Evaluation of sterols as markers of fungal spoilage in red pepper powder.

Red pepper powder (RPP) made from ground dried red pepper (Capsicum annuum L.) is prone to adulteration with fungal-spoiled RPP to gain unfair profits in Korea. This study aimed to investigate the effects of fungal infection on the ergosterol and phytosterol content of RPP and evaluate the potential of the sterol content as a marker for identifying fungal-spoiled RPP. Ergosterol was detected only in fungal-spoiled RPP and not in unspoiled RPP [

Geographical discrimination of Asian red pepper powders using 1H NMR spectroscopy and deep learning-based convolution neural networks.

This study investigated an innovative approach to discriminate the geographical origins of Asian red pepper powders by analyzing one-dimensional 1H NMR spectra through a deep learning-based convolution neural network (CNN). 1H NMR spectra were collected from 300 samples originating from China, Korea, and Vietnam and used as input data. Principal component analysis - linear discriminant analysis and support vector machine models were employed for comparison. Bayesian optimization was used for hyperparameter optimization, and cross-validation was performed to prevent overfitting. As a result, all three models discriminated the origins of the test samples with over 95 % accuracy. Specifically, the CNN models achieved a 100 % accuracy rate. Gradient-weighted class activation mapping analysis verified that the CNN models recognized the origins of the samples based on variations in metabolite distributions. This research demonstrated the potential of deep learning-based classification of 1H NMR spectra as an accurate and reliable approach for determining the geographical origins of various foods.

A colorimetric and fluorescent signaling probe for assaying Pd2+ in practical samples.

We developed an optical signaling probe to detect Pd2+ ions in Pd-containing catalyst and drug candidate. The Pd2+ signaling probe (Res-DT) was readily prepared by reacting the versatile fluorochrome resorufin with phenyl chlorodithioformate. In a phosphate-buffered saline solution (pH 7.4) containing sodium dodecyl sulfate (SDS) as a signal-boosting surfactant, Res-DT exhibited a pronounced colorimetric response with a chromogenic yellow to magenta shift, leading to a substantial increase in the fluorescence intensity. The Pd2+ signaling performance of Res-DT was attributed to the Pd2+-promoted hydrolysis of the dithioate moiety. The probe displayed high selectivity toward Pd2+ ions and remained unaffected by commonly encountered coexisting components. Moreover, the detection limit of Res-DT for Pd2+ ions was 10 nM, and the signaling was achieved within 7 min. Furthermore, to demonstrate the real-world applicability of Res-DT, a Pd2+ assay was performed in Pd-containing catalyst and drug candidate using an office scanner as an easily accessible measurement device. Our results highlight the prospects of Res-DT as a tool to detect Pd2+ ions in various practical samples, with potential applications in catalysis, medicine, and environmental science.

Changes of molecular mobility of ascorbyl palmitate and α-tocopherol by phospholipid and their effects on antioxidant properties in bulk oil.

Molecular mobility of ascorbyl palmitate and α-tocopherol in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were determined by NMR relaxation technique. Synergistic effects of DOPC on the antioxidative capacities of ascorbyl palmitate were evaluated in DPPH radical scavenging assay and bulk oil matrix. NMR relaxation technique can provide information on the mobility of protons. Molecular mobility of two protons in hydroxyl group of ascorbyl palmitate decreased by 85 and 78% in the presence of DOPC compared to those without DOPC. However, proton mobility of α-tocopherol increased by 41% when DOPC was present. DOPC significantly enhanced the DPPH reactivity in medium chain triacylglycerol, while this effect was not observed in α-tocopherol. Mixture of ascorbyl palmitate with DOPC showed synergistic antioxidant properties in corn oil at 60 °C. DOPC may make protons of ascorbyl palmitate in more rigid state, which can enhance hydrogen donating ability and antioxidant properties of ascorbyl palmitate in bulk oils.

Colorimetric screening of elevated urinary mercury levels by a novel Hg2+-selective probe of resorufin phosphinothioate.

Urinary mercury levels are the most reliable indicators of mercury exposure but identifying them requires complex techniques and heavy instruments. In this research, we reported a simple and convenient urinary mercury analysis method using a readily available office scanner. Probe MP-1 synthesized by the reaction of resorufin and dimethylthiophosphinoyl chloride revealed Hg2+-selective chromogenic and fluorescent signaling behavior. Signaling was realized through Hg2+-induced deprotection of the phosphinothioate protecting group in the resorufin-based probe MP-1 to yield the parent fluorochrome. A pronounced colorimetric response of color change from light yellow to pink alongside a turn-on type fluorescence enhancement was perceived exclusively toward Hg2+ ions over other metal ions and anions. The colorimetry provided a more advantageous ratiometric approach than the simple fluorometric analysis exhibiting an off-on type response, with a detection limit of 12 nM (2.4 ppb). The Hg2+ signaling of the MP-1 probe was not disturbed by the presence of coexisting metal ions and anions. The sensitive and convenient diagnosis of clinically important neurological symptoms and fatal inorganic mercury levels in urine was successfully demonstrated using a standard office scanner.

Combined analysis of inorganic elements and sugars for the identification of red pepper powder containing undeclared ingredients.

This study sought to identify adulterated red pepper powder (RPP) containing undeclared ingredients, such as salts, glucose, Monascus red pigments, and other plant ingredients (e.g., wheat flour, garlic powder, onion powder) using element and sugar analysis methods. Analytical data were obtained for 66 samples of authentic RPP and 12 samples of adulterated RPP. The variables selected to identify the authenticity of RPP include Na, Cl, K, maltohexaose, and maltoheptaose, which partly or totally originate from RPP, salts, or Monascus red pigments. All the 12 samples of commercial seasoned RPP used as models of adulterated RPP and all the 20 blind samples containing ≥10% (w/w) of commercial seasoned RPP were correctly identified by applying the range of the five variables found for the authentic RPP samples. Our findings suggest that combined analyses of the above five constituents could be used to identify adulterated RPP containing undeclared ingredients. PRACTICAL APPLICATION: Adulteration of high-priced spice products, including red pepper powder (RPP), has increasingly become a public concern worldwide as it endangers consumer health and represents economic fraud. This study provides analytical methods that can accurately determine the authenticity of RPP. They would become effective means for protecting producers and suppliers against unfair competition and consumers against health threats.

Hydrazone Photoswitches for Structural Modulation of Short Peptides.

Molecules that undergo light-driven structural transformations constitute the core components in photoswitchable molecular systems and materials. Among various families of photoswitches, photochromic hydrazones have recently emerged as a novel class of photoswitches with superb properties, such as high photochemical conversion, spectral tunability, thermal stability, and fatigue resistance. Hydrazone photoswitches have been adopted in various adaptive materials at different length scales, however, their utilization for modulating biomolecules still has not been explored. Herein, we present new hydrazone switches that can photomodulate the structures of short peptides. Systematic investigation on a set of hydrazone derivatives revealed that installation of the amide group does not significantly alter the photoswitching behaviors. Importantly, a hydrazone switch comprising an upper phenyl ring and a lower quinolinyl ring was effective for structural control of peptides. We anticipate that this work, as a new milestone in the research of hydrazone switches, will open a new avenue for structural and functional control of biomolecules.

Distinguishing Korean and Chinese red pepper powder using inductively coupled plasma and X-ray fluorescence-based analysis.

This study aimed to distinguish between Korean and Chinese red pepper powder (RPP) using inorganic elemental analysis data combined with orthogonal partial least squares-discriminant analysis (OPLS-DA). Elemental concentrations were obtained for 31 Korean and 31 Chinese RPP samples that were collected in Korea. Energy dispersive X-ray fluorescence spectroscopy detected 11 elements in these samples. Rb and Cl concentrations were selected as the variables which best allowed distinguishing between Korean and Chinese RPP using an S-plot from OPLS-DA. Rb and Cl concentrations in the Korean RPP samples were ≤ 1.6 mg/100 g (measured by inductively coupled plasma-optical emission spectroscopy) and ≤ 215 mg/100 g, respectively. A blind trial demonstrated that Korean RPP containing ≥ 50 g/100 g of Chinese RPP could be identified by applying predetermined ranges of Rb and Cl concentrations, suggesting that analysis of these two elements is a possible approach to distinguish between Korean and Chinese RPP.

Discriminant Analysis of the Geographical Origin of Asian Red Pepper Powders Using Second-Derivative FT-IR Spectroscopy.

This study aimed to discriminate between the geographical origins of Asian red pepper powders distributed in Korea using Fourier-transform infrared (FT-IR) spectroscopy coupled with multivariate statistical analyses. Second-derivative spectral data were obtained from a total of 105 red pepper powder samples, 86 of which were used for statistical analysis, and the remaining 19 were used for blind testing. A one-way analysis of variance (ANOVA) test confirmed that eight peak variables exhibited significant origin-dependent differences, and the canonical discriminant functions derived from these variables were used to correctly classify all the red pepper powder samples based on their origins. The applicability of the canonical discriminant functions was examined by performing a blind test wherein the origins of 19 new red pepper powder samples were correctly classified. For simplicity, the four most significant variables were selected as discriminant indicator variables, and the applicable range for each indicator variable was set for each geographical origin. By applying the indicator variable ranges, the origins of the red pepper powders of all the statistical and blind samples were correctly identified. The study findings indicate the feasibility of using FT-IR spectroscopy in combination with multivariate analysis for identifying the geographical origins of red pepper powders.

Development and Validation of a Simple Method to Quantify Contents of Phospholipids in Krill Oil by Fourier-Transform Infrared Spectroscopy.

This study focuses on developing a quantification method for phosphatidylcholine (PC) and total phospholipid (PL) in krill oil using Fourier-transform infrared (FT-IR) spectroscopy. Signals derived from the choline and phosphate groups were selected as indicator variables for determining PC and total PL content; calibration curves with a correlation coefficient of >0.988 were constructed with calibration samples prepared by mixing krill oil raw material and fish oil in different ratios. The limit of detection (LOD, 0.35-3.29%) of the method was suitable for the designed assay with good accuracy (97.90-100.33%). The relative standard deviations for repeatability (0.90-2.31%) were acceptable. Therefore, both the methods using absorbance and that using second-derivative were confirmed to be suitable for quantitative analysis. When applying this method to test samples, including supplements, the PC content and total PL content were in good agreement with an average difference of 2-3% compared to the 31P NMR method. These results confirmed that the FT-IR method can be used as a convenient and rapid alternative to the 31P NMR method for quantifying PLs in krill oil.

Rubidium analysis as a possible approach for discriminating between Korean and Chinese perilla seeds distributed in Korea.

The aim of this study was to discriminate between Korean and Chinese perilla seeds by using inorganic elemental analysis data combined with orthogonal partial least squares-discriminant analysis (OPLS-DA). Inorganic element content data were obtained from 29 Korean and 11 Chinese perilla seed samples distributed in Korea. Using energy dispersive X-ray fluorescence spectroscopy, 11 species of inorganic elements were detected in the perilla seed samples and eight of them were quantified. The Rb content was selected as the variable to best discriminate between Korean and Chinese perilla seeds using an S-plot generated from OPLS-DA. An accurate range for the Rb content was determined using inductively coupled plasma-optical emission spectroscopy. The Rb content is remarkably higher in Chinese perilla seeds (8.7-19.0 mg/kg) than in Korean perilla seeds (0.0-7.6 mg/kg), thereby suggesting that Rb analysis may be an appropriate approach to discriminate Chinese perilla seeds from Korean perilla seeds.

The first hydride-Meisenheimer adduct of electron-deficient 3-nitronaphthalimide: application to colorimetric borohydride determination.

The first hydride-Meisenheimer adduct of 3-nitronaphthalimide was used for the colorimetric borohydride assay. To explain the regioselectivity of the adduct, the reaction enthalpies of the two most plausible Meisenheimer adducts were obtained via computational calculation. Using the adduct formation, the assay of borohydride reagents was successfully conducted.

A Second Derivative Fourier-Transform Infrared Spectroscopy Method to Discriminate Perilla Oil Authenticity.

The aim of this study was to discriminate the authenticity of perilla oils distributed in Korea using their Fourier-Transform infrared spectroscopy (FT-IR) spectra with attenuated total reflectance accessory. By using orthogonal projections for latent structures discriminant analysis (OPLS-DA) technique, the =C-H cis-double bond, -C-H asymmetric and -C-H symmetric stretching are determined to be the best variables for discriminating the perilla oil authenticity. Comparing the integral and the second derivative methods between authentic and adulterated perilla oil samples, the most obvious and significant differences among the three variables is =C-H cis-double bond stretching. The procedure for applying the second derivative range of variables found in authentic perilla oil samples correctly discriminated between the adulterated samples of perilla oils with soybean oils and/or corn oils added at concentrations of ≥ 5 vol%. These results showed that the second derivative FT-IR analysis can be used as a simple and alternative method for discriminating the authenticity of perilla oil.

Electronic Effect on the Molecular Motion of Aromatic Amides: Combined Studies Using VT-NMR and Quantum Calculations.

Rotational barrier energy studies to date have focused on the amide bond of aromatic compounds from a kinetic perspective using quantum calculations and nuclear magnetic resonance (NMR). These studies provide valuable information, not only regarding the basic conformational properties of amide bonds but also the molecular gear system, which has recently gained interest. Thus, we investigate the precise motion of the amide bonds of two aromatic compounds using an experimental rotational barrier energy estimation by NMR experiments and a theoretical evaluation of the density functional theory calculation. The theoretical potential energy surface scan method combined with the quadratic synchronous transit 3 method and consideration of additional functional group rotation with optimization and frequency calculations support the results of the variable temperature ¹H NMR, with deviations of less than 1 kcal/mol. This detailed experimental and theoretical research strongly supports molecular gear motion in the aromatic amide system, and the difference in kinetic energy indicates that the electronic effect from the aromatic structure has a key role in conformational movements at different temperatures. Our study provides an enhanced basis for future amide structural dynamics research.

High-performance and scalable metal-chalcogenide semiconductors and devices via chalco-gel routes.

We report a general strategy for obtaining high-quality, large-area metal-chalcogenide semiconductor films from precursors combining chelated metal salts with chalcoureas or chalcoamides. Using conventional organic solvents, such precursors enable the expeditious formation of chalco-gels, which are easily transformed into the corresponding high-performance metal-chalcogenide thin films with large, uniform areas. Diverse metal chalcogenides and their alloys (MQ x : M = Zn, Cd, In, Sb, Pb; Q = S, Se, Te) are successfully synthesized at relatively low processing temperatures (<400°C). The versatility of this scalable route is demonstrated by the fabrication of large-area thin-film transistors (TFTs), optoelectronic devices, and integrated circuits on a 4-inch Si wafer and 2.5-inch borosilicate glass substrates in ambient air using CdS, CdSe, and In2Se3 active layers. The CdSe TFTs exhibit a maximum field-effect mobility greater than 300 cm2 V-1 s-1 with an on/off current ratio of >107 and good operational stability (threshold voltage shift < 0.5 V at a positive gate bias stress of 10 ks). In addition, metal chalcogenide-based phototransistors with a photodetectivity of >1013 Jones and seven-stage ring oscillators operating at a speed of ~2.6 MHz (propagation delay of < 27 ns per stage) are demonstrated.

A 43 MHz Low-Field Benchtop 1H Nuclear Magnetic Resonance Method to Discriminate Perilla Oil Authenticity.

The aim of this study was to discriminate the authenticity of perilla oils distributed in Korea using their 1H nuclear magnetic resonance (NMR) spectra acquired by a 43 MHz low-field benchtop NMR spectrometer. Significant differences existed in the integration values of all 6 peaks found in the spectrum between authentic and adulterated perilla oil samples. The integration values of 4 peaks that signify the methylene protons present in all fatty acids (FA) and allylic or olefinic protons present in all unsaturated FA were the best variables for establishing perilla oil authenticity. The procedure for applying the range of variables found in authentic perilla oil samples correctly discriminated between the samples of perilla oils with soybean oils added at concentrations of ≥ 6 vol%. The results demonstrated that this NMR procedure is a possible cost-effective alternative to the high-field 1H NMR method for discriminating the authenticity of perilla oils.

A Nuclear Magnetic Resonance Spectroscopy Approach to Discriminate the Geographic Origin of Roasted Asian Sesame Oils.

The aim of this study was to discriminate the geographic origin of Korean, Chinese, and Indian sesame oils distributed in Korea using 1H NMR spectroscopy in combination with canonical discriminant analysis (CDA). 1H NMR spectra were obtained from 84 roasted oil samples prepared from 51 Korean, 19 Chinese, and 14 Indian sesame seeds. The integration values of 26 peaks observed in the NMR spectra were determined and normalized on the basis of the peak derived from the terminal CH3 of the fatty acids (0.7446-1.0445 ppm). The variables selected for the CDA include the integration value of one peak (2.7208-2.8533 ppm) that signifies the CH2 between two C=C bonds from linoleic acid and the integration values of three peaks (2.9811-3.1151 ppm, 3.5914-3.6819 ppm, and 5.9471-5.9625 ppm) attributed to the protons of sesamolin. The CDA results showed that 80 of the 84 oil samples and five of the six additional commercial sesame oil samples were correctly classified based on their production site. This study demonstrated that 1H NMR spectroscopy is a useful tool to simultaneously analyze the relative abundance of linoleic acid and sesamolin in the sesame oils and good discrimination between the three Asian sesame oils could be achieved when the 1H NMR analytical data were used in combination with CDA.

Combined Analysis of Stable Isotope, (1)H NMR, and Fatty Acid To Verify Sesame Oil Authenticity.

The aim of this study was to verify the authenticity of sesame oils using combined analysis of stable isotope ratio, (1)H NMR spectroscopy, and fatty acid profiles of the oils. Analytical data were obtained from 35 samples of authentic sesame oils and 29 samples of adulterated sesame oils currently distributed in Korea. The orthogonal projection to latent structure discriminant analysis technique was used to select variables that most effectively verify the sesame oil authenticity. The variables include δ(13)C value, integration values of NMR peaks that signify the CH3 of n-3 fatty acids, CH2 between two C═C, protons from sesamin/sesamolin, and 18:1n-9, 18:3n-3, 18:2t, and 18:3t content values. The authenticity of 65 of 70 blind samples was correctly verified by applying the range of the eight variables found in the authentic sesame oil samples, suggesting that triple analysis is a useful approach to verify sesame oil authenticity.

High resolution in vivo 31P-MRS of the liver: potential advantages in the assessment of non-alcoholic fatty liver disease.

BACKGROUND: Biopsy remains the current gold-standard for assessing non-alcoholic fatty liver disease (NAFLD). To develop a non-invasive means of assessing the disease, 31P magnetic resonance spectroscopy (31P-MRS) has been explored, but the severe spectral overlaps and low signal-to-noise-ratio in 31P-MRS spectra at clinical field strength are clearly limiting factors. PURPOSE: To investigate potential advantages of high resolution in vivo 31P-MRS in assessing NAFLD. MATERIAL AND METHODS: The study was conducted at 9.4T in control and carbon tetrachloride (CCl4)-treated rats. Rats were divided according to histopathologic findings into a control group (n = 15), a non-alcoholic steatohepatitis group (n = 17), and a cirrhosis group (n = 12). Data were presented with different reference peaks that are commonly used for peak normalization such as total phosphorous signal, phosphomonoester + phosphodiester (PME + PDE), and nucleotide triphosphate (NTP). Then, multivariate analyses were performed. RESULTS: In all spectra PME and PDE were well resolved into phosphoethanolamine (PE) and phosphocholine (PC), and into glycerophosphorylethanolamine (GPE) and glycerophosphorylcholine (GPC), respectively. Those MRS measures quantifiable only in highly resolved spectra had higher correlations with histology than those conventional MRS measures such as PME, PDE, and NTP. The optimized partial least-squares discriminant analysis (PLS-DA) model correctly classified 79% (22/28) of the rats in the training set and correctly predicted 69% (11/16) of the rats in the test set. CONCLUSION: PE, PC, GPE, GPC, and nicotinamide adenine dinucleotide phosphate (NADP) that can be separately quantifiable in highly resolved spectra may further improve the potential efficacy of 31P-MRS in the diagnosis of NAFLD.

In vivo (1)H-MRS hepatic lipid profiling in nonalcoholic fatty liver disease: an animal study at 9.4 T.

The applicability of the in vivo proton magnetic resonance spectroscopy hepatic lipid profiling (MR-HLP) technique in nonalcoholic fatty liver disease was investigated. Using magnetic resonance spectroscopy, the relative fractions of diunsaturated (fdi), monounsaturated (fmono), and saturated (fsat) fatty acids as well as total hepatic lipid content were estimated in the livers of 8 control and 23 CCl4-treated rats at 9.4 T. The mean steatosis, necrosis, inflammation, and fibrosis scores of the treated group were all significantly higher than those of the control group (P < 0.01). There was a strong correlation between the histopathologic parameters and the MR-HLP parameters (r = 0.775, P < 0.01) where both steatosis and fibrosis are positively correlated with fmono and negatively correlated with fdi. Both necrosis and inflammation, however, were not correlated with any of the MR-HLP parameters. Hepatic lipid composition appears to be changed in association with the severity of steatosis and fibrosis in nonalcoholic fatty liver disease, and these changes can be depicted in vivo by using the MR-HLP method at 9.4 T. Thus, while it may not likely be that MR-HLP helps differentiate between steatohepatitis in its early stages and simple steatosis, these findings altogether are in support of potential applicability of in vivo MR-HLP at high field in nonalcoholic fatty liver disease.