Bioactivity-guided fractionation of the volatile oil of Angelica sinensis radix designed to preserve the synergistic effects of the mixture followed by identification of the active principles.

In natural product research, it is a common experience that fractionation of biologically-active crude extracts can lead to the loss of their original activity. This is attributed to synergistic effects, where two or more components are required to be present together for full activity of the sample. Our previous study showed that a volatile oil of Angelica sinensis radix (VOAS) inhibited endothelial cell proliferation in culture. Here we have used a bioactivity-guided fractionation method to preserve any synergistic effects of VOAS combining countercurrent chromatography (CCC), the MTS cell viability assay and gas chromatography (GC). Using a two-phase CCC solvent system (heptane-ethyl acetate-methanol-water at a volume ratio of 27:23:27:23%), forty-five fractions were isolated, nine of which exhibited anti-endothelial properties. GC analysis showed two bioactive alkylphthalides, Z-ligustilide and n-butylidenephthalide (BP) were the major compounds detected in the bioactive fractions, and were absent in non-bioactive fractions. Our results indicate that Z-ligustilide and BP are the main constituents responsible for the anti-endothelial properties of VOAS. This rapid and reliable approach in preserving sample activity while isolating and identifying its active compounds suggests that this protocol can be a powerful tool for drug discovery from natural products.

Improved hydrophilic interaction chromatography method for the identification and quantification of glucosinolates.

An improved hydrophilic interaction liquid chromatography (HILIC) method has been developed to separate members of a closely related family of chemoprotective phytochemicals called glucosinolates. This method exploits the emergence of a second generation of HILIC chemistry, using a silica-based permanently zwitterionic stationary phase. These columns are more robust, durable, and glucosinolates separations are more reproducible than with the original polyhydroxyethyl aspartamide columns. Furthermore, the HILIC system that we report herein permits much greater alteration of the mobile phase composition for customized separation of glucosinolates from plant extracts, across a wide spectrum of polarity.