Combining high-speed countercurrent chromatography three-phase solvent system with electrospray ionization-mass spectrometry and nuclear magnetic resonance to profile the unconventional food plant Syzygium malaccense.

Syzygium malaccense (L.) Merr. & L.M. Perry is a native tree to Malaysia, but also occurs in other tropical regions of the world, including Brazil. The increasing interest in the consumption of its leaves motivated the investigation of compounds of the plant. Metabolite profiling of S. malaccense leaves was achieved by high-speed countercurrent chromatography (HSCCC) fractionation coupled off-line to electrospray mass-spectrometry (ESI-MS) detection and nuclear magnetic resonance (NMR) analysis. The ethanolic leaf extract was submitted to HSCCC using a three-phase solvent system (TPSS) composed by n-hexane - ethyl acetate - acetonitrile - H2O (2:1:1:1, v/v). The stepwise gradient elution was employed due to the extract's chemical complexity. HSCCC fractions were further analyzed by ESI-MS/MS using a flow injection experiment and by NMR acquiring 1H, HSQC and HMBC spectra. MS based dereplication was achieved by comparing acquired data to those available in public and commercial databases. Results were also correlated to previously isolated compounds described for the Syzygium genus. This process led to the annotation of 90 compounds. The NMR data provided structural confirmation and substitution patterns for some of them. Extract chemical composition is characterized by having flavonoids, benzoic acids, hydroxycinnamic acids, quinic acids, hydrolizable tannins, fatty acids, anacardic acids and others primary metabolites. Most of these compounds were described for the first time in the plant. This approach greatly facilitates phytochemical analysis and could be applied to improve metabolite discovery in other studies.

Synthetic Peptide Purification via Solid-Phase Extraction with Gradient Elution: A Simple, Economical, Fast, and Efficient Methodology.

A methodology was implemented for purifying peptides in one chromatographic run via solid-phase extraction (SPE), reverse phase mode (RP), and gradient elution, obtaining high-purity products with good yields. Crude peptides were analyzed by reverse phase high performance liquid chromatography and a new mathematical model based on its retention time was developed in order to predict the percentage of organic modifier in which the peptide will elute in RP-SPE. This information was used for designing the elution program of each molecule. It was possible to purify peptides with different physicochemical properties, showing that this method is versatile and requires low solvent consumption, making it the least polluting one. Reverse phase-SPE can easily be routinely implemented. It is an alternative to enrich and purified synthetic or natural molecules.