The Investigation Of Anti-hypertension Components In Various Parts Of Hawthorn (Crateagus Pinnatifida)

Hawthorn（Crateagus pinnatifida） is rich in flavonoids which have potent activities in reducing blood pressure.The preliminary results of the investigations in various fractions of Hawthorn extracts in lowering blood pressure activity are summarized in this thesis.Such study is very important in discovering and developing novel anti-hypertension pharmaceuticals.Utilizing the ACE-HHL-ACEI system,the content of Hip in the enzyme-substrate system was quantified using High Performance Liquid Chromatography（HPLC）.The ACE inhibition activity was examined.The methodology has been evaluated.Using ACE as the target enzyme,20 common traditional Chinese medicines have also been screened for anti-hypertension activities.Various fractions from Hawthorn have been examined for ACE inhibition activities,utilizing the activity directed fractionation methodology.The active components have been separated,purified and qualitatively identified.The anti-hypertension activities of the active components were examined on animal models.The results are documented in this thesis.HPLC in the evaluation of active components in traditional Chinese medicines for ACE inhibition has been demonstrated to be a simple,fast,robust,accurate,and precise technique.For the 20 common traditional Chinese medicine screened,the 100%ethanol extract from Hawthorn exhibited a potent activity with an IC50 of 9.50 mg/mL.Thus,additional investigation with Hawthorn in the inhibition of ACE was carried out.The active components were separated and purified.Summarized below are the isolation and purification of active components in Hawthorn:First, the ethanol extracts of Hawthorn were separated using D101 macroporous adsorptive resins. Compared to other fractions,the 100%methanol eluted fraction has demonstrated the highest inhibition activities.Then,petroleum ether,ethyl acetate,and acetone were used for further separations.It was found that the acetone fraction contains the highest ACE inhibition activity, which was further purified using silica gel columns.The fractions eluted using dichloromethane:ethanol（50:50;V/V）showed highest activities.However,using semi prep-HPLC, 8 fractions were collected and the inhibition activities for all 8 fractions are significantly decreased compare to the dichloromethane:ethanol（50:50;V/V） eluents.Thus,it has been demonstrated that the active components are in the dichloromethane:ethanol（50:50;V/V） eluted fractions and the IC₅₀ determined to be 46.9μg/mL。Qualitative evaluation of the active fraction found that flavanoids are the major components in the fraction.The active fractions of Hawthorn have shown significant high blood pressure reduction activities in animal models.The blood pressure reduction is rather gradual and the low blood pressure can be maintained effectively.