Antioxidant activity relationship of phenolic compounds in Hypericum perforatum L.

<p>Abstract</p> <p>Background</p> <p>The St John's Wort (<it>Hypericum perforatum</it>; Clusiaceae) has been used in traditional and modern medicine for a long time due to its high content of biologically active phenolics. The purpose of this work was to develop a method for their fractionation and identification, and to determine the most active antioxidant compounds in plant extract.</p> <p>Results</p> <p>An LC-MS method which enables fast qualitative and semiquantitative analysis was developed. The composition determined is in agreement with the previous results, where 6 flavonoids, 4 naphthodianthrones and 4 phloroglucinols have been identified. Significant antioxidant activity was determined for most of the fractions by DPPH assay (the lowest IC₅₀of 0.52 μg/ml), NO scavenging (6.11 μg/ml), superoxide scavenging (1.86 μg/ml), lipid peroxidation (0.0079 μg/ml) and FRAP (the highest reduction capacity of 104 mg Fe equivalents/g) assays.</p> <p>Conclusion</p> <p>LC-MS technique has been successfully applied for a quick separation and identification of the major components of <it>H. perforatum </it>fractions. Majority of the fractions analyzed have expressed a very high antioxidative activity when compared to synthetic antioxidants. The antioxidant activity could be attributed to flavonoids and phenolic acids, while phloroglucinols and naphthodianthrones showed no significant activity. It is demonstrated that it is possible to obtain, by fractionation, <it>H. perforatum </it>preparations with significantly increased phloroglucinols-to-naphthodianthrones ratio (up to 95:5).</p

1H NMR-based metabolomics combined with HPLC-PDA-MS-SPE-NMR for investigation of standardized Ginkgo biloba preparations

Commercial preparations of Ginkgo biloba are very complex mixtures prepared from raw leaf extracts by a series of extraction and prepurification steps. The pharmacological activity is attributed to a number of flavonoid glycosides and unique terpene trilactones (TTLs), with largely uncharacterized pharmacological profiles on targets involved in neurological disorders. It is therefore important to complement existing targeted analytical methods for analysis of Ginkgo biloba preparations with alternative technology platforms for their comprehensive and global characterization. In this work, 1H NMR-based metabolomics and hyphenation of high-performance liquid chromatography, photo-diode array detection, mass spectrometry, solid-phase extraction, and nuclear magnetic resonance spectroscopy (HPLC-PDA-MS-SPE-NMR) were used for investigation of 16 commercially available preparations of Ginkgo biloba. The standardized extracts originated from Denmark, Italy, Sweden, and United Kingdom, and the results show that 1H NMR spectra allow simultaneous assessment of the content as well as identity of flavonoid glycosides and TTLs based on a very simple sample-preparation procedure consisting of extraction, evaporation and reconstitution in acetone-d6. Unexpected or unwanted extract constituents were also easily identified in the 1H NMR spectra, which contrasts traditional methods that depend on UV absorption or MS ionizability and usually require availability of reference standards. Automated integration of 1H NMR spectral segments (buckets or bins of 0.02 ppm width) provides relative distribution plots of TTLs based on their H-12 resonances. The present study shows that 1H NMR-based metabolomics is an attractive method for non-selective and comprehensive analysis of Ginkgo extracts

Analysis of the marker compounds of Rhodiola rosea L. (golden root) by reversed phase high performance liquid chromatography

WOS: 000167818100020PubMed ID: 11310675An HPLC method permitting the first simultaneous detection of 5 marker compounds (salidroside, rosarin, rosavin, rosin, rosiridin) of R, rosea was developed, A separation was achieved within 27 min by using C-18 column material, a phosphate buffer/acetonitrile gradient system and at a separation temperature of 60 degreesC. All five compounds could be detected at concentrations as low as 0.62 mug/ml and were clearly assignable in R. rosea plant material and commercial products. Therefore, this quantitative and qualitative applicability of the method offers efficient and reliable means for the evaluation of R. rosea and products thereof

Quantitative analysis of pungent and anti-inflammatory phenolic compounds in olive oil by capillary electrophoresis

The first CE procedure for the quantitative determination of pharmacologically relevant secoiridoids in olive oil, oleocanthal and oleacein, is described. Together with their precursors tyrosol and hydroxytyrosol they could be baseline separated in less than 15 min using a borax buffer with pH 9.5, at 25 kV and 30 °C. Method validation confirmed that the procedure is selective, accurate (recovery rates from 94.0 to 104.6%), reproducible (σmax ≤ 6.8%) and precise (inter-day precision ≤ 6.4%), and that the compounds do not degrade quickly if non-aqueous acetonitrile is used as solvent. Quantitative results indicated a low occurrence of oleocanthal (0.004-0.021%) and oleacein (0.002-0.048%) in olive oil samples, which is in agreement to published HPLC data. The CE method impresses with its simple instrumental and methodological design, combined with reproducible and valid quantitative results. © 2014 Elsevier Ltd. All rights reserved