LC-MS, if the ionization technique is chosen appropriately, can be an extremely powerful and informative tool for screening crude plant extracts. The currently available various selleck chem inhibitor types of LC-MS systems allow the analysis of small nonpolar compounds to large polar constituents like oligosaccharides, proteins, and tannins present in natural product extracts. Alkaloids Alkaloids are a large group of nitrogen-containing secondary metabolites of plant, microbial, or animal origin. Various hyphenated techniques have been used in the analysis of several types of alkaloids to date. With the development and wider availability of bench-top systems, GC-MS has become the method of choice for the analysis of various pyrolizidine and quinolizidine types of alkaloids.
Quinolizidine alkaloids, the main class of alkaloids found in the family Leguminosae, have been analyzed by GC-MS recently. Most of these alkaloids are sufficiently volatile and thermostable under GC conditions to permit analysis without chemical modification. However, some hydroxylated pyrolizidine alkaloids need to be analyzed as their trimethylsilyl derivatives. Ephedrine-type alkaloids, in dietary supplements containing the Chinese herb ma huang, were analyzed by GC-MS and GC-FTIR. A number of protoberberine metabolites, differing in the number and the placement of various oxygen functions on the aromatic rings, have been identified prior to isolation from the Corydalis cell cultures by LC-NMR and LC-MS.
 This study provided the preliminary evidence for biosynthetic pathways to the formation of these alkaloids, especially the metabolic pathway to 2, 3, 10, 11-oxygenated tetrahydroprotoberberines in cultured cells. An APCI interface was used in the LC-MS system, and the mass spectra were obtained with selected ion monitoring (SIM) and total ion monitoring (TIM) in the positive ion mode. Molecular ion information was obtained on the basis of protonated molecular ion [M + H]+ or a cluster ion [M + HCF3]+. The LC-NMR analysis was carried out on a Varian UNITY-INOVA-500 NMR spectrometer equipped with a PFG indirect detection LC-NMR probe with a 60 mL flow cell, using stop-flow mode. The LC operation was performed on a Cosmosil 5 C18-AR (4.6 �� 150 mm) reversed-phase column, using a mobile phase composed of solvent A ? 0.1 M NH4OAc (0.05% TAF) and solvent B ? ACN.
A gradient elution protocol was adopted as follows: 20�C30% B in 10 min, 30% B in 10 min, and 30�C155% B in 10 min, flow rate 1 mL/min, Drug_discovery detection at 280 nm. Coumarins The coumarins are the largest class of 1-benzopyran derivatives that are found mainly in higher plants. HPLC-PDA can be used successfully in the analysis of various phenolic compounds, including coumarins, because of the presence of significant amounts of chromophores in these molecules.