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Metabolomics in natural products research: application to in vivo bioactivity studies involving nutraceuticals
Full text linkThe analysis of urinary metabolite changes can provide information on the effects of food supplements or health-promoting products on healthy subjects or animal models. Specimen collection is non-invasive, long-term experiments can be easily conducted and urinary biomarkers of oxidative stress can also be measured, offering the opportunity to study the effects of a nutritional intervention and evaluate the redox status of the considered organism. In this thesis, three natural extracts were selected, namely Polygonum cuspidatum Sieb. et Zucc. (rich in resveratrol), Vaccinium macrocarpon Aiton (cranberry, rich in type A procyanidins) and green Coffea canephora Pierre ex Froehn. beans (GCBE, rich in chlorogenic acids), on the basis of their distribution on the market and on the basis of the information regarding their in vivo activity actually available in literature. In the first part of the work, the effects of P. cuspidatum dry extract were studied in healthy adult rats during a 49-days supplementation, using a combined 1H NMR and UPLC-HRMS metabolomics approach. Because of the reported antioxidant activity of resveratrol, the urinary amounts of two oxidative stress biomarkers were measured by targeted HPLC–MS/MS analyses and, due to the supposed “anti-aging” effects of resveratrol, multivariate models were designed in order to compare the aging effects between control and treated animals. Specific biomarkers were then selected and identified, and their amounts in urine were monitored throughout the experimental period.
UPLC-MS metabolomics approaches were used to evaluate the mode of action of cranberry against uropathogenic Escherichia coli in two independent experiments, using an animal model and enrolling healthy adult volunteers, respectively. The experimental design was similar for the two trials, and the aim was to observe if the results obtained from the first animal experiment were reproducible in humans, being cranberry supplements claimed for treatment of UTIs in human consumers. In the first experiment, healthy Sprague−Dawley rats were orally supplemented with a standardized cranberry extract for 35 days, to mimic a prolonged consumption of cranberry by healthy subjects. 24-h urinary outputs were collected weekly during the experiment, and samples were subjected to UPLC−MS analysis using an untargeted approach. In a second experiment on the same animal model, a single dose of cranberry was administered to animals and the changes of urinary composition at 2, 4, 8, and 24 h after extract administration were monitored. Anti-adhesive properties of all the urine samples were studied. Furthermore, the markers related to cranberry intake were discovered using a multivariate data analysis approach. Finally, a specific chromatographic method was developed for the measurement of unmodified PAC-A in urine. In the experiment involving human volunteers, these consumed an oral sachet containing 360 mg of dry cranberry extract and 100 mg of quercetin. Urine samples were collected at 2, 4, 6, 8 ad 24 hours after product administration and the anti-adhesive properties of urine samples were tested using an in vitro assay on E. coli. In order to correlate possible observed bioactivity with modification of urinary composition, LC-MS-based targeted and untargeted metabolomics approaches were used.
Finally, a clinical trial on a small number of healthy adult volunteers was performed to study the effects of a prolonged (30 days) supplementation with 400 mg of green coffee bean extract. The 24-h urinary samples were collected weekly, and analyzed by LC-MS. Multivariate data analysis approaches were applied and also targeted analysis were performed to measure urinary oxidative stress biomarkers, namely allantoin and 8-hydroxydeoxyguanosine (8-OHdG), in order to assess the potential antioxidant activity of GCBE in vivo
Supplementation with resveratrol as Polygonum cuspidatum Sieb. et Zucc. extract induces changes in the excretion of urinary markers associated to aging in rats
No full textPhytochemical analysis of the labdanum-poor Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy
No full textPhenolic constituents and essential oil from the aerial parts of Cistus creticus subsp. eriocephalus (Viv.) Greuter et Burdet growing in central Italy were analysed by HPLC-MSn and GC-MS, respectively. Furthermore, six constituents were isolated by semipreparative HPLC from the methanol extract and their structures were determined on the basis of 1D and 2D NMR measurements as well as MS spectra. Isolated compounds were one new natural product, i.e. the shikimic acid ester 3,5-diihydroxy-4-(O-β-d-glucopyranosyl)-cyclohex-1-en-1-(O-β-d-glucopyranosyl)-ester (27), and six flavonoid glycosides, namely quercetin-3-O-β-D glucopyranoside (16), quercetin-3-O-rhamnoside (17), tricetin-4'-O-β-D glucopyranoside (24), tricetin-4'-O-β-D rutinoside (21), 3'-methoxy-quercetin-3-O-(3-β-Dglucopyranosyl-2-rhamnopyranosil-4-glucopyranosyl-2-rhamnopyranosil)-glucoside (25) and 3',4'dimethoxyquercetin-3-O-rhamnopyranoside (26). GC-MS analysis of the essential oil highlighted the occurrence of aliphatic compounds, mainly fatty acids, whereas labdane-type compounds were very scant. Our results showed that C. creticus subsp. eriocephalus has a different chemical profile with respect to the other subspecies due to the lack of labdane derivatives. On the other hand, this subspecies contains several phenolic constituents like ellagitannins, gallotannins and flavonoids, some of which can be of chemotaxonomic valu
Nutraceuticals, a new challenge for medicinal chemistry
No full text"Nutraceuticals" are food-derived products largely used for their presumed health-promoting or disease-preventing effects. In recent years, many efforts have been aimed at assessing nutraceutical efficacy and safety, but these factors are difficult to address because of the complex chemical compositions and multiple mode of actions. Thus, the study of nutraceutical ingredients poses several challenges for the medicinal chemistry field, some of which are related to extraction and chemical characterization, some to in vitro and in vivo bioactivity evaluation, and some to the bioavailability and interaction of these natural mixtures with organs and microbiota. Furthermore, because of their nature as medicinal and food products, these nutraceuticals can also be considered as a valuable source of new "lead compounds", creating the opportunity to discover new classes of therapeutic agents. This review provides information on these themes, showing the new challenges that comprehensive medicinal chemistry research is called to answer in the field of nutraceuticals
Development and validation of an HPLC-ELSD method for the quantification of 1-triacontanol in solid and liquid samples
Full text link1-Triacontanol (TRIA) is gaining a lot of interest in agricultural practice due to its use as bio-stimulant and different types of TRIA-containing products have been presented on the market. Up to date, TRIA determination is performed by GC analysis after chemical derivatization, but in aqueous samples containing low amounts of TRIA determination can be problematic and the derivatization step can be troublesome. Hence, there is the need for an analysis method without derivatization. TRIA-based products are in general plant extracts that can be obtained with different extraction procedures. These products can contain different ranges of concentration of TRIA from units to thousands of mg/kg. Thus, there is the need for a method that can be applied to different sample matrices like plant materials and different plant extracts. In this paper we present a HPLC-ELSD method for the analysis of TRIA without derivatization. The method has been fully validated and it has been tested analyzing the content of TRIA in different dried vegetal matrices, plant extracts, and products. The method is characterized by high sensitivity (LOD = 0.2 mg/L, LOQ = 0.6 mg/L) and good precision (intra-day: <11.2%, inter-day: 10.2%) being suitable for routine analysis of this fatty alcohol both for quality control or research purposes
The antiadhesive activity of cranberry phytocomplex studied by metabolomics: Intestinal PAC-A metabolites but not intact PAC-A are identified as markers in active urines against uropathogenic Escherichia coli
No full textCranberry procyanidins and quercetin derivatives are considered possible active compounds against urinary tract infections (UTIs). In this paper a small group (n = 6) of healthy subjects consumed a product containing 360 mg of cranberry extract (42.6% w/w of PAC-A and 14.6% w/w of PAC-B) and 200 mg of quercetin. Urine samples were collected after 2,4,6,8, and 24 h. The changes in antiadhesive properties against urophatogenic E. coli of the urinary output were determined in vitro and modification to urinary metabolome were studied by LC-MS. Significant antiadhesive properties of urine samples were observed, with the greatest effect 6–8 h after oral administration, confirming the possible usefulness of cranberry containing products in urinary tract infections (UTI). Metabolomic analysis revealed that valeric acid and valerolactone derivatives that were detected in 6 and 8 h sample, while 4-hydroxy-5-(phenyl)-valeric acid-O-glucuronide and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone at 6 h and 4-hydroxy-5-(phenyl)-valeric acid-O-sulphate, 3-hydroxyphenyl-valeric acid, 5-(4′-hydroxyphenyl)-gamma-valerolactone-4′-O-glucuronide and 4-hydroxy-5-(3′-hydroxyphenyl)-valeric acid-3′-O-sulphate were the most abundant at 8 h. The present study shows that the antiadhesive properties of urine sample after cranberry consumption are not ascribable to the direct effect of PAC-A, because their levels in urinary output are in the range of ng/mL. On the other hand, significant metabolites that were detected are mainly metabolites of intestinal action on polyphenols and PACs, as well as glucuronidated and sulphated quercetin, suggesting an important role of intestinal modification of phytoconstituents in the cranberry extract mechanism of action
Chemical composition and antibacterial activity of essential oils from Daucus sahariensis Murb. roots and stems
No full textDaucus genus (Apiaceae) comprises economically relevant plants distributed in temperate regions. These plants are used mainly as food but are also known for their biological properties. Here, the essential oils (EOs) obtained by hydro-distillation of roots and stems of D.sahariensis Murb. growing in Algerian Sahara were studied by GC-MS analysis. Fifty-two and fifty-five compounds were identified from the roots and stems, representing 95.1% and 93.8% of the whole EOs respectively. The main constituents of the EO from roots were myristicin (29.2%), (E)-anethole (14.2%), cis-chrysanthenyl acetate (8%) and estragol (7.5%). In the EO from stems, the main constituents were α-pinene (18.6%), myrcene (16.7%), limonene (13.7%) and myristicin (8%). The antibacterial activity of EOs was evaluated by disc diffusion method and tested against Gram-positive and Gram-negative bacteria. Results showed a mild activity against Bacillus subtilis and Klebsiella pneumoniae for both EOs, which can be potentially used as antibacterial in phytotherapy
Total phytochemical analysis of Thymus munbyanus subsp. coloratus from Algeria by HS-SPME-GC-MS, NMR and HPLC-MSn studies
Full text linkIn this article, we report a comprehensive characterization of volatile and polar constituents extracted from the aerial parts of Thymus munbyanus subsp. coloratus, a shrub that is used as culinary ingredient and as traditional medicine in Algeria, mainly to treat respiratory and gastrointestinal disorders and endocrine dysfunctions. Headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to assess volatile constituents, whereas the phytochemical composition of solid residues obtained from extraction with solvents at diffrent polarity was obtained by an integrated Nuclear Magnetic Resonance (NMR) and liquid chromatography coupled with tandem mass spectrometry (LC-MSn) approach. Fourty-five apolar ccompounds were identified, mainly oxygenated monoterpenes (65.8%), sesquiterpene hydrocarbons and nonoterpene hydrocarbons (18.6 and 14.5%, respectively). On the other hand, LC-MSn and NMR analyses revealed the presence of aglyconic and glycosilated flavonoids, phenylpropanoid derivatives and triterpenoid acids related to oleanolic acid, mainly in the methanol, dichloromethane and hexane extracts. Overall, these data indicate that Thymus munbyanus subsp. coloratus could be a potential source of antioxidants and bioactive compounds, and our results represent a starting point for further research on this plant species
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