Qualitative and quantitative analysis of amorfrutins, novel antidiabetic dietary natural products, by HPLC

Context: Initially isolated from fruits of Amorpha fruticosa L. (Fabaceae), amorfrutins are promising antidiabetic natural products as selective peroxisome proliferator-activated receptor gamma-agonists. Objective: The objective of this study is to develop a sensitive and convenient HPLC method to analysis amorfrutins in plant materials derived from genera Amorpha and Glycyrrhiza. Materials and methods: The reference compounds were isolated from fruits of A. fruticosa and characterized by UV, HR-ESI-MS, and NMR spectrometric techniques. Three amorfrutins were analyzed by HPLC on a Hypersil BDS C18 column (Waters Corporation, Milford, MA) within a gradient elution of acetonitrile and 0.2% glacial acetic acid. HR-ESI-MS spectra were acquired on a quadrupole-time-of-flight (Q-TOF) mass spectrometer. Results: Three amorfrutins showed good linearity (r(2)>0.999) in the ranges of 4.2-84.5, 4.5-90.2, and 4.6-92.7g/mL. The amorfrutins were only detected in fruits of A. fruticosa with the contents of 2-carboxy-3,5-dihydroxy-4-geranylbibenzyl, amorfrutin A, and amorfrutin B in the ranges of 1.31-7.43, 0.54-3.52, and 0.64-4.63mg/g, respectively. No amorfrutin was detected in fruits of Amorpha canescens Pursh and roots of Glycyrrhiza uralensis Fisch. (Fabaceae), Glycyrrhiza inflate Bat., or Glycyrrhiza glabra L. Discussion and conclusion: A novel HPLC method was developed, validated, and applied to identify and quantify amorfrutins in complex botanic matrixes and the characteristic MS fragmentation behaviors of amorfrutins were revealed for the first time. The analytical method presented in this study could be used for the quality control of related plant materials and amorfrutin-based nutraceuticals.