Characterization of Corn Silk Extract Using HPLC/HRMS/MS Analyses and Bioinformatic Data Processing.

In addition to having different biological activities of interest, corn silks play a role in the defense of plants. While benzoxamines and flavonoids have already been identified as molecules of plant defense and growth mechanisms, knowledge on the phytochemical composition of corn silk is lacking. Such knowledge would make it possible to better select the most effective varieties to improve resistance or bioactive properties. In this article, an approach was implemented to map a corn silk extract in two complementary ways. The first one involved working with UHPLC/HRMS data and Kendrick and van Krevelen plots to highlight a homologous series of compounds, such as lipids from 17 to 23 carbons, monoglycosylated flavonoids from 21 to 24 carbons, diglycosylated flavonoids of 26 to 28 carbons and organic acids of 14 to 19 carbons. The second way was to analyze the sample in UHPLC/HRMS2 and to plot mass spectral similarity networks with the GNPS platform and Cytoscape software to refine identification. By combining the information obtained, we were able to propose an identification for 104 detected molecules, including 7 nitrogenous, 28 lipidic and 67 phenolic compounds, leading to the first detailed phytochemical analysis of corn silk extract.

Centrifugal partition chromatography elution gradient for isolation of sesquiterpene lactones and flavonoids from Anvillea radiata.

An innovative procedure coupling pressurized solvent extraction and centrifugal partition chromatography (CPC) used in linear gradient elution mode was developed to isolate two pure germacranolides (9α-hydroxyparthenolide and 9ß-hydroxyparthenolide) and to separate flavonoids (nepetin, isorhamnetin and jaceosidin) and chlorophyll pigments from aerial parts of Anvillea radiata (Coss.&Durieu). The two main germacranolides recovered using this method represent 2 and 5% of the dried plant material respectively. These molecules were extracted using accelerated solvent extraction with chloroform. After optimization of the CPC method, a two-phase solvent system composed of heptane/ethyl acetate/methanol/water (1:5:1:5 v/v/v/v) was employed in descending mode to isolate the germacranolides. Then the lower phase of a heptane/ethyl acetate/methanol/water (6:5:6:5 v/v/v/v) system was pumped in descending mode to generate a linear elution gradient, progressively decreasing the mobile phase polarity, that enabled the flavonoid compounds to be separated in the same run. The efficiency of the preparative separation was controlled through RP-HPLC analysis of the obtained fractions using UV, evaporative light scattering and mass spectrometry detection. The structural identification of the two germacranolides purified over 99% was established by (1)H NMR and (13)C NMR. The least abundant flavonoids were identified by mass spectrometry.

Investigations on the chromatographic behaviour of zwitterionic stationary phases used in hydrophilic interaction chromatography.

Two commercial stationary phases possessing a sulfobetaine zwitterionic bonded ligand (ZIC-HILIC and Nucleodur HILIC) were compared under hydrophilic interaction chromatographic (HILIC) conditions. First of all, the separation of 12 model compounds chosen among neurotransmitters and presenting a diversity of ionization states (anionic, cationic and zwitterionic) was studied under varied operating conditions. The effects of the percentage of acetonitrile, ammonium acetate concentration and temperature of the mobile phase were compared on the two columns. Secondly, a generally applicable retention model was established, based on chromatographic retention data (logk) acquired for 76 model compounds. The chosen compounds are small molecules presenting a wide diversity of molecular structures and are relevant to biomedical and pharmaceutical studies. To account for their retention behaviour, a modified version of the solvation parameter model was designed: two additional molecular descriptors were introduced, to account for ionic interactions with anionic and cationic species. The retention equations obtained allow a rationalization of the interactions contributing to retention and separation in the HILIC systems considered.