The Chemistry of High Molecular Weight Fulvic Acid Fractions

1974 ◽  
Vol 52 (24) ◽  
pp. 4123-4132 ◽  
Author(s):  
Jean A. Neyroud ◽  
Morris Schnitzer
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Ethyl Acetate ◽  
Fulvic Acid ◽  
Phenolic Acids ◽  
Degradation Products ◽  
Building Blocks ◽  
Oh Groups ◽  
Molecular Weights ◽  
Chemical Structures

Fulvic acid (FA) was methylated, dissolved in benzene, and fractionated over Al2O3 with the aid of organic solvents of increasing polarities. This paper is concerned with fractions eluted with ethyl acetate (III), ethyl acetate — methanol (1:1) (IV), and methanol (V), which were quantitatively the most abundant ones and which we consider as being most representative of the original FA. Each fraction was characterized by chemical and spectroscopic methods and by degradation with alkaline permanganate. Fractions IV and V were also degraded by NaOH hydrolysis and by alkaline CuO-oxidation. The degradation products were identified with the aid of a gas chromatograph — mass spectrometer — computer system.The number-average molecular weights of the three fractions were: III, 821; IV, 945; and V, 1,397. Infrared, proton n.m.r., and carbon-13 n.m.r. spectra provided, except for functional groups, little detailed information on the chemical structures of the fractions. The major degradation products were benzenecarboxylic and phenolic acids in addition to smaller amounts of aliphatic (mainly n-fatty) acids. Evidence is presented that may be interpreted to indicate: (a) esterification of some of the fatty acids to OH groups of phenolic acids; (b) the existence in the fractions of ether (C—O) linkages; and (c) rupture of C—C bonds during degradation. While in both the lower and the higher molecular weight FA fractions benzenecarboxylic and phenolic acids were the basic "building blocks", the latter appeared to be more complex and more stable in the higher-molecular weight fractions, possibly because chemical bonding as well as hydrogen bonding, van der Waal's forces, and π-bonding were involved simultaneously.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

scholarly journals The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 538 ◽  
Author(s):  
Yadong Zhao ◽  
Ayumu Tagami ◽  
Galina Dobele ◽  
Mikael E. Lindström ◽  
Olena Sevastyanova
Keyword(s):  
Molecular Weight ◽  
Cellulose Nanofibers ◽  
Composite Films ◽  
Structural Diversity ◽  
Decomposition Temperature ◽  
Solvent Fractionation ◽  
Film Performance ◽  
Oh Groups ◽  
Chemical Structures ◽  
The Impact

Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF)—starch mixture to prepare 100% bio-based composite films. The aim was to investigate the impact of lignin structural diversity on film performance. It was confirmed that lignin’s distribution in the films was dependent on the polarity of solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The –OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to decrease in thermal stability and increase in Young’s modulus of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic –OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol content, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the relationship between the chemical structure of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin’s applications in bio-based materials based on their specific characteristics.

Synthesis and Properties of a High-Molecular-Weight Polyimide Based on 4, 4'-(hexafluoroisopropylidene) Diphthalic Anhydride

2012 ◽  
Vol 550-553 ◽  
pp. 742-746
Author(s):  
Hui Wen Wu ◽  
Hua Li ◽  
He Zhou Liu
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Organic Solvents ◽  
Membrane Separation ◽  
Amic Acid ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Synthesis Parameters ◽  
Soluble Polyimide

A soluble polyimide with high molecular weight was synthesized from 4, 4'-(hexafluoroiso propylidene) diphthalic anhydride (6FDA) and 2, 2’-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAPAF) via two-step polycondesation procedure involving the preparation of poly(amic acid) (PAA) followed by chemical imidization. Effect of synthesis parameters on polyimide molecular weight involving material ratio, imidization temperature and imidization catalyst were studied. Synthesized PI was analyzed with respect to their molecular weights, chemical structures and solubility through GPC, FTIR, XRD and solubility tests respectively. The results showed that a high-molecular-weight PI was successfully synthesized from 4, 4'-(hexafluoroisopropylidene) diphthalic anhydride and 2, 2’-bis (3-amino-4-hydroxyphenyl) hexafluoropropane with imidization at 80°C for 3h, material ratio of n(BAPAF):n(6FDA) equal to 1:1 and catalyst of n(triethylamine):n (pyridine) less than1:3. The obtained PI showed excellent solubility in polar aprotic organic solvents such as NMP, DMAc, DMSO, THF and Acetone. Poly(6FDA-BAPAF) PI, with high molecular weight and excellent solubility, which was synthesized under lower imidization temperature that was equal to 80°C,could be easily obtained and convenient to process, thus it is a potential material for membrane separation.

Further Investigations on the Chemistry of Fulvic Acid, a Soil Humic Fraction

1971 ◽  
Vol 49 (13) ◽  
pp. 2302-2309 ◽  
Author(s):  
S. U. Khan ◽  
M. Schnitzer
Keyword(s):  
Fatty Acids ◽  
Hydrogen Bonds ◽  
Fulvic Acid ◽  
Phenolic Acids ◽  
Complex Structures ◽  
Isolation And Identification ◽  
Fractionation Scheme ◽  
Humic Fraction ◽  
Benzenecarboxylic Acids

The fractionation scheme described in this and in an earlier paper resulted in the isolation and identification of about 2.0 g of pure components from 100 g of fulvic acid. About 28% of these compounds were phenolic acids, 19% benzenecarboxylic acids, 13% alkanes and fatty acids, and 40% dialkyl phthalates. The isolation of appreciable amounts of dialkyl phthalates was somewhat surprising but their presence was shown not be an artifact. The KMnO4 oxidation of the same fractions increased the yields of methylated phenolic and benzenecarboxylic acids by between 3 and 11 times.Following KMnO4 oxidation of methylated but unfractioned fulvic acid, the yield of phenolic and benzenecarboxylic acids increased substantially. The increased yields, after oxidation, of the same compounds as those that were separated without oxidation indicate that either these compounds originated from more complex structures or that they came from a structure of the type proposed earlier, which consists of phenolic and benzenecarboxylic acids joined by hydrogen-bonds, on which alkanes, fatty acids, and dialkyl phthalates are adsorbed.

Synthesis, characterization and enzymatic degradation of copolymers of ε-caprolactone and hydroxy-fatty acids

2016 ◽  
Vol 88 (12) ◽  
pp. 1191-1201 ◽  
Author(s):  
Diana Aparaschivei ◽  
Anamaria Todea ◽  
Iulia Păuşescu ◽  
Valentin Badea ◽  
Mihai Medeleanu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Degradation Products ◽  
Hydroxy Fatty Acids ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Chemical Structures ◽  
Buffer Solutions ◽  
Different Temperatures ◽  
Ft Ir ◽  
Candida Antarctica B

AbstractNew copolymers of ε-caprolactone with three hydroxy-fatty acids, 12-hydroxy stearic acid, 16-hydroxyhexadecanoic acid and ricinoleic acid, were synthesized by catalytic polyesterification. The reactions were carried out in solvent-free systems and in organic solvents as well, using tin(II) 2-ethylhexanoate as catalyst, at different temperatures and molar ratios of the comonomers. Cyclic and linear polymeric products with medium molar weight of about 2000 Da have been synthesized and their chemical structures were confirmed by FT-IR, NMR and MALDI-TOF MS analysis. The synthesis parameters were optimized and the ε-caprolactone/hydroxy acid molar ratio was set as 5:1, according to mass spectrometry results. The biodegradability of the newly synthesized polymers was studied in the presence of Candida antarctica B lipase in phosphate buffer solutions (pH=7.4), at 37°C. The weight-loss profile emphasized the degradation of the 16-hydroxyhexadecanoic acid based polymer samples at more than 50% of their initial weight in 18 days of incubation in the presence of the lipase. The composition of the degradation products was assessed using the GC-MS technique and displayed residues of the comonomers moieties.

scholarly journals Structural Characterization, Antioxidant Activity, and Biomedical Application of Astragalus Polysaccharide Degradation Products

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Jian-Min Wang ◽  
Xin-Yuan Sun ◽  
Jian-Ming Ouyang
Keyword(s):  
Molecular Weight ◽  
Antioxidant Activity ◽  
Biomedical Application ◽  
Degradation Products ◽  
Human Kidney ◽  
Degradation Process ◽  
Chain Structure ◽  
Molecular Weights ◽  
Reducing Ability

To study the antioxidant capacity of Astragalus polysaccharides (APS) with different molecular weights, we used hydrogen peroxide to degrade original Astragalus polysaccharide (APS0) with an initial molecular weight of 11.03 kDa and obtained three degraded polysaccharides with molecular weights of 8.38 (APS1), 4.72 (APS2), and 2.60 kDa (APS3). The structures of these polysaccharides were characterized by 1H NMR, 13C NMR, FT-IR, and GC/MS. The degradation process did not cause significant changes in the main chain structure of APS. The monosaccharide component of APS before and after degradation was slightly changed. The antioxidant ability in vitro (removing hydroxyl and ABTS radicals and reducing ability) and in cells (superoxide dismutase and malondialdehyde generation) of these polysaccharides is closely related to their molecular weight. If the molecular weight of APS is very high or low, it is not conducive to their activity. Only APS2 with moderate molecular weight showed the greatest antioxidant activity and ability to repair human kidney epithelial (HK-2) cells. Therefore, APS2 can be used as a potential antistone polysaccharide drug.

Evaluation of Acid-Treated Hyaluronic Acid-Based Hydrogelation

2007 ◽  
Vol 342-343 ◽  
pp. 745-748
Author(s):  
Mi Sook Kim ◽  
Yoon Jeong Choi ◽  
Gun Woo Kim ◽  
In Sup Noh ◽  
Yong Doo Park ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hyaluronic Acid ◽  
Gel Permeation Chromatography ◽  
Biological Properties ◽  
Cellular Interactions ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Though hyaluronic acid (HA)-based hydrogel has drawn great attention in biomedical society, it’s long molecular weights sometimes have been problematic due to its difficulty in handling. After reduction of its high molecular weight into smaller sizes with various concentrations of hydrogen chloride solutions, its chemical and biological properties have been examined by changes in viscosity, FTIR spectroscopy and gel permeation chromatography as well as cellular interactions. While FTIR analysis indicated maintenance of its original chemical structures, its viscosity has been remarkably reduced and its extent was dependent upon the employment of acid concentrations. After controlling its molecular weight to approximately 100 kDa and coupling of aminopropymethacrylate to the treated HA, we evaluated in vitro cellular interactions and cell proliferations of the HA-poly(ethylene oxide) (PEO) hydrogel.

FATTY ACIDS AND THEIR ESTERS: II. MOLECULAR WEIGHTS OF POLYMERIZED ESTERS

1936 ◽  
Vol 14b (6) ◽  
pp. 231-236
Author(s):  
H. N. Brocklesby
Keyword(s):  
Fatty Acids ◽  
Molecular Weight ◽  
Unsaturated Fatty Acids ◽  
Normal Values ◽  
Linseed Oil ◽  
Molecular Weights ◽  
A Value

When a value of K that allows for the effect of the solute on the dissociation of the solvent is used, raw linseed oil shows normal values for the molecular weight when determined cryoscopically or ebullioscopically in a number of diverse solvents. Similarly, polymerized oils and esters show identical molecular weights in different solvents when determined either cryoscopically or ebullioscopically. The data indicate that polymerized esters of unsaturated fatty acids cannot be assumed to be associated.

In Vitro Formation of Fibrin-Monomer Complexes in the Presence of Isotope Labelled Fibrinogen-Fibrin Degradation Products. An Agarose Gel Filtration Study

1975 ◽  
Author(s):  
F. Asbeck ◽  
van de J. Loo
Keyword(s):  
Molecular Weight ◽  
Complex Formation ◽  
Degradation Products ◽  
Gel Filtration ◽  
Agarose Gel ◽  
Fibrinogen Degradation Products ◽  
Molecular Weights ◽  
Fibrin Degradation Products ◽  
Fibrin Monomer

Human citrated plasmas were mixed with purified 131I-fibrinogen and 131I-fibrinogen degradation products (FDP) or 125I-fibrin degradation products (fdp). After incubation with small amounts of thrombin (0.01–0.02 imits/ml Pl.), these mixtures were gel filtrated on Biogel A5m columns and the elution patterns of the 131I- and -labelled materials were determined.In control experiments without thrombin incubation, no complex formation between fibrinogen, FDP or fdp in citrated plasmas could be detected. This was even true for fdp with a higher molecular weight than fibrinogen.After thrombin incubation, up to 11% fibrin-monomer complexes were formed. Irrespective of their molecular weights, labelled fdp were not incorporated into these complexes.Only large FDP – presumably derivative X – did partially copolymerize with fibrin-monomer complexes in citrated plasmas.

Influence of Chelation Rate on the Oligochitosan Preparation by Enzymolysis of CTS-Cu (II)

2014 ◽  
Vol 962-965 ◽  
pp. 1252-1257
Author(s):  
Hong Wei Wu ◽  
Wan Cui Xie ◽  
Xi Hong Yang ◽  
Fu Rao Lai ◽  
Hui Wu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Physiological Activity ◽  
Product Yield ◽  
Chitosan Oligosaccharide ◽  
High Solubility ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Low Molecular Weight Chitosan ◽  
Weight Distributions

To prepare a homogenous low-molecular-weight chitosan oligosaccharide with high solubility and physiological activity, the CTS-Cu (II) chelate was degraded by cellulose, xylanase, semi-cellulase, pectinase, lipase. Cellulose was used to investigate the enzymolysis of the CTS-Cu (II) chelates at various chelation rates. The oligochitosan yields were determined by ultrafiltration and spectrophotometry. The molecular weight distributions of the degradation products were compared by gel column chromatography. Results showed that the generation of the CTS-Cu (II) chelate promoted chitosan degradation. Product yield can be changed by controlling the chelation rates of the CTS-Cu (II) chelates. When the CTS-Cu (II) chelate was degraded at a chelation rate of 100%, most molecular weights of the products were about 2500 Da, and the oligochitosan yield was 89.21%. All these results provided a theoretical basis and experimental method for preparing oligochitosan with a homogenous molecular weight.

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