Validation of an UPLC-PDA Method for the Simultaneous Quantification of 4-Phenylcoumarins and Chlorogenic Acid in Exostema caribaeum Stem-Bark

The stem-bark of Exostema caribaeum (Rubiaceae) is widely used in Mexican folk medicine for treating diabetes and malaria. Previous investigations revealed that the active principles of the plant are 4-phenylcoumarins. Hence, a simple and reliable chromatographic method useful for quality control procedures of this valuable herb using UPLC-PDA was developed and validated according to the International Conference on Harmonization (ICH). The method allows simultaneous quantification of 4-phenylcoumarins (2-8) and chlorogenic acid (1) in the crude drug. During this process a new 4-phenylcoumarin (2) was isolated and characterized using 1D and 2D-NMR analyses.

	R 1	R 2
2	H	β-D-xylopyranosyl-(1→6)-β-D-glucopyranosyl
3	H	β-D-glucopyranosyl
4	CH3	β-D-xylopyranosyl-(1→6)-β-D-glucopyranosyl
5	CH3	β-D-galactopyranosyl
6	CH3	β-D-glucopyranosyl
7	H	6''-acetyl-β-D-glucopyranosyl
8	CH3	6''-acetyl-β-D-galactopyranosyl