Curcumin In Food Samples Research Articles

Fluorescent Molybdenum Disulfide Quantum Dots for Sensitive Detecting Curcumin in Food Samples through FRET Mechanism.

A selective and sensitive fluorometric assay was developed for specific determination of curcumin (Cur) based on fluorescence resonance energy transfer (FRET) between molybdenum disulfide quantum dots (MoS2 QDs) and Cur. The MoS2 QDs were prepared via a one-step hydrothermal protocol using sodium molybdate dihydrate, L-cysteine (Cys) as precursors, and sodium cholate (SC) as a modification agent. The as-prepared MoS2 QDs possessed maximum fluorescence emission at 460nm with a 20% of fluorescence quantum yield (FQY). It was found that the fluorescence of MoS2 QDs could be quantitatively quenched by Cur through FRET mechanism. Therefore, Cur could be detected in the range of 0.1-20µg mL- 1 with a detection limit of 5 ng mL- 1. Additionally, the developed MoS2 QDs based fluorescent assay has been successfully applied for real food sample analysis with satisfactory results.

Solvent-free synthesis of recyclable hydrophobic carbon dots for highly selective detecting curcumin in food samples

A highly selective fluorometric method was developed for the specific determination of curcumin (Cur) based on hydrophobic carbon dots (HB-CDs) derived from flaxseed oil by a solvent-free reaction. The as-prepared HB-CDs possessed blue fluorescence emission (at 425 nm) with a fluorescence quantum yield (QY) of 21.1 %. It was that the fluorescence of HB-CDs could be quantitatively quenched by Cur, and the fluorescence quenching mechanism was proved to be a combination of dynamic and static quenching. The detection limit of the method for Cur was 20 nM with a linear response range of 0.2–200 µM. Additionally, HB-CDs can be quickly recovered from the tested solutions through solvent change precipitation. The developed HB-CDs based fluorescent method has been successfully applied for real food samples analysis with satisfactory results.

Synthesis and Characteristics of Polymer-Mediated Curcumin Molecular Imprinting for Quantitative Determination of Curcumin in Food Samples

In this study, a molecularly imprinted polymer (MIP)-based extraction process for determining curcumin in food samples was carried out. MIP and NIP were thermally synthesized in acetonitrile solvent (porogen) using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linking agent, azobisisobutyronitrile as an initiator, and curcumin as a template molecule. Parameters affecting the synthesis process, such as temperature, the ratio of the components in the reaction, and the extraction solvent, were investigated. The characteristics of the synthesized material were examined using infrared spectroscopy and scanning electron microscopy. The maximum adsorption capacity of the material was found to be 1.34 mg/g MIP with an adsorption efficiency of 89.96% for MIP and 12.35% for NIP. The MIP material exhibited high selectivity for curcumin compared to other compounds such as quercetin (18.00%), rutin (14.74%), and ketoconazole (0.00%). The analysis method for curcumin using the MIP material was performed with validated parameters including linear range (1 – 25 mg/L, r2 = 0.9997), accuracy (recovery rate of 90.90 %), precision (RSDR = 0.338 %, RSDr = 1.591 %), detection limit (0.051 mg/L), and quantification limit (0.156 mg/L). The validation results indicated that the HPLC-DAD method was entirely suitable for analyzing the curcumin content in food samples.

Electrochemical Sensing of Curcumin: A Review.

Curcumin is a natural polyphenol derived from turmeric (Curcuma longa) root that has been used for centuries as a spice, coloring agent, and medicine. Curcumin presents anti-inflammatory, antioxidant, anticarcinogenic, antimicrobial, antiviral, antimalarial, hepatoprotective, thrombosuppressive, cardiovascular, hypoglycemic, antiarthritic, and anti-neurodegenerative properties. It scavenges different forms of free radicals and acts on transcription factors, growth factors and their receptors, cytokines, enzymes, and genes, regulating cell proliferation and apoptosis. Curcumin is electroactive, and a relationship between its electron transfer properties and radical-scavenging activity has been highlighted. The objective of this review is to provide a comprehensive overview of the curcumin electron transfer reactions, with emphasis on the controversial aspects related to its oxidation mechanism. The final sections will focus on the electroanalysis of curcumin in natural products, highlighting the most important sensing strategies, based on functional electrodes and nanostructured materials, essential for the development of more efficient in vitro methods of detection and quantification of curcumin in food samples, supplements, and nutripharmaceuticals.

Synergistic Cloud Point Microextraction Prior to Spectrophotometric Determination of Curcumin in Food Samples

Synergistic cloud point microextraction (SCPME) significantly simplifies and accelerates traditional cloud point extraction (CPE). The use of medium- to long-chain alcohols such as pentan-1-ol reduces the cloud point temperature of the surfactant below room temperature without salt addition or heating, which minimizes the extraction time. In this work, SCPME with Triton X-405, as a nonionic surfactant, and pentan-1-ol, as a synergic agent, were applied for the extraction of curcumin prior to its determination with UV/Vis spectrophotometry. The optimum SCPME conditions were achieved with 500 µL of Triton X-405 and 600 µL of pentan-1-ol in 10.0 mL of the sample solution with an analysis time of 8.5 min. Curcumin was monitored at 430.0 nm. The limits of detection ranged from 0.012 to 0.027 µg mL−1 and the coefficients of determination (R 2) of the calibration graphs were higher than 0.9974. The proposed SCPME-UV/Vis method was applied for the extraction and determination of curcumin in food samples. The relative recoveries ranged from 90.6 to 105.4% with relative standard deviations below 7.5%.

Supramolecular solvent-liquid-liquid microextraction followed by smartphone digital image colorimetry for the determination of curcumin in food samples

Smartphone digital image colorimetry (SDIC) was coupled with supramolecular solvent-based liquid-liquid microextraction (SMS-LLME) for the determination of curcumin. Images, captured for sample solutions placed inside a homemade colorimetric box, were split into their red-green-blue channels and the intensity of the blue channel was correlated to the concentration of curcumin. Optimum SDIC performance was achieved at a distance of 9.0 cm between the sample cuvette and the detection camera, a region of interest of 1600 px2 and a light source at 15% brightness. Optimum SMS-LLME efficiency was obtained with 1000 μL of tetrahydrofuran/1-undecanol (4:1, v/v) as the supramolecular extraction solvent, pH of sample solution adjusted to 7.0, and 2.0% (w/v) sodium chloride within 60 s extraction time. Limits of detection (LOD) were found in the range of 0.2–0.9 μg mL−1 (0.04–0.18%, w/w). Calibration graphs demonstrated good linearity with coefficients of determination higher than 0.9965 and relative standard deviations lower than 8.5%. The proposed SMS-LLME-SDIC method was applied to determine curcumin in turmeric and tea samples from which percentage relative recoveries between 94.0 and 104.0% were obtained.

An ultra-sensitive analytical platform based on bluish green emitting carbon quantum dots for the detection of curcumin in dietary foods

This work reports the development of a new analytical method for the rapid detection of curcumin in food samples by using bluish green emissive fluorescence carbon quantum dots (BG-CQDs) as nanoprobe. The sensing mechanism behind the detection work is the quenching effect of curcumin on the fluorescence intensity of BG-CQDs, where curcumin and BG-CQDs interact via a combined effect of inner filter effect (IFE) and dynamic interaction process. After optimisation of the experimental parameters, the developed analytical method is capable of detecting curcumin with good selectivity and high sensitivity, achieving good linearity in the concentration range of 0.01–25.0 μM. A limit of detection (LOD) of 28.7 nM was obtained, which is lower than that of any of the previously reported CQDs-based fluorescence methods. The developed analytical method was applied to the analyses of food samples with a high degree of accuracy and precision. This work highlights a robust BG-CQDs-based analytical platform of rapid response, low cost, great simplicity, high selectivity and favourable sensitivity, which exhibits immense potential for the accurate monitoring of the curcumin content in dietary food samples.

Application of aeration-assisted homogeneous liquid-liquid microextraction procedure using Box-Behnken design for determination of curcumin by HPLC.

A simple, efficient, and rapid sample preparation method based on aeration-assisted homogeneous liquid-liquid microextraction was developed for determination of curcumin in food samples by high-performance liquid chromatography. The centrifuge step has been eliminated in this procedure. The effects of some variables, such as pH, volume of extraction solvent, extraction time, and salt effect, were studied through a Box-Behnken design method. Under the optimum conditions, calibration curves of curcumin were linear in the range of 0.08-4000μg/mL with R2 =0.997. Limit of detection and relative standard deviation were 0.019 μg/mL and 3.01%, respectively. The preconcentration factor achieved was 166. The proposed method was successfully applied to determination of curcumin in various food samples.

Rapid measurements of curcumin from complex samples coupled with magnetic biocompatibilitymolecularly imprinted polymer using electrochemical detection.

Curcumin widely exists in food, and rapid selective and accurate detection of curcumin have great significance in chemical industry. In this experiment, a new magnetic biocompatibility molecularly imprinted polymer was prepared with nontoxic and biocompatible Zein to adsorb curcumin selectively. The polymer has high biocompatibility, good adsorption capacity, and specific adsorption for curcumin. Combined with portable electrochemical workstations, the polymer can be used to detect curcumin rapidly and cost-effectively. Using curcumin as a template and Zein as the crosslinking agent, the polymers were synthesized on the surface of Fe3 O4 particles for solid phase extraction. The experimental results showed that the polymer reached large adsorption capacity (32.12mg/g) with fast kinetics (20 min). The adsorption characteristic of the polymer followed the Langmuir isotherm and pseudo-second-order kinetic models. Hexacyanoferrate was used as electrochemical probe to generate signals, and the linear range was 5-200 µg/mL for measuring curcumin. The experimental analysis showed that the polymer was an ideal material for selective accumulation of curcumin from complex samples. This approach has been successfully applied to the determination of curcumin in food samples with electrochemical detection, indicating that this is a feasible and practical technique.

Preparation and application of alcohol based deep eutectic solvents for extraction of curcumin in food samples prior to its spectrophotometric determination

In this study, a novel, simple and economic vortex-assisted alcohol-based deep eutectic solvent microextraction (VA-DES-ME) procedure has been developed for the preconcentration of curcumin in food samples prior to its spectrophotometric determination. A alcohol-based-DES consists of betaine hydrochloride - glycerol (1:3) as extraction solvent and acetone as aprotic solvent at pH 6.0 were used for the preconcentration of curcumin from sample matrix. Some experimental variables such as pH, DES solvent type and volume, aprotic solvent type and volume, vortex time, sample volume and matrix effect etc. were investigated and optimized in detail. Under optimized conditions, the working range, limit of detection and pre-concentration factor were determined to be as 5–300 μg L−1 and 1.5 μg L−1 and 100 respectively. Validity of the proposed method was proved by the intra-day/inter-day precision studies and addition-recovery test. Consequently, the VA-DES-ME procedure was successfully applied for the extraction and determination of curcumin in food samples.

Ultrasound-Assisted Ionic Liquid-Dispersive Liquid-Liquid of Curcumin in Food Samples Microextraction and Its Spectrophotometric Determination.

Background: A rapid and new ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction method (UA-IL-DLLME) was presented for the determination of curcumin by spectrophotometry. Objective: To determine trace levels of curcumin in food samples by using green and low-cost method development. Methods: 1-Butyl-3-methylimidazolium hexafluorophosphate was used to extract curcumin from sample solutions with the aid of sonication. Optimum extraction efficiency was determined by examining extraction solvents, pH, centrifugation speed, time, sonication period, and temperature. The influences of diverse ions on the recovery of curcumin were examined. The concentration of curcumin in the final solution was measured by spectrophotometer at 425 nm. Results: The enrichment factor achieved was 167. The LOD and the RSD were 0.51 μg/L and 4.3%, respectively. The presented method was performed to detect curcumin in 20 food samples. Conclusions: The presented UA-IL-DLLME method is simple, low in cost, environmentally friendly, rapid, and sensitive and requires minimal use of toxic organic solvents. Highlights: A microextraction method was applied to increase sensitivity. Higher enrichment factors and lower detection limits were observed. The proposed technique is easy, cost-effective, accurate, and precise.

Magnetic molecularly imprinted polymers for spectrophotometric quantification of curcumin in food

Herein, we present a simple and rapid method for monitoring curcumin in food samples using a magnetic molecularly imprinted technique combined with ultraviolet–visible (UV–Vis) spectrophotometry. Magnetic molecularly imprinted polymers (mag-MIPs) were first synthesized by fabricating MIPs on to the surface of Fe3O4 nanobeads using curcumin as a template and methacrylic acid as a functional monomer. The obtained mag-MIPs were evaluated in detail with different techniques (such as binding isotherm, Scatchard analysis, and selectivity) and various adsorption experiments. Finally, mag-MIPs were constructed and UV–Vis spectrophotometry was used to quantify curcumin under optimized conditions. Good recoveries between 79.37% and 88.89% were obtained with the limits of detection and quantification of 1.31 and 4.38μg/mL, respectively.