HPLC Determination of Three Main Components of Rhododendron dauricum L.and Their Relaxing Effects on Rat Tracheal Smooth Muscle
[Objective]To establish a method for the simultaneous determination of hyperin,quercetin and farrerol in Rhododendron dauricum by HPLC,and to discuss the effects of Rhododendron dauricum extract and its three main components on the relaxation of rat tracheal smooth muscle and the mechanism.[Method]The contents of hypericin,quercetin and farrerol in Rhododendron dauricum were determined by HPLC and the methodology was investigated.Rat tracheal rings were obtained by in vivo air tube perfusion method,and fixed in a Mack's bath.The tracheal rings were pre-incubated with chlorphenamine,indometacin,glibenclamide,L-nitroarginine methyl ester(L-NAME),nifedipine and propranolol.After the tension of the tracheal ring stabilized,60 mmol/L KCl solution was added to shrink the tracheal ring.The relaxation ex-periment of tracheal ring by Rhododendron dauricum was conducted to observe the changes of tracheal smooth muscle tension in rats.[Result]The investigation results of the HPLC determination method for three main components in Rhododendron dauricum showed that the linear rela-tionship between the three components was good in the range of 2-80 μg/mL.The average recovery rates were 100.3%(RSD=2.63%)of hypericin,102.7%(RSD=2.89%)of quercetin and 102.1%(RSD=2.36%)of farrerol.The diastolic effects of the extract and the three main components of Rhododendron dauricum in the incubated tissue of indometacin,glibenclamide and propranolol were not significantly differ-ent from those in the unincubated group.The diastolic effects of Rhododendron dauricum and hypericin in the tissues incubated with chlorphen-amine,L-NAME and nifedipine were significantly different from those in the unincubated tissues.This phenomenon may be achieved through inhibition of histamine H1 receptors,nitric oxide synthase pathways,and calcium channel mediated calcium influx.[Conclusion]The estab-lished method is simple,accurate,and can quickly determine the content of hypericin,quercetin and farrerol in Rhododendron dauricum,pro-viding an effective analytical means for quality evaluation and control.In addition,these three components are related to the effect of diastolic trachea of Rhododendron dauricum L.,and can be used as a theoretical basis for the development of bronchodilators.
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