Methods for differentiation and phytochemical investigation of Crataegus by nuclear magnetic resonance spectroscopy

Crataegus (hawthorn) is a genus of flowering, fruit-bearing, small-to-medium-sized trees native to northern temperate zones. Hawthorn has an extensive ethnobotany with numerous examples of use in the food and medicine of the Chinese, North American Aboriginals, and Europeans. Modern hawthorn natural health products (NHPs) are used for cardiovascular ailments and have shown promise for adjunctive therapy in treatment of chronic heart failure. Although many NHPs containing Crataegus are licensed for sale in Canada, and there is extensive ethnobotanical use, little is known about the potentially therapeutic phytochemistry of North American hawthorns. NHP monographs allow three Crataegus spp. for use in NHPs. Regulatory requirements demand that specifications for NHPs include identity of the source material. Hence, it is important that there are methods available to differentiate species and this is the rationale for the work in this thesis. The first objective of this thesis was to explore differentiation of Crataegus spp. by nuclear magnetic resonance (NMR) spectroscopy and multivariate data analysis (MVDA) of leaf extracts. Two European and two North American species were harvested in late summer 2008 from the same test farm and used in this study. The results suggest that we may best differentiate Crataegus spp. by 1D ¹H-PRESAT-NMR-acquired data that correlate to phenolic compounds. Multiple significance analysis methods were used to provide lists of potential biomarkers in the phenolics spectral region that may give insight to differential therapeutic effects of hawthorn NHPs. Machine learning was applied to chemometrics data and results correlated with and outperformed model accuracy in traditional methods of MVDA. The second objective of this thesis was to quantify flavonoids in the same samples. I found that vitexin and its derivatives were significantly more concentrated in the European leaves and rutin significantly more concentrated in the North American leaves. The concentrations of rutin and naringenin reported in this study are the highest reported for Crataegus. The results were validated by comparison to high performance liquid chromatography, which produced generally consistent results of mean concentrations as measured in the leaf extracts.Arts and Sciences, Irving K. Barber School of (Okanagan)Chemistry, Department of (Okanagan)Graduat