The Structural Modification And Anti-asthma Evaluation Of Natural Product α-terpineol

Asthma is a bronchial hyperresponsiveness disease caused by inflammatory lesions.The number of global asthmatic patients has reached 300 million.It is not only a serious influence on people’s normal life,even a life threatening to patients.However,there’s no a radical cure means for asthma treatment so far.The treatment and prevention of asthma is only by effective drug to improve symptoms.The current clinical drug treating asthma is organized into two categories called bronchial diastolic drugs(mainly β2 adrenergic receptor agonist)and anti-inflammatory drug(mainly hormone).However β2 adrenergic receptor agonist would bring critically ill patients heart function damage,and closely related to the severity of asthma.The combination drug therapy would increase the risk of congestive heart failure in critically ill patients.Therefore,it would be an important clinical significance to find a kind of novel anti-asthmatic drug which has no influence on cardiac function and hormonal effects while treating asthma.Our research group found that monoterpenoids,α-terpinenol,had a direct relaxation effect on airway smooth muscle,what’s more it performed a good action on eliminating phlegm,relieving cough,antiallergic.But there’s a low content in folium artemisiae argyi,we couldn’t extract it by vapor distillation.The source of a-terpinenol was limited that it needed to found a new way to resolve this problem.In addition,its spasmolysis effect is rapid but the effective time is too short(only about half hour),so α-terpinenol has a lot of restrictions in clinical use.For the limited source issue of α-terpinenol,writer carried on the method of extraction and separation research in this article.We isolated α-terpinenol from folium artemisiae argyi by supercritical CO2 extraction integrated high-speed counter-current chromatography.We archived the a-terpinenol with the content more than 90%through this extraction method.What’s more,the extractive a-terpinenol preliminary pharmacokinetic in vivo showed that Half-life(T1/2)was 2.148h,the clearance(CL/F)was 1.544L/h/kg.The results indicated that the quick oral absorption and short acting time of a-terpinenol was decided by its pharmacokinetic characteristics.To solve the deficiency of α-terpinenol metabolism,we designed and synthesized 17 a-terpinenol ester prodrugs by making the esterification modification on the hydroxyl inα-terpinenol to improve its molecular bistability.On the other side,we introduced the NO donor segment nitrous acid ester(ONO2)into α-terpinenol to form two kinds ofα-terpinenol derivatives within nitrous acid ester relied on combination principles.Besides,we synthesized α-terpinenol double bond reduction product,and did preliminary activity exploration of olefins fragment.We tested the 21 compounds’ activity of smooth muscle relaxation on isolated trachea.Results display,there were 8 modificatory compounds showed a stronger bronchial diastolic activity than the positive control aminophylline(diastolic rate 45%).Especially the 6a and 6d,their diastolic rate was 83%and 85%respectively at the concentration of 1.25mmol/L.The mechanism study showed that compound 6a,6b,6c,6d,6f,6g and 6i could significantly rise the intracellular cAMP content of smooth muscle cell,it indicated that the compounds might relax bronchial smooth through rising intracellular cAMP level,but not related with β2 receptor.And the results of MTT indicated that the above 7 compounds had no inhibiting effect on rats bronchial smooth muscle cell proliferation at the concentration of 1.25 and 0.625 mmol/L.The preliminary pharmacokinetic study of high-activity compound 6a and 6d displayed that the T1/2 was 2.309h and 3.386h respectively,which were higher than a-terpinenol(T1/2=2.148h).It was proved that the prodrug design strategy in our article was feasibility and rationality.Moreover,through testing the lung function,inflammatory factors IL-17A,IL-4 etc on asthma rat model,we evaluated the activity of relieving asthma of high-activity compound 6a and 6d.From the results,we found compound 6a and 6d could improve pulmonary function by enhancing the airway compliance and reducing the airway resistance on asthmatic rats,reduce the content of IL-4,IL-17A in serum,and control inflammation at the same time but with no influence on rats heart rate.Therefore,the above compounds showed a double active on both relaxing bronchial smooth muscle and anti-inflammatory effect,and had a clinical potential to replace the combination of β2 agonists and hormone.