Cristina Avonto

Quantitative determination of phenolic compounds by UHPLC-UV–MS and use of partial least-square discriminant analysis to differentiate chemo-types of Chamomile/Chrysanthemum flower heads

A new rapid UHPLC-UV-QTOF/MS method has been developed for the simultaneous analysis of nine phenolic compounds [(Z)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (cis-GMCA), chlorogenic acid, (E)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (trans-GMCA), quercetagetin-7-O-β-d-glucopyranoside, luteolin-7-O-β-d-glucoside, apigenin-7-O-β-d-glucoside, chamaemeloside, apigenin 7-O-(6″-O-acetyl-β-d-glucopyranoside), apigenin] and one polyacetylene (tonghaosu) from the flower heads of Chamomile/Chrysanthemum samples. The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. The ten compounds were completely separated within 15min at a flow rate of 0.25mL/min with a 2μL injection volume. The different chemo-types of Chamomiles/Chrysanthemum displayed variations in the presence of chemical constituents. German Chamomile samples confirmed the presence of cis-GMCA, trans-GMCA, apigenin-7-O-β-d-glucoside and tonghaosu as major constituents whereas Roman chamomile samples confirmed the presence of chamamaeloside and apigenin as major compounds. The Chrysanthemum morifolium samples showed the presence of luteolin-7-O-β-d-glucose as the major compound. The method was applied for the analysis of various commercial products including capsules, tea bags, body and hair care products. LC-mass spectrometry with electrospray ionization (ESI) interface method is described for the evaluation of ten compounds in plant samples and commercial products. This method involved the detection of [M+Na](+) and [M+H](+) ions in the positive mode. Partial least squares discriminant analysis (PLS-DA) was used to visualize commercial samples quality and may be of value for discriminating between chamomile types and Chrysanthemum with regards to the relative content of individual constituents. The results indicated that the method is suitable as a quality control test for various Chamomile/Chrysanthemum samples and market products.

Bioactivity-Guided Investigation of Geranium Essential Oils as Natural Tick Repellents

The evaluation of 10 essential oils of geranium, Pelargonium graveolens (Geraniaceae), were all shown to have repellent activity against nymphs of the medically important lone star tick, Amblyomma americanum (L.). The biological tests were carried out using a vertical filter paper bioassay, where ticks must cross an area of the paper treated with repellent to approach host stimuli. One of the essential oil samples that repelled >90% of the ticks at 0.103 mg/cm(2) was selected for further fractionation studies. The sesquiterpene alcohol, (-)-10-epi-γ-eudesmol, was isolated and identified by spectral methods. (-)-10-epi-γ-Eudesmol at 0.103 and 0.052 mg of compound/cm(2) of filter paper repelled 90 and 73.3% of the ticks, respectively. (-)-10-epi-γ-Eudesmol exhibited similar repellency to the reference standard N,N-diethyl-meta-toluamide (DEET) at concentrations of ≥0.052 mg of compound/cm(2) of filter paper, with (-)-10-epi-γ-eudesmol losing much of its repellency at 0.026 mg of compound/cm(2) and DEET at 0.013 mg of compound/cm(2). Isomenthone and linalool did not repel ticks at the concentrations tested. Most repellents are marketed with much higher concentrations of active ingredient than the concentrations of the natural repellents tested herein; therefore, effective compounds, such as (-)-10-epi-γ-eudesmol, found in geranium oil, have the potential for commercial development.

An integrated approach utilising chemometrics and GC/MS for classification of chamomile flowers, essential oils and commercial products

As part of an ongoing research program on authentication, safety and biological evaluation of phytochemicals and dietary supplements, an in-depth chemical investigation of different types of chamomile was performed. A collection of chamomile samples including authenticated plants, commercial products and essential oils was analysed by GC/MS. Twenty-seven authenticated plant samples representing three types of chamomile, viz. German chamomile, Roman chamomile and Juhua were analysed. This set of data was employed to construct a sample class prediction (SCP) model based on stepwise reduction of data dimensionality followed by principle component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The model was cross-validated with samples including authenticated plants and commercial products. The model demonstrated 100.0% accuracy for both recognition and prediction abilities. In addition, 35 commercial products and 11 essential oils purported to contain chamomile were subsequently predicted by the validated PLS-DA model. Furthermore, tentative identification of the marker compounds correlated with different types of chamomile was explored.

Comparative Investigation of Umbellularia californica and Laurus nobilis Leaf Essential Oils and Identification of Constituents Active against Aedes aegypti

Umbellularia californica (California bay laurel) and Laurus nobilis (Mediterranean bay laurel) leaves may be mistaken or used as a substitute on the market due to their morphological similarity. In this study, a comparison of anatomical and chemical features and biological activity of both plants is presented. L. nobilis essential oil biting deterrent and larvicidal activity were negligible. On the other hand, U. californica leaf oil showed biting deterrent activity against Aedes aegypti . The identified active repellents was thymol, along with (-)-umbellulone, 1,8-cineole, and (-)-α-terpineol. U. californica essential oil also demonstrated good larvicidal activity against 1-day-old Ae. aegypti larvae with a LD50 value of 52.6 ppm. Thymol (LD50 = 17.6 ppm), p-cymene, (-)-umbellulone, and methyleugenol were the primary larvicidal in this oil. Umbellulone was found as the principal compound (37%) of U. californica essential oil, but was not present in L. nobilis essential oil. Umbellulone mosquito activity is here reported for the first time.

Echinacea purpurea up-regulates CYP1A2, CYP3A4 and MDR1 gene expression by activation of pregnane X receptor pathway.

Abstract 1. This study investigated the mechanism underlying Echinacea-mediated induction of CYP1A2, CYP3A4 and MDR1 in terms of human pregnane X receptor (PXR) activation. 2. Crude extracts and fractions of Echinacea purpurea were tested for PXR activation in HepG2 cells by a reporter gene assay. Quantitative real-time PCR was carried out to determine their effects on CYP1A2 and CYP3A4 mRNA expressions. Capsules and fractions were risk ranked as high, intermediate and remote risk of drug-metabolizing enzymes induction based on EC50 values determined for respective CYPs. 3. Fractions F1, F2 and capsule (2660) strongly activated PXR with 5-, 4- and 3.5-fold increase in activity, respectively. Echinacea preparations potentiated up-regulation of CYP1A2, CYP3A4 and MDR1 via PXR activation. 4. Thus E. purpurea preparations cause herb–drug interaction by up-regulating CYP1A2, CYP3A4 and P-gp via PXR activation.

Investigating sub-2 μm particle stationary phase supercritical fluid chromatography coupled to mass spectrometry for chemical profiling of chamomile extracts.

Roman and German chamomile are widely used throughout the world. Chamomiles contain a wide variety of active constituents including sesquiterpene lactones. Various extraction techniques were performed on these two types of chamomile. A packed-column supercritical fluid chromatography-mass spectrometry method was designed for the identification of sesquiterpenes and other constituents from chamomile extracts with no derivatization step prior to analysis. Mass spectrometry detection was achieved by using electrospray ionization. All of the compounds of interest were separated within 15 min. The chamomile extracts were analyzed and compared for similarities and distinct differences. Multivariate statistical analysis including principal component analysis and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to differentiate between the chamomile samples. German chamomile samples confirmed the presence of cis- and trans-tonghaosu, chrysosplenols, apigenin diglucoside whereas Roman chamomile samples confirmed the presence of apigenin, nobilin, 1,10-epioxynobilin, and hydroxyisonobilin.

Identification of a compound isolated from German chamomile (Matricaria chamomilla) with dermal sensitization potential

&NA; German chamomile is one of the most popular herbal ingredients used in cosmetics and personal care products. Allergic skin reactions following topical application of German chamomile have been occasionally reported, although it is not fully understood which of the chemical constituents is responsible for this adverse effect. In the present work, three candidate sensitizers were isolated from German chamomile based on activity‐guided fractionation of chamomile extracts tested using the in vitro KeratinoSens™ assay. The compounds were identified as the polyacetylene tonghaosu (1), and both trans‐ and cis‐glucomethoxycinnamic acids (2 and 3). These three compounds were classified as non‐ to weakly reactive using in chemico methods; however, aged tonghaosu was found to be more reactive when compared to freshly isolated tonghaosu. The polyacetylene (1) constituent was determined to be chemically unstable, generating a small electrophilic spirolactone, 1,6‐dioxaspiro[4.4]non‐3‐en‐2‐one (4), upon aging. This small lactone (4) was strongly reactive in both in chemico HTS‐ and NMR‐DCYA methods and further confirmed as a potential skin sensitizer by Local Lymph Node Assay (LLNA). HighlightsFractions of German chamomile tested positive in the KeratinoSens™ assay.Three compounds containing structural alerts were isolated and tested with in chemico methods.The polyacetylene tonghaosu was found to be unstable and categorized as potential pre‐hapten.A degradation product of tonghaosu tested as positive dermal sensitizer in animal studies.

Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment

Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds.

Comparative studies on the chemical and enzymatic stability of alpha- and beta-arbutin

The aim of this study was to establish a comparative analysis of the chemical and enzymatic stability of α‐ and β‐arbutins as potential sources of the substance of concern hydroquinone (HQ). The study was performed using an array of techniques including HPLC‐PDA, nuclear magnetic resonance (NMR) and optical rotation (OR). Both arbutins are emerging as popular and effective skin whiteners, acting as tyrosinase inhibitors in a fashion similar to the popular whitening agent HQ. Due to their structural similarity to the regulated agent HQ, both arbutins may be regarded as potential sources of the active aglycone after chemical or metabolic conversion.

In chemico assessment of potential sensitizers: Stability and direct peptide reactivity of 24 fragrance ingredients: Stability and direct peptide reactivity of 24 fragrance ingredients

Twenty‐four pure fragrance ingredients of concern as potential skin sensitizers were previously subjected to degradation studies and evaluated using the high throughput with dansyl cysteamine (HTS‐DCYA) method. The experimental results showed that two‐thirds of the 24 fragrance ingredients underwent chemical degradation. In some cases, such degradation was accompanied by an increase in thio‐reactivity. These results prompted us to investigate the reactivity of the same ingredients using the direct peptide reactivity assay (DPRA). In the present work, the 24 chemicals were subjected to forced degradation for 150 days, and evaluated with both DPRA and HTS‐DCYA methods. At the end of the study, four and eight compounds remained non‐reactive in the DPRA and DCYA assay, respectively. Coumarin, benzyl salicylate, benzyl cinnamate and hexyl cinnamal were found unreactive in both assays, while cinnamal, cinnamyl alcohol, hydroxycitronellal and lilial were found negative in the DCYA but positive in the DPRA method. The incongruity in reactivity of these four compounds was attributed to a possible role of pro‐oxidants formed upon degradation, resulting in depletion of peptide without formation of apparent covalent adducts with the test chemical. To validate this hypothesis, the effect of hydrogen peroxide as model pro‐oxidant on both lysine‐ and cysteine‐heptapeptide depletion in the DPRA method was thus investigated. The obtained results showed little effect of oxidative conditions on lysine depletion, while cysteine depletion was significantly affected by concentrations above 1.1 mg/L of hydrogen peroxide. Overall, both in chemico methods confirmed chemical instability should be considered when assessing the skin sensitization potential of (un)known chemicals with alternative methods.