Investigation of the hydrolysis of ginsenosides by high performance liquid chromatography-electrospray ionization mass spectrometry

The hydrolysis of ginsenoside standards and the crude extracts of ginseng has been investigated at different pH values (2.4 - 11.2) using high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS). The experimental results indicated that the pH value of aqueous solutions is an important factor in changing the composition of ginsenosides. For (20S)-protopanaxadiol ginsenosides, ginsenosides with a large mass hydrolyzed to form hydrolysates (20S)-Rg(3) and (20R)-Rg(3) at pH 4.3. There were more hydrolyzed products observed at pH 3.3: (20S)-F-2, C-25,26 hydrated ginsenoside "C-Y-1" and "C-Y-2" (MW = 802 Da) accompanied with (20S)-Rg(3), (20R)-Rg(3). At pH 2.4, only (20R)-Rg(3), (20S)-F-2, a small quantity of (20S)-Rg(3) and three C-25,26 hydrated ginsenosides were obtained. For (20S)protopanaxatriol Re, no hydrolysates were observed at pH 4.3; it was hydrolyzed at pH 3.3 to form hydrolysates (20S)-Rg, (20R)Rg(2) and hydrated C-25,26 (MW = 802 Da) and at pH 2.4 only C-25,26 hydrated ginsenosides "C-Y-1" and "C-Y-2" (MW = 802 Da) were left in the solution. Similar hydrolysis reactions could be also observed for the crude extracts of ginseng. It showed that HPLC/ESI-MS is a fast and convenient method to study the hydrolysis of ginseng.

Synthesis of dodecenyl succinic anhydride (DDSA) corn starch

Dodecenly succinic anhydride (DDSA) starches were prepared commercially by the base catalyzed reaction of DDSA in pre-emulsion with starch granular in aqueous slurry. The results indicated that the degree of substitution and reaction efficiency were 0.0256% and 42.7%, respectively, at the parameters for the preparation of DDSA starches in starch slurry 30%, DDSA/starch radio 10% (wt/wt), pH 8.5-9.0, reaction temperature 313 K. After modification, product surface chemical composite had been changed which was prone to migrate into less polar solution. The chemical structural characteristics were investigated by methods of FTIR and H-1 NMR. The results of X-ray diffraction showed the native A-type crystalline pattern, indicating that reaction of corn starch with DDSA caused no change in the crystalline structure. Compared to native starch, the hydrophobic performance of esters was greatly increased. With the DS increasing, contact angles were gradually increased, however, the adhesion works were decreased. The maximum contact angle of DDSA starch could attend to 123 degrees, and the corresponding adhesion work was 33.2 mJ m(-2).

Poly(L-lactide)/starch blends compatibilized with poly(L-lactide)-g-starch copolymer

The poly(L-lactide) (PLLA)/starch blends were prepared by the PLLA grafting starch (PLLA-g-St) copolymers as a compatibilizer, and their thermal, mechanical and morphological characterizations were performed to show the better performance of these blends compared to the virgin PLLA/starch blend without the compatibilizer, including PLLA crystallinity, interfacial adhesion between the PLLA matrix and starch dispersive phases, mechanical test, medium resistance, and contact angle. The 50/50 composite of PLLA/starch compatibilized by 10% PLLA-g-St gave a tensile strength of 24.7 MPa and an elongation at break of 8.7%, respectively, vs. 11.3 MPa and 1.5%, respectively, for the simple 50/50 blend of PLLA/starch.

Studies on the stability of polyazamacrocycle-Eu (Tb) by potentiometry and its catalytic hydrolysis on phosphate diester

The stability constants and species distributions of complexes of two lanthanide ions, Eu (III) and Tb(III), with a macrocyclic ligand, 3,6, 9, 17 20, 23-hexaazo-29, 30-dihydroxy-13, 27-dimethyl-tricylco-[23,3,1,1(11,15)] triaconta-1 (28) 11,13,15 (30), 25 26-hexane (BDBPH), in 1: 1 and 2: 1 system, were determined potentiometrically in 50% ethanol solution, at 35.0 degrees C and I = 0.100 mol/L (KCl). The two metal ions could form deprotonated mono- or dinuclear complexes with BDBPH with high stability after the three protons of the ligand completely neutralized. At higher pH values, Eu(M) could not form hydroxo complexes with BDBPH, while Tb(III) could form hydroxo complexes in the types of M2L(OH) M2L(OH)(2) and M2L (OH)(2). The kinetic study on the hydrolysis reaction of his (4-nitrophenyl) phosphate (BNPP) catalyzed by Tb-BDBPH system (2:1) was carried out in aqueous solution (pH 7.0 similar to 10.0) at 35 degrees C with I = 0.1000 mol/L (KCl). The second-order rate constant k(BNPP) (2.3 x 10(-3) (mol/L)(-1)center dot s(-1)) was determined. The dinuclear monohydroxo species, L-Tb-2-OH, is kinetically active species.

Characterization of Full-Biodegradable Starch-PVA-Polyester Film

IntroductionConventional polymers such as polyethyleneand polypropylene persistfor many years after landdisposal.Furthermore,plastics are often soiled byfood and other biological substances,making phys-ical recycling of those materials impractical andgenerally undesirable. In contrast,biodegradablepolymers disposed in bioactive environment are de-graded by the enzymatic action of microorganismssuch as bacteria,fungi,and algae.The worldwideconsumption of biodegradable polymers increasedfrom1.4×107kg in ...

Studies on Mechanical Properties of Full-Biodegradable Starch-PVA-Polyester Films

A kind of full-biodegradable film material is discussed in this article. The film material is composed of starch, PVA, degradable polyesters(PHB, PHB-V, PCL) with built plasticizer, a cross-linking reinforcing agent and a wet strengthening agent. It contains a high percentage of starch, costs cheap and is excellent in weather fastness, temperature resistance and waterproof and it could be completely biodegraded. The present paper deals mainly with a new technical route using a new type of electromagnetic dynamic blow molding extruder and some effects on mechanical properties of the system.

Intramolecular amide hydrolysis in N-methylmaleamic acid revisited

The intramolecular amide hydrolysis of N-methylmaleamic acid have been revisited by use of density functional theory and inclusion of solvent effects. The results indicate that concerted reaction mechanism is favored over stepwise reaction mechanism. This is in agreement with the previous theoretical study. Sovlent effects have significant influence on the reaction barrier.

Binuclear lanthanide complexes as catalysts for the hydrolysis of double-stranded DNA

The efficient cleavage of plasmid DNA ( pCAT) by binuclear lanthanide complexes was investigated. At 37 degrees C and neutral pH, both Ho23+L and Er23+L promoted 100% conversion of supercoiled plasmid to the nicked circular form and linear form in 1 h. The corresponding saturation kinetics curve of cleavage of pCAT plasmid by binuclear lanthanide complexes showed the expected increase with catalyst concentration. (C) 1999 Elsevier Science S.A. All rights reserved.

Rare earth complexes with Ge-132 and their catalytic hydrolysis to phosphatide bond of mononucleotide

The complexes of a series of rare earths with Ge-132 have been prepared. The carboxyl anions of Ge-132 molecule were coordinated to rare earth ion with chelate style. In the complexes molecule, the GeO3/2 group of Ge-132 were hydrolyzed to become -Ge(OH)(3) group, and later does:not coordinate with rare earth ions. All of the complexes possess similar properties. In aqueous solution of pH 6 and 50 degrees C, these complexes can obviously selectively catalytically hydrolize the phosphatide bond of 5'-AMP and 5'-dAMP into phosphatic acid and riboside.

Use of lanthanide metal complexes for the hydrolysis of 3 ',5 '- and 2 ',3 ' cyclic nucleotides

Lutetium(III) and lanthanum(III) complexes of 2-carboxyethylgermanium sesquioxide (Ge-132) can hydrolyze the phosphodiester linkage of 3',5'-cyclic adenosine monophosphate (cAMP), 3',5'-cyclic deoxyadenosine monophosphate (dcAMP) and 2',3'-cyclic adenosine monophosphate (2',3'-cAMP). Both cAMP and dcAMP are hydrolyzed with high selectivity, yielding predominantly 3'-monophosphates. 2',3'-cAMP is converted to 3'-AMP and 2'-AMP, the ratio of 3'-AMP to 2'-AMP produced being 1.4.

Lanthanide ions for the hydrolysis of 5'-mononucleotides and 3'-mononucleotides

Cleavage of adenosine-5'-monophosphate (5'-AMP), guanosine-5'-monophosphate (5'-GMP), adenosine-3'-monophosphate (3'-AMP) and guanosine-3'-monophosphate (3'-GMP) by lanthanides was investigated by NMR and the method of measuring the liberated phosphates. Rapid cleavage of both 5'-mononucleotides and 3'-mononucleotides by Ce-III and Ce-IV under air at pH 9 and 37 degrees C was observed. Other lanthanides showed less efficiency for hydrolyzing 5'-mononucleotides but 3'-mononucleotides were catalyzed by a range of lanthanide ions. The mechanism for hydrolyzing 3'-mononucleotides by lanthanides was:investigated. The notable difference in reactivity between Ce-III and the other lanthanide ions under air was further studied showing that the cleavage is enhanced with increasing molar fraction of Ce-IV. The fast cleavage of mononucleotides by Ce-III under air at pH 9 is ascribed to the resultant Ce-IV in the reaction mixture. (C) 1997 Elsevier Science Ltd.

Lanthanide metal complexes for the hydrolysis of adenosine-5'-monophosphate and deoxyadenosine-5'-monophosphate

The hydrolysis of adenosine-5'-monophosphate and deoxyadenosine-5'-monophosphate has been studied with lanthanide(III) metal complexes of 2-carboxyethylgermanium sesquioxide (Ge-132) by NMR and HPLC and by measuring the liberated inorganic phosphates.

Preparation of TiO2 Film through Hydrolysis of Titanium Butoxide and Interaction between Sensitizing Dyes and the Film

A method of preparation of stable, homogeneous and controlled thickness TiO2 film through hydrolysis of Ti(OC4H(9))(4) is introduced in detail. The structure and property of the film have been investigated by means of SEM and FT-IR techniques. The strong quenching effect between sensitizing dyes and TiO2 film is observed in their fluorescence spectra.

Lanthanide metal complexes for the hydrolysis of ribonucleoside 3',5'-cyclic phosphate and deoxyribonucleoside 3',5'-cyclic phosphate

Ytterbium(III) and praseodymium(III) complexes of 2-carboxyethylgermanium sesquioxide (Ge-132) can hydrolyze the phosphodiester linkage of 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic deoxyadenosine monophosphate (dcAMP). Both cAMP and dcAMP are hydrolyzed with high selectivity, yielding predominantly 3'-monophosphates. The selectivity and activity for hydrolyzing cAMP and dcAMP by lanthanide metal(III) complexes and lanthanide metal ions are compared.