The Evaluation And Research On Pharmacological Effects Of Loquat Flower As An Ethnopharmacy

As the new medicinal part of Eriobotrya japonica (Thunb.) Lindl., loquat flower has been applied to treat cough and asthma in fork for a very long history, which has also been recorded in Compendium of Materia Medica written by Li Shizhen in the Ming dynasty. And loquat flower, which is used widely among the Buyi in Guizhou and the Tujia in Hunan, could supplement the medicinal part of Eriobotrya japonica as well as make good use of herbal resources, possessed of significantly medical value and development potential. In recent years, the related studies have focused on chemical ingredients, extraction and purification techniques, pharmacological functions and developments. However, the problems, such as the vague effective dose, the unsystematic efficacy evaluation, etc., are still existed.Objective:To determine the equivalent dosage of loquat flower for the antitussive effect, and comprehensively evaluate the functions of antitussive, expectorant, antiasthma and anti-inflammatory.Methods:The mice models of saturated ammonia liquid-induced asthma had been applied to preliminarily screen the effective dose of loquat flower. Combined with the method of parallel dose-effect relationship, the dose-effect equation had been obtained for further making a decision about the equivalent dosage of the antitussive effect (theoretical value). Futhermore, based on the animal cough models induced by aturated ammonia liquid, citric acid, mechanical stimulation and electrical stimulation, the antitussive effect of the loquat flower extract had been systematically evaluated as well as PCA method had been used to compare the intensities of the different doses of loquat flower, eriobotryae folium, and listed Chinese patent medicines. Guinea pig models of isolated trachea in vitro and histamine-induced asthma had verified the anti-asthmatic effec of loquat flower; its expectorant function had been certified by the phenol red secretion method and the volumes of rat tracheal secretion drained; and the anti-inflammatory effects had been proved respectively by the mouse models of acute inflammation with increase of capillary permeability induced by intraperitoneal injection of acetic acid, with acute auricle swelling induced by dimethylbenzene and with the proliferation of granulation induced by cotton balling.Results:(1) The dose-effect relationship and its equation of antitussive action of loquat flower were revealed.The effective dose of the loquat flower extract for relieving a cough was 79.06mg～25000.OOmg (crude drugs)/kg/d, which enhanced the efficacy as the dosed increased. The dose-effect relationship, closed to double-S log-linear trend model, was consistent with dose-effect equation E =0.9735Dose/(26.3800+Dose)-0.4978Dose4.1370/(135.4580+Dose4.1370), and then the equivalent dose of the loquat flower extract was 501.22 mg (crude drug)/kg/d.(2) The equivalent dose of the loquat flower extract was identified.According to the theoretical derivation of dose-effect equation, the validity of loquat flower was confirmed, and overall evaluation of principal component analysis (PCA) finalized that adult daily dose (equivalent dose) of the loquat flower extract was 50mg (crude drug)/kg/d, that was 0.6g (extract)/d.(3) The effectiveness of folk medicine loquat flower was systematically evaluated.Integrated the pharmacodynamic evaluation system of multiple pathogenic factors (such as chemical, physical and electrical stimulation, etc.), multimodel animals (such as mice, guinea pigs, cats, etc.) and multi-pharmacological effects (such as antitussive, expectorant, antiasthma, anti-inflammatory, etc.), the results showed that in the dose range (31.25～1000 mg(crude drug)/kg/d), the loquat flower extract has significantlt antitussive, expectorant, antiasthmatic and anti-inflammatory effects, especially in the equivalent dose (adult daily dose of 50 mg (crude drug)/kg/ d).Conclusions:With obviously antitussive, expectorant, antiasthmatic and anti-inflammatory functions, folk medicine loquat flower consisted the dose-effect relationship and its adult daily dose (equivalent dose) was 50 mg (crude drug)/kg/d, which provided a reference for the effectiveness evaluation and the assessment of the equivalent dosage for folk medicine.Inovations(1) The approach of parallel dose-effect relationship was firstly applied to reveal the dose-effect relationship of loquat flower, and to establish the dose-effect equation.(2) PCA method was firstly carried out to comprehensively compare antitussive functions of the different doses of loquat flower, eriobotryae folium, and listed Chinese patent medicines.