ABSTRACT
The HPLC enantiomeric separation of the racemic cularinoid alkaloids N-p-methoxy-1,alpha-dihydroaristoyagonine (1) and 4',5'-demethoxy-1,alpha-dihydroaristoyagonine (2) was accomplished using five chiral stationary phases (CSPs), some of them polysaccharide-derived ones. The molecular size and conjugative effect strongly affect the different enantioselectivity of the compounds 1 and 2 on the various CSPs investigated. Single enantiomers of 1 were isolated by repeated injections on an analytical HPLC column, and their circular dichroism spectra and optical rotations were measured. The cytotoxicity of the isolated enantiomers was measured on a human colon carcinoma cell line and compared with that of the racemic compound.
Subject(s)
Alkaloids/analysis , Chromatography, High Pressure Liquid/methods , Circular Dichroism/methods , Isoquinolines/analysis , Alkaloids/chemistry , Alkaloids/pharmacology , Cell Survival/drug effects , HT29 Cells , Humans , Isoquinolines/chemistry , Isoquinolines/pharmacology , Reproducibility of Results , StereoisomerismABSTRACT
Naringin is the chief flavanone glycoside of grapefruit (Citrus paradisi). It is responsible for part of the bitter taste of the fruit and can cause the inhibition of some cytochrome P450s. The direct separation of (2R)- and (2S)-naringin in the albedo of grapefruits was obtained in normal phase HPLC mode using Chiralcel OD as chiral stationary phase and n-hexane/ethanol with 0.1% of TFA as mobile phase. Chiralpak AD was almost ineffective in the separation. This procedure was used to evaluate the stereochemistry at C-2 during maturation of the grapefruit. The CD curves of (2R)- and (2S)-naringin isolated by semipreparative chiral HPLC were determined and the elution order of the chromatographic peaks was related to the absolute C-2 configuration. Partial resolution of the C-2 diastereomers of narirutin was obtained on Chiralpak AD.
Subject(s)
Antioxidants/chemistry , Citrus paradisi/growth & development , Citrus paradisi/metabolism , Flavanones/chemistry , Antioxidants/isolation & purification , Chromatography, High Pressure Liquid , Circular Dichroism , Flavanones/isolation & purification , Reproducibility of Results , StereoisomerismABSTRACT
The HPLC enantiomeric separation of racemic and non-racemic samples of dimethyl alpha-hydroxyfarnesylphosphonate (1) was accomplished using Chiralcel OD as chiral stationary phase. Single enantiomers were isolated by semipreparative HPLC and their CD spectra and optical rotations were measured. The method ascertains enantiomeric excess of 1, obtained by oxidation of dimethylfarnesylphosphonate with enantiopure oxaziridines, avoiding converting the enantiomers to diastereomers by the use of a chiral auxiliary. Stability of the solutions of 1 is strongly dependent on the nature of the solvent.
