Tania Naessens

Quantification of xanthohumol, isoxanthohumol, 8-prenylnaringenin, and 6-prenylnaringenin in hop extracts and derived capsules using secondary standards

Hop is a well-known and already frequently used estrogenic phytotherapeutic, containing the interesting prenylflavonoids, xanthohumol (XN), isoxanthohumol (IXN), 8- and 6-prenylnaringenin (8-PN and 6-PN). Since the use of secondary standards can form a solution whenever the determination is required of certain components, not commercially available or too expensive, it was decided to develop an accessible HPLC-DAD method for the determination of these prenylflavonoids. The amounts were determined in hop extract and capsules, using quercetin and naringenin as secondary standards. After optimization of the sample preparation and HPLC conditions, the analysis was validated according to the ICH guidelines. The response function of XN, 8-PN, quercetin and naringenin showed a linear relationship. For the determination of XN, a calibration line of at least three concentrations of quercetin has to be constructed. The correction factors for XN (quercetin) and for 8-PN (naringenin) were validated and determined to be 0.583 for XN, and 1.296 for IXN, 8-PN and 6-PN. The intermediate precision was investigated and it could be concluded that the standard deviation of the method was equal considering time and concentration (RSD of 2.5-5%). By means of a recovery experiment, it was proven that the method is accurate (recoveries of 96.1-100.1%). Additionally, by analysing preparations containing hop extracts on the Belgian market, it was shown that the method is suitable for its use, namely the determination of XN, IXN, 8-PN and 6-PN in hop extract and capsules, using quercetin and naringenin as secondary standards.

Development and validation of a robust high-performance liquid chromatographic method for the analysis of monacolins in red yeast rice

A robust analytical method, using reversed phase high-performance liquid chromatography with diode array detection, was developed and validated for the quantification of monacolins in red yeast rice bulk products. Tests on the composition of the extraction solvent, extraction time and the number of repetitions of extraction were evaluated with the aim of complete extraction of the monacolins and minimal transitions between the monacolins during analysis. Monacolin K (acid form), monacolin K (lactone form) and minor monacolin peaks were separated on a C18 column (250×4.6mm, 5µm) using acetonitrile/0.1% trifluoroacetic acid as the mobile phase. For the calibration curve of monacolin K (lactone form), a linear correlation in the range 6-119µg/mL was found. The precision of the method for time and concentration gave a relative standard deviation of less than 5%, which was deemed acceptable. The recovery of the method was 98.75%.

Severe allergic contact dermatitis caused by octylisothiazolinone in a leather sofa: two new cases

Nadia Raison-Peyron1 , Emmanuelle Amsler2 , Catherine Pecquet2, Aurélie Du-Thanh1, Tania Naessens3, Sandra Apers3,† and Olivier Aerts4 1Department of Dermatology, Hôpital Saint-Eloi, CHU de Montpellier, 34295 Montpellier, France, 2Dermatology and Allergology Department, Tenon Hospital (AP-HP), Sorbonne Universities, UPMC University Paris 06, 75020 Paris, France, 3Research Group Natural Products and Food – Research and Analysis (NatuRA), Department of Pharmaceutical Sciences, University of Antwerp (UA), 2610 Antwerp, Belgium, and 4Department of Dermatology, University Hospital Antwerp (UZA) and University of Antwerp (UA), 2650 Antwerp, Belgium

Advantages of a validated UPLC–MS/MS standard addition method for the quantification of A-type dimeric and trimeric proanthocyanidins in cranberry extracts in comparison with well-known quantification methods

Graphical abstract Figure. No Caption available. HighlightsAn LC–MS/MS method for A‐type procyanidins in cranberry was developed and validated.Twelve cranberry extracts were analyzed by different methods and the results compared.Combination of the DMAC or butanol‐HCl assay with the new LC–MS/MS assay is advisable. ABSTRACT The berries of Vaccinium macrocarpon, cranberry, are widely used for the prevention of urinary tract infections. This species contains A‐type proanthocyanidins (PACs), which intervene in the initial phase of the development of urinary tract infections by preventing the adherence of Escherichia coli by their P‐type fimbriae to uroepithelial cells. Unfortunately, the existing clinical studies used different cranberry preparations, which were poorly standardized. Because of this, the results were hard to compare, which led sometimes to conflicting results. Currently, PACs are quantified using the rather non‐specific spectrophotometric 4‐dimethylaminocinnamaldehyde (DMAC) method. In addition, a normal phase HPTLC‐densitometric method, a HPLC‐UV method and three LC–MS/MS methods for quantification of procyanidin A2 were recently published. All these methods contain some shortcomings and errors. Hence, the development and validation of a fast and sensitive standard addition LC–MS/MS method for the simultaneous quantification of A‐type dimers and trimers in a cranberry dry extract was carried out. A linear calibration model could be adopted for dimers and, after logaritmic transformation, for trimers. The maximal interday and interconcentration precision was found to be 4.86% and 4.28% for procyanidin A2, and 5.61% and 7.65% for trimeric PACs, which are all acceptable values for an analytical method using LC–MS/MS. In addition, twelve different cranberry extracts were analyzed by means of the newly validated method and other widely used methods. There appeared to be an enormous variation in dimeric and trimeric PAC content. Comparison of these results with LC–MS/MS analysis without standard addition showed the presence of matrix effects for some of the extracts and proved the necessity of standard addition. A comparison of the well‐known and widely used DMAC method, the butanol‐HCl assay and this newly developed LC–MS/MS method clearly indicated the need for a reliable method able to quantify A‐type PACs, which are considered to be the pharmacologically active constituents of cranberry, since neither the DMAC or butanol‐HCl assays are capable of distinguishing between A and B‐type PACs and therefore cannot detect adulterations with, for example, extracts with a high B‐type PAC content. Hence, the combination of the DMAC method or butanol‐HCl assay with this more specific LC–MS/MS assay could overcome these shortcomings.

Allergic contact dermatitis caused by wet wipes containing steareth-10: Is stearyl alcohol to blame?

Olivier Aerts1 , Tania Naessens2, Julie Dandelooy1, Julie Leysen1, Julien Lambert1 and Sandra Apers2 1Contact Allergy Unit, Department of Dermatology, University Hospital Antwerp (UZA) and University of Antwerp (UA), 2650 Edegem, Antwerp, Belgium and 2Department of Pharmaceutical Sciences, Research group Natural Products and Food – Research and Analysis (NatuRA), University of Antwerp (UA), 2610 Wilrijk, Antwerp, Belgium

Facial dermatitis caused by undeclared methylisothiazolinone in a gel mask: is the preservation of raw materials in cosmetics a cause of concern?: UNDECLARED METHYLISOTHIAZOLINONE IN A FACIAL MASK

Facial dermatitis caused by undeclared methylisothiazolinone in a gel mask: is the preservation of raw materials in cosmetics a cause of concern? Stefan Kerre1 , Tania Naessens2, Mart Theunis2, Kenn Foubert2, An Goossens3 and Olivier Aerts4 1Gijmelsesteenweg 14A, 3200 Aarschot, Belgium, 2Natural Products and Food – Research and Analysis (NatuRA), Department of Pharmaceutical Sciences, University of Antwerp (UA), 2610 Antwerp, Belgium, 3Department of Dermatology, University Hospitals KU Leuven, 3000 Leuven, Belgium and 4Department of Dermatology, University Hospital Antwerp (UZA) and University of Antwerp (UA), 2650 Antwerp, Belgium