), the complexes showed two and three times higher cytotoxicity towards HeLa and MCF-7 cells, respectively, than DOX itself after both 24- and 48-h incubation. The 1 µM concentration for a 1:4 POSS:DOX molecular ratio and the 2.5 µM concentration for all complexes were more toxic towards MCF-7 cells than free DOX after 48-h incubation. In the case of POSS:DAU complexes, there was higher toxicity than that of free drug after 48-h incubation. It can be concluded that the formation of non-covalent complexes increases toxicity of anthracycline drugs towards Hela and MCF-7 cells. The novel complexes are inexpensive to prepare and more effective than free drugs at low systemic toxicity.

THE PROBLEM OF PLASTEIN FORMATION: II. THE CHEMICAL CHANGES INVOLVED IN PLASTEIN FORMATION BY PAPAIN AND BY PEPSIN

1940 ◽  
Vol 18b (9) ◽  
pp. 272-280 ◽  
Author(s):  
H. B. Collier
Keyword(s):  
Enzymatic Hydrolysis ◽  
Free Amino ◽  
Essential Role ◽  
Phenolic Hydroxyl ◽  
Carboxyl Groups ◽  
Hydroxyl Groups ◽  
Chemical Changes ◽  
Phenolic Hydroxyl Groups ◽  
Hydrolysis Of

It has been confirmed that free amino and carboxyl groups disappear during plastein formation from concentrated proteose by crystalline pepsin. Using papain, the changes are obscured by simultaneous hydrolysis. Enzymatic hydrolysis of the plasteins results in the liberation of free amino and carboxyl groups.Reactive "tyrosine" decreases during plastein formation by either enzyme. The same groups are liberated on enzymatic hydrolysis of the plasteins, in a manner analogous to that which takes place in the hydrolysis of typical proteins.It is concluded that in so far as the changes in amino, carboxyl, and "tyrosine" groups are concerned, the plasteins are similar to typical proteins. It is further suggested that the phenolic hydroxyl groups of tyrosine play an essential role in the structure of the protein molecule.Benzaldehyde was found to have no effect on the formation of plastein from proteose by crystalline pepsin.

scholarly journals Enrichment of Larval Fish Feed with Free Amino Acids and Proteins by Coating with Lactobacillus paracasei subsp. paracasei BGHN14 Homogenate

2021 ◽  
Vol 21 (11) ◽  
pp. 569-573
Author(s):  
Jovanka Lukić ◽  
Nemanja Stanisavljević ◽  
Goran Vukotić ◽  
Amarela Terzić-Vidojević ◽  
Jelena Begović ◽  
...  
Keyword(s):  
Amino Acid ◽  
Free Amino ◽  
Larval Fish ◽  
Lactobacillus Paracasei ◽  
Total Amino Acid ◽  
Fish Feed ◽  
Hydroxy Proline ◽  
Growth Promoting ◽  
Animal Feedstuffs ◽  
Feed Samples

This research aimed to test whether coating with Lactobacillus paracasei subsp. paracasei BGHN14 homogenate may increase soluble protein and amino acid amount on larval fish feed surface. Total amino acid and protein, as well as taste stimulating and growth promoting amino acid amounts were analyzed in coated feed samples. Results indicated that coating with BGHN14 homogenate increased the amount of soluble proteins and free Glycine on feed surface, as well as the availability of protein-bound (hydroxy-)Proline. This lab-scale research provides the basis for use of lactobacilli as resource efficient source of soluble nutrients for animal feedstuffs.

scholarly journals Valorization of a high-acidity residual oil generated in the waste cooking oils recycling industries

2019 ◽  
Vol 70 (4) ◽  
pp. 335 ◽  
Author(s):  
P. Álvarez-Mateos ◽  
J. F. García-Martín ◽  
F. J. Guerrero-Vacas ◽  
C. Naranjo-Calderón ◽  
C. C. Barrios-Sánchez ◽  
...  
Keyword(s):  
Methyl Esters ◽  
Candida Rugosa ◽  
Esterification Reaction ◽  
Residual Oil ◽  
Molar Ratios ◽  
High Acidity ◽  
Triglyceride Hydrolysis ◽  
Waste Cooking Oils ◽  
Cooking Oils ◽  
Favorable Conditions

A sludge fraction is obtained from the industries which recycle cooking oil and this sludge contains a large amount of oil with an extremely high acidity ( > 60%). In this work, we propose a scheme for methyl ester production from this residual oil consisting of the esterification of the free fatty acids followed by the transesterification of the remaining triglycerides. Esterifications were carried out with different methanol:oil molar ratios, and various catalysts in different weight ratios. The results revealed that homogeneous catalysts produced higher yields than heterogeneous ones in the esterification reaction. With the aim of improving the process, a previous triglyceride hydrolysis was assayed using lipases from Candida rugosa. Finally, the 3-stage process was performed under the most favorable conditions for each stage obtaining 84% wt. fatty acid methyl esters, which shows the potential of this residual oil as a source of biodiesel.

scholarly journals PRODUCTION OF CELLULOSE NANOCRYSTALS BY HYDROLYSIS IN MIXTURE OF HYDROCHLORIC AND NITRIC ACIDS

2019 ◽  
Vol 62 (12) ◽  
pp. 85-93
Author(s):  
Natalia V. Rubleva ◽  
Marina I. Voronova ◽  
Oleg V. Surov ◽  
Anatoly G. Zakharov ◽  
Ekaterina O. Lebedeva ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Thermal Destruction ◽  
Colloidal Stability ◽  
High Surface ◽  
Degree Of Polymerization ◽  
Polymerization Temperature ◽  
Hydroxyl Groups ◽  
Polarization Optical Microscopy ◽  
Molar Ratios ◽  
Hydrolysis Of

In this work, cellulose nanocrystals (CNC) have been produced by hydrothermal method in a mixture of hydrochloric and nitric acids in molar ratios of 8:2, 7:3, 6:4 and 5:5. Hydrolysis of sulphate cellulose in the mixtures of nitric and hydrochloric acids was conducted in a sealed thick-walled stainless steel vessel with a teflon insert for 3 h at 110 °С. Properties of CNC have been characterized by applying different methods: elemental analysis, thermogravimetric analysis, IR spectroscopy, polarization optical microscopy, scanning electron microscopy, and dynamic light scattering. Yield of CNC, size and charge of the CNC particles, degree of polymerization, temperature of thermal destruction have been determined, and morphology of the CNC samples has been characterized. The highest CNC yield (32%) has been observed at a 7:3 ratio of nitric and hydrochloric acids. It has been established that the CNC particles are spherical and have an average size of 60-80 nm. An assumption has been made that presence of a strong oxidant (nitric acid) may cause hydrolysis of both amorphous and crystalline (in part) regions of cellulose, which affects the final shape of the CNC particles. It has been shown that the hydrolysis in a mixture of nitric and hydrochloric acids causes an oxidation of primary hydroxyl groups of the cellulose pyranose ring and formation of surface carboxyl groups. The CNC aqueous suspensions demonstrate high colloidal stability due to a rather high surface charge. It is noted that the CNC thermal stability is much higher than that of the CNC samples obtained by the standard sulfuric acid hydrolysis: the temperature of thermal destruction increases by 130-148 °С.

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