Evaluation of in vitro testing strategies for hazard assessment of the skin sensitization potential of "real-life" mixtures: The case of henna-based hair-colouring products containing p-phenylenediamine.

BACKGROUND: Allergic contact dermatitis caused by henna-based hair-colouring products has been associated with adulteration of henna with p-phenylenediamine (PPD). OBJECTIVES: To develop a testing approach based on in vitro techniques that address key events within the skin sensitization adverse outcome pathway in order to evaluate the allergenic potential of hair-colouring products. METHODS: The following in vitro assays were used to test the sensitizing capacity of hair dye ingredients: the micro-direct peptide reactivity assay (mDPRA); the HaCaT keratinocyte-associated interleukin (IL)-18 assay; the U937 cell line activation test (U-SENS)/IL-8 levels; the blood monocyte-derived dendritic cell test; and genomic allergen rapid detection (GARD skin). Those techniques with better human concordance were selected to evaluate the allergenic potential of 10 hair-colouring products. RESULTS: In contrast to the information on the label, chromatographic analyses identified PPD in all products. The main henna biomarker, lawsone, was not detected in one of the 10 products. Among the techniques evaluated by testing hair dye ingredients, the mDPRA, the IL-18 assay, GARD skin and the U-SENS correlated better with human classification (concordances of 91.7%-100%) and were superior to the animal testing (concordance of 78.5%). Thus, these assays were used to evaluate hair-colouring products, which were classified as skin sensitizers by the use of different two-of-three approaches. CONCLUSIONS: Our findings highlight the toxicological consequences of, and risks associated with, the undisclosed use of PPD in henna-based "natural" "real-life" products.

Lapachol biotransformation by filamentous fungi yields bioactive quinone derivatives and lapachol-stimulated secondary metabolites.

Lapachol is a natural naphthoquinone with a range of biological effects, including anticancer activity. Microbial transformations of lapachol can lead to the formation of new biologically active compounds. In addition, fungi can produce secondary metabolites that are also important for drug discovery. The goal of this study was to evaluate the ability of filamentous fungi to biotransform lapachol into biologically active compounds and identify secondary metabolites produced in the presence of lapachol. Seven out of nine strains of filamentous fungi tested exhibited the ability to biotransform or biodegrade lapachol. The bioactive derivatives norlapachol and isolapachol were identified among biotransformation products. Moreover, lapachol stimulated the production of pyrrolo-[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) and phenol-2,4-bis-(1,1-dimethylethyl), secondary metabolites already known to have antimicrobial and antioxidant activities. These results open the perspective of using these strains of filamentous fungi for lapachol biotransformation and efficient production of several biologically active compounds.

Dayak onions ( Eleutherine bulbosa (Mill.) Urb. ) bulbs extracts reduces blood pressure of hypoestrogen model rats by controlling lipids profile / El extracto de bulbos de cebollas dayak ( Eleutherine bulbosa (Mill. ) Urb. ) reduce la presión sanguínea en un modelo hipoestrogénico en ratas controlando el perfil lipídico

To determine the effects of 70 % ethanolic extract of Eleutherine bulbosa (Mill.) L. bulbs contained naphtoquinone in blood pressure and lipids profile level of ovariectomized rats. Thin layer chromatography was performed to analyze the content of the Eleutherine bulbosa (Mill.) bulbs extracts using Chloroform : Methanol (7:1) as eluent. This study used white female Sprague-Dawley rats which were divided into 6 groups: SHAM and OVX, both given 0.5 % carboxymethyl cellulose; the positive control group that was given tamoxifen (0.36 mg/200 g B.W.); the three various of doses of extract namely dose 1, 2, and 3 that were given 8, 12, and 18 mg/200 g BW respectively on day 29 until 50. All groups were ovariectomized on day 1, except sham group. Measurement of blood pressure were performed on the day before ovariectomy using non-invasive tool CODA®; and on the second, third, and fourth weeks post-ovariectomy. Three weeks after treatment of hypoestrogen rats by the dose 18 mg/200 g B.W, Eleutherine bulbosa extracts could decrease the systolic blood pressure level to 28.06 %, the diastolic to 30.47 %. Lipid profile of Dose 3 also showed recovery of Triglyceride, LDL and also Total Cholesterol. Eleutherine bulbosa extracts could improve blood pressure of ovariectomized rats by controlling lipids profile level.

Para determinar los efectos del 70 % de extracto etanólico de Eleutherine bulbosa (Mill.) L. en bulbos que contenían naftoquinona, se analizó la presión arterial de ratas ovariectomizadas. Se realizó un estudio de cromatografía de capa fina para analizar el contenido de los extractos de bulbos de Eleutherine bulbosa (Mill.) usando cloroformo:metanol (7:1) como diluyente. En este estudio se utilizaron ratas blancas Sprague-Dawley hembras, que se dividieron en 6 grupos: SHAM y OVX, ambos grupos fueron administrados con carboximetilcelulosa al 0,5 %; grupo control positivo, recibió tamoxifeno (0,36 mg / 200 g de B.W.); y tres grupos restantes, que recibieron tres dosis diferentes de extracto, es decir, dosis 1, 2 y 3 a las que se les administró 8, 12 y 18 mg / 200 g de por peso, respectivamente el día 29 hasta el día 50. Todos los grupos fueron sometidos a ovariectomía en el día 1, excepto el grupo simulado. La medición de la presión arterial se realizó el día anterior a la ovariectomía con la herramienta no invasiva CODA®, y, posteriormente, en la segunda, tercera y cuarta semanas de realizada la ovariectomía. Tres semanas después del tratamiento aplicado a las ratas hipoestrógenas, con la dosis de 18 mg / 200 g por peso, los extractos de Eleutherine bulbosa podrían disminuir el nivel de presión arterial sistólica al 28,06 %, y la diastólica al 30,47 %. La dosis 3 del perfil lipídico mostró mejoría en los niveles de Triglicéridos, LDL y Colesterol Total. Los extractos de Eleutherine bulbosa podrían mejorar la presión sanguínea de ratas ovariectomizadas controlando el nivel del perfil lipídico.

Anti-inflammatory and antioxidative effects of the methanolic extract of the aerial parts of Mitracarpus frigidus in established animal models.

OBJECTIVES: This study reports the in vivo anti-inflammatory and antioxidative effects of the methanolic extract of the aerial parts of Mitracarpus frigidus (MFM) and its chemical fingerprint. METHODS: The acute anti-inflammatory activity was performed using the carrageenan-induced paw oedema and peritonitis, ear oedema induced by croton oil and ethyl phenylpropiolate methods. Total COX, COX-1 and COX-2 expression was also evaluated. Chronic activity was determined by cotton pellet granuloma model. The antioxidative activity was assessed using liver tissue malondialdehyde, catalase and myeloperoxidase activities. KEY FINDINGS: M. frigidus showed an intense acute anti-inflammatory action (100 and 300 mg/kg) in a nondose-dependent manner with selective inhibition of COX-2 expression. This activity may be also related to the strong antioxidative effect observed. By the other side, the chronic anti-inflammatory activity of MFM was not expressive. Kaempferol, kaempferol-O-rutenoside, rutin, ursolic acid and psychorubrin were identified in MFM. CONCLUSIONS: The anti-inflammatory activity of MFM was probably due to inhibition of COX expression in a selective manner for COX-2. Other mechanisms, such as inhibition of inflammatory mediators and of the oxidative stress were possibly involved in the effects observed. To the best of our knowledge, it is the first time those activities are reported for M. frigidus.

Determination of lapachol in the presence of other naphthoquinones using 3MPA-CdTe quantum dots fluorescent probe.

3MPA-CdTe QDs in aqueous dispersion was used as a fluorescent probe for the determination of lapachol, a natural naphthoquinone found in plants of the Bignoniaceae family genus Tabebuia. Working QDs dispersions (4.5×10(-8) mol L(-1) of QDs) was prepared in aqueous media containing Tris-HCl buffer pH 7.4 and methanol (10% in volume). The excitation was made at 380 nm with signal measurement at 540 nm. To establish a relationship between fluorescence (corrected to inner filter effect) and concentration of lapachol, a Stern-Volmer model was used. The linear range obtained was from 1.0×10(-5) to 1.0×10(-4) mol L(-1). The limit of detection (x(b)-3s(b)) was 8.0×10(-6) mol L(-1). The 3MPA-CdTe QDs probe was tested in the determination of lapachol in urine, previously cleansed in an acrylic polymer. The average recovery was satisfactory.

Application of the atoms in molecules theory and computational chemistry in mass spectrometry analysis of 1,4-naphthoquinone derivatives.

Mass spectrometry analysis of 2-(acylamino)-1,4-naphthoquinone derivatives was carried out using electrospray ionization ion source in combination with tandem mass spectrometry. Protonated molecules were dissociated by application of the collision-induced dissociation (CID), and the protonation sites were suggested on the basis of the HOMO, molecular electrostatic potential map (MEP), proton affinity, and Fukui functions calculated by B3LYP/6-31+G(d,p). The main fragmentation mechanisms undergone by the protonated ions were elucidated on the basis of energy, geometry, and topology analysis of equilibrium geometries. Compounds exhibiting only aliphatic hydrogens at the lateral chain undergo interesting ketene elimination. On the other hand, only the benzoylium ion formation is detected for 2-benzoylamino-1,4-naphthoquinone. The bonds geometric and atoms in molecules parameters give evidence that acidic hydrogen atoms play an important role in the fragmentation pathways.

UV/Vis spectra and solubility of some naphthoquinones, and the extraction behavior of plumbagin from Plumbago scandens roots in supercritical CO2.

The solubility of 1,4-naphthoquinone, plumbagin, lawsone, and juglone in supercritical carbon dioxide was determined spectroscopically at 40 degrees C, and in the pressure range 8-18 MPa. Their solubilities at 12 MPa were between 0.3 and 10 g L(-1). Plumbagin from Plumbago scandens L. roots was extracted at 40 degrees C and 20 MPa. The extracted plumbagin mass fraction was up to 0.2% in fresh roots but down to about 0.006% in aged roots. n-Hexane and chloroform extraction of such aged roots indicates that the older and dryer the roots are, the stronger they bind plumbagin. Reversed-phase HPLC indicated a relatively pure plumbagin extract with supercritical carbon dioxide.

The crystal structure and physicochemical characteristics of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine, a new antitrypanosomal compound.

This study was designed to investigate the physical characteristics and crystalline structure of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine (PNQ), a new active compound against Trypanosoma cruzi, the causative agent of American trypanosomiasis. Methods used included differential scanning calorimetry, thermogravimetry, hot stage microscopy, polarized light microscopy (PLM), Fourier-transform infrared (FTIR) spectroscopy, and high-resolution X-ray powder diffraction (HR-XRPD). According to PLM and HR-XRPD data, PNQ crystallized as red oolitic crystals (absolute methanol) or prisms (dimethyl sulfoxide [DMSO]-water) with the same internal structure. The findings obtained with HR-XRPD data (applying molecular location methods) showed a monoclinic unit cell [a = 18.4437(1) A, b = 3.9968(2) A, c = 14.5304(1) A, alpha = 90 degrees , beta = 102.71(6) degrees , gamma = 90 degrees , V = 1044.9(1) A(3), Z = 4, space group P2(1)/c], and a crystal structure (excluding H-positions) described by parallel layers in the direction of the b-axis, with molecules held by homochemical (phenyl-phenyl and pyrazole-pyrazole) van der Waals interactions. In addition, FTIR spectra displayed the NH-pyrazole stretch overlapped with the OH absorption at 3222 cm(-1), typical of -NH and -OH groups associated through H-bondings; and a carbonyl stretching absorption at 1694 cm(-1), indicating a nonextensively H-bonded quinonic C=O, which was in accordance with the solved crystal structure of PNQ. The existence of such cohesive forces shed light on the thermoanalytical data, which revealed that PNQ is a stable solid, unaffected by oxygen that decomposed without melting above 260 degrees C.

Qualitative and quantitative reversed-phase liquid chromatography of a new bisisoxazolylnaphthoquinone.

The main objective of this study was to develop and test the applicability of a sensitive, accurate, and precise liquid chromatographic (LC) method for evaluating the stability characteristics of a new bisisoxazolylnaphthoquinone, 2-(3,5-dimethyl-4-isoxazolylamino)-N-(3,5-dimethyl-4-isoxazolyl)-1,4-naphthoquinone-4-imine compound 1. The method was shown to be selective and stability-indicating. Isocratic elution with a mobile phase of methanol-water (75 + 25, v/v) on a reversed-phase column with UV detection at ambient temperature completely resolved compound 1 from its degradation products. The LC system was calibrated by plotting peak responses versus known concentrations of a reference standard by using an internal standardization procedure. Complete elution occurred after 12 min with a peak symmetry factor of 0.95 for the drug peak. The kinetic degradation of compound 1 was studied over a pH range of 0.88-14.00 to determine the kinetic parameters involved in its decomposition path in aqueous solution.

Isoxazoles. VI: Aspects of the chemical stability of a new naphthoquinone-amine in acidic aqueous solution.

Some aspects of the chemical degradation of N-(3,4-dimethyl-5-isoxazolyl)-4-amino-1,2-naphthoquinone were investigated as a function of pH and temperature. In acid and neutral pH, four main degradation products were identified: 2-hydroxy-1,4-naphthoquinone, 2-butanone, ammonia, and hydroxylamine. No significant buffer effects were observed for the buffer species used in this study. The pH-rate profile exhibited a specific acid catalysis which is important at pH values less than 3.5, and an inflection point at pH 1.10 corresponding to a pKa value. From Arrhenius plots, the activation energy was found to be 17.8 +/- 0.3 kcal/mol.