scholarly journals Antibacterial and hypoglycemic activity in vitro of polysaccharide obtained from Periconia byssoides

2021 ◽  
Vol 10 (12) ◽  
pp. e493101218433
Author(s):  
Anny Carolinny Tigre Almeida Chaves ◽  
Raphael Ferreira Queiroz ◽  
Sandra Aparecida de Assis
Keyword(s):  
Molecular Weight ◽  
Biological Activity ◽  
Average Molecular Weight ◽  
Degree Of Polymerization ◽  
Hypoglycemic Activity ◽  
Number Average Molecular Weight

Fungi are source of polysaccharides that can show biological activity. The objective of this research was obtained polysaccharides from Periconia byssoides and evaluate antibacterial and hypoglycemic activity in vitro. The number-average molecular weight and degree of polymerization were determined. The results show that the polysaccharide of P. byssoides has potential as hypoglycemic. Therefore, it would be interesting to conduct in vivo research with this polysaccharide, to know about its hypoglycemic activity.

scholarly journals Selection of Water-Soluble Chitosan by Microwave-Assisted Degradation and pH-Controlled Precipitation

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1274 ◽  
Author(s):  
Céline M. A. Journot ◽  
Laura Nicolle ◽  
Yann Lavanchy ◽  
Sandrine Gerber-Lemaire
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Aqueous Media ◽  
Phase Changes ◽  
Water Soluble ◽  
In Vivo Evaluation ◽  
Microwave Assisted ◽  
Selection Of

In the field of gene therapy, chitosan (CS) gained interest for its promise as a non-viral DNA vector. However, commercial sources of CS lack precise characterization and do not generally reach sufficient solubility in aqueous media for in vitro and in vivo evaluation. As low molecular weight CS showed improved solubility, we investigated the process of CS depolymerization by acidic hydrolysis, using either long time heating at 80 °C or short time microwave-enhanced heating. The resulting depolymerized chitosan (dCS) were analyzed by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) to determine their average molecular weight (Mn, Mp and Mw), polydispersity index (PD) and degree of deacetylation (DD). We emphasized the production of water-soluble CS (solubility > 5 mg/mL), obtained in reproducible yield and characteristics, and suitable for downstream functionalization. Optimal microwave-assisted conditions provided dCS with a molecular weight (MW) = 12.6 ± 0.6 kDa, PD = 1.41 ± 0.05 and DD = 85%. While almost never discussed in the literature, we observed the partial post-production aggregation of dCS when exposed to phase changes (from liquid to solid). Repeated cycles of freezing/thawing allowed the selection of dCS fractions which were exempt of crystalline particles formation upon solubilization from frozen samples.

Molecular Weight Defined in Sol-Gel Analysis and Its Application to Evaluate Branching

1995 ◽  
Vol 68 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Asahiro Ahagon
Keyword(s):  
Molecular Weight ◽  
Crosslink Density ◽  
Sol Gel ◽  
Average Molecular Weight ◽  
Degree Of Polymerization ◽  
Gel Point ◽  
Linear Polymers ◽  
Molecular Parameter ◽  
Branch Points ◽  
Number Average Molecular Weight

Abstract It is considered that many “linear” polymers are actually branched; however, it is difficult to show this with ordinary methods for an arbitrarily chosen polymer. Branching can be regarded as premature crosslinking below the gel point. Attention is then paid to the well-established Charlesby-Pinner Equation used for sol-gel analysis in crosslinking studies. It contains the number average degree of polymerization before crosslinking as a parameter. The molecular parameter is considered here to be that of the virtual linear polymer which would be obtained by unlinking any branch points contained in the polymer. Evidence is shown to support this. It is then possible to estimate the total number of linear components on an average molecule of a branched polymer by taking the ratio of the number average molecular weight measured by two methods, i.e., sol-gel analysis and an ordinary method like GPC. Further information about the branching structure can be obtained by additional measurements of effective crosslink density for a series of polymers obtained from similar polymerization processes.

scholarly journals Degradation of 3D-Printed Porous Polylactic Acid Scaffolds Under Mechanical Stimulus

2021 ◽  
Vol 9 ◽  
Author(s):  
Heming Chen ◽  
Quan Shi ◽  
Hengtao Shui ◽  
Peng Wang ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Numerical Model ◽  
Young’S Modulus ◽  
Polylactic Acid ◽  
Young's Modulus ◽  
Average Molecular Weight ◽  
Mechanical Stimulus ◽  
Number Average Molecular Weight ◽  
3D Printed

Polylactic acid (PLA) is a biodegradable polymer commonly used as a scaffold material to repair tissue defects, and its degradation is associated with mechanical stimulus. In this study, the effect of mechanical stimulus on the degradation of 3D-printed PLA scaffolds was investigated by in vitro experiments and an author-developed numerical model. Forty-five samples with porosity 64.8% were printed to carry out the degradation experiment within 90 days. Statistical analyses of the mass, volume fraction, Young’s modulus, and number average molecular weight were made, and the in vitro experiments were further used to verify the proposed numerical model of the scaffold degradation. The results indicated that the mechanical stimulus accelerated the degradation of the PLA scaffold, and the higher mechanical stimulus led to a faster degradation of the scaffolds at the late stage of the degradation process. In addition, the Young’s modulus and the normalized number average molecular weight of the PLA scaffolds between the experiments and the numerical simulations were comparable, especially for the number average molecular weight. The present study could be helpful in the design of the biodegradable PLA scaffolds.

CONSTITUTION OF THE HEMICELLULOSE FROM MESTA FIBER (HIBISCUS CANNABINUS)

1963 ◽  
Vol 41 (9) ◽  
pp. 2346-2350 ◽  
Author(s):  
S. K. Sen
Keyword(s):  
Molecular Weight ◽  
Uronic Acid ◽  
Average Molecular Weight ◽  
Analytical Data ◽  
Degree Of Polymerization ◽  
Hibiscus Cannabinus ◽  
Molar Ratio ◽  
Alkaline Solutions ◽  
Number Average Molecular Weight ◽  
Hydrolysis Of

The chlorite holocellulose of mesta fiber (Hibiscus cannabinus) was extracted with alkaline solutions of successively increasing concentration and finally with alkaline borate solution. Hemicellulose fractions (I–IV) were thus obtained. Analytical data are recorded for each fraction.Partial acid hydrolysis of the mesta hemicellulose gave 2-O-(4-O-methyl-α-D-glucopyranosyl uronic acid)-D-xylopyranose. Methanolysis and hydrolysis of the fully methylated hemicellulose (fraction II) gave a mixture of 3-O-methyl-D-xylose, 2,3-di-O-methyl-D-xylose, 2,3,4-tri-O-methyl-D-xylose, and 2-O-(2,3,4-tri-O-methyl-α-D-glucopyranosyl uronic acid)-3-O-methyl-D-xylopyranose in the approximate molar ratio of 1.6:34:1:6.4. The number-average molecular weight of the methylated polysaccharide was 18,400 ± 500 (degree of polymerization, 110 ± 3). The number-average molecular weight of the original hemicellulose (fraction II) was found to be 23,000 ± 500 (degree of polymerization, 164 ± 3). On the basis of this and other evidences it is suggested that the polysaccharide is composed of chains of 144 (1 → 4)-linked β-D-xylopyranose residues having approximately every seventh residue carrying a terminal 4-O-methyl-α-D-glucuronic acid residue linked through position 2. A small degree of branching in the backbone of D-xylose is indicated.

scholarly journals Low Molecular Weight Oligosaccharide from Panax ginseng C.A. Meyer against UV-Mediated Apoptosis and Inhibits Tyrosinase Activity In Vitro and In Vivo

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yu-Lin Dai ◽  
Di Yang ◽  
Lai-Hui Song ◽  
Hong-Mei Yang ◽  
Jiang-Bo Yu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Inhibitory Activity ◽  
Average Molecular Weight ◽  
Inhibitory Effects ◽  
Zebrafish Model ◽  
Tyrosinase Inhibitory Activity ◽  
Black Ginseng ◽  
White Ginseng

To find new anti-UV and whitening agents, 21 fractions isolated from three preparations of ginseng (white, red, and black ginseng) were screened, and their antioxidant effects on AAPH- or H2O2-induced damage were investigated. Furthermore, the protective effect against UV-mediated apoptosis and the tyrosinase inhibitory activity of the targeted fractions were evaluated in vitro and in a zebrafish model. Among all fractions, F10 from white ginseng was selected as having the strongest anti-UV and antimelanogenesis activities. This fraction exhibited excellent inhibitory effects on the pigmentation of zebrafish, which may be due to its potential tyrosinase inhibitory activity. Additionally, the chemical composition of F10 was evaluated by UPLC-MS and NMR instruments. The results indicated that F10 had a carbohydrate content of more than 76%, and the weight-average molecular weight was approximately 239 Da. Disaccharide sucrose was the main active compound in F10. These results suggest that F10 could be used as an ingredient for whitening cosmetics and regarded as an anti-UV filter in the future.

Effects of Unfractionated and Low Molecular Weight Heparins on Platelet Thromboxane Biosynthesis “In Vivo”

1994 ◽  
Vol 72 (06) ◽  
pp. 942-946 ◽  
Author(s):  
Raffaele Landolfi ◽  
Erica De Candia ◽  
Bianca Rocca ◽  
Giovanni Ciabattoni ◽  
Armando Antinori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Unfractionated Heparin ◽  
Low Molecular Weight Heparin ◽  
Primary Source ◽  
In Vivo Studies ◽  
Low Molecular Weight ◽  
Heparin Administration ◽  
To Receive

SummarySeveral “in vitro” and “in vivo” studies indicate that heparin administration may affect platelet function. In this study we investigated the effects of prophylactic heparin on thromboxane (Tx)A2 biosynthesis “in vivo”, as assessed by the urinary excretion of major enzymatic metabolites 11-dehydro-TxB2 and 2,3-dinor-TxB2. Twenty-four patients who were candidates for cholecystectomy because of uncomplicated lithiasis were randomly assigned to receive placebo, unfractionated heparin, low molecular weight heparin or unfractionaed heparin plus 100 mg aspirin. Measurements of daily excretion of Tx metabolites were performed before and during the treatment. In the groups assigned to placebo and to low molecular weight heparin there was no statistically significant modification of Tx metabolite excretion while patients receiving unfractionated heparin had a significant increase of both metabolites (11-dehydro-TxB2: 3844 ± 1388 vs 2092 ±777, p <0.05; 2,3-dinor-TxB2: 2737 ± 808 vs 1535 ± 771 pg/mg creatinine, p <0.05). In patients randomized to receive low-dose aspirin plus unfractionated heparin the excretion of the two metabolites was largely suppressed thus suggesting that platelets are the primary source of enhanced thromboxane biosynthesis associated with heparin administration. These data indicate that unfractionated heparin causes platelet activation “in vivo” and suggest that the use of low molecular weight heparin may avoid this complication.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

Neutralization of a Low Molecular Weight Heparin (LHN-1) and Conventional Heparin by Protamine Sulfate in Rats

1986 ◽  
Vol 56 (03) ◽  
pp. 318-322 ◽  
Author(s):  
V Diness ◽  
P B Østergaard
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Thrombus Formation ◽  
Experimental Models ◽  
Protamine Sulfate ◽  
Low Molecular Weight ◽  
Antithrombotic Effect ◽  
Higher Doses

SummaryThe neutralization of a low molecular weight heparin (LHN-1) and conventional heparin (CH) by protamine sulfate has been studied in vitro and in vivo. In vitro, the APTT activity of CH was completely neutralized in parallel with the anti-Xa activity. The APTT activity of LHN-1 was almost completely neutralized in a way similar to the APTT activity of CH, whereas the anti-Xa activity of LHN-1 was only partially neutralized.In vivo, CH 3 mg/kg and LHN-1 7.2 mg/kg was given intravenously in rats. The APTT and anti-Xa activities, after neutralization by protamine sulfate in vivo, were similar to the results in vitro. In CH treated rats no haemorrhagic effect in the rat tail bleeding test and no antithrombotic effect in the rat stasis model was found at a protamine sulfate to heparin ratio of about 1, which neutralized APTT and anti-Xa activities. In LHN-1 treated rats the haemorrhagic effect was neutralized when APTT was close to normal whereas higher doses of protamine sulfate were required for neutralization of the antithrombotic effect. This probably reflects the fact that in most experimental models higher doses of heparin are needed to induce bleeding than to prevent thrombus formation. Our results demonstrate that even if complete neutralization of APTT and anti-Xa activities were not seen in LHN-1 treated rats, the in vivo effects of LHN-1 could be neutralized as efficiently as those of conventional heparin. The large fall in blood pressure caused by high doses of protamine sulfate alone was prevented by the prior injection of LHN-1.

Studies on Metabolism of Urokinase and Mechanism of Thrombolysis by Urokinase

1979 ◽  
Vol 42 (03) ◽  
pp. 885-894 ◽  
Author(s):  
Tatsuo Ueno ◽  
Norio Kobayashi ◽  
Tadashi Maekawa
Keyword(s):  
Molecular Weight ◽  
Plasma Clearance ◽  
Radioactive Material ◽  
Optimal Dosage ◽  
Plasma Clot ◽  
Optimal Dosage Regimen ◽  
Arterial Thrombus ◽  
Contact Experiment

SummaryPharmacokinetics of intravenously injected 125I-labeled urokinase (125I-UK) of a molecular weight of 33,000 daltons in normal rabbits and patients with various diseases were investigated. The plasma clearance of 125I-UK in rabbits was described by a biexponential curve within six hours with a half-life of 8 minutes, 2.3 hours, respectively. The radioactivity in the liver and kidneys 15 minutes after iv injection with 125I-UK was 9.6% and 14.0% of the radioactivity injected, respectively. Approximately 80% of the total radioactive material injected was excreted in the urine in 18 hours. No increase in activator activity in the urine was observed after a large amount of UK injection. Activity uptake of 125I-UK by experimentally induced arterial thrombus was little. Lysis of the stasis thrombus was produced by injecting 7.5 × 104 IU of UK in only one out of 8 rabbits. In vitro contact experiment revealed that transfer of 125I-UK to plasma clot is slow (24 hours for 10% of 125I-UK by plasma clot). In 4 patients plasma clearance of 125I-UK was essentially similar to that in rabbits. From the results obtained optimal dosage regimen of UK administration for complete thrombolysis in vivo was discussed.

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