172 research outputs found
Analytical methods for the study of bioactive compounds from medicinally used Echinacea species
No full textEchinacea purpurea (L.) Moench, Echinacea angustifolia DC. var. angustifolia and Echinacea pallida (Nutt.) Nutt. are frequently used as medicinal plants and their preparations are among the most widely used herbal medicines. The extracts from these species have shown a highly complex chemical composition, including polar compounds (caffeic acid derivatives, CADs), non-polar compounds (alkylamides and acetylenic secondary metabolites; essential oil) and high molecular weight constituents (polysaccharides and glycoproteins). All these chemical classes of compounds have demonstrated to possess interesting biological activities. In the light of all the above, this paper is focused on the analytical techniques, including sample preparation tools and chromatographic procedures, for the chemical analysis of bioactive compounds in medicinally used Echinacea species. Since sample preparation is considered to be a crucial step in the development of analytical methods for the determination of constituents present in herbal preparations, the strength and weakness of different extraction techniques are discussed. As regards the analysis of compounds present in Echinacea plant material and derivatives, the application of different techniques, mainly HPLC, HPLC-ESI-MS, HPLC-ESI-MS/MS, HPCE, HPTLC and GC, is discussed in detail. The strength, weakness and applicability of the different separation tools are stated.Echinacea purpurea (L.) Moench, Echinacea angustifolia DC. var. angustifolia and Echinacea pallida (Nutt.) Nutt. are frequently used as medicinal plants and their preparations are among the most widely used herbal medicines. The extracts from these species have shown a highly complex chemical composition, including polar compounds (caffeic acid derivatives, CADs), non-polar compounds (alkylamides and acetylenic secondary metabolites; essential oil) and high molecular weight constituents (polysaccharides and glycoproteins). All these chemical classes of compounds have demonstrated to possess interesting biological activities. In the light of all the above, this paper is focused on the analytical techniques, including sample preparation tools and chromatographic procedures, for the chemical analysis of bioactive compounds in medicinally used Echinacea species. Since sample preparation is considered to be a crucial step in the development of analytical methods for the determination of constituents present in herbal preparations, the strength and weakness of different extraction techniques are discussed. As regards the analysis of compounds present in Echinacea plant material and derivatives, the application of different techniques, mainly HPLC, HPLC-ESI-MS, HPLC-ESI-MS/MS, HPCE, HPTLC and GC, is discussed in detail. The strength, weakness and applicability of the different separation tools are stated
Biochemometrics for Natural Products Research: Comparison of Data Analysis Approaches and Application to Identification of Bioactive Compounds
No full text[The original abstract for this article contains images that cannot be displayed here. Please click on the link below to read the full abstract and article.]]]>
2016
English
http://libres.uncg.edu/ir/uncg/f/H_Raja_Biochemometrics_2016.pdf
oai:libres.uncg.edu/25296
2021-02-21T08:40:34Z
UNCG
Mycopyranone: A 8,8'-binaphthopyranone with potent anti-MRSA activity from the fungus Phialemoniopsis sp.
Cech, Nadja B.
NC DOCKS at The University of North Carolina at Greensboro
Oberlies, Nicholas
Raja, Huzefa A.
2019
English
http://libres.uncg.edu/ir/uncg/f/H_Raja_Mycopyranone_2019.pdf
oai:libres.uncg.edu/25297
2020-02-07T08:29:13Z
UNCG
Prenylated Diresorcinols Inhibit Bacterial Quorum Sensing
Cech, Nadja B.
Figueroa Saldivar, Mario
NC DOCKS at The University of North Carolina at Greensboro
Oberlies, Nicholas
Raja, Huzefa A.
Todd, Daniel A.
2019
English
http://libres.uncg.edu/ir/uncg/f/H_Raja_Prenylated_2019.pdf
oai:libres.uncg.edu/25298
2019-03-15T10:30:56Z
UNCG
The Old Hippie and The College Graduate
Adams, Rebecca G.
NC DOCKS at The University of North Carolina at Greensboro
<
No full textDespite the value of mass spectrometry in modern natural products discovery workflows, it remains very difficult to compare data sets between laboratories. In this study we compared mass spectrometry data for the same sample set from two different laboratories (quadrupole time-of-flight and quadrupole-Orbitrap) and evaluated the similarity between these two data sets in terms of both mass spectrometry features and their ability to describe the chemical composition of the sample set. Somewhat surprisingly, the two data sets, collected with appropriate controls and replication, had very low feature overlap (25.7% of Laboratory A features overlapping 21.8% of Laboratory B features). Our data clearly demonstrate that differences in fragmentation, charge state, and adduct formation in the ionization source are a major underlying cause for these differences. Consistent with other recent literature, these findings challenge the conventional wisdom that electrospray ionization mass spectrometry (ESI-MS) yields a simple one-to-one correspondence between analytes in solution and features in the data set. Importantly, despite low overlap in feature lists, principal component analysis (PCA) generated qualitatively similar PCA plots. Overall, our findings demonstrate that comparing untargeted metabolomics data between laboratories is challenging, but that data sets with low feature overlap can yield the same qualitative description of a sample set using PCA
Maplexins, new a-glucosidase inhibitors from red maple (Acer rubrum) stems
No full textThirteen gallic acid derivatives including five new gallotannins, named maplexins A–E, were isolated from red maple (Acer rubrum) stems. The compounds were identified by spectral analyses. The maplexins varied in number and location of galloyl groups attached to 1,5-anhydro-d-glucitol. The isolates were evaluated for a-glucosidase inhibitory and antioxidant activities. Maplexin E, the first compound identified with three galloyl groups linked to three different positions of 1,5-anhydro-d-glucitol, was 20 fold more potent than the a-glucosidase inhibitory drug, Acarbose (IC50 = 8 vs 160 µM). Structure–activity related studies suggested that both number and position of galloyls attached to 1,5-anhydro-d-glucitol were important for a-glucosidase inhibition.Graphical abstractThirteen gallic acid derivatives, including five new gallotannins, 2, 3, 5, 6, 9, assigned the common names of maplexins A–E, respectively, were isolated from red maple stems. The isolates were evaluated for a-glucosidase inhibitory and antioxidant activities in vitro. [The original abstract for this article contains an image that cannot be displayed here. Please click on the link below to read the full abstract and article.]]]>
2012
English
http://libres.uncg.edu/ir/uncg/f/N_Cech_Maplexins_2012.pdf
oai:libres.uncg.edu/17449
2014-12-02T15:18:25Z
UNCG
Inhibition of H1N1 influenza A virus growth and induction of inflammatory mediators by the isoquinoline alkaloid berberine and extracts of goldenseal (Hydrastis canadensis)
Cech, Nadja B.
NC DOCKS at The University of North Carolina at Greensboro
<
No full text
Relative Importance of Basicity in the Gas Phase and in Solution for Determining Selectivity in Electrospray Ionization Mass Spectrometry
No full textElectrospray ionization mass spectrometry is a critically important technique for the determination of small molecules, but its application for this purpose is complicated by its selectivity. For positive ion ESI-MS analysis of basic analytes, several investigators have pointed to the importance of analyte basicity as a source of selectivity. Currently, however, it is not known whether basicity in the gas phase or in solution is ultimately most important in determining responsiveness. The objective of these studies was to investigate the relative importance of basicity in solution and in the gas phase as factors that predict selectivity in positive ion ESI-MS analysis. ESI-MS response was compared for a diverse series of protonatable analytes in two different solvents, neat methanol and methanol with 0.5% acetic acid. A correlation was observed between analyte pKb and electrospray response. However, the response for the analytes with very high pKb values was significantly higher than would be expected based on concentration of the protonated form or the analyte in solution, and this higher response did not appear to result from gas-phase proton transfer reactions. Although all of the analytes investigated had higher gas-phase basicities than the solvent, their relative responses were not dictated by gas-phase basicity. Higher response was observed for all of the analytes studied in acidified methanol compared with neat methanol, and this higher response was most pronounced for weakly basic analytes. These findings support the use of analyte pKb for rational method development in ESI-MS analysis of small molecules
- …
