Simultaneous Determination of Aspirin, Dipyridamole and Two of Their Related Impurities in Capsules by Validated TLC-Densitometric and HPLC Methods.

Aspirin (ASP) and dipyridamole (DIP) are widely used as a combination in pharmaceutical formulations for treatment of strokes. Many of these formulations are containing tartaric acid as an excipient (in DIP pellets formulation for sustained release), which increases the probability of formation of dipyridamole tartaric acid ester impurity (DIP-I). On the other hand, salicylic acid (SAL) is considered to be one of the synthesis impurities and a degradation product of ASP. In this work, two chromatographic methods, namely, TLC-densitometry and HPLC, have been established and validated for simultaneous determination of ASP, DIP, SAL and DIP-I. Good separation was achieved by using silica gel as stationary phase and toluene-methanol-ethyl acetate (2:3:5, by volume) as mobile phase in the case of TLC-densitometry and Zorbax ODS column with mobile phase consisting of phosphate buffer (pH 3.3)-acetonitrile-triethylamine (40:60:0.03, by volume) for HPLC. Influence of different organic solvents in mobile phase composition has been studied to optimize the separation efficiency in TLC densitometry. Moreover, factors affecting the efficiency of HPLC, like pH of the buffer used, organic solvent ratio in the mobile phase and flow rate, have been carefully studied using one variable at a time approach. Finally, the proposed methods were validated as per ICH guidelines.

Electromembrane Extraction of Organic Acid Compounds in Biological Samples Followed by High-Performance Liquid Chromatography.

Electromembrane extraction (EME) coupled with high-performance liquid chromatography was developed for determination of organic compounds including citric, tartaric and oxalic acid in biological samples. Organic compounds moved from aqueous samples, through a thin layer of 1-octanol immobilized in the pores of a porous hand-made polypropylene tube, and into a basic aqueous acceptor solution present inside the lumen of the tube. This new set-up for EME has a future potential such as simple, cheap and fast sample preparation technique for extraction of organic compounds in various complicated matrices. The pH of acceptor phase, extraction time, voltage, ionic strength, temperature and stirring speed were studied and optimized. Optimum conditions were: the pH of acceptor phase, 7; extraction time, 30 min; voltage, 30 V and stirring speed, 500 rpm. At the optimum conditions, the preconcentration factors of 175-200, the limits of detection of 1.9-3.1 µg L(-1) were obtained for the analytes. The developed procedure was then applied to the extraction and determination of organic acid compounds from biological samples.

A novel green template assisted synthesis of hydroxyapatite nanorods and their spectral characterization.

Hydroxyapatite [HAP, Ca10(PO4)6(OH)2] is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper we have reported the synthesis of hydroxyapatite nanorods by green template method using the extracts of three different natural sources which contain tartaric acid and also from commercially available one. The extracts of banana, grape and tamarind are taken as the sources of tartaric acid. The as-synthesized samples were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). Also the antibacterial activity of HAP with different concentrations against two pathogen bacteria strains Escherichia coli (E. coli) and Klebsiella (Gram-negative bacteria) were tested. The results show that the particles of all the samples are of nanosized and pure. The crystallinity decreases as changing the sources of tartaric acid from commercial to natural one and also changing the natural sources from banana to tamarind extracts. The formation of nanorods are found in all the samples but the nanorods with uniform size distribution can be obtained only by using the tamarind extract as the source of tartaric acid. Moreover, the as-synthesised HAP nanorods derived from natural sources exhibited a strong antibacterial activity against both E. coli and Klebsiella at a concentration of 100 µl. The HAP nanorods synthesized by this method can act as a potential candidate for various biomedical applications.

Long-range effects on the capture and release of a chiral guest by a helical molecular capsule.

Helically folded molecular capsules based on oligoamide sequences of aromatic amino acids which are capable of binding tartaric acid in organic solvents with high affinity and diastereoselectivity have been synthesized, and their structures and binding properties investigated by (1)H NMR, X-ray crystallography, circular dichroism, and molecular modeling. We found that elongating the helices at their extremities by adding monomers remote from the tartaric binding site results in a strong increase of the overall helix stability, but it does not influence the host-guest complex stability. The effect of this elongation on the binding and release rates of the guest molecules follows an unexpected non-monotonous trend. Three independent observations (direct monitoring of exchange over time, 2D-EXSY NMR, and molecular modeling) concur and show that guest exchange rates tend to first increase upon increasing helix length and then decrease when helix length is increased further. This investigation thus reveals the complex effects of adding monomers in a helically folded sequence on a binding event that occurs at a remote site and sheds light on possible binding and release mechanisms.

Chemical composition and antidiabetic activity of Opuntia Milpa Alta extracts.

Three new compounds, 1-3, and 20 known compounds were isolated from the AcOEt and BuOH extract of edible Opuntia Milpa Alta. The petroleum ether extract was examined by GC and MS. A total of 26 compounds were identified, representing 95.6% of the total extract, phytosterol (36.03%) being the most abundant component, and polyunsaturated fatty acids (18.57%) represented the second largest group, followed by phytol (12.28%), palmitic acid, palmitate (13.54%), vitamin E (4.51%), and other compounds (7.47%). The effects of various extracts from edible Opuntia Milpa Alta (petroleum ether extract, AcOEt extract, BuOH extract, aqueous extract, H2O parts) and the positive control (received dimethylbiguanide) were tested on streptozotocin (STZ)-induced diabetic mice. The results indicated that all the treatment groups could significantly decrease blood glucose levels in STZ-induced diabetic mice compared to the model control group (P<0.01), except the aqueous extract group (P<0.05). Especially, the petroleum ether extract group and the positive control group showed remarkable decrease of blood glucose levels. Taken together, the results indicate that the petroleum ether extract is the major hypoglycemic part in edible Opuntia Milpa Alta, which may be developed to a potential natural hypoglycemic functional ingredient.

Improving downstream processes to recover tartaric acid, tartrate and nutrients from vinasses and formulation of inexpensive fermentative broths for xylitol production.

BACKGROUND: Vinasses, the main liquid wastes from the distillation process of grape marc and wine lees, are acidic effluents with high organic content, including acids, carbohydrates, phenols, and unsaturated compounds with high chemical oxygen demand, biological oxygen demand and solid concentrations. These wastes can be revalued to provide additional benefits when they are employed as feedstock of some compounds including tartaric acid, calcium tartrate and economic nutrients for the elaboration of fermentable broths. RESULT: This study attempts to recover tartaric acid and calcium tartrate from vinasses. All the tartaric acid initially solubilised was recovered in both processes. The residual streams can be successfully employed as economic nutrients for the xylose to xylitol bioconversion, achieving higher global volumetric productivities (Q(P, xylitol) = 0.232 g L(-1) h(-1)) and products yields (Y(xylitol/S) = 0.57 g g(-1)) than fermentations carried out using commercial nutrients (Q(P, xylitol) = 0.193 g L(-1) h(-1) and Y(xylitol/S) = 0.55 g g(-1) respectively). CONCLUSION: Tartaric acid can be recovered from vinasses in the form of tartaric acid crystals and calcium tartrate. The residual streams generated in the process can be used as economic nutrients for the production of xylitol by D. hansenii.

1-methylmalate from camu-camu (Myrciaria dubia) suppressed D-galactosamine-induced liver injury in rats.

To evaluate the protective effects of fruit juices against D-galactosamine (GalN)-induced liver injury, lyophilized fruit juices (total 12 kinds) were fed to rats for 7 d, and then we evoked liver injury by injecting GalN. The juice of camu-camu (Myrciaria dubia) significantly suppressed GalN-induced liver injury when the magnitude of liver injury was assessed by plasma alanine aminotransferase and aspartate aminotransferase activities, although some other juices (acerola, dragon fruit, shekwasha, and star fruit) also tended to have suppressive effects. An active compound was isolated from camu-camu juice by solvent fractionation and silica gel column chromatography. The structure was determined to be 1-methylmalate. On the other hand, malate, 1,4-dimethylmalate, citrate, and tartrate had no significant effect on GalN-induced liver injury. It is suggested that 1-methylmalate might be a rather specific compound among organic acids and their derivatives in fruit juices in suppressing GalN-induced liver injury.

Metal(II)-ligand molar ratio dependence of enantioseparation of tartaric acid by ligand exchange CE with Cu(II) and Ni(II)-D-quinic acid systems.

Enantioseparation of tartaric acid by ligand exchange CE with a Cu(II)-D-quinic acid system was studied. Racemic tartaric acid was enantioseparated by ligand exchange CE using BGEs containing relatively low Cu(II)-D-quinic acid molar ratios ranging from 1:1 to 1:3 and high molar ratios ranging from 1:8 to 1:12 but was not enantioseparated using BGEs with medium molar ratios ranging from 1:4 to 1:6. While the migration order of D-tartaric acid was prior to L-tartaric acid at the lower Cu(II)-D-quinic acid molar ratios, the enantiomer migration order was reversed at the higher molar ratios. These results were compared with those for Ni(II)-D-quinic acid system. The molar ratio dependence of enantiomer migration order can be attributed to a change in the coordination structure of Cu(II) ion with D-quinic acid.

Immobilization of Escherichia coli cells with cis-epoxysuccinate hydrolase activity for D(-)-tartaric acid production.

Immobilization of cis-epoxysuccinate hydrolase-containing E. coli for D(-)-tartaric acid production was screened by various methods. The highest recovery of activity was obtained by entrapment in kappa-carrageenan gel. 23.6 g biomass/l and 43.4 g kappa-carrageenan/l were the best immobilization conditions optimized by response surface methodology with 83% yield (114 U/g). Cell autolysis was observed after immobilization. Immobilized cells showed high pH (5-10) stability, thermal (up to 65 degrees C) stability, conversion rate (>99.5%), enantioselectivity (ee > 99.6%), and were less affected by metal ions and surfactants compared with free cells. Conversion rate for immobilized cells preserved 93% after 10 repeated batches (5% for free cells).

Development of chitosan-coated liposomes for sustained delivery of tamarind fruit pulp's extract to the skin.

In this study, chitosan-coated liposomes were developed. To entrap lyophilized tamarind extract containing alpha-hydroxy acids (AHAs) together with tartaric acid, the reverse phase evaporation method was used to obtain well-formed liposomes loaded with the extract. The highest entrapment efficiency of 68.3 +/- 3.0% into the liposomes was obtained with liposomes consisting of phosphatidylcholine and cholesterol in a molar ratio of 2 : 1 after the extrusion process. The average particle size of the prepared liposomes was 158 +/- 26 nm showing a negative zeta potential of -6 mV. For the preparation of the chitosan-coated liposomes, two selected independent parameters were varied: chitosan concentrations of 0.1, 0.5 and 1.0% w/v and volumes of the chitosan solutions of 1, 2 and 3 mL, to study the effects of such parameters on the entrapment efficiency of the extract-loaded liposomes. Variation in the volumes of the chitosan solution did not affect the entrapment efficiency of the liposomes. However, the entrapment efficiency of the AHAs in the chitosan-coated liposomes significantly increased with increasing chitosan concentrations. The size of the chitosan-coated liposomes was in the range of 200-300 nm with a positive zeta potential in the range of 6-29 mV. An in vitro release study using dialysis technique was performed to evaluate the release profile of the tartaric acid from the chitosan-coated liposomes. The obtained results showed the effect of the chitosan-coated liposomes on the lower release rate and on the amount of tartaric acid in comparison with that of the uncoated liposomes. The study in an in vitro skin cell model indicated that the developed system could enhance the potential of tamarind's AHAs on the stimulation of human keratinocyte proliferation being two-fold higher than the solution of the tamarind extract.

Tartaric acid recovery from distilled lees and use of the residual solid as an economic nutrient for lactobacillus.

The recovery of tartaric acid (TA) from distilled vinification lees coming from the white and red winemaking technology was optimized using response surface methodology and Statistica 5.0 software. The sequential treatment of dissolving TA and further calcium tartrate (CaT) precipitation could be used to recover up to 92.4% of the initial TA when distilled white lees were used. The residual lees were employed as economic nutrients for lactic acid production by Lactobacillus pentosus CECT-4023 using hemicellulosic vine shoot hydrolysates as carbon source. Distilled lees after TA extraction used as nutrients provided values of lactic acid (18.4-18.9 g/L), global volumetric productivities (0.82-0.84 g/L.h), and product yields (0.69-0.70 g/g) similar to those achieved when using the general medium for Lactobacilli (18.6 g/L, 1.11 g/L.h, and 0.62 g/g, respectively) or lees without TA extraction (16.4-17.2 g/L, 0.96-1.21 g/L.h, and 0.61-0.66 g/g, respectively). This technology not only avoids pollutant disposal but also represents a commercial source of tartaric acid and economic nutrients for biotechnological processes.

Identification of oxalic acid and tartaric acid as major persistent pain-inducing toxins in the stinging hairs of the nettle, Urtica thunbergiana.

BACKGROUND AND AIMS: Once human skin contacts stinging hairs of Urtica spp. (stinging nettles), the irritant is released and produces pain, wheals or a stinging sensation which may last for >12 h. However, the existence of pain-inducing toxins in the stinging hairs of Urtica thunbergiana has never been systematically demonstrated. Experiments were therefore conducted to identify the persistent pain-inducing agents in the stinging hairs of U. thunbergiana. METHODS: The stinging hairs of U. thunbergiana were removed and immersed in deionized water. After centrifugation, the clear supernatants were then subjected to high-performance liquid chromatography (HPLC), enzymatic analysis and/or behavioural bioassays. KEY RESULTS: The HPLC results showed that the major constituents in the stinging hairs of U. thunbergiana were histamine, oxalic acid and tartaric acid. However, the well-recognized pain-inducing agents, serotonin and formic acid, existed at a low concentration as estimated by HPLC and/or enzymatic analyses. The behavioural tests showed that 2% oxalic acid and 10% tartaric acid dramatically elicited persistent pain sensations in rats. In contrast, 10% formic acid and 2% serotonin only elicited moderate pain sensation in the first 10 min. Moreover, no significant pain-related behavioural response was observed after injecting 10% acetylcholine and histamine in rats. CONCLUSIONS: Oxalic acid and tartaric acid were identified, for the first time, as major long-lasting pain-inducing toxins in the stinging hairs of U. thunbergiana. The general view that formic acid, histamine and serotonin are the pain-inducing agents in the stinging hairs of U. dioica may require updating, since their concentrations in U. thunbergiana were too low to induce significant pain sensation in behavioural bioassays.

Enantiospecific electrodeposition of chiral CuO films on single-crystal Cu(111).

Epitaxial films of monoclinic CuO have been electrodeposited on single-crystal Cu(111) from solutions containing either (S,S)- or (R,R)-tartrate. X-ray pole figure analysis reveals that the CuO film grown from (S,S)-tartrate exhibits a (1) out-of-plane orientation while the film grown from (R,R)-tartrate has a (11) orientation. Even though CuO does not crystallize within a chiral space group, the orientations obtained exhibit a surface chirality similar to that obtained from high index fcc metal surfaces. The films were shown to be enantioselective toward the catalytic oxidation of tartrate molecules by cyclic voltammetry. The technique should prove to be applicable to the electrodeposition of chiral surfaces of other low-symmetry materials on achiral substrates and should prove to be of use to those interested in the synthesis, separation, and detection of chiral molecules.

Direct chiral resolution of tartaric acid by ion-pair capillary electrophoresis using an aqueous background electrolyte with (1R,2R)-(-)-1,2-diaminocyclohexane as a chiral counterion.

Chiral resolution of native DL-tartaric acid was achieved by ion-pair capillary electrophoresis (CE) using an aqueous-ethanol background electrolyte with (1R,2R)-(-)-1,2-diaminocyclohexane (R-DACH) as a chiral counterion. Factors affecting chiral resolution and migration time of tartaric acid were studied. By increasing the viscosity of the background electrolyte and the ion-pair formation, using organic solvents with a lower relative dielectric constant, resulted in a longer migration time. The optimum conditions for both high resolution and short migration time of tartaric acid were found to be a mixture of 65% v/v ethanol and 35% v/v aqueous solution containing 30 mM R-DACH and 75 mM phosphoric acid (pH 5.1) with an applied voltage of -30 kV at 25 degrees C, using direct detection at 200 nm. By using this system, the resolution (Rs) of racemic tartaric acid was approximately 1. The electrophoretic patterns of tartaric and malic acids suggest that two carboxyl groups and two hydroxyl groups of tartaric acid are associated with the enantioseparation of tartaric acid by the proposed CE method.

The separation of racemic crystals into enantiomers by chiral block copolymers.

A series of chiral double hydrophilic block copolymers (DHBCs) was synthesized and employed as additives in the crystallization of calcium tartrate tetrahydrate (CaT). We found that appropriate polymers can slow down the formation of the thermodynamically most stable racemic crystals as well as the formation of one of the pure enantiomeric crystals so that chiral separation by crystallization occurs even when racemic crystals can be formed. In addition, the presence of DHBCs results in major modifications of crystal morphology, creating unusual morphologies of higher complexity. Our study demonstrates the potential application of chiral DHBCs in the control of chirality throughout crystallization, in particular for racemic crystal systems, and also shows that enantiomeric excess of one enantiomer can be maximized by the kinetic control of crystallization.

Simultaneous analysis of alkamides and caffeic acid derivatives for the identification of Echinacea purpurea, Echinacea angustifolia, Echinacea pallida and Parthenium integrifolium roots.

A reversed-phase HPLC method was developed using a computer simulation program for the identification of dried roots of Echinacea purpurea, E. angustifolia, E. pallida and Parthenium integrifolium. Hydrophilic and lipophilic compounds were analysed simultaneously leading to a two-fold decrease in analysis time compared to traditional HPLC methods.

Isolation and characterization of Mn(III) tartrate from Phanerochaete chrysosporium culture broth.

High initial Mn(II) concentration results in accumulation of a Mn(III) tartrate complex in the growth medium of Phanerochaete chrysosporium. Since Mn(III) is the major oxidant in ligninolysis by manganese peroxidase, the role of accumulated complex should not be neglected when degradation experiments by a crude culture filtrate are performed. To study the Mn(III) complex oxidative potential it was isolated by absorption to polyamide followed by desorption with an alkaline methanol solution. High performance liquid chromatography analysis and atomic absorption spectroscopy confirmed that the isolate was Mn(III) tartrate. Oxidation of 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonate) was used for testing the temperature and pH stability of the isolate that also intensively oxidized 2,6-dimethoxyphenol. In comparison with the non-isolated complex in the culture filtrate, the isolate showed increased temperature and pH stability. The oxidative potential of the isolated Mn(III) tartrate was additionally tested by decolorization of the synthetic dye Indigo carmine.

Purification and N-terminal amino acid sequence of the tartrate-resistant acid phosphatase from human osteoclastoma: evidence for a single structure.

Tartrate-resistant acid phosphatase type-5 was purified to apparent homogeneity from human osteoclastomas by sequential chromatography on CM-Sepharose, Phenyl-Sepharose, concanavalin A-Sepharose, FPLC Superose-12, and FPLC Mono-S. The purification over the original tissue extract was 1167-fold, with a yield of 16%. An identity in the N-terminal amino acid sequence and Mr was found between this enzyme and two type-5 tartrate-resistant acid phosphatases isolated from hairy cell leukemia spleen. However, they appeared to be different as assessed by amino acid composition. In contrast to a previous report, no evidence was found for two subunits of the tartrate-resistant acid phosphatase.

[2 methods of preparing solvent systems for the chromatographic separation of organic acids]. / Dva sposoba prigotovleniia sistem rastvoritelei dlia khromatograficheskogo razdeleniia organicheskikh kislot

The solvent system of alcohol-acid-water gradually forms an equilibrated amount of ester which facilitates the separation of di- and tri-carboxylic acids on paper chromatograms. Using the system of n-butanol-formic acid-water (3:1:1) as an illustration, two methods of accelerating the system ageing are demonstrated: 1) butanol-acid mixture at a required ratio is kept for several hours before water is added and 2) butanol-acid mixture is passed through the KU-2 layer in the H-form. The effect identical to that achieved as a result of 5-day storage of the solvent system under usual conditions can be reached with the first scheme during 6 hours and with the second scheme during 20-30 min.