Study On Extraction Of Two Main Flavone Glvcosides From Pyrola[P. Calliantha H. Andr.] And Their Antioxidant Activities

In the present study, a HPLC method was set up for determination two main flavone glycosides from pyrola, and simultaneous negative pressure cavitation and microwave assisted extraction of hyperin and2"-O-galloylhyperin from pyrola [P. calliantha H. Andr.] was studied for the first time. Moreover, the antioxidant activities of the crude extract and its different fractions from pyrola were systematically studied. The results as follow:1. The RP-HPLC method for determination two main flavone glycosides from pyrola was developed as follows:Chromatographic column HIQ Sil C18W(250mm×4.6mm,5μm), flow rate1mL/min, column temperature30℃, detection wavelength254nm and265nm, injection volume10μL. A mobile phase programme was acetonitrile (A)-0.5%formic acid in water (B)(v/v), gradient elution as follows:0-8min3%-5%A,8-10min5%-18%A,10-32min18%-25%A.2. Simultaneous negative pressure cavitation and microwave assisted extraction of hyperin and2"-O-galloylhyperin from pyrola were optimized, and each factor influencing the extraction yields were studied. The optimum extraction parameters were as follows:Extraction solvent:ethanol-water (50:50, v/.v) solutionParticle size:50meshRatio of liquid/solid:30:1Extraction temperature:55℃Negative-pressure:-0.06MPaExtraction power:500WExtraction time:15minUnder the above optimum conditions, the extraction yields of hyperin and2"-O-galloylhyperin were1.258and4.911mg/g, respectively.3. The antioxidant activities of the crude extract and its different fractions from pyrola were studied, and Pearson correlation analysis was applied.In the DPPH radical scavenging assay, the crude extract and ethyl acetate fraction exhibited better activity, the IC50for the crude extract and ethyl acetate fraction were0.063and0.122mg/mL, respectively. In the ABTS free radical scavenging ability experiment, the crude extract has the strongest scavenging ability, equivalent to0.627mmol/gTrolox, the IC50values decreased in the order of ethyl acetate fraction> n-butanol fraction> petroleum ether fraction> water fraction. The resulis of reducing power experiment showed that the strongest reducing power was ethyl acetate fraction, the IC50value was0.066mg/mL, reducing power ability of ethyl acetate fraction is (?)ce to the control BHT. In the β-carotene bleaching test, the IC50of crude extract (0.029mg/mL) and ethyl acetate fra(?)on (0.027mg/mL) were nearly comparable to the positive control BHT (0.021mg/mL).Pearson correlation analysis indicated that the antioxidant capacity of pyrola associated with its total flavonoid content. Pearson’s correlation analysis showed that a significant correlation (p value>0.08) between the four kinds of antioxidant experiments (DPPH, ABTS, reducing power, β-carotene bleaching).