Sensitive analysis of curcuminoids via micellar electrokinetic chromatography with laser-induced native fluorescence detection and mixed micelles-induced fluorescence synergism

Smartphone-based imaging colorimetric assay for monitoring the quality of curcumin in turmeric powder

This research developed a colorimetric assay for semi-quantitative curcumin detection. The screening test was performed using a ferric chloride to form a brownish color which was further used to evaluate the amount of curcumin in the turmeric powder samples. The quantitative assay was performed based on the color intensity of the curcumin target using a smartphone digital image colorimetry with a developed lightbox constructed with a white light-emitting diodes (LED) light source as the measurement device. Images in red, green, and blue (RGB) color were processed to obtain relevant colors from the image and the color values were used to analyze curcumin concentrations. The intensity of the ΔB was correlated to the concentration of curcumin with high sensitivity. The method showed a linear range between 0.25 and 5 mg L-1 with the LOD and LOQ of 0.12 and 0.41 mg L-1, respectively. Sample analysis was carried out in turmeric powders. Curcumin in turmeric powder samples was simply extracted using acetonitrile followed by dilution 100 times for sample preparation. The accuracy was tested by spiking 0.25, 1.00, and 4.00 mg L-1 of standard curcumin into the turmeric sample solution. The average percentage recoveries were acceptable in all samples (90-104%). The method was validated by comparing the results obtained from the proposed method and high-performance liquid chromatography (HPLC). There was no statistically significant difference between the two methods (P = 0.05).

Novel reusable and switchable deep eutectic solvent for extraction and determination of curcumin in water and food samples

For the first time, a fast and easy extraction method based on a unique reusable and switchable deep eutectic solvent (made of octylamine, succinic acid, and water as precursors) was presented and utilized for the microextraction and determination of curcumin as a model analyte. The main factors used to induce a phase transition in the as-prepared deep eutectic solvent were solutions of NaOH and HCl. Among the standout characteristics of the suggested deep eutectic solvent are the removal of toxic organic solvents like THF, the lack of a need for centrifugation, and the ability to be reused in subsequent extractions. The influence of effective parameters (i.e., proportions of deep eutectic solvent structure components, volume of prepared deep eutectic solvent, volume and concertation of NaOH, volume of HCl, and salt effect) on the extraction procedure were investigated. The calibration curve also was linear in the range of 35-500 μg L-1 with coefficients of determination (R2) of 0.9976. Limit of detection (S/N = 3) 10.0 μg L-1, the limit of quantification (LOQ) of 35.0 μg L-1, the relative standard deviations (RSDs %) composed of intra-day RSD (4.7) and inter-day RSD (6.4), preconcentration factor of 40.0, enrichment factor of 38.68, and relative recovery of 92.6%-100.3 % were achieved. The reusable and switchable deep eutectic solvent based-dispersive liquid-liquid microextraction technique was proficiently employed to expedite easy and fast extraction of curcumin from water and food samples.

Spice and Herb Frauds: Types, Incidence, and Detection: The State of the Art

There is a necessity to protect the quality and authenticity of herbs and spices because of the increase in the fraud and adulteration incidence during the last 30 years. There are several aspects that make herbs and spices quite vulnerable to fraud and adulteration, including their positive and desirable sensorial and health-related properties, the form in which they are sold, which is mostly powdered, and their economic relevance around the world, even in developing countries. For these reasons, sensitive, rapid, and reliable techniques are needed to verify the authenticity of these agri-food products and implement effective adulteration prevention measures. This review highlights why spices and herbs are highly valued ingredients, their economic importance, and the official quality schemes to protect their quality and authenticity. In addition to this, the type of frauds that can take place with spices and herbs have been disclosed, and the fraud incidence and an overview of scientific articles related to fraud and adulteration based on the Rapid Alert System Feed and Food (RASFF) and the Web of Science databases, respectively, during the last 30 years, is carried out here. Next, the methods used to detect adulterants in spices and herbs are reviewed, with DNA-based techniques and mainly spectroscopy and image analysis methods being the most recommended. Finally, the available adulteration prevention measurements for spices and herbs are presented, and future perspectives are also discussed.

Curcumin: Overview of Extraction Methods, Health Benefits, and Encapsulation and Delivery Using Microemulsions and Nanoemulsions

Curcumin is the principal curcuminoid found in the rhizomes of turmeric. Due to its therapeutic action against cancer, depression, diabetes, some bacteria, and oxidative stress, it has been used widely in medicine since ancient times. Due to its low solubility, the human organism cannot completely absorb it. Advanced extraction technologies, followed by encapsulation in microemulsion and nanoemulsion systems, are currently being used to improve bioavailability. This review discusses the different methods available for curcumin extraction from plant material, methods for the identification of curcumin in the resulting extracts, its beneficial effects on human health, and the encapsulation techniques into small colloidal systems that have been used over the past decade to deliver this compound.

Turn on fluorescence detection of curcumin in food matrices by the novel fluorescence sensitizer

In this study, silane reagents were for the first time explored as the fluorescence sensitizer. They were demonstrated to have fluorescence sensitization effect on curcumin and 3-glycidoxypropyltrimethoxysilane (GPTMS) possessed the strongest effect. Thus, GPTMS was adopted as the novel fluorescence sensitizer to turn on the fluorescence of curcumin by more than two orders of magnitude for detection. In this way, curcumin could be determined with a linear range of 0.2-2000 ng/mL and an LOD of 0.067 ng/mL. The method was applicable to determine curcumin in several actual food samples, which had the good consistency with the high performance liquid chromatographic method, demonstrating the high accuracy of the proposed method. In addition, the curcumins sensitized by GPTMS could be cured under certain conditions and held the potential for solid fluorescence application. This study expanded the scope of fluorescence sensitizer to silane reagents, and provided the novel approach for fluorescence detection of curcumin and further to generate new solid fluorescence system.

High-Resolution Micro-object Separation by Rotating Magnetic Chromatography

The development of new technologies for the separation, selection, and isolation of microparticles such as rare target cells, circulating tumor cells, cancer stem cells, and immune cells has become increasingly important in the last few years. Microparticle separation technologies are usually applied to the analysis of disease-associated cells, but these procedures often face a cell separation problem that is often insufficient for single specific cell analyses. To overcome these limitations, a highly accurate size-based microparticle separation technique, herein called "rotating magnetic chromatography", is proposed in this work. Magnetic nanoparticles, placed in a microfluidic separation channel, are forced to move in well-defined trajectories by an external magnetic field, colliding with microparticles that are in this way separated on the basis of their dimensions with high accuracy and reproducibility. The method was optimized by using fluorescein isothiocyanate-modified polystyrene particles (chosen as a reference standard) and then applied to the analysis of cancer cells like Hep-3B and SK-Hep-1, allowing their fast and high-resolution chromatographic separation as a function of their dimensions. Due to its unmatched sub-micrometer cell separation capabilities, RMC can be considered a break-through technique that can unlock new perspectives in different scientific fields, that is, in medical oncology.

Enhanced capillary zone electrophoresis in cyclic olefin copolymer microchannels using the combination of dynamic and static coatings for rapid analysis of carnosine and niacinamide in cosmetics

Cosmetics having medicinal effects, including anti-inflammatory and antioxidant, have become a daily care routine consumption. The peptide additives, such as carnosine and nicotinamide, were frequently used to realize these medicinal effects. To accomplish rapid and effective quantitation of carnosine and niacinamide in cosmetics, a capillary zone electrophoresis was executed in cyclic olefin copolymer microchips having both dynamic and static coatings. The static coating of cyclic olefin copolymer microchannel was constructed from bovine albumin adsorption, immobilization and active site closure, while the dynamic coating was formed by adding surfactant into running buffer of capillary zone electrophoresis. The static coating can improve the hydrophilicity of cyclic olefin copolymer surface and avoid nonspecific peptide adsorption. The dynamic coating of sodium dodecyl sulfate in running buffer proved to be useful in flow velocity adjustment and the column efficiency enhancement in capillary zone electrophoresis separation channel of the cyclic olefin copolymer microchip device. A separation resolution up to 4.24 on the mixture of carnosine and nicotinamide was obtained. Moreover, an analysis method was established and applied to simultaneous carnosine and nicotinamide determination in a liquid whitening essence and a solid antiglycation pill and the results were verified by comparison with HPLC methods, indicating its potential in complex sample analysis. This article is protected by copyright. All rights reserved.

Hydrophilic silicon nanoparticles as a turn-off and colorimetric fluorescent probe for curcuminoids detection in food samples and cell imaging

Hydrophilic fluorescent silicon nanoparticles (SiNPs) with good pH stability, salt-tolerance and anti-photobleaching were for the first time prepared from hydrophobic 3-glycidoxypropyltrimethoxysilane. Employing SiNPs as the fluorescence probe, selective quantification of curcuminoids based on the quenching effect was realized with a linearity of 0.046-7.4 μg/mL and a limit of detection of 17.6 ng/mL. Moreover, in light of fluorescence redshift of SiNPs corresponding to the elevated concentration of curcuminoids, a fluorescence colorimetric method was established based on only one extra probe, i.e. herein SiNPs. Thus, semi-quantification of curcuminoids (0-14.7 μg/mL) was visualized from blue to yellow color. Both the developed quantitative and semi-quantitative probe were successfully applied to determine curcuminoids in various actual food samples. Furthermore, SiNPs possessed low cytotoxicity and succeeded in intracellular curcuminoids imaging. The proposed SiNPs could be a promising fluorescence probe for multiple applications.

Analytical method for the determination of curcumin entrapped in polymeric micellar powder using HPLC

OBJECTIVES

Curcumin belongs to the family of curcuminoids, natural polyphenolic compounds that possesses neuroprotective properties, anti inflammatory and anticancer. Its entrapment in the developed casein-based micellar powder (CMP) and poloxamer-based micellar powder (PMP) was to enhance the solubility and improve the bioavailability. Henceforth, the present study aimed to acquire an efficient analytical method for the curcumin analysis in polymeric micellar formulations.

METHODS

A fast and specific HPLC method was developed for analyzing curcumin in two different micellar matrices using casein and poloxamer. The HPLC was equipped with a C18 column (250 × 4 mm, 5 µm) and diode array detector. A designated isocratic elution of curcumin was employed using mobile phase with a composition of water (1%, v/v acetic acid) and acetonitrile in a ratio of 50:50 v/v. The employed flow rate was 1.0 mL/min and the analyte was examined at 421 nm.

RESULTS

An effective analysis in HPLC was successfully achieved by the predetermined HPLC condition. A good resolution of peaks at the employed flow rate was achieved. The linearity was excellent in two different range of concentrations, 2-20 and 10-50 μg/mL. The selectivity, accuracy and precision fulfilled the acceptable requirements.

CONCLUSIONS

The developed method was practically effective to qualitatively identified curcumin. In addition, the assay also effectively quantified the amount of curcumin in the polymeric entrapping matrices which demonstrates that it has great potential to be used in natural compound analysis.

Two-Dimensional Cytometry Platform for Single-Particle/Cell Analysis with Laser-Induced Fluorescence and ICP-MS

A two-dimensional cytometry platform (CytoLM) with high sensitivity and high temporal resolution is developed for single-particle and single-cell sampling and analysis. First, a Dean flow-assisted vortex capillary cell sampling (VCCS) unit confines the sample stream in curved flow and drives to focus and align the particles or cells in a small probe volume. By coupling VCCS to a laser-induced fluorescence (LIF) detector with data acquisition and processing capability, a high-throughput single-particle/cell analysis system (VCCS-LIF) was established. The particle analysis throughput of 119.42/s and a detection recovery of 78.20 ± 1.75% were achieved at a density of 9.16 × 10⁴/mL for fluorescent particles, and the cell analysis throughput is 48.20/s at a density of 1.5 × 10⁵/mL. Second, the CytoLM platform is constructed by hyphenating VCCS-LIF with inductively coupled plasma mass spectrometry (ICP-MS). In the analysis of HepG2 cells by Ag⁺ incubation and AO staining, 10,760 fluorescence bursts and 3068 MS events were observed in 240 s. Invalid signals due to undispersed cells were controlled at 3.80% for LIF and 1.01% for MS, with a proportion of effective signal of >96.20%. After peak identification and integral processing of the original data, the statistical results including peak area, height, width, and spacing are obtained concurrently and the information on concentration and elemental quantification of single cells is evaluated. CytoLM facilitates high-throughput, multi-dimensional, and multi-parameter characterization of particles and cells, and it may provide vast potential in life science analysis.

After enjoying curry: urine metabolism analysis of curcuminoids by microemulsion electrokinetic chromatography with laser-induced native fluorescence detection

Considering pH-dependent fluorescence of curcuminoids, a microemulsion electrokinetic chromatographic (MEEKC) method was developed under acidic conditions for their separation and detection using laser-induced native fluorescence (LINF), so as to solve the analysis of urine metabolism for curcuminoids. The microemulsion composition was optimized by response surface methodology (RSM), and the effects of buffer pH and organic modifiers were systematically investigated. The optimal buffer for the separation of curcuminoids was chosen as follows: 2.8% (v/v) ethyl acetate, 80 mM SDS and 2.8% (v/v) n-butanol to form microemulsion, 28% (v/v) ethanol as organic modifier, and 20 mM phosphoric acid as electrolyte at pH 3.0. Under these conditions, four curcuminoids including curcumin, demethoxy curcumin (DMC), bisdemethoxy curcumin (BDMC) and demethyl curcumin (DEC) could be well separated within 18 min, and the detection limits (LOD, based on S/N=3) were calculated to be 71, 60, 22, and 147 pg mL^-1, respectively. Combined with solid-phase extraction (SPE), the developed MEEKC-LINF method has been successfully applied to continuously monitor the curcuminoids and related metabolites in human urine collected from a healthy volunteer after oral administration of curry, testifying that this method has potential for evaluating the pharmacological activity of curcuminoids.

Sensitive analysis of doxorubicin and curcumin by micellar electromagnetic chromatography with a double wavelength excitation source

Doxorubicin has been extensively used to treat cancers, and there are recent findings that the anticancer activities can be enhanced by curcumin. Although the two compounds have native fluorescence, they can hardly be quantified directly simultaneously using the laser-induced fluorescence (LIF) detection method. To avoid complex fluorescence derivatization and introduction of interfering components, a highly sensitive double wavelength excitation source LIF (D-W-Ex-LIF) detector composed of a 445-nm and 488-nm commercial laser diode was constructed to detect them simultaneously. Rhodamine 6G was selected as an internal standard, because its fluorescence can be excited at 445 nm and 488 nm. The native fluorescence of doxorubicin and curcumin and their resolution were enhanced by introducing mixed micelles. The optimal electrophoretic separation buffer was 10 mM borate buffer containing 20 mM Triton X-100, 5 mM sodium dodecyl sulfate, and 30% (v/v) methanol at pH 9.00. Therefore, the developed method was specific, accurate, and easily operable. Its limits of detection for doxorubicin and curcumin in human urine samples were 4.00 × 10^-3 and 1.00 × 10^-2 μg/mL, respectively, and the limits of quantification were 1.00 × 10^-2 and 3.00 × 10^-2 μg/mL, respectively. The recoveries were 94.9-109.1%. Graphical abstract.

Characterization, Classification and Authentication of Turmeric and Curry Samples by Targeted LC-HRMS Polyphenolic and Curcuminoid Profiling and Chemometrics

The importance of monitoring bioactive substances as food features to address sample classification and authentication is increasing. In this work, targeted liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) polyphenolic and curcuminoid profiles were evaluated as chemical descriptors to deal with the characterization and classification of turmeric and curry samples. The profiles corresponding to bioactive substances were obtained by TraceFinder^TM software using accurate mass databases with 53 and 24 polyphenolic and curcuminoid related compounds, respectively. For that purpose, 21 turmeric and 9 curry samples commercially available were analyzed in triplicate by a simple liquid-solid extraction procedure using dimethyl sulfoxide as extracting solvent. The obtained results demonstrate that the proposed profiles were excellent chemical descriptors for sample characterization and classification by principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA), achieving 100% classification rates. Curcuminoids and some specific phenolic acids such as trans-cinnamic, ferulic and sinapic acids, helped on the discrimination of turmeric samples; polyphenols, in general, were responsible for the curry sample distinction. Besides, the combination of both polyphenolic and curcuminoid profiles was necessary for the simultaneous characterization and classification of turmeric and curry samples. Discrimination among turmeric species such as Curcuma longa vs. Curcuma zedoaria, as well as among different Curcuma longa varieties (Alleppey, Madras and Erode) was also accomplished.

Non-Targeted Ultra-High Performance Liquid Chromatography-High-Resolution Mass Spectrometry (UHPLC-HRMS) Fingerprints for the Chemometric Characterization and Classification of Turmeric and Curry Samples

In this work, non-targeted ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) fingerprints obtained by C18 reversed-phase chromatography were proposed as sample chemical descriptors for the characterization and classification of turmeric and curry samples. A total of 21 turmeric and 9 curry commercially available samples were analyzed in triplicate after extraction with dimethyl sulfoxide (DMSO). The results demonstrated the feasibility of non-targeted UHPLC-HRMS fingerprints for sample classification, showing very good classification capabilities by partial least squares regression-discriminant analysis (PLS-DA), with 100% classification rates being obtained by PLS-DA when randomly selected samples were processed as “unknown” ones. Besides, turmeric curcuma species (Curcuma longa vs. Curcuma zedoaria) and turmeric Curcuma longa varieties (Madras, Erodes, and Alleppey) discrimination was also observed by PLS-DA when using the proposed fingerprints as chemical descriptors. As a conclusion, non-targeted UHPLC-HRMS fingerprinting is a suitable methodology for the characterization, classification, and authentication of turmeric and curry samples, without the requirement of using commercially available standards for quantification nor the necessity of metabolite identification.

Characterization of Turmeric and Curry Samples by Liquid Chromatography with Spectroscopic Detection Based on Polyphenolic and Curcuminoid Contents

This paper deals with the characterization of turmeric and related products using the compositional fingerprints of curcuminoids (e.g., curcumin, demethoxycurcumin and bisdemethoxycurcumin) and other phenolic compounds (e.g., hydroxybenzoic and hydroxycinnamic acids and flavonoids) as the source of analytical information. Under this approach, the quantitative determination of analytes becomes unnecessary and even data from unknown components can be advantageously exploited for sample exploration and authentication. The methodology relied on sample extraction with hydro-organic solvents to recover the components of interest and further analysis of the corresponding extracts by liquid chromatography with diode array detection (HPLC-DAD). Extraction conditions were optimized focusing on the independent recovery of curcuminoids and polyphenols. Two different HPLC methods under reversed-phase mode were used to generate the chromatographic fingerprints at 420 and 280 nm for the specific monitoring of curcuminoids and polyphenols, respectively. Both extraction and separation steps were optimized under experimental design approaches to achieve the richest compositional fingerprints in terms of variety of components. The resulting data was subsequently treated chemometrically by principal component analysis (PCA) and related classification methods to achieve a better overall description of samples. Polyphenolic fingerprints were appropriate to discriminate among turmeric and mixed spices, while curcuminoid fingerprints could be useful to distinguish turmeric varieties.

A critical review of analytical methods for determination of curcuminoids in turmeric

Turmeric (Curcuma longa) is one of the most important ingredients in Indian and Chinese cuisine. Curcuminoids and volatile oils present in turmeric are known for their functional and nutraceutical properties. Health benefits attributed to curcuminoids have resulted in their wide utilization in food and pharmaceutical formulations. Therefore, characterization and estimation of the curcuminoids in fresh/dry turmeric, food and nutraceutical products are essential for their quality control during processing and storage. To meet the demand for analytical methods of curcuminoids, several methods have been developed for their quantification in turmeric powder and food formulations. In the present review, various analytical methods (spectrophotometric, chromatographic, capillary electrophoresis and biosensor techniques) which are used for monitoring curcuminoids have been thoroughly summarized and discussed. The spectrophotometric method is not useful when individual components of curcuminoids are required. Mobile phase optimization, the broadness of spots, plate-to-plate variations are significant limitations for TLC and HPTLC methods. Many analysts believe that HPLC method is the best choice for curcuminoids determination because of its rapid analysis. Spectrofluorimetry and Electrochemical methods are the more advanced methods with high sensitivity as well as rapid analysis. However, the selection of analytical method for curcuminoids analysis depends on the type of sample matrix, purpose of the analysis and limit of detection and limit of quantitation of the method.