Content Determination and Ultrasonic-assistant Extraction Technology of the Functional Compositions in Ligustrum robustum
Objective To establish a UV method for the determination of the functional compositions(cinnamic acid derivatives,total flavonoids)in Ligustrum robustum,to predict the contents of trans-p-hydroxycinnamic acid,trans-p-hydroxycinnamic acid esters,and rhoifolin based on UV/HPLC,and to optimize the technological conditions of ultrasonic-assistant extraction of L.robustum.Methods ①In the determination of the functional compositions in L.robustum,total cinnamic acid derivatives were determined by dual-wavelength isobestic point UV method(detection wavelength 316 nm,reference wavelength 268 nm),and total flavonoids were determined by single-wavelength UV method(detection wavelength 268 nm),while rhoifolin was determined by HPLC(C 18 column,eluting with methanol-0.1%acetic acid=40∶60,detection wavelength 310 nm).②The conversion factors were used to establish a UV/HPLC-based prediction model,and the precision of the predicted results was evaluated with other 3 test samples.③ The technological conditions of ultrasonic-assisted extraction were optimized by an orthogonal test.Results ① The linear ranges of total cinnamic acid derivatives,total flavonoids,and rhoifolin were 4.64-20.88,8.24-28.84,5.15-51.50 μg·mL-1(r≥0.999 5),respectively.RSDs of the precision,stability,and reproducibility tests were no more than 1.4%.The recoveries were 97.9%-100.5%(RSD≤ 1.2%,n=6).②The relative errors of the values predicted by UV/HPLC from the results measured by HPLC were from-5.3%to 1.7%.There was no significant difference between the UV/HPLC predicted values and the HPLC determined results(P>0.05)for the contents of trans-p-hydroxycinnamic acid and rhoifolin.③The optimal technological conditions of ultrasonic-assistant extraction of L.robustum were as follows:ethanol concentration 80%,temperature 50 ℃,liquid-solid ratio 20 mL·g 1,extraction frequency 2 times,extraction time 20 min.The total yield of functional compositions under above conditions was 42.0%.Conclusion The above determination methods are accurate and rapid,and the above extraction technology is effective,energy-saving and rapid,which provide an experimental base for the quality control and application of L.robustum.