Acid Ninhydrin Research Articles

INTERACTION OF (4E)-3-ALKYL(BENZYL)AMINO-4-(HYDROXYIMINO)NAPHTHALENE-1(4H)-ONES WITH 2,2-DIHYDROXY-1,3-INDANEDIONE

Many natural and synthetic quinone, including naphthoquinone derivatives, have some valuable properties. They are known as dyes, antibiotics, vitamins, and antioxidants. Some naphthoquinone derivatives act as cytostatic and antitumor reagents. However, the reduction of the quinoid fragment to the semiquinone radical and, as a consequence, the formation of toxic anion radicals, makes these substances cardiotoxic. The replacement of one or both carbonyl groups with the imino fragment can be one of the ways to solve this problem because iminoquinones have a weak redox cycle. This paper presents the results of the MTT test (primary screening for antitumor activity) of some 3-arylamino-1,4-naphthoquinone-4-oximes which were synthesized earlier. It has been shown that (4E)-4-(hydroxyimino)-3-(p-ethoxyphenylamino)naphtho-1(4H)-one and (4E)-4-(hydroxyimino)-3-(p-tolylamino)naphtho-1(4H)-one are most active against the colon adenocarcinoma and chronic myeloid leukemia in the tumor cell lines, respectively. We have performed the oximation reaction of 2-alkyl(benzyl)amino-1,4-naphthoquinones with hydroxylamine in ethanol to obtain a series of (4E)-3-alkyl(benzyl)amino-4-(hydroxyimino)naphthalene-1(4H)-ones. The reactions of synthesized products with 2,2-dihydroxy-1,3-indanedione (ninhydrin) have been studied under various conditions, i.e., in acetic acid under moderate heating and in dimethyl sulfoxide in the presence of methanesulfonic acid at different temperatures. It has been demonstrated that the interaction of (4E)-3-alkyl(benzyl)amino-4-(hydroxyimino)naphthalene-1(4H)-ones with ninhydrin in acetic acid leads to (6E)-5-alkyl(benzyl)amino-6-гhudroxyimino-4b,11b-dihydroxy-4b,5-dihydrobenzo[f]indeno[1,2-b]indol-11,12(6H,11bH)-diones. More severe conditions (dimethyl sulfoxide, methanesulfonic acid, and heating) leads to a mixture of products, the main of which are 1–alkyl-3'H-spiro[benzo[f]indole-2,1’-isobenzofuran]-3,3’,4,9(1H)-tetraones and 13-alkyl(benzyl)benzo[f]isochromeno[4,3-b]indole-5,7,12(13H)-triones. The yields of the products depend on the chosen temperature regime of the reaction. The structure of all synthesized compounds is confirmed by the physico-chemical methods, i.e., 1H and 13C NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry, spectrophotometry and elemental analysis. For citation: Gornostaev L.M., Rudenko D.S., Kirik S.D., Krasnov V.I. Interaction of (4E)-3-alkyl(benzyl)amino-4-(hydroxyimino)naphthalene-1(4H)-ones with 2,2-dihydroxy-1,3-indanedione. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 24-35. DOI: 10.6060/ivkkt.20246705.7015.

Integrative leaf anatomy structure, physiology, and metabolome analyses revealed the response to drought stress in sainfoin at the seedling stage.

Sainfoin (Onobrychis viciaefolia) is a vital legume forage, and drought is the primary element impeding sainfoin growth. The anatomical structure, physiological indexes, and metabolites of the leaves of sainfoin seedlings with a drought-resistant line of P1 (DRL) and a drought-sensitive material of 2049 (DSM) were analyzed under drought (-1.0 MPa) with polyethylene glycol-6000 (PEG-6000). The leaf anatomy was studied by the paraffin section method. The related physiological indexes were measured by the hydroxylamine oxidation method, titanium sulfate colorimetric method, thiobarbituric acid method, acidic ninhydrin colorimetric method, and Coomassie brilliant blue method. The metabolomics analysis was composed of liquid chromatography tandem high-resolution mass spectrometry (LC-MS/MS). The results revealed that the thickness of the epidermis, palisade tissue, and sponge tissue of DRL were significantly greater than those of DSM. The leaves of DRL exhibited lower levels of superoxide anion (O2 •-) production rate, hydrogen peroxide (H2O2) content, and malondialdehyde (MDA) content compared with DSM, while proline (Pro) content and soluble protein (SP) content were significantly higher than those of DSM. A total of 391 differential metabolites were identified in two samples. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that the primary differential metabolites were concentrated into the tyrosine metabolism; isoquinoline alkaloid biosynthesis; ubiquinone and other terpenoid quinone biosynthesis; neomycin, kanamycin, and gentamicin biosynthesis; and anthocyanin biosynthesis metabolic pathways. Compared with DSM, DRL had more complete anatomical structure, lower active oxygen content, and higher antioxidant level. The results improved our insights into the drought-resistant mechanisms in sainfoin.

Designing stimuli-responsive upconversion nanoparticles based on a mimetic immunoassay for potential accurate diabetic nephropathy diagnosis.

Diabetic nephropathy (DN) is the most common microvascular complication associated with incurable diabetes. The gold standard diagnostic method for DN is based on the detection of proteinuria but it overlooks cases of non-proteinuria (NP-DN). To address this limitation, urinary sialic acid (SA) has been confirmed as an effective biomarker for various DNs. Herein, we constructed an ultrasensitive non-proteinuria assay platform to accurately diagnose DN within 20 min. This platform utilized the ninhydrin reaction between acidic ninhydrin and urinary sialic acid (SA) as an effective biomarker for various DNs. A compound with a maximum absorption peak at 470 nm was produced in this reaction and contributed to the fluorescence decrease of the blue-emission core-shell upconverting nanoparticles through the inner filter effect (IFE). By integrating the inner filter effect (IFE) with a mimetic immunoassay, the imperceptible color was converted into highly sensitive fluorescence signals. This protocol shows a stable and high sensitivity with a detection limit of 20 nmol L-1 and provides 100% positive prediction for urine samples, demonstrating its potential for clinical diagnosis and long-term monitoring of DN.

Comparative Evaluation of Salivary Sialic Acid Levels Among Beedi Rollers and Tobacco Users in Mangalore, South India.

Introduction: According to World Health Organization, the global cancer burden is estimated to have risen to 18.1 million new cases and 9.6 million deaths in 2018. Tobacco use is a leading cause of cancer and of death from cancer. Beedis are the most popular smoking form of tobacco in India. Thirty-four percent of the tobacco produced in India is used for making beedis. The beedi sector is agroforestry-based and the second largest industry in India with approximately 4.4 million full-time beedi workers in India. Toxic constituents present in tobacco are released into the ambient air during the processing of beedis.Methods: A descriptive cross-sectional study was conducted to assess and compare salivary sialic acid levels among beedi rollers, tobacco smokers, smokeless tobacco users and individuals with no tobacco exposure. The study sample comprised of 140 individuals who were 30 to 60 years old, who attended dental screening and treatment camps in rural and urban areas in Mangalore, conducted by the Department of Public Health Dentistry, Yenepoya Dental College and patients who visited the Department of Oral Medicine and Radiology of Yenepoya Dental College. Saliva was collected by passive drool method into a sterile container. Biochemical analysis of salivary sialic acid was done using the acidic ninhydrin method. Continuous variables are expressed in terms of mean and standard deviation. Categorical variables are expressed in terms of frequencies and percentages. To compare salivary sialic acid levels between the groups ANOVA was used. The Chi-square test was used to compare categorical variables between the groups.Results: A total of 140 participants, 35 beedi rollers, 35 smokers, 35 smokeless tobacco users and 35 individuals with no tobacco exposure participated in the study. Among the 140 participants, 90 participants were males and 50 participants were females. There was a statistically significant difference in the mean salivary sialic acid level between the different groups (p<0.001) with smokeless tobacco users having the highest (10.60 mg/dL) mean salivary sialic acid level. It was found that the mean salivary sialic acid level reduced as the age progressed, even though there was no statistically significant difference. There was a statistically significant difference in the mean salivary sialic acid level between the different groups (p=0.010) with participants with 11 to 20 years of exposure to tobacco having the highest (8.67 mg/dL) mean salivary sialic acid level and participants with no tobacco exposure having least (3.06 mg/dL) mean salivary sialic acid level.Conclusion: The salivary sialic acid level was more in beedi rollers than individuals with no tobacco exposure, even though the difference was not statistically significant. The results showed elevated levels of salivary sialic acid in smokeless tobacco users followed by tobacco smokers. This may be an indication that smokeless tobacco use has harmful effects similar to or more than tobacco smoking since salivary sialic acid levels in smokeless tobacco users were higher than those in smokers.

Usefulness of salivary sialic acid as a tumor marker in tobacco chewers with oral cancer.

This study aims to assess the usefulness of salivary sialic acid (SA) as a tumor marker in the detection of oral squamous cell carcinoma (OSCC) among tobacco chewers. After the approval of study protocol by the Institutional Ethics Committee and informed voluntary consent, salivary samples were collected from 96 participants in each group of tobacco chewers with OSCC, tobacco chewers without precancerous or cancerous lesion, and healthy controls. Salivary protein-bound SA (PBSA) and salivary-free SA (FSA) were measured by Yao et al.'s method of acid ninhydrin reaction, and the data were subjected to appropriate statistical analysis. The salivary PBSA and FSA levels in the Groups 1, 2, and 3 participants were 31.17 ± 7.6 mg/dL and 63.45 ± 9.8 mg/dL, 25.45 ± 16.61 mg/dL and 33.18 ± 11.38 mg/dL, and 22.73 ± 3.01 mg/dL and 21.62 ± 8.86 mg/dL, respectively. Salivary FSA levels were significantly increased among the tobacco chewers with OSCC patients (Group 1) and tobacco chewers with no premalignant lesions of the oral cavity (Group 2) compared to the healthy controls (Group 3) with P < 0.05 being statistically significant. Salivary FSA levels were significantly increased in Group 1 as compared with Group 2. The salivary PBSA was high among Group 1 as compared to the control Group 3; there was however no significant difference in the levels of salivary PBSA between Group 1 and Group 2. There was no significant difference in the PBSA levels between OSCC patients of Group 1 and the tobacco chewers without precancerous or cancerous lesion in the oral cavity of Group 2. Salivary PBSA and FSA are significantly raised in both tobacco chewers with OSCC and in tobacco chewers with no precancerous or cancerous lesions in the oral cavity. SA should therefore be used cautiously while considering it as a marker for the early detection of oral cancer. Tobacco can be a crucial confounding factor when SA is used as a biomarker in OSCC since their levels are elevated to some extent even in tobacco chewers without any clinically obvious precancerous or cancerous lesions in the oral cavity.

A spectrophotometric procedure for sialic acid determination in milk employing a flow-batch analysis system with direct heating

The quantitative determination of sialic acid can indicate the addition of cheese whey to milk. This work describes an automated procedure to determine sialic acid in milk samples using a flow-batch system analysis with direct heating. The sialic acid quantification was based on a reaction between the sialic acid and acid ninhydrin producing a stable compound with maximum absorption at 470 nm. The flow-batch system was designed using heating and spectrophotometric detection in the reaction chamber. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg L−1 sialic acid (R = 0.99 and n = 7), a detection (3σ criterion) and quantification (10σ criterion) limit estimated at 0.239 and 0.726 mg L−1, respectively, a relative standard deviation of 1.90% (n = 10) for a reference solution of 4.0 mg L−1 sialic acid and a sampling rate of 7 determinations per hour were achieved. Analysis of eleven milk samples, application of the t-test to the results found, and comparison with the official method provided no significant differences at a 95% confidence level. Compared to the official method, the proposed system reduced reaction time by 50%, temperature of the reaction by 30%, and diminished the consumption of reagents and samples by 90%. Thus, the use of the proposed system is an economically viable and environmentally friendly option for the determination of sialic acid in milk.

Metabolic recuperation in valine production by mutant strain

The contemplation of present research work to get over scantiness of amino acid by amelioration ofmicroorganism. As a matter of fact the use of chemical and physical factors symbolize a new era in the excerption of microorganism for proficient of producing a desired product. In this workbiosynthetic pathway of valine and their regulation was observed in Bacillus cereus, Corynebacterium and Pseudomonas fluoresence. The contrivance of operation of ems mutants was analyze in different fermentation media at 24, 48, 72 and 96 h incubation under optimum condition by acidic ninhydrin method. Optical density was recorded by spectrophotometer 470 nm for Valine. The effects of carbon and nitrogen sources and growth factors on the production of valine were studied. In this studies mutant evince that mutation confabulate upon the bacteria the ability to produce valine many times more than its parental strain within the same span of incubation period. The objective of this work to step up headway to search unconventional sources to overcome nutritional exhortation of valine.

Synthesis of New Functionally Substituted Aryl- and Hetarylcarbamates Based on Ninhydrin

The condensation of methyl (ethyl) phenylcarbamates with ninhydrin in concentrated sulfuric acid gave dialkyl [1,3-dioxoindan-2,2-diyldi(4,1-phenylene)]biscarbamates. Treatment of the latter with hydrazine hydrate resulted in the transformation of the indandione fragment into phthalazinone. Ninhydrin reacted with methyl (hydroxyphenyl)carbamates in glacial acetic acid to produce dihydroxy derivative of oxotrihydroindeno[ 1,2-b][1]benzofuran possessing a carbamate group. Tandem reaction of ninhydrin with methyl (acetylphenyl) carbamates on heating in boiling glacial acetic acid, followed by addition of hydrazine hydrate in acetonitrile, afforded methyl (5-oxo-5H-indeno[1,2-c]pyridazin-3-yl)phenylcarbamates.

Analysis, Nutrition, and Health Benefits of Tryptophan.

Tryptophan is an essential plant-derived amino acid that is needed for the in vivo biosynthesis of proteins. After consumption, it is metabolically transformed to bioactive metabolites, including serotonin, melatonin, kynurenine, and the vitamin niacin (nicotinamide). This brief integrated overview surveys and interprets our current knowledge of the reported multiple analytical methods for free and protein-bound tryptophan in pure proteins, protein-containing foods, and in human fluids and tissues, the nutritional significance of l-tryptophan and its isomer d-tryptophan in fortified infant foods and corn tortillas as well the possible function of tryptophan in the diagnosis and mitigation of multiple human diseases. Analytical methods include the use of acid ninhydrin, near-infrared reflectance spectroscopy, colorimetry, basic hydrolysis; acid hydrolysis of S-pyridylethylated proteins, and high-performance liquid and gas chromatography-mass spectrometry. Also covered are the nutritional values of tryptophan-fortified infant formulas and corn-based tortillas, safety of tryptophan for human consumption and the analysis of maize (corn), rice, and soybean plants that have been successfully genetically engineered to produce increasing tryptophan. Dietary tryptophan and its metabolites seem to have the potential to contribute to the therapy of autism, cardiovascular disease, cognitive function, chronic kidney disease, depression, inflammatory bowel disease, multiple sclerosis, sleep, social function, and microbial infections. Tryptophan can also facilitate the diagnosis of certain conditions such as human cataracts, colon neoplasms, renal cell carcinoma, and the prognosis of diabetic nephropathy. The described findings are not only of fundamental scientific interest but also have practical implications for agriculture, food processing, food safety, nutrition, and animal and human health. The collated information and suggested research need will hopefully facilitate and guide further studies needed to optimize the use of free and protein-bound tryptophan and metabolites to help improve animal and human nutrition and health.

Synthesis of methyl 4-aryl-4-oxo-2-[(4-sulfamoylphenyl)amino]but-2-enoates and their reaction with ninhydrin

The reaction of methyl 4-aryl-2,4-dioxobut-2-enoates with 4-aminobenzenesulfonamide in acetic acid–ethanol (1: 1) afforded methyl (2Z)-4-aryl-4-oxo-2-(4-sulfamoylanilino)but-2-enoates which reacted with ninhydrin in glacial acetic acid to give 3-aroyl-4-(4-sulfamoylanilino]-5H-spiro[furan-2,2′-indene]-1′,3′,5-triones.

N-acetylneuraminic acid: A scrutinizing tool in oral squamous cell carcinoma diagnosis

Oral cancer has one of the highest mortality rate among other malignancies. An attempt has been made to assess the genetic expression of a cell surface glycoprotein component - sialic acid released by the malignant cells which will reflect on the oral squamous cell carcinoma (OSCC). The aim of this study was to estimate and correlate the salivary and serum sialic acid levels in OSCC. In our case-control study, saliva and blood samples were obtained from Group 1 - 10 healthy controls, Group 2 - 12 well-differentiated OSCC, Group 3 - 7 moderately differentiated and 2 poorly differentiated OSCC. Serum and salivary total sialic acid levels were analyzed by Warren's thiobarbituric acid method and acidic ninhydrin method, respectively. The results were analyzed statistically by Student's t-test and Pearson's correlation coefficient (P ≤ 0.05). A significant difference in the serum and salivary sialic acid levels was observed between Group 1 and Group 3 (P = 0.01 and < 0.0001) and in salivary sialic acid between Group 2 and Group 3 (P = 0.02). A significant positive correlation was observed between salivary and serum sialic acid in Groups 2 and 3 together (P = 0.015). As the histopathological grade progresses, there is a marked increase in level of sialic acid. There is a significant positive correlation between serum and salivary sialic acid levels in OSCC. Further research with larger sample size along with grading and staging system may highlight its significance in OSCC.

A rapid, ideal, and eco-friendlier protocol for quantifying proline

Proline, a stress marker, is routinely quantified by a protocol that essentially uses hazardous toluene. Negative impacts of toluene on human health prompted us to develop a reliable alternate protocol for proline quantification. Absorbance of the proline-ninhydrin condensation product formed by reaction of proline with ninhydrin at 100°C in the reaction mixture was significantly higher than that recorded after its transfer to toluene, revealing that toluene lowers sensitivity of this assay. λ max of the proline-ninhydrin complex in the reaction mixture and toluene were 508 and 513nm, respectively. Ninhydrin in glacial acetic acid yielded higher quantity of the proline-ninhydrin condensation product compared to ninhydrin in mixture of glacial acetic acid and H3PO4, indicating negative impact of H3PO4 on proline quantification. Further, maximum yield of the proline-ninhydrin complex with ninhydrin in glacial acetic acid and ninhydrin in mixture of glacial acetic acid and H3PO4 was achieved within 30 and 60min, respectively. This revealed that H3PO4 has negative impact on the reaction rate and quantity of the proline-ninhydrin complex formed. In brief, our proline quantification protocol involves reaction of a 1-ml proline sample with 2ml of 1.25% ninhydrin in glacial acetic acid at 100°C for 30min, followed by recording absorbance of the proline-ninhydrin condensation product in the reaction mixture itself at 508nm. Amongst proline quantification protocols known till date, our protocol is the most simple, rapid, reliable, cost-effective, and eco-friendlier.

Protein-inorganic hybrid nanoflowers as ultrasensitive electrochemical cytosensing Interfaces for evaluation of cell surface sialic acid

The identification of biocompatible nanomaterials with high conductivities as sensing interfaces is important in developing novel electrochemical cytosensors. We prepared a novel protein-inorganic nanomaterial-bovine serum albumin (BSA) incorporated Ag nanoflowers with three-dimensional porous architectures, using a simple biomimetic method. The BSA-incorporated Ag nanoflowers were modified on a glassy carbon electrode (GCE) surface and conjugated with a targeting lectin molecule, i.e., Sambucus nigra agglutinin (SNA), for sensing DLD-1 human colon cancer cells. The BSA-incorporated Ag nanoflowers were a suitable platform, and showed improved cell-immobilization capacity, and good biocompatibility, with retention of activity of the immobilized cells. These properties are attributed to the large surface area of the porous structure and the natural BSA layer acting as a biocompatible support. The attachment of DLD-1 cells to the GCE increased the electron-transfer resistance, with a good correlation with the logarithm of the concentration from 1.35×102 to 1.35×107cellsmL−1, with a low detection limit of 40cellsmL−1. Based on the affinity between SNA and sialic acid (SA), the UV–vis absorption spectrum of the one-step reaction between SA and acidic ninhydrin indicated that the average number of SA molecules on a single living DLD-1 cell surface was approximately 2.16×1012. This proposed cytosensing strategy had good reproducibility, acceptable precision, and high specificity for SA-over-expressed cells, indicating that it has potential applications for the early monitoring of tumor cells and convenient evaluation of SA on living cells.

Superparamagnetic Au-Fe3O4 nanoparticles: one-pot synthesis, biofunctionalization and toxicity evaluation

Superparamagnetic Au-Fe3O4 bifunctional nanoparticles have been synthesized using a single step hot-injection precipitation method. The synthesis involved using Fe(CO)5 as iron precursor and HAuCl4 as gold precursor in the presence of oleylamine and oleic acid. Oleylamine helps in reducing Au3+ to Au0 seeds which simultaneously oxidizes Fe(0) to form Au-Fe3O4 bifunctional nanoparticles. Triton® X-100 was employed as a highly viscous solvent to prevent agglomeration of Fe3O4 nanoparticles. Detailed characterization of these nanoparticles was performed by using x-ray powder diffraction, transmission electron microscopy, scanning tunneling electron microscopy, UV-visible spectroscopy, Mössbauer and magnetometry studies. To evaluate these nanoparticles’ applicability in biomedical applications, L-cysteine was attached to the Au-Fe3O4 nanoparticles and cytotoxicity of Au-Fe3O4 nanoparticles was tested using CHO cells by employing MTS assay. L-cysteine modified Au-Fe3O4 nanoparticles were qualitatively characterized using Fourier transform infrared spectroscopy and Raman spectroscopy; and quantitatively using acid ninhydrin assay. Investigations reveal that that this approach yields Au-Fe3O4 bifunctional nanoparticles with an average particle size of 80 nm. Mössbauer studies indicated the presence of Fe in Fe3+ in A and B sites (tetrahedral and octahedral, respectively) and Fe2+ in B sites (octahedral). Magnetic measurements also indicated that these nanoparticles were superparamagnetic in nature due to Fe3O4 region. The saturation magnetization for the bifunctional nanoparticles was observed to be ∼74 emu g−1, which is significantly higher than the previously reported Fe3O4 nanoparticles. Mössbauer studies indicated that there was no significant Fe(0) impurity that could be responsible for the superparamagnetic nature of these nanoparticles. None of the investigations showed any presence of other impurities such as Fe2O3 and FeOOH. These Au-Fe3O4 bifunctional nanoparticles showed no significant cytotoxicity to the CHO cells up to 48 h even at concentrations of 1 mg ml−1 making them suitable for biomedical applications such as local heat generators (hyperthermia) for cancer treatment and drug delivery vehicles.

Application of FT-Raman Spectroscopy and Chemometric Analysis for Determination of Adulteration in Milk Powder

In this work, FT-Raman spectroscopy is explored as a rapid technique for the assessment of the milk powder quality. Based on information provided by Raman spectra of samples adulterated with starch and whey, a quantitative method is developed to identify the fraud, using Partial Least Squares regression (PLS). In regression models using PLS the results are satisfactory, and such models can be used to identify and quantify samples presenting whey and starch in milk powder at concentrations of 2.32% and 1.64% (w/w), respectively. In the whey determination, the obtained values in the PLS model of the new samples are compared with those obtained by the spectrophotometric method of acid ninhydrin. This result shows that there is no significant difference with the 95% level of confidence between the values provided by the PLS regression method and the acid ninhydrin. The present work shows Raman spectroscopy as an analytical tool which can be used in quality control of milk powder, even in fraud processes, and the calculated figures of merit such as sensitivity, accuracy, limit of detection and limit of quantification clearly demonstrate this potential use. Although the multivariate models developed are not strictly quantitative, especially for low concentrations, they can be used as screening methods for routine analysis, as showed by this work.

A Spectrophotometric Method for the Detection of Cheese Whey in Milk

A spectrophotometric method for the detection of cheese whey in milk is described. The method is based on the colour reaction of sialic acid bound to the glycomacropeptide (GMP) - a marker peptide of cheese whey. In this method, GMP present in adulterated milk is first selectively precipitated by employing double precipitation method, wherein, trichloroacetic acid (TCA) concentration in milk is first raised to 8% to precipitate all the major proteins from milk followed by raising the TCA concentration to 14% to precipitate out GMP. The sialic acid in washed GMP precipitates was reacted with acidic ninhydrin reagent which gave yellowish- brown colour (maxima 470 nm), the intensity of which increases with the increase in the level of cheese whey in milk. The reagent blank as well as control milk sample (unadulterated milk) also gave faint yellow colour with OD values of 0.004±0.002 and 0.032±0.01, respectively. The method can detect presence of 10% cheese whey in milk where OD value increased to 0.1±0.01. The method was validated in milk samples added with different levels of cheese whey.

Determination of micro amounts of 3-(dithien-2-ylmethylene)-1-methylpiperidine, a non-narcotic antitussive.

Abstract A specific colorimetric method for the determination of micro amounts of 3-(dithien-2-ylmethylene)-1-methylpiperidine, a new antitussive and expectorant, is described. Depending on amount, a characteristic colour varying from rose pink to deep bluish purple appears when 2 volumes of a 0·01% solution of ninhydrin in concentrated sulphuric acid are added to 1 volume of an aqueous solution of the drug. After 24 hr at room temperature the colour produced has an absorption maximum at 590 mμ and follows Beer's Law over the range 1–25 μg/ml. The colour is specific for the drug and is sensitive at the μg/ml level. Recoveries from aqueous solution and human urine were 97·4 ± 2·1 and 97·4 ± 1·7% respectively.

A study of low-energy ion induced radiolysis of thiol-containing amino acid cysteine in the solid and aqueous solution states

The radiolysis of cysteine under plasma discharge and irradiation of low-energy ion beam was investigated. The damage of cysteine in aqueous solution under discharge was assessed via the acid ninhydrin reagent and the yield of cystine produced from the reaction was analyzed by FTIR. In addition, the generation of hydrogen sulfide was also identified. The destruction of solid cysteine under low-energy ion beam irradiation was estimated via monitoring IR bands of different functional groups (–SH, –NH 3, –COO −) of cysteine, and the production of cystine from ion-irradiated solid cysteine after dissolution in water was also verified. These results may help us to understand the inactivation of sulphydryl enzymes under direct and indirect interaction with the low-energy ion irradiation.

Superacid mediated hydroxyalkylation reaction of 1,2,3‐indanetrione: a theoretical study

AbstractEnergies of mono‐ and multiprotonation for 1,2,3‐indanetrione and ninhydrin in triflic acid (TFSA) media were estimated at PBE0/aug‐cc‐pvtz//6‐31+G** level of theory. The reactivity of formed intermediates in the reaction of aromatic electrophilic substitution has been studied at the same level of theory. It appears that the basicity of carbonyl groups in 1,2,3‐indanetrione is extremely low due to mutual influences of carbonyl groups. Carbonyl 2 is the least basic but the most reactive in accordance with experiment. Calculations demonstrated that monoprotonated intermediates are the principal reactive species in the reaction of hydroxyalkylation of 1,2,3‐indanetrione in TFSA. A new isomerization mechanism of 2,2‐diaryl‐1,3‐indanediones to 3‐(diarylmethylene)isobenzofuranones in TFSA media has been proposed. Copyright © 2010 John Wiley &amp; Sons, Ltd.

A histochemical study of the hypopharangeal glands of the dwarf honey bees Apis andreniformis and Apis florea

SummaryThe structure of the hypopharyngeal glands of Apis andreniformis and Apis florea workers was studied. Glands from pupae, nurse bees and foraging bees were investigated using paraffin and staining techniques. Periodic Acid Schiff's reagent (PAS) and Ninhydrin Schiffs reagent were used for the histochemical study of carbohydrates and proteins respectively. The glands of the two bee species were found to be quite similar in terms of histochemical structures, but differences were found between the three life stages. Pupae showed an incomplete glandular structure which was irregular in shape. Each secretory unit was composed of two to eight aggregated oval to cuboidal secretory cells with lenticular and abundant euchromatin nuclei. Weak staining with PAS and Ninhydrin Schiff's reagent indicated that the glands contained small amounts of carbohydrates and proteins. In nurse and foraging bees, however, each secretory unit was completely developed, and consisted of four to eight aggregated secretory cells with numerous large secretory vesicles. Each secretory cell was pyramidal in shape and stained strongly with both PAS and Ninhydrin Schiff's reagent, indicating that these glands were producing abundant carbohydrates and proteins, which then accumulate within the secretory vesicles. The plasma membrane between adjacent secretory cells in the secretory unit of foraging bees showed wider extracellular space than those of the nurse bees.