Determination of glucosamine in impure chitin samples by high-performance liquid chromatography

A New and Rapid HPLC Method to Determine the Degree of Deacetylation of Glutaraldehyde-Cross-Linked Chitosan

Chitosan is a linear biopolymer composed of D-glucosamine and N-acetylglucosamine units. The percentage of D-glucosamine in the polymeric chain can vary from one sample to another and is expressed as the degree of deacetylation (DDA). Since this parameter has an impact on many properties, its determination is often critical, and potentiometric titration is a common analytical technique to measure the DDA. Cross-linking with glutaraldehyde is one of the most explored modifications of chitosan; however, the determination of the DDA for the resulting reticulated chitosan resins can be challenging. In this paper, we report a new, rapid, and efficient method to determine the DDA of glutaraldehyde-cross-linked chitosan resins via HPLC. This method relies on the use of 2,4-dinitrophenylhydrazine (DNPH) as a derivatizing agent to measure the level of reticulation of the polymer (LR) after the reticulation step. In this study, we prepare three calibration curves (with an R2 value over 0.92) for three series of reticulated polymers covering a large range of reticulation levels to demonstrate that a correlation can be established between the LR established via HPLC and the DDA obtained via titration. The polymers are derived from three different chitosan starting materials. These standard calibration curves are now used on a routine basis in our lab, and the HPLC method has allowed us to change our DDA analysis time from 20 h to 5 min.

ELECTROPHORETIC DETERMINATION OF CHITIN IN INSECTS

An electrophoretic method (on-line coupled capillary isotachophoresis with capillary zone electrophoresis with conductometric detection (cITP-CZE-COND)) for the determination of chitin in insects based on the analysis of glucosamine after acidic hydrolysis of the sample is described. Chitin is deacetylated and hydrolyzed to glucosamine by acidic hydrolysis (6 M sulfuric acid, 110 °C, 6 h). Under optimized electrophoresis conditions, glucosamine (GlcN) is separated from other sample components in cationic mode and detected with a conductometer within 15 min. The performance method characteristics of the GlcN assay, i.e., linearity (0.2-20 μmol), accuracy (103 ± 5%), repeatability (1.9%), reproducibility (3.4%), limits of detection (0.06 μmol/L) and quantification (0.2 μmol/L), were evaluated. On a series of 28 insect samples, it was proven that cITP-CZE-COND provides results of chitin content in insects comparable to the literature data. The important features of the developed cITP-CZE-COND method are easy sample treatment, high sensitivity and selectivity, and low running costs. It is clear from the above that the cITP-CZE-COND method is suitable for analysis of insect samples for chitin content.

The effect of dechitinization on iron absorption from mealworm larvae (Tenebrio molitor) flour added to maize meals: stable-isotope studies in young females with low iron stores

BACKGROUND

Edible insects have a low ecological footprint and could serve as an alternative dietary iron source. However, chitin, a major component of insects, avidly binds iron and might inhibit iron absorption.

OBJECTIVES

We aimed to measure fractional iron absorption (FIA) from Tenebrio molitor-based test meals with and without dechitinization, and to assess the effect of native and low chitin T. molitor on FIA from iron-fortified maize porridge.

METHODS

We measured iron absorption in young females with low iron stores (n = 21) from 1) labeled (54FeSO4) fortified maize porridge (maize alone); 2) intrinsically labeled (57Fe added during rearing) T. molitor larvae with native chitin content (NC) added to maize alone; and 3) dechitinized intrinsically labeled (57Fe) T. molitor larvae with low chitin content (LC) added to maize alone. We determined FIA using erythrocyte isotope incorporation and measured in vitro iron dialyzability from the 3 meals.

RESULTS

NC and LC T. molitor had similar mean ± SD iron content (12.0 ± 0.1 mg/100 g). Geometric mean (95% CI) FIAs from the 3 test meals were 1) maize alone: 5.8% (3.2%, 10.8%); 2) maize + NC T. molitor: 5.3% (2.5%, 11.3%) and 4.1% (1.9%, 8.7%); and 3) maize + LC T. molitor: 4.6% (2.0%, 10.3%) and 4.0% (1.8%, 9.2%), for extrinsic and intrinsic labels, respectively. FIA from NC and LC T. molitor did not significantly differ, and both were lower (P < 0.005) than FIA from the labeled maize porridge in the 3 meals, which did not significantly differ. The slopes of the relations between FIA and serum ferritin in the different meals and from the intrinsic and extrinsic labels did not significantly differ.

CONCLUSIONS

T. molitor biomass does not strongly affect iron absorption when added to maize porridge. Our data suggest T. molitor iron is absorbed from the common nonheme iron pool. Native T. molitor is high in iron which is moderately well absorbed, suggesting it could be a valuable dietary iron source.This trial was registered at clinicaltrials.gov as NCT04510831.

Development of a Quantitative UPLC-ESI/MS Method for the Simultaneous Determination of the Chitin and Protein Content in Insects

In a context where the commercial and nutritional interest in insect chitin is always increasing, an accurate and precise method to quantify this biopolymer, especially in food/feed, is required. In addition, quantification of insect crude protein through nitrogen determination is normally overestimated due to the presence of chitin. In this work, for the first time, an RP-UPLC-ESI/MS method for the simultaneous quantification in insects of chitin, as glucosamine (GlcN), and protein, as total amino acids, is presented. The method is based on acid hydrolysis and derivatization of amino acids and GlcN with the AccQ Tag reagent. Method was optimized and validated in terms of linearity, LOD and LOQ, intraday and inter-day repeatability, and accuracy. A hydrolysed commercial chitin was selected as reference standard for calibration. The instrumental LOD and LOQ correspond respectively to a concentration of 0.00068 mM and 0.00204 mM. The intraday precision satisfied the Horwitz ratio. Data from inter-day precision showed the necessity to perform the analysis within 1 week utilizing standard calibration solutions freshly prepared. A matrix effect was observed, which suggested the necessity to use an internal calibration curve or to work in a particular concentration range of GlcN. The chitin and protein content in black soldier fly (Hermetia illucens) and lesser mealworm (Alphitobius diaperinus) were found in agreement with results obtained by independent methods. The optimized method was also tested on two different commercial food supplements, suggesting its applicability on a wide range of matrices. This newly developed method proved to be simple, more accurate, and faster if compared to methods which separately analyse chitin and protein content.

Chitin Determination in Residual Streams Derived From Insect Production by LC-ECD and LC-MS/MS Methods

Chitin, a biopolymer present in fungi and arthropods, is a compound of interest for various applications, such as in the agricultural and medical fields. With the recently growing interest in the development of insect farming, the availability of chitin-containing residual streams, particularly the molting skins (exuviae), is expected to increase in the near future. For application purposes, accurate quantification of chitin in these insect sources is essential. Previous studies on chitin extraction and quantification often overlooked the purity of the extracted chitin, making the outcomes inconsistent and prone to overestimation. The present study aims to determine chitin content in the exuviae of three insect species mass-reared worldwide: black soldier fly (BSF), mealworm, and house cricket. Chitin was chemically extracted using acid and alkali treatments to remove minerals and proteins. The purity of extracted chitin was evaluated by hydrolyzing the chitin into glucosamine, followed by quantitative determination of the latter using two liquid chromatography methods: electrochemical detection (ECD) and tandem mass spectrometry (MS/MS). Both methods proved accurate and precise, without the need for labor-intensive derivatization steps. Pearson's correlation and Bland-Altman plots showed that the glucosamine determination results obtained by the two methods were comparable, and there is no consistent bias of one approach vs. the other. The chitin content in extracted residues ranged between 7.9 and 18.5%, with the highest amount found in BSF puparium. In summary, the study demonstrated that (1) the residual streams of the insect farming industry have a great potential for utilization as an alternative chitin source, and (2) both LC-ECD and LC-MS/MS are reliable for the quantitative determination of glucosamine in insect chitin.

Determination of chitosan content with Schiff base method and HPLC

Tremendous awareness of determination of chitosan content accurately is increasing, due to it has great significance to the quality control of chitosan. In this article, two kinds of chitosan-Schiff base derivatives (BCSB and PCSB) were synthesized by the different average degrees of deacetylation (DD) of chitosan with benzaldehyde or propanal, respectively. The total mass of Schiff base derivative product was dried and obtained without washing and loss. Then, a certain amount of the prepared Schiff base compound was taken to hydrolyze into glucosamine hydrochloride (GAH) in strong hydrochloric acidic environment, whose concentration was quantified by HPLC, and the mass of GAH contained in hydrolysis solution could be calculated. Subsequently, the total quality of GAH obtained by hydrolysis of all of the Schiff base product was calculated and obtained, and then the theoretical mass of chitosan could be deduced and calculated by further converse calculation. Finally, the chitosan content was obtained by combining the sample mass used in Schiff base reaction and the theoretical mass of chitosan. This method was accurate and convenient, providing a preeminent idea and method for the determination of chitosan content.

Enhancing the specificity of chitin determinations through glucosamine analysis via ultra-performance LC-MS

As chitin is gaining an increased attention as feedstock for industry, quantification thereof is becoming increasingly important. While gravimetric procedures are long, not specific and highly labour-intensive, acidic hydrolysis of chitin into glucosamine followed by quantification of the latter is more performant. Even though several quantification procedures for the determination of chitin can be found in the literature, they give inconsistent results and their accuracy was not assessed due to the lack of certified analytical standards. Therefore, in the present study, commercially available chitin from practical grade was characterised in detail, allowing the assessment of method accuracy. The procedure for the hydrolysis of chitin into glucosamine and subsequent quantification via UPLC-MS was investigated in detail as well. Using 9-fluorenylmethyl chloroformate (FMOC-Cl) as derivatisation reagent, glucosamine was quantified using reversed-phase chromatography. For the chitin hydrolysis, the highest glucosamine recovery was obtained with 8.0 M HCl for 2 h at 100 °C. The entire procedure for chitin quantification, including the hydrolysis, was characterised by high interday and intraday precision and accuracy. The specificity of the procedure was assessed as well by analysing different mixtures of cellulose and chitin. Chitin recoveries from these analyses ranged from 98.8 to 105.8% while no signal was observed for 100% cellulose, indicating the high specificity of the procedure. It was also concluded that the procedure is much faster and less labour-intensive compared to the gravimetric procedure.

Development of ultra-high performance liquid chromatographic and fluorescent method for the analysis of insect chitin

A precise quantification of insect chitin is needed in order to avoid overestimation of crude protein due to chitin-bound nitrogen. An UPLC/FLR method was optimized and validated for the determination of glucosamine (GlcN) hydrolyzed from chitin in insect materials. The method was applied for quantifying the chitin content in mealworms (Tenebrio molitor) and crickets (Acheta domesticus). A baseline separation was obtained using an Acquity HSS T3 C18 column, with an external calibration curve of excellent linearity, and a low limit of detection and quantification of GlcN. Even though the recovery of GlcN from spiked cricket material was slightly lower compared to that using spectrophotometric method, the UPLC/FLR method proved a sensitive and specific method of quantification of insect chitin. Chitin contents in T. molitor and A. domesticus were 4.6 ± 0.1% and 4.5 ± 0.0% on dry matter basis, respectively. Less than 0.01% of chitin was present in insect protein-enriched fractions extracted with 0.1 N NaCl at pH 10.

General Protocol to Obtain D-Glucosamine from Biomass Residues: Shrimp Shells, Cicada Sloughs and Cockroaches

A general protocol is developed to obtain D-glucosamine from three widely available biomass residues: shrimp shells, cicada sloughs, and cockroaches. The protocol includes three steps: (1) demineralization, (2) deproteinization, and (3) chitin hydrolysis. This simple, general protocol opens the door to obtain an invaluable nitrogen-containing compound from three biomass residues, and it can potentially be applied to other chitin sources. White needle-like crystals of pure D-glucosamine are obtained in all cases upon purification by crystallization. Characterization data (NMR, IR, and mass spectrometry) of D-glucosamine obtained from the three chitin sources are similar and confirm its high purity. NMR investigation demonstrates that D-glucosamine is obtained mainly as the α-anomer, which undergoes mutarotation in aqueous solution achieving equilibrium after 440 min, in which the anomeric glucosamine distribution is 60% α-anomer and 40% β-anomer.

Study on Brilliant Blue-chitosan System by Dual-wavelength Overlapping Resonance Rayleigh Scattering Method and its Analytical Applications

The method was presented for the sensitive and selective determination of chitosan (CTS) in health products with Brilliant Blue (BB) as a probe, based on dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS). In weakly acidic buffer solution, the binding of CTS and BB could result in the RRS intensities getting enhanced significantly at RRS peaks of 344nm and 452nm, and the scattering intensities of the two peaks were proportional to the concentration of CTS within a certain range. When the RRS intensities of the two wavelengths were superposed, the results showed higher sensitivity. Under the optimum experimental conditions, the total of the two increased RRS intensities was linear to the CTS concentration in the range of 0.02-1.80μg/mL and the limit of detection (LOD) was 7.45ng/mL. In this work, the optimum conditions and the effects of some foreign substances were studied. Accordingly, the new method based on DWO-RRS for the determination of CTS was developed. In addition, the effect of the molecular weight and the deacetylation degree between different chitosan molecules was discussed. Finally, this assay was applied to determine the concentration of CTS in health products with satisfactory results.

Elephant's breast milk contains large amounts of glucosamine

Hand-reared elephant calves that are nursed with milk substitutes sometimes suffer bone fractures, probably due to problems associated with nutrition, exercise, sunshine levels and/or genetic factors. As we were expecting the birth of an Asian elephant (Elephas maximus), we analyzed elephant’s breast milk to improve the milk substitutes for elephant calves. Although there were few nutritional differences between conventional substitutes and elephant’s breast milk, we found a large unknown peak in the breast milk during high-performance liquid chromatography-based amino acid analysis and determined that it was glucosamine (GlcN) using liquid chromatography/mass spectrometry. We detected the following GlcN concentrations [mean ± SD] (mg/100 g) in milk hydrolysates produced by treating samples with 6M HCl for 24 hr at 110°C: four elephant’s breast milk samples: 516 ± 42, three cow’s milk mixtures: 4.0 ± 2.2, three mare’s milk samples: 12 ± 1.2 and two human milk samples: 38. The GlcN content of the elephant’s milk was 128, 43 and 14 times greater than those of the cow’s, mare’s and human milk, respectively. Then, we examined the degradation of GlcN during 0–24 hr hydrolyzation with HCl. We estimated that elephant’s milk contains >880 mg/100 g GlcN, which is similar to the levels of major amino acids in elephant’s milk. We concluded that a novel GlcN-containing milk substitute should be developed for elephant calves. The efficacy of GlcN supplements is disputed, and free GlcN is rare in bodily fluids; thus, the optimal molecular form of GlcN requires a further study.

Resonance Rayleigh Scattering Spectra of an Ion-Association Complex of Naphthol Green B-Chitosan System and Its Application in the Highly Sensitive Determination of Chitosan

This work describes a highly-sensitive and accurate approach for the determination of chitosan (CTS) using Naphthol Green B (NGB) as a probe in the Resonance Rayleigh scattering (RRS) method. The interaction between CTS and NGB leads to notable enhancement of RRS, and the enhancement is proportional to the concentration of CTS over a certain range. Under optimum conditions, the calibration curve of ΔI against CTS concentration was ΔI = 1860.5c + 86.125 (c, µg/mL), R² = 0.9999, and the linear range and detection limit (DL) were 0.01–5.5 µg/mL and 8.87 ng/mL. Moreover, the effect of the molecular weight of CTS on the accurate quantification of CTS was studied. The experimental data were analyzed through linear regression analysis using SPSS20.0, and the molecular weight was found to have no statistical significance. This method has been applied to assay two CTS samples and obtained good recovery and reproducibility.

Distinction of fungal polysaccharides by N/C ratio and mid infrared spectroscopy

A set of fungal polysaccharide samples was characterised by elemental analysis and FTIR spectroscopy and compared with reference chitins, chitosans and β-D-glucans. The nitrogen to carbon (N/C) values and FTIR spectra were used to compare the samples based on their composition. It was found that the N/C ratio correlates well with deacetylation degree (DD) of chitosans and chitin/glucan ratio R(chit) of fungal chitin – β-D-glucan complexes with the exception of some samples having significant nitrogen and/or carbon admixtures. FTIR spectroscopy was indicative for the N-acetylation of chitins (chitosans) as well as for the chitin (chitosan) contribution to fungal polysaccharide preparations. Multivariate analyses of the FTIR data (HCA, PCA) discriminated samples and reference materials into several clusters depending on their similarity. Chitosan lactates, chitosan – β-D-glucans and chitin – β-D-glucans of high and low amounts of chitin were successfully discriminated from the reference polysaccharides and from each other. The proposed procedures based on the N/C ratio and multivariate analyses of FTIR spectra may be used in screening fungal polysaccharide preparations.

Determination of glucosamine in fungal cell walls by high-performance liquid chromatography (HPLC)

Glucosamine (GlcN) is a major and valuable component in the cell wall of zygomycetes fungi. In this study, a time independent and accurate method was developed for the determination of GlcN. In this method, the cell wall was treated via a two-stage sulfuric acid process, and chitin and chitosan were fully deacetylated, partially depolymerized, and converted to GlcN oligosaccharides. Then, the oligosaccharides were deaminated to 2,5-anhydromannose using nitrous acid. Finally, 2,5-anhydromannose was analyzed by high performance liquid chromatography (HPLC). The determinations of pure GlcN solutions were stable at least for 10 days, while those of the conventional colorimetric method were not stable for more than one hour. The alkali insoluble material (AIM) of biomass of purely yeast-like, mostly yeast-like, and filamentous forms of the fungus Mucor indicus was analyzed by the developed method. The respective GlcN content of AIM of the fungus was 0.232, 0.204, and 0.458 (g/g).

Ultra-high pressure LC determination of glucosamine in shrimp by-products and migration tests of chitosan films

Chitosan, a multiple applications molecule, was isolated from shrimp by-products by fermentation. The amount of chitosan in the solid fraction of the fermented extract was measured after its conversion in the respective glucosamine units. The procedure includes an acid hydrolysis (110 °C, 4 h with HCl 8 M) and a derivatization with 9-fluorenylmethyl chloroformate (Fmoc-Cl). Ultra-high-pressure liquid chromatography method was developed and optimized. Excellent peaks resolution was achieved in just 10 min. The method was evaluated in what concerns to validation parameters such as linearity, repeatability, quantification limit, and recovery. Migration tests of films prepared with chitosan were carried out in two simulants: ultrapure water and ethanol 95% (v/v).

A New Rapid and Sensitive Spectrophotometric Method for Determination of a Biopolymer Chitosan

A novel approach of spectrophotometric quantification of chitosan based on one-step depolymerization with sodium nitrite followed by reaction of the end product with thiobarbituric acid has been proposed, optimized, and validated. In this process, chitosan is converted into 2,5-anhydro-D-mannose that reacts with thiobarbituric acid to form pink color. The color that resulted from the reaction was stabilized and measured at 555 nm. The method optimization was essential as many procedural parameters influenced the accuracy of the determination including hydrolysis conditions, thiobarbituric acid concentration, reaction time, pH, reaction temperature, and color stability period. Under given optimized conditions that appeared to be critical, chitosan was quantitatively analyzed and the calibration graph was linear over the range of 10–50 μg/mL (). This approach was applied for determination of chitosan in pharmaceutical formulation (chitocal) and had a recovery rate of higher than 96%. The developed method is easy to use and highly accurate.

Precolumn derivatization LC-MS/MS method for the determination and pharmacokinetic study of glucosamine in human plasma and urine

A selective precolumn derivatization liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of glucosamine in human plasma and urine has been developed and validated. Glucosamine was derivatized by o-phthalaldehyde/3-mercaptopropionic acid. Chromatographic separation was performed on a Phenomenex ODS column (150 mm×4.6 mm, 5 μm) using linear gradient elution by a mobile phase consisting of methanol (A), and an aqueous solution containing 0.2% ammonium acetate and 0.1% formic acid (B) at a flow rate of 1 mL/min. Tolterodine tartrate was used as the internal standard (IS). With protein precipitation by acetonitrile and then the simple one-step derivatization, a sensitive bio-assay was achieved with the lower limit of quantitation (LLOQ) as low as 12 ng/mL for plasma. The standard addition calibration curves suitable for clinical sample analysis showed good linearity over the range of 0.012-8.27 μg/mL in plasma and 1.80-84.1 μg/mL in urine. The fully validated method has been successfully applied to a pharmacokinetic study of compound glucosamine sulfate dispersible tablets in health Chinese volunteers receiving single oral doses at 500, 1000 and 1500 mg of glucosamine sulfate, as well as multiple oral doses of 500 mg t.i.d. for 7 consecutive days.

Chitin

A comprehensive profile of chitin with 61 references is reported. A full description including nomenclature, formulae, elemental analysis, and appearance is included. Methods of preparation for chitin and its derivative, such as chitosan, are discussed. Physical properties, analytical methods, uses and applications, stability, biodegradability, and toxicity of chitin are also reviewed.

Parasitic growth of Pseudomonas aeruginosa in co-culture with the chitinolytic bacterium Aeromonas hydrophila

Polymer-degrading bacteria face exploitation by opportunistic bacteria that grow with the degradation products without investing energy into production of extracellular hydrolytic enzymes. This scenario was investigated with a co-culture of Aeromonas hydrophila and Pseudomonas aeruginosa with chitin as carbon, nitrogen and energy source. In single cultures, A. hydrophila could grow with chitin, while P. aeruginosa could not. Co-cultures with both strains had a biphasic course. In the first phase, P. aeruginosa grew along with A. hydrophila without affecting it. The second phase was initiated by a rapid inactivation of and a massive acetate release by A. hydrophila. Both processes coincided and were dependent on quorum sensing-regulated production of secondary metabolites by P. aeruginosa. Among these the redox-active phenazine compound pyocyanin caused the release of acetate by A. hydrophila by blocking the citric acid cycle through inhibition of aconitase. Thus, A. hydrophila was forced into an incomplete oxidation of chitin with acetate as end-product, which supported substantial growth of P. aeruginosa in the second phase of the co-culture. In conclusion, P. aeruginosa could profit from a substrate that was originally not bioavailable to it by influencing the metabolism and viability of A. hydrophila in a parasitic way.

Semi-solid state fermentation of sweet sorghum for the biotechnological production of single cell oil

A semi-solid fermentation process for the production of biodiesel from sweet sorghum is introduced. The microorganism used is the oleaginous fungus Mortierella isabellina, which is able to transform efficiently sugar to storage lipid. Kinetic experiments were performed at various water content percentages. The fungus consumed simultaneously sugars and nitrogen contained in sorghum and after nitrogen depletion the biomass growth was completed and oil accumulation began. Water content of 92% presented the highest oil efficiency of 11 g/100 g dry weight of substrate. The semi-solid process is shown to have certain advantages compared to liquid cultures or solid-state fermentation and gives oil of high quality.

Elevated CO and nitrogen influence exudation of soluble organic compounds by ectomycorrhizal root systems

Root and mycelial exudation contributes significantly to soil carbon (C) fluxes, and is likely to be altered by an elevated atmospheric carbon dioxide (CO(2)) concentration and nitrogen (N) deposition. We quantified soluble, low-molecular-weight (LMW) organic compounds exuded by ectomycorrhizal plants grown under ambient (360 p.p.m.) or elevated (710 p.p.m.) CO(2) concentrations and with different N sources. Scots pine seedlings, colonized by one of five different ectomycorrhizal or nonmycorrhizal fungi, received 70 muM N, either as NH(4)Cl or as alanine, in a liquid growth medium. Exudation of LMW organic acids (LMWOAs), dissolved monosaccharides and total dissolved organic carbon were determined. Both N and CO(2) had a significant impact on exudation, especially of LMWOAs. Exudation of LMWOAs was negatively affected by inorganic N and decreased by 30-85% compared with the organic N treatment, irrespective of the CO(2) treatment. Elevated CO(2) had a clear impact on the production of individual LMWOAs, although with very contrasting effects depending on which N source was supplied.

Determination of glucosamine and N-acetyl glucosamine in fungal cell walls

A new method was developed to determine glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) in materials containing chitin and chitosan, such as fungal cell walls. It is based on two steps of hydrolysis with (i) concentrated sulfuric acid at low temperature and (ii) dilute sulfuric acid at high temperature, followed by one-step degradation with nitrous acid. In this process, chitin and chitosan are converted into anhydromannose and acetic acid. Anhydromannose represents the sum of GlcN and GlcNAc, whereas acetic acid is a marker for GlcNAc only. The method showed recovery of 90.1% of chitin and 85.7-92.4% of chitosan from commercial preparations. Furthermore, alkali insoluble material (AIM) from biomass of three strains of zygomycetes, Rhizopus oryzae, Mucor indicus, and Rhizomucor pusillus, was analyzed by this method. The glucosamine contents of AIM from R. oryzae and M. indicus were almost constant (41.7 +/- 2.2% and 42.0 +/- 1.7%, respectively), while in R. pusillus, it decreased from 40.0 to 30.0% during cultivation from 1 to 6 days. The GlcNAc content of AIM from R. oryzae and R. pusillus increased from 24.9 to 31.0% and from 36.3 to 50.8%, respectively, in 6 days, while it remained almost constant during the cultivation of M. indicus (23.5 +/- 0.8%).

High performance liquid chromatography for the determination of glucosamine sulfate in human plasma after derivatization with 9-fluorenylmethyl chloroformate

In this study, we developed a simple, rapid, sensitive, and reliable method for the determination of glucosamine sulfate in human plasma, which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) followed by reverse-phase HPLC-FLD. For the first time, FMOC-Cl was introduced into derivatization of glucosamine sulfate in human plasma. The amino groups of glucosamine sulfate and vertilmicin sulfate (the internal standard) were trapped with FMOC-Cl to form glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts, which can be very suitable for HPLC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C18 column (DIAMONSIL 150 x 4 mm id, 5 microm) with a mobile phase gradient consisting of acetonitrile and water at a flow-rate of 1 mL/min. The retention times of glucosamine-FMOC-Cl and vertilmicin-FMOC-Cl adducts were 8.9 and 21.2 min, respectively. This method was shown to be selective and sensitive for glucosamine sulfate. The limit of detection was 15 ng/mL for glucosamine sulfate in plasma and the linear range was 0.1-10 mg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 5.2-8.1% and 6.1- 8.5%, respectively. Extraction recoveries of glucosamine sulfate in plasma were greater than 90%. The validated method was successfully applied to the determination of glucosamine sulfate in human plasma samples.

Nutritional considerations in joint health

Osteoarthritis, a debilitating joint disorder, is the most common form of arthritis in the United States, where it affects an estimated 21 million people. In 2004, the direct and indirect health care costs associated with all forms of arthritis were approximately 86 billion dollars. Joint discomfort from osteoarthritis and other joint disorders may reduce physical activity in individuals experiencing this condition, resulting in energy imbalance and weight gain. Increased weight can exacerbate existing problems, as additional stress on joints stimulates risk of additional joint disorders. Dietitians play a role in preventing or reversing the problem of joint disorders by promoting nutrient-rich diets that support joint health through improvement in cartilage metabolism. In addition, counseling individuals on weight management and active lifestyles are key strategies for the management of joint health.

The efficacy of glucosamine and chondroitin sulfate in the treatment of osteoarthritis: are these saccharides drugs or nutraceuticals?

This review summarizes recent knowledge on the efficacy of glucosamine (GS) and/or chondroitin sulfate (CS) in the therapy of mild to moderate osteoarthritis (OA). OA, the most common joint disease is a significant source of disability, quality of life impairment and a considerable burden to any health care system. In the Czech Republic, glucosamine sulfate (GS) and chondroitin sulfate (CS) are available both as prescription drugs and as food supplements. Based on available data both are useful in the earlier stages of OA when combined with other modalities such as weight loss and exercises. They appear to relieve pain and improve range of the joint motion. In addition, they also display mild anti-inflammatory effects. However, controversy still exists over their ability to change significantly the natural history of the osteoarthritic joint. This effect is not easy to demonstrate for any other treatment modalities apart from joint replacement. Monitoring the cure efficacy by X-ray has been recently criticised and hence future techniques are anticipated for this reason. Further, long-term oral administration is required to obtain slightly increased levels of GS and/or CS in human blood. Both reviewed saccharides are well tolerated with negligible adverse reactions. In conclusion, the authors suggest that GS and CS should be classified as food supplements only.