Experimental Design And Optimization Of Parameters For Chlorogenic Acid Extraction Process

Chinese medicine resources are the treasures and have been a strong support for the survival of Chinese civilization 5,000 years.Herbs such as honeysuckle played an important role in the battle against COVID-19.Chinese medicine is gradually being recognized worldwide.Therefore,explore the extraction of effective substances from herbs is in urgent need.Due to the limitations of productivity and cognitive level in the past,honeysuckle was only grinded or directly steamed prior to the use of medicine,which not only failed to fully extract the active ingredients,but also might destroy the active ingredient.With the development of science and technology and the accumulation of empirical knowledge,the active ingredients in honeysuckle,such as chlorogenic acid,are gradually being explored,thus providing more referential value for its use in Chinese medicine.In this study,chlorogenic acid（CGA）was extracted from honeysuckle by using ultrasonic-aided extraction（UAE）and microwave-aided extraction（MAE）and ionic liquid（ILs）assisted methods.The UAE facilitate penetration of the cell wall and extract substances from the cytoplasm,while MAE is using high frequency electromagnetic radiation to reach the microtubule bundles and cell systems inside the honeysuckle cell wall.The anions and cations of the ILs are engineered to bind to groups such as the hydroxyl group of CGA,facilitating extraction of CGA from inside the cells.The honeysuckle raw material was pre-treated per literature and then CGA was extracted with UAE.Alcohols with different carbon numbers were selected as mixed extractants to determine the extraction effect of ethanol,n-propanol and n-butanol on CGA yield from honeysuckle.The results show that the extraction rate of CGA varies with the carbon chain length of the alcohol.Higher yield was obtained when n-butanol was used in the double aqueous phase extractant than other alcohols.However,when n-amyl alcohol was used,the extraction rate decreases significantly.CGA was extracted from honeysuckle by MAE.Solvents of different polarity such as ethanol,ethylene glycol and propanetriol were selected to determine the extraction rate of CGA under the same microwave conditions.The best extractant was selected for single-factor experiments and microwave extraction of CGA were optimized using Box-Behnken simulations and identified as CGA using infrared spectroscopy.The MAE was compared with UAE to investigate the mechanism by which MAE is superior to UAE.Using imidazole ILs to assist the extraction process,imidazole cations were first used to screen extractants with suitable carbon chain lengths and[HMIM]was found to be more effective than other ILs extractants.Due to the hydrophilic nature,CGA is more readily to bind to the hydrophilic anionic groups.Anions such as HSO₄^-,OAC^-,Br^-,PF₆^-,BF₄^-and Cl^-were selected for extraction in this study.It was found that the highest extraction rate of 4.8%can be achieved when Cl^-was used,and thus the[HMIM]Cl^-extractant was identified for the purpose.By single-factor experimental design to optimize the parameters,such as ILs concentration,extraction time and microwave power.The relation between the parameters and the response values was systematically investigated using response surface optimization method to determine the optimum extraction solution.