Quantification of Arbutin and its degradation products, hydroquinone and p-Benzoquinone, in hyperpigmentation topical formulation: Effect of extraction procedure and interference assessment.

The utilization of Hydroquinone (HQ) in over-the-counter skincare items is subject to restrictions. Consequently, Arbutin (AR) serves as a reliable alternative for addressing hyperpigmentation in non-prescription topical formulations. Nevertheless, AR undergoes decomposition into HQ and p-Benzoquinone (BZ) when exposed to temperature stress, ultraviolet light, or dilution in an acidic environment, all of which can induce skin toxicity. The intention of this paper is to investigate the effect of extraction procedure on the conversion of AR to HQ and or BZ and to evaluate kinetics of AR hydrolysis to HQ. Meanwhile this study aims to evaluate AR and BZ interference with the United States Pharmacopoeia (USP) identification and assessment method for HQ Hydrolytic stress during extraction conditions underwent optimization through systematic screening tests. Subsequent assessment of the residual drug and its degradation products were achieved by HPLC method. The resulting data were meticulously fitted to various kinetic models. To analyze the potential interference of AR in HQ measurement using USP method, the standard concentrations of AR and HQ were analyzed through UV-VIS spectrophotometry. For enhanced certainty, a validated HPLC method analysis was also conducted. Notably, the acid hydrolysis of AR exhibited independence from its initial concentration. So, the hydrolytic degradation of AR exhibited a Zero-order kinetic profile. Furthermore, the proven interference of AR in the UV-VIS spectrophotometry method was identified within the context of the USP method. This study successfully utilized an adopted HPLC method for the concurrent quantification of AR, HQ, and BZ. The potential interference of AR in the UV-VIS spectrophotometric assay for HQ may lead to false results especially for regulatory purposes.

Metabolomic analysis and bioactivities of Arbutus unedo leaves harvested across the seasons in different natural habitats of Sardinia (Italy).

BACKGROUND: Arbutus unedo L. is a wild tree of Mediterranean regions used as food and in traditional medicine and important for afforestation programs. There is no detailed information available on the variation of A. unedo leaves metabolome across the seasons. The leaves were analyzed by Proton nuclear magnetic resonance (1 H NMR)-based metabolomics, comparing samples harvested across the seasons and in ten different natural habitats of Sardinia (Italy). RESULTS: Multivariate analysis showed the impact of seasonal variation on the metabolome: glucose and quinic acid increased in summer, while in spring sucrose was accumulated. ß-Arbutin, the main known active principle of A. unedo, generally reached the highest concentration in autumn. In winter, O-ß-methylglucose, γ-aminobutyric acid (GABA), flavonols (quercetin-3-O-α-rhamnoside, myricetin-3-O-α-rhamnoside, kaempferol-3-O-α-rhamnoside), catechin, and gallocatechin increased. Characteristic metabolomic features were found also for samples collected in different locations. For instance, trees growing at the highest altitude and exposed to lower temperatures produced less flavonols and catechins. The only sample collected on trees growing on limestones, dolomites, and dolomitic limestones type of soil showed generally the highest content of arbutin. The highest phenolics content was found during spring, while samples collected on flowering branches in winter were the ones with the highest flavonoid content. The antioxidant activity was also variated, ranging from 1.3 to 10.1 mg of Trolox equivalents (TE)/mL of extract, and it was positively correlated to both total phenolics and flavonoid content. Winter samples showed the lowest antibacterial activity, while summer and autumn ones exhibited the highest activity (IC50 values ranging from 17.3 to 42.3 µg/mL against Staphylococcal species). CONCLUSION: This work provides 1 H-NMR fingerprinting of A. unedo leaves, elucidating the main metabolites and their variations during seasons. On the basis of arbutin content, autumn could be considered the balsamic period of this taxon. Samples collected in this season were also the most active ones as antibacterial. Moreover, an interesting metabolomic profile enriched in catechins and flavonols was observed in leaves collected in winter on flowering branches which were endowed with high antioxidant potential.

Simultaneous HPLC Determination of Arbutin, Niacinamide and 3-O-Ethyl Ascorbic Acid in Whitening Cream Products in the Presence of Parabens.

Arbutin, niacinamide and 3-O-ethyl ascorbic acid (a new generation of vitamin C derivatives) are compounds that have a whitening effect on skin and are widely used in whitening cream products wherein parabens such as methyl paraben, ethyl paraben, propyl paraben and butyl paraben are also often added as preservatives. This study aims to develop a validated high-performance liquid chromatography (HPLC) method that can be used to determine arbutin, niacinamide and 3-O-ethyl ascorbic acid simultaneously in whitening cream products without interference from the parabens. The optimum conditions for the HPLC system were obtained using ODS-3 RP-C18 Inertsil column, mobile phase consisting of a mixture of aquabides, methanol and acetonitrile with gradient elution mode. Detection was carried out using a UV detector at 220 nm. Validation studies demonstrated a good linearity for all analytes over each range concentration with a correlation coefficient >0.999 and Vx0 < 2%. The accuracy test also met the requirements with the recoveries being 96.93-99.55%, 98.60-99.73% and 97.88-100.63% for arbutin, niacinamide and 3-O-ethyl ascorbic acid, respectively. Intra-day and inter-day precision test gave a relative standard deviation (% RSD) of <2% along with a HorRat value of <2 for all analytes. The results of this study indicate that the developed HPLC method has a good selectivity, linearity, accuracy and precision. Due to its simplicity, the method can be used to analyze arbutin, niacinamide and 3-O-ethyl ascorbic acid in the presence of parabens in whitening cream products simultaneously.

A new electrochemical sensor for simultaneous determination of arbutin and vitamin C based on hydroxyapatite-ZnO-Pd nanoparticles modified carbon paste electrode.

A highly sensitive and selective sensor was fabricated based on Hydroxyapatite-ZnO-Pd NPs modified carbon paste electrode (HAP- ZnO-Pd NPs/CPE) for simultaneous determination of Arbutin (AT) and vitamin C (VC) for the first time. Characterization was performed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. The modified electrode was studied by different methods including electrochemical impedance spectroscopy and cyclic voltammetry. The HAP- ZnO-Pd NPs/CPE exhibited excellent electrocatalytic activity towards the oxidations of AT and VC in phosphate buffer solution (pH 7.0) and the corresponding electrochemical signals have appeared as two well resolved oxidation peaks with significant peak potential differences of 0.23 V. Kinetic parameters such as charge transfer coefficient (0.52 and 0.44 for AT and VC respectively), standard heterogeneous electron transfer rate constant (0.336 s-1 and 0.590 s-1 for AT and VC respectively), and other electrochemical parameters were calculated via voltammetry techniques. Differential pulse voltammetry was used for simultaneous determination of AT and VC using the HAP- ZnO-Pd NPs/CPE electrode. At the optimum conditions, for simultaneous determination by synchronous change of the analyte concentrations, the linear response ranges were between 0.12-56 µM for AT and 0.12-55.36 µM for VC with detection limits of 85.7 and 19.4 nM respectively while sensitivity of proposed sensor for AT and VC was 0.98 µA/µM and 0.94 µA/µM. Reproducibility (intra-; 1.16% and 1.16% for AT and VC respectively and inter-electrode reproducibility of 2.03% and 3.28 for AT and VC respectively), and response time about 3.5 min were obtained. Furthermore, HAP- ZnO-Pd NPs/CPE was successfully applied for the independent determination of VC in fruit juice as well as the simultaneous determination of AT and VC in lightening cream samples.

Arbutin attenuates cognitive impairment and inflammatory response in pentylenetetrazol-induced kindling model of epilepsy.

Arbutin as a natural soluble glycosylated phenol possesses a wide range of pharmacological activities including anti-inflammatory and anti-oxidant effects. The present study was designed to evaluate the effect of arbutin supplementation on seizures behavior, memory performance, glial activation, release of inflammatory factors and neuroprotection in pentylenetetrazole-induced kindling model. Chemical kindling was induced by repetitive injections of PTZ at subconvulsive doses (36 mg/kg). Arbutin at doses of 25 or 50 mg/kg was administrated intraperitoneally (i.p.), 10 days before PTZ injection and its application was continued 1 h before each PTZ injection. High performance liquid chromatography (HPLC) analysis was performed to measure the arbutin content in hippocampus. After monitoring the behavioral signs of seizures, Morris water maze task was used to assess the spatial learning and memory of animals. Gene expression analysis was carried out to evaluate the effect of arbutin on expression of inflammatory mediators and astrocyte activation. Furthermore, immunostaining was used to assess the protein levels of astrocytes and neurons in hippocampus. The results of HPLC analysis showed that high amount of arbutin can be detected in hippocampus of arbutin + PTZ receiving animals. The seizure behavioral manifestations and memory dysfunction were reduced by arbutin in a dose-dependent manner. The mRNA levels of TNF-α, IL-6 and GFAP were significantly downregulated in animals treated by arbutin. Additionally, the levels of astrocytes activation and neuronal damage were attenuated in arbutin treated animals. These results suggest that arbutin attenuates glial activation, memory impairment and release of inflammatory mediators in model of chronic epilepsy.

Effect of environmental variables on phytonutrients of Origanum vulgare L. in the sub-humid region of the northwestern Himalayas.

Ecological and soil physiochemical parameters impact the crop quality and development. In spite of the huge commercial prospective, the phytonutrient and chemometric profiles of Himalayan oregano (Origanum vulgare L.) have not been evaluated, and their relationships with ecological parameters are still lacking. The objective of this research study was to evaluate the disparity in the phytonutrient profiles of different ecotypes of O. vulgare in wild and cultivated populations and determine whether such variation was related to the diverse climatic and edaphic conditions prevailing in the northwestern Himalayas. Micrometeorological, atomic absorption spectroscopy for micro-elemental analysis was determined for soil. HPLC was used to determine the disparity in phytonutrient (quercetin, betacarotene, ascorbic acid, and catechin) and phytochemical (arbutin) levels. Cultivated populations had lower phytonutrient levels than wild populations. The habitat exhibiting pH values ranging from 6 to 7 elevated organic carbon (2.42%), nitrogen (97.41 kg ha-1), and manganese (10-12 µg g-1) and zinc contents (0.39-0.50%) show luxirant growth of Origanum vulgarel. The phytonutrient (quercetin, betacarotene, ascorbic acid, arbutin, and catechin) levels had a direct relationship with UV-B flux (r2 = 0.82) and potassium (r2 = 0.97). Wild accessions predominantly contained catechin and ascorbic acid, with maximum values of 163.8 and 46.88 µg g-1, respectively, while the cultivated accessions had the highest level of arbutin (53.42 µg g-1). Maximum variation was observed in quercetin (114.61%) followed by ß-carotene (87.53%). Cultivated accessions had less quercetin (0.04-1.25 µg g-1) than wild accessions (1.25-2.87 µg g-1). Wild accessions had higher phytonutrient values for catechin, ß-carotene, and ascorbic acid while cultivated accessions had maximum values for arbutin. The correlation of environmental variables with phytonutrient levels paves the way for metabolomic-guided enhancement of agricultural practices for better herb quality.

An integrated metabolomic strategy for the characterization of the effects of Chinese yam and its three active components on septic cardiomyopathy.

Chinese yam (CY), used as both a traditional Chinese medicine and a nutritious food, is an excellent candidate for treating septic cardiomyopathy (SCM). Adenosine, arbutin and allantoin are the major active components in the aqueous extract of CY. The aim of the present study was to interpret the roles of CY, adenosine, arbutin and allantoin in SCM treatment. Firstly, significant physiological indexes were examined to assess the model and treatment effects of CY, adenosine, arbutin and allantoin. Then, a metabolomic approach was utilized to reveal the metabolic disorders in SCM concerning the intervention of CY/adenosine/arbutin/allantoin. The integrated results demonstrated that adenosine, arbutin and allantoin are responsible for the efficacy of CY on SCM treatment by regulating amino acid, arachidonic acid, sphingolipid, glycerophospholipid and glycol metabolism. Moreover, adenosine and/or arbutin could be used as a substitute for CY in treating SCM, and allantoin efficacy was slightly weaker. This integrated metabolomic approach performed excellently in understanding the herbal function and the roles of its components.

Drosophila melanogaster as a function-based high-throughput screening model for antinephrolithiasis agents in kidney stone patients.

Kidney stone disease involves the aggregation of stone-forming salts consequent to solute supersaturation in urine. The development of novel therapeutic agents for this predominantly metabolic and biochemical disorder have been hampered by the lack of a practical pre-clinical model amenable to drug screening. Here, Drosophila melanogaster, an emerging model for kidney stone disease research, was adapted as a high-throughput functional drug screening platform independent of the multifactorial nature of mammalian nephrolithiasis. Through functional screening, the therapeutic potential of a novel compound commonly known as arbutin that specifically binds to oxalate, a key component of kidney calculi, was identified. Through isothermal titration calorimetry, high-performance liquid chromatography and atomic force microscopy, arbutin was determined to interact with calcium and oxalate in both free and bound states, disrupting crystal lattice structure, growth and crystallization. When used to treat patient urine samples, arbutin significantly abrogated calculus formation in vivo and outperformed potassium citrate in low pH urine conditions, owing to its oxalate-centric mode of action. The discovery of this novel antilithogenic compound via D. melanogaster, independent of a mammalian model, brings greater recognition to this platform, for which metabolic features are primary outcomes, underscoring the power of D. melanogaster as a high-throughput drug screening platform in similar disorders. This is the first description of the use of D. melanogaster as the model system for a high-throughput chemical library screen. This article has an associated First Person interview with the first authors of the paper.

Iridoid glycosides and polyphenolic compounds from Teucrium chamaedrys L.

In this work, the phytochemical analysis of Teucrium chamaedrys L. collected in Italy was reported. Eight compounds were isolated and identified by means of classical column chromatography and spectroscopic techniques, such as NMR and MS. In detail, these compounds were: verbascoside (1), forsythoside b (2), samioside (3), alyssonoside (4), harpagide (5), 8-O-acetyl-harpagide (6), cirsiliol (7) and ß-arbutin (8). The presence of these compounds, in particular iridoids and phenyl-ethanoid glycosides, has a chemotaxonomic relevance and results to be in perfect accordance with the current botanical classification of the species. In addition, it provides a phytochemical rationale for the use of this particular plant in the ethno-pharmacological field. Conversely, it is worth of mention the absence of potentially toxic components, unlike to what observed in other species of the genus which can no longer be used for ethno-medicinal purposes.

Arbutin Content and Tyrosinase Activity of Bergenia Extracts.

The total arbutin content in the leaves of all the studied Bergenia plants (B. crassifolia, B. ciliata and B. x ornata) was determined. The highest values of the arbutin content have been established for B. crassifolia (58.9 ± 0.7 mg.g-¹ DW) and B. x ornata (51.0 ± 1.21 mg.g-¹ DW), and the lowest for B. ciliata (5.9 ± 0.6 mg.g-¹ DW). Arbutin concentration in the Bergenia leaves was the lowest in spring, in the autumn, on the contrary it increased. All the tested aqueous extracts caused a dose-dependent increase in diphenolase activity of fungal tyrosinase in a similar way as arbutin. On the other hand, all the ethanol extracts inhibited the diphenolase activity of tyrosinase.

Fermentation scale up for α-arbutin production by Xanthomonas BT-112.

α-Arbutin is a glycosylated hydroquinone that has an inhibitory function against tyrosinase. The aim of the present study is to develop an efficient and inexpensive method for large-scale production of α-arbutin by using Xanthomonas BT-112 as biocatalyst. To accomplish this goal, various surfactants were tested to enhance the α-arbutin production, and the optimal operational conditions for 30L jar fermenter were scaled up for a production level of 3000L with using a constant volumetric oxygen transfer coefficient (KLa) and the volumetric aeration rate per volume unit (Q/V) as scale-up criteria. Under the optimized conditions, the α-arbutin produced in the presence of 0.4% (w/v) Tween-80 was 124.8% higher than that of the control, and the yield of α-arbutin in 3000L fermenter was 38.2g/L with a molar conversion ratio of 93.7% based on the amount of hydroquinone supplied. This result is comparable to the results from laboratory-scale fermenter. Hence, 100-fold scale-up was successfully achieved.

Analysis of salicylic acid, arbutin and corticosteroids in skin whitening creams available in Pakistan using chromatographic techniques.

BACKGROUND: A simple, new and efficient reversed-phase high-performance liquid chromatography method was developed and validated for the separation of most popular ingredients in skin whitening creams. METHODS: For RP-HPLC analysis, a Hibar(®) C18 250 mm × 4.6 mm, 5 µm column (Merck Millipore, Carolina, USA) as stationary phase with a mobile phase consisting a mixture of acetonitrile, methanol and water 40 : 40 : 20 (pH 7.0), respectively, at flow rate of 0.8 mL min(-1) (total run time 10 min) at room temperature was used. Detection was performed at 254 and 280 nm using photodiode array detector. The method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, specificity, limit of detection and quantification. RESULTS: The method results in excellent separation of skin whitening agents in cosmetic creams. The method is specific for salicylic acid, arbutin, cortisone, hydrocortisone, betamethasone valerate and betamethasone dipropionate. The calibration curve of skin whitening agents was linear with the regression analysis showed r(2) ≥ 0.999. %RSD for inter- and intraday precision were determined as 0.461 and 0.329 for salicylic acid, 0.427 and 0.317 for arbutin, 0.360 and 0.346 for cortisone, 0.336 and 0.350 for hydrocortisone, 0.463 and 0.339 for betamethasone valerate and 0.385 and 0.372 for betamethasone dipropionate, respectively. LOD and LOQ were calculated as 0.48 and 1.20 µg mL(-1) for salicylic acid, 0.09 and 0.22 µg mL(-1) for arbutin, 0.07 and 0.18 µg mL(-1) for cortisone, 0.06 and 0.24 µg mL(-1) for hydrocortisone, 0.07 and 0.20 µg mL(-1) for betamethasone valerate and 0.02 and 0.06 µg mL(-1) for betamethasone dipropionate. The recovery of skin whitening agents were 97.18% for salicylic acid, 97.99% for arbutin, 98.30% cortisone, 97.63% for hydrocortisone, 98.65% for betamethasone valerate and 98.18% for betamethasone dipropionate, respectively. According to this study, salicylic acid is present in 87.88% skin whitening creams, arbutin in 96.97%, cortisone in 60.60%, hydrocortisone in 48.48%, betamethasone valerate in 15.15% and betamethasone dipropionate present in 12.12% cosmetic creams available in Pakistan.

Opinion of the Scientific Committee on Consumer safety (SCCS) - Opinion on the safety of the use of deoxyarbutin in cosmetic products.

CONCLUSION OF THE OPINION: Although on the basis of the provided scientific data the use of deoxyarbutin as such can be considered safe for consumers in cosmetic products in a concentration up to 3% in face creams, hydroquinone will be formed at levels which raise concerns with regard to the safety of such products during life-cycle of the product (e.g. storage conditions and stability under in-use conditions). Therefore, the overall conclusion of the SCCS is that the use of deoxyarbutin up to 3% in face creams is not safe.

Opinion of the Scientific Committee on Consumer safety (SCCS)--Opinion on the safety of the use of α-arbutin in cosmetic products.

CONCLUSION OF THE OPINION: The SCCS considers the use of α-Arbutin safe for consumers in cosmetic products in a concentration up to 2% in face creams and up to 0.5% in body lotions. A potential combined use of α-Arbutin and other hydroquinone releasing substances in cosmetic products has not been evaluated in this Opinion.

Quantitative analysis of arbutin and hydroquinone in strawberry tree (Arbutus unedo L., Ericaceae) leaves by gas chromatography-mass spectrometry.

The phenolic glycoside arbutin and its metabolite with uroantiseptic activity hydroquinone occur naturally in the leaves of various medicinal plants and spices. In this study, an extraction procedure coupled with gas chromatography-mass spectrometry (GC-MS) was developed to determine arbutin and hydroquinone content in strawberry tree (Arbutus unedo L., Ericaceae) leaves. The method showed good linearity (R2>0.9987) in the tested concentration range (0.5-200 µg mL(-1)), as well as good precision (RSD<5%), analytical recovery (96.2-98.0%), and sensitivity (limit of detection=0.009 and 0.004 µg mL(-1) for arbutin and hydroquinone, respectively). The results obtained by the validated GC-MS method corresponded well to those obtained by high performance liquid chromatography (HPLC) method. The proposed method was then applied for determining arbutin and hydroquinone content in methanolic leaf extracts. The amount of arbutin in the leaves collected on the island of Kolocep (6.82 mg g(-1) dry weight) was found to be higher (tpaired=43.57, tc=2.92) in comparison to the amount of arbutin in the leaves collected on the island of Mali Losinj (2.75 mg g(-1) dry weight). Hydroquinone was not detected in any of the samples. The analytical features of the proposed GC-MS method demonstrated that arbutin and hydroquinone could be determined alternatively by gas chromatography. Due to its wide concentration range, the method could also be suitable for arbutin and hydroquinone analysis in leaves of other plant families (Rosaceae, Lamiaceae, etc.).

Determination of arbutin and bergenin in Bergeniae Rhizoma by capillary electrophoresis with a carbon nanotube-epoxy composite electrode.

This report describes the fabrication and the application of a novel carbon nanotube (CNT)-epoxy composite electrode as a sensitive amperometric detector for the capillary electrophoresis (CE). The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of CNTs and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. It was coupled with CE for the separation and detection of arbutin and bergenin in Bergeniae Rhizoma, a traditional Chinese medicine, to demonstrate its feasibility and performance. The two phenolic constituents were well separated within 10min in a 45cm capillary length at a separation voltage of 12kV using a 50mM borate buffer (pH 9.2). The CNT-based detector offered higher sensitivity, significantly lower operating potential, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of analytical applications. It showed long-term stability and reproducibility with relative standard deviations of less than 5% for the peak current (n=15).

An effective homogenate-assisted negative pressure cavitation extraction for the determination of phenolic compounds in pyrola by LC-MS/MS and the evaluation of its antioxidant activity.

A novel extraction method, homogenate-assisted negative pressure cavitation extraction (HNPCE), was designed for the extraction and determination of the main phenolic compounds of Pyrola incarnata Fisch. by LC-MS/MS. The particle sizes and extraction yields in the process of homogenization were compared with conventional pulverization. The results showed that homogenization for less than 120 s could produce more suitable particle size powders for analyte extraction. The following NPCE parameters were optimized by a BBD test and under the optimal conditions, the maximum extraction yields of arbutin, epicatechin, hyperin, 2'-O-galloylhyperin and chimaphilin increased by 68.7%, 72.0%, 43.3%, 62.5% and 34.5% with respect to normal NPCE. The LC-MS/MS method was successfully applied for the quantification of five target compounds in pyrola, and the results of the precision test indicated a high accuracy of the present method for the quantification of the target compounds in pyrola. Furthermore, the antioxidant activities of the pyrola extracts were also determined. The results showed that pyrola had good antioxidant activities and it was a valuable antioxidant natural source.

A double-blind, placebo-controlled randomized trial of Serratulae quinquefoliae folium, a new source of ß-arbutin, in selected skin hyperpigmentations.

BACKGROUND: Arbutin is one of the most effective lightening substances. Serratula quinquefolia is a new source of its ß-anomer. The HPLC method showed that the solid content of this compound in the dried plant raw material accounts for 6.86%. The leaves of Serratula quinquefolia do not contain hydroquinone. AIMS: To assess the efficacy of the aqueous extract from' leaf of five-leaf serratula as a skin-lightening agent. PATIENTS/METHODS: We did a randomized, placebo-controlled, double-blind trial. The study involved 102 women aged 26-55, with two kinds of hyperpigmentary diseases: melasma and lentigo solaris. Patients were randomly assigned to one of the treatment groups: a study group (N = 54) or a control group (N = 48). The study group applied the cream with the aqueous extract from leaf of five-leaf serratula containing 2.51% of arbutin. The cream was applied twice a day on the discolored side for 8 weeks. RESULTS: The experimental data showed that the cream with the extract causes decreased level of melanin in the skin pigmentation spot. Clinical effect in the form of lightening and evening skin tone on the discolored side was observed in 75.86% of the female patients with melasma and 56.00 % of the female patients with lentigo solaris. CONCLUSIONS: The cream with the aqueous extract from leaf of five-leaf serratula proved to be an effective and safe preparation for lightening skin discolorations (66.67 % of the female patients in the study group).

Simultaneous determination of arbutin and its decomposed product hydroquinone in whitening creams using high-performance liquid chromatography with photodiode array detection: Effect of temperature and pH on decomposition.

OBJECTIVE: Arbutin is an effective agent for the treatment of melanin disorders. Arbutin may be converted to hydroquinone under conditions of high temperature, ultraviolet (UV) radiation and dilute acid. The aim of the current study was to develop an analytical method to determine the levels of arbutin and hydroquinone in whitening cosmetic products using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). In addition, we investigated the effects of high temperature and pH on the decomposition of arbutin. METHODS: Samples extracted using two-step sonications were separated on a C18 column using a gradient mobile phase consisting of water and methanol. A 60-mm (40 µL) DAD cell was used to enhance the sensitivity of hydroquinone determination. Thermal decomposition of arbutin was evaluated at temperatures ranging from 60 to 120°C for 1-36 h. RESULTS: The method showed good linearity (R(2) ≥ 0.9997), precision (relative standard deviation, RSD < 5%) and acceptable extraction recovery (90-102.6%). The limits of quantitation for arbutin and hydroquinone were 0.0085 and 0.0119 µg mL(-1) , respectively. One sample of 21 cosmetic products tested contained arbutin at a concentration 1.61 g 100 g(-1) cream and 0.12 g 100 g(-1) cream of hydroquinone. Arbutin (327.18 ppm) decomposed after 6 h at 120°C and produced 10.73 ppm of hydroquinone. CONCLUSION: The developed method is simple to detect both arbutin and hydroquinone simultaneously in cosmetic products, at an adequate level of sensitivity. Notably, temperature and pH did not influence the decomposition of arbutin to hydroquinone in a 2% arbutin cream.