Determination of antioxidants in cosmetics by micellar electrokinetic capillary chromatography with electrochemical detection

Impact of antioxidants on PM2.5 oxidative potential, radical level, and cytotoxicity

Antioxidants are typically seen as agents that mitigate environmental health risks due to their ability to scavenge free radicals. However, our research presents a paradox where these molecules, particularly those within lung fluid, act as prooxidants in the presence of airborne particulate matter (PM2.5), thus enhancing PM2.5 oxidative potential (OP). In our study, we examined a range of antioxidants found in the respiratory system (e.g., vitamin C, glutathione (GSH), and N-acetylcysteine (NAC)), in plasma (vitamin A, vitamin E, and β-carotene), and in food (tert-butylhydroquinone (TBHQ)). We aimed to explore antioxidants' prooxidant and antioxidant interactions with PM2.5 and the resulting OP and cytotoxicity. We employed OH generation assays and electron paramagnetic resonance assays to assess the pro-oxidative and anti-oxidative effects of antioxidants. Additionally, we assessed cytotoxicity interaction using a Chinese hamster ovary cell cytotoxicity assay. Our findings revealed that, in the presence of PM2.5, all antioxidants except vitamin E significantly increased the PM2.5 OP by generating more OH radicals (OH generation rate: 0.16-24.67 pmol·min-1·m-3). However, it's noteworthy that these generated OH radicals were at least partially neutralized by the antioxidants themselves. Among the pro-oxidative antioxidants, vitamin A, β-carotene, and TBHQ showed the least ability to quench these radicals, consistent with their observed impact in enhancing PM2.5 cytotoxicity (PM2.5 LC50 reduced to 91.2 %, 88.8 %, and 75.1 % of PM2.5's original level, respectively). Notably, vitamin A and TBHQ-enhanced PM2.5 OP were strongly associated with the presence of metals and organic compounds, particularly with copper (Cu) contributing significantly (35 %) to TBHQ's pro-oxidative effect. Our study underscores the potential health risks associated with the interaction between antioxidants and ambient pollutants.

Arbutus unedo: Innovative Source of Antioxidant, Anti-Inflammatory and Anti-Tyrosinase Phenolics for Novel Cosmeceuticals

Phenolic compounds are valuable cosmetic ingredients. They display skin protective potential and play an important role in preserving cosmetic formulations due to their ability to neutralize free radicals. Considering this fact, the current study aims to obtain a phenolic-enriched fraction from Arbutus unedo for topical application in cosmeceutical products. The chemical composition and the antioxidant, anti-inflammatory, and anti-tyrosinase activities of different extracts from the plant were investigated and compared. Samples were obtained by maceration, reflux, and ultrasound using water and ethanol. The findings indicated that the extraction methods impacted the phytochemical composition of the extracts. The high-performance liquid chromatography with diode-array detection (HPLC–DAD) analysis showed a wide range of phenolic compounds, comprising phenolic acids and flavonoids. Among the extracts, the water reflux had significant levels of both total polyphenols, flavonoids, and tannins and possessed the most important content on hyperoside. It displayed the most significant antioxidant activities with high antiradical and reducing power, as well as strong total antioxidant activity. It possesses a promising whitening effect with high anti-tyrosinase activities. Furthermore, it shows no cytotoxicity and moderate anti-inflammatory activity. Finally, due to its high yield efficiency and activities, water reflux was selected to formulate a cosmeceutical oil-in-water nanoemulsion that displayed optimal pH and stability.

A MWCNTs-COOH/PSS nanocomposite-modified screen-printed electrode for the determination of synthetic phenolic antioxidants by HPLC with amperometric detection

New sensing platforms based on screen-printed carbon electrodes modified with composites based on polystyrene sulfonate and oxidized multi-walled carbon nanotubes (PSS/MWCNTs-COOH/SPCE) have been used to develop a novel HPLC method with electrochemical detection (ECD) for the determination of the most used synthetic phenolic antioxidants in cosmetics: butylhydroxytoluene (BHT), butylhydroxyanisole (BHA), tert-butylhydroquinone (TBHQ) and propyl gallate (PG). Optimal separation conditions were achieved using methanol: 0.10 mol L^-1 acetate solution at pH 6 as mobile phase with a gradient elution program from 60 to 90% of methanol percentage in 15 min. The electrochemical detection was carried out in amperometric mode using the PSS/MWCNTs-COOH/SPCE at + 0.80 V vs. Ag. Under these optimal separation and detection conditions, the limits of detection (LOD) were between 0.11 and 0.25 mg L^-1. These LOD values were better, especially for BHT, than those previously published in other HPLC methods. Linear ranges from 0.37 mg L^-1, 0.83 mg L^-1, 0.69 mg L^-1 and 0.56 mg L^-1 to 10 mg L^-1 were obtained for PG, TBHQ, BHA and BHT, respectively. RSD values equal or lower than 5% and 8% were achieved for repeatability and reproducibility, respectively. The HPLC-ECD method was successfully applied to analyze different cosmetic samples. Recovery values within 83-109% were obtained in the validation studies.

Synthesis of Caffeoyl-Prolyl-Histidyl-Xaa Derivatives and Evaluation of Their Activities and Stability upon Long-Term Storage

Antioxidants play a critical role in the treatment of degenerative diseases and delaying the aging of dermal tissue. Caffeic acid (CA) is a representative example of the antioxidants found in plants. However, CA is unsuitable for long-term storage because of its poor stability under ambient conditions. Caffeoyl-Pro-His-NH₂ (CA-Pro-His-NH₂, CA-PH) exhibits the highest antioxidant activity, free radical scavenging and lipid peroxidation inhibition activity among the histidine-containing CA-conjugated dipeptides reported to date. The addition of short peptides to CA, such as Pro-His, is assumed to synergistically enhance its antioxidative activity. In this study, several caffeoyl-prolyl-histidyl-Xaa-NH₂ derivatives were synthesized and their antioxidative activities evaluated. CA-Pro-His-Asn-NH₂ showed enhanced antioxidative activity and higher structural stability than CA-PH, even after long-term storage. CA-Pro-His-Asn-NH₂ was stable for 3 months, its stability being evaluated by observing the changes in its NMR spectra. Moreover, the solid-phase synthetic strategy used to prepare these CA-Pro-His-Xaa-NH₂ derivatives was optimized for large-scale production. We envision that CA-Pro-His-Xaa-NH₂ derivatives can be used as potent dermal therapeutic agents and useful cosmetic ingredients.

Electrochemical sensor for determination of butylated hydroxyanisole (BHA) in food products using poly O-cresolphthalein complexone coated multiwalledcarbon nanotubes electrode

In this study, we have reported an electrochemical sensor for the determination of butylated hydroxyanisole (BHA) by electropolymerization of O-cresolphthalein complexone (OC) over the multiwalled carbon nanotubes (MWCNTs). In order to confirm the surface morphology, oxidation states, functional groups and charge transfer property of POC/MWCNTs electrode, the resulting POC film with MWCNTs electrode was characterized by spectroscopy, microscopy, and electrochemical techniques. The fabricated electrode was evaluated for its electrochemical performance in oxidation of BHA and the study showed that at POC/MWCNTs electrodes BHA oxidation occurred at 0.27 V. POC/MWCNTs electrode has shown a linear range for the detection of BHA from 0.33 µM to 110 µM with the detection limit of 0.11 µM (S/N = 3). Amperometric determination of BHA was also done using chronoamperometric techniques and the result was found to be linear. The real time analysis of sensors is also validated by analysing the packed potato chips samples.

Easy-to-use and inexpensive sensors for assessing the quality and traceability of cosmetic antioxidants

We describe an easy-to-use sensor as a tool to quantify and authenticate antioxidant active ingredients in cosmetic products. The sensing platform comprises a responsive nanoengineered surface that reacts specifically and generates distinct optically detectable signals that are representative of the chemical composition and concentration of active ingredients. The platform can be inexpensively produced in large quantities and a procedure to manufacture the sensors by 3D printing is described. These sensors can be used as smart labels to check the quality of antioxidant constituents in a large variety of cosmetic products without involving any sample pretreatment. Possible applications include at home and on site testing by consumers or manufacturing companies to check the quality, shelf life and origin of raw materials and products during their manufacturing, storage and use.

Simultaneous determination of parabens and inorganic anions in cosmetics by a two-dimensional ultrahigh-performance liquid chromatography-ion chromatography valve-switching method

Simultaneous determination of parabens and inorganic anions in cosmetics in a single injection was obtained in a two-dimensional UHPLC-IC valve switching system.

Electrochemical methods as a tool for determining the antioxidant capacity of food and beverages: A review

The growing interest in functional foods had led to the use of analytical techniques to quantify some properties, among which is the antioxidant capacity (AC). In order to identify and quantify this capacity, some techniques are used, based on synthetic radicals capture; and they are monitored by UV-vis spectrophotometry. Electrochemical techniques are emerging as alternatives, given some of the disadvantages faced by spectrophotometric methods such as the use of expensive reagent not environmentally friendly, undefined reaction time, long sample pretreatment, and low precision and sensitivity. This review focuses on the four most commonly used electrochemical techniques (cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and chronoamperometry). Some of the applications to determine AC in foods and beverages are presented, as well as the correlation between both spectrophotometric and electrochemical techniques that have been reported.

Preparation of organogel with tea polyphenols complex for enhancing the antioxidation properties of edible oil

Food-grade organogels are semisolid systems with immobilized liquid edible oil in a three-dimensional network of self-assembled gelators, and they are supposed to have a broad range of potential applications in food industries. In this work, an edible organogel with tea polyphenols was developed, which possesses a highly effective antioxidative function. To enhance the dispersibility of the tea polyphenols in the oil phase, a solid lipid-surfactant-tea polyphenols complex (organogel complex) was first prepared according to a novel method. Then, a food-grade organogel was prepared by mixing this organogel complex with fresh peanut oil. Compared with adding free tea polyphenols, the organogel complex could be more homogeneously distributed in the prepared organogel system, especially under heating condition. Furthermore, the organogel loading of tea polyphenols performed a 2.5-fold higher antioxidation compared with other chemically synthesized antioxidants (butylated hydroxytoluene and propyl gallate) by evaluating the peroxide value of the fresh peanut oil based organogel in accelerated oxidation conditions.

Voltammetric determination of TBHQ at a glassy carbon electrode surface activated by in situ chemical oxidation

Bare GCE surface is directly activated by in situ chemical method, and the modified GCE exhibits a rougher surface and a negative-charge characteristic.

Characterization of protein hydrolysates of cosmetic use by CE-MS

Protein hydrolysates have been used as active principles in cosmetic products conferring different properties to the final formulations, which are mostly controlled by the peptide size and its amino acid sequence. In this work, capillary electrophoresis coupled to mass spectrometry analyses were carried out in order to investigate such characteristics of protein hydrolysates. Samples of different origins (milk, soy and rice) were obtained from a local company, and were analyzed without a previous preparation step. The background electrolyte (BGE) and sheath liquid compositions were optimized for each sample. The best BGE composition (860 mmol/L formic acid--pH 1.8--in 70:30 v/v water/methanol hydro-organic solvent) was chosen based on the overall peak resolution whereas the best sheath liquid was selected based on increased sensitivity and presented different compositions to each sample (10.9-217 mmol/L formic acid in 75:25-25:75 v/v water/methanol hydro-organic solvent). Most of the putative peptides in the hydrolysate samples under investigation presented molecular masses of 1000 Da or less. De novo sequencing was carried out for some of the analytes, revealing the hydrophobicity/polarity of the peptides. Hence, the technique has proved to be an advantageous tool for the quality control of industrial protein hydrolysates.

Voltammetric determination of tert-butylhydroquinone in biodiesel using a carbon paste electrode in the presence of surfactant

This paper reports an electroanalytical method developed for determining the antioxidant tert-butylhydroquinone (TBHQ) in biodiesel, based on the enhancement effect of cetyltrimethylammonium bromide (CTAB). In pH 6.5 Britton-Robinson buffer, a poorly defined oxidation peak was observed for TBHQ at a carbon paste electrode (CPE). In the presence of low concentrations of CTAB, however, the oxidation peak current was markedly increased. Several parameters were studied and optimized for the development of this methodology, and under optimal conditions the oxidation peak current was proportional to TBHQ concentration in the range of (1.05-10.15) x 10(-6) mol L(-1), with limits of detection and quantification of 7.11 x 10(-8) mol L(-1) and 2.37 x 10(-7) mol L(-1), respectively, by linear sweep voltammetry (LSV). The method was applied to TBHQ determination in soybean biodiesel samples. The results were satisfactory in comparison with those obtained using high-performance liquid chromatography (HPLC).

Determination of additives in cosmetics by supercritical fluid extraction on-line headspace solid-phase microextraction combined with gas chromatography-mass spectrometry

A new hyphenated technique couples supercritical fluid extraction in situ derivatization and on-line headspace solid-phase microextraction to gas chromatography-mass spectrometry (SFE in situ derivatization on-line HS-SPME-GC-MS) for the determination of paraben preservatives and polyphenolic antioxidants in cosmetics. The preservatives and antioxidants were extracted from the cosmetic matrices with supercritical carbon dioxide at a pressure of 13,840 kPa. The supercritical fluid extraction was performed at 55 degrees C for 10 min of static extraction then 15 min of dynamic extraction. The extractant subsequently was derivatized in situ with the silylation reagent N,O-bis(trimethylsilyl)trifluoroacetamide with 0.1% trimethylchlorosilane. The product was then adsorbed on a polyacrylate solid-phase microextraction (SPME) fiber in the headspace. Sea sand was used as a dispersive material in the SFE step. The analytical linear ranges for the preservatives and antioxidants were found to be from 10 to 1000 ng g(-1) with RSD values below 7.8%. The detection limits ranged from 0.5 to 8.3 ng g(-1). These results are better than those obtained by using only SPME or SFE for trace preservatives and antioxidants analysis in cosmetic matrices. The new method was successfully utilized to determine the amounts of preservatives and antioxidants in real cosmetics without the need for tedious pretreatments.

Capillary electrophoresis coupled with electrochemical detection using porous etched joint for determination of antioxidants

Capillary electrophoresis coupled with electrochemical detection (CE-EC) for determination of antioxidants, propyl gallate (PG) and tert-butylhydroquinone (TBHQ), in cosmetic samples was proposed in this work. A porous etched joint was used to isolate the electrochemical detection from the electrophoretic high voltage. Compared with the 25 microm i.d. capillary without a decoupler in a CE-EC system, a 75 microm i.d. capillary applied in the present system gave an improvement in both sample injection and sensitivity. Moreover, the carbon fiber working electrode could be directly in touch with the end of separation capillary due to the elimination of the effect of separation voltage on the EC detection, so the alignment of working electrode and capillary became easy and the dead volume was also decreased. Baseline separation of the two antioxidants was achieved by CE in a 50 cm long x 75 microm i.d. capillary at 20 kV using 5.0 mmol L(-1) phosphate buffer (pH 8.00). 0.7 V (versus Ag/AgCl) was applied to the carbon fiber electrode for electrochemical detection. Under the optimal condition, the precisions (RSD, n=4) of peak height and migration time of PG and TBHQ were 2.39-3.59% and 0.34-0.44%, respectively. The detection limits of PG and TBHQ were 2.51x10(-6) and 4.88 x 10(-6) mol L(-1) for standard solution and 0.0751 and 0.0328 mg g(-1) for the real cosmetic samples with consumption of 0.3g sample. Analysis of TBHQ and PG in cosmetics samples was also achieved with the present system and the spiked recoveries of two analytes in cosmetics samples were in the range of 93.6-98.8%.

Simultaneous determination of antioxidants, preservatives and sweetener additives in food and cosmetics by flow injection analysis coupled to a monolithic column

Today it is common to find samples with various additives from several families. This is the case of sweeteners, preservatives and antioxidants. We have selected a set of additives broadly used in foods and cosmetics with an ample variety of polarities, namely: aspartame (AS), acesulfame (AK)/saccharin (SA), methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), propylgallate (PG) and butylhydroxyanisole (BA). The monolithic column used as separative system is a 5 mm commercial precolumn of silica C18 coupled to a flow injection manifold working with a peristaltic pump. The mixture was separated in only 400 s with resolution factors greater than 1.1 in all cases. To achieve the separation in the FIA system we used two carriers: first, a mixture of ACN/water buffered with 10 mM pH 6.0 phosphate buffer and second, a methanol:water mixture to improve the carrier strength and speed up the more apolar analytes at 3.5 mL min(-1). Detection is accomplished by means of a diode array spectrometer at the respective wavelength of each compound. The comparison of the analytical parameters obtained for this procedure with a standard HPLC method validates our new method, obtaining a method that is quick, with high repeatability and reproducibility and with good resolution between analytes. We have successfully applied the method to real food and cosmetics samples.

Simultaneous determination of pharmacologically active ingredients in Rhodiola by capillary chromatography with electrochemical detection

Rhodiola, in which there are abundant pharmacologically active ingredients, is one of the functional adaptogenic agent that aid specific bodily functions to adapt to the changes and stress of life in addition to being tonic. In an attempt to qualitatively and quantitatively determine the pharmacologically active ingredients in Rhodiola, a new method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well separated within 24 min at the separation voltage of 18 kV in a 80 mmol L(-1) borax running buffer (pH 9.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 3.16 x 10(-7) to 1.11 x 10(-7)g mL(-1) for all target ingredients. This proposed method has been successfully applied for the analysis of real samples, with satisfactory results.

Study on capillary electrophoresis–amperometric detection profiles of different parts of Morus alba L

A high-performance capillary electrophoresis with amperometric detection (CE-AD) method has been developed for the determination of the pharmacologically active ingredients in different parts of Morus alba L. after a relatively simple extraction procedure. This method was also used in the comparison of bioactive constituent difference in the five parts, based on their electropherograms or characteristic "CE-AD profiles". The effects of several factors such as the acidity and concentration of running buffer, separation voltage, applied potential and injection time were investigated to find the optimum conditions. Method detection limits (S/N = 3) ranged from 1.5 x 10(-7) to 1.4 x 10(-8)g/mL for all 10 analytes, and the assay results were satisfactory.

Simultaneous analysis of antioxidants and preservatives in cosmetics by supercritical fluid extraction combined with liquid chromatography-mass spectrometry

This study evaluated supercritical fluid extraction (SFE) combined with liquid chromatography-mass spectrometry (LC-MS) to determine trace preservatives and antioxidants including methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), alpha-tocopherol (alpha-t) and alpha-tocopherol acetate (alpha-ta) in cosmetic products. A supercritical fluid extraction procedure was used to isolate four paraben preservatives and four antioxidants from the cosmetic matrix before quantitative analysis. The optimum extraction condition was performed with static extraction for 5 min, then dynamic extraction for 20 min by using carbon dioxide supercritical fluid at 14,000 kPa and 65 degrees C. Methanol was used as collection solvent and the sea sand was chosen as a filling material. The analytes were separated on a C18 reversed-phase column using methanol-water as mobile phase and quantified by measuring its mass spectrometry. The linearity range is from 10 to 20,000 ng/g with RSD values below 18%. Detection limits are achieved at the level of 4.7-142 ng/g. It was successfully applied to the determination of paraben preservatives and antioxidants in cosmetics without tedious pretreatment.