Study On Flavonoid Extraction, Antioxidantion And Antibacterial Activity In The Endocarp Of Carya Cathayensis

In this paper, the endocarp of Carya cathayensis was used as experimental materials, we obtained powder by adding liquid nitrogen and shattering. Then we used ultrasonic-assisted extraction technology to study the influence of different solvents, ultrasonic time, solid-liquid ratio, ethanol concentration and ultrasonic power on the yield of flavonoids of Carya cathayensis endocarp. Based on single-factor experiment, the method of response surface analysis with 3 factors on the yield of flavonoids was adopted. The optimal conditions of ultrasonic-assisted extraction were as follows: ultrasonic time 10 min, ultrasonic power 370 W, ethanol concentration 56% and solid-liquid ratio 1:44; the theory value of flavonoids was 44.91 mg/g, and actual value of flavonoids was 44.74 mg/g. It showed an accurate and reliable model.We got crude extracts by adding methyl alcohol into endocarp powder. Then we got different split-phase extracts by adding mineral ether, acetic ether, n-butyl alcohol in turn. Based on five different spilt-phase extracts, we measured their flavonoid and phenolic contents. Finally, we evaluate the antioxidant ability of endocarp and correlation by reducing power, DPPH· and anti-oxidation capacity of lipid. The result showed that flavonoid contents richest in water extracts was 551.23mg/g, phenolic contents richest in acetic ether extracts was 945.15mg/g; flavonoid contents poorest in mineral ether extracts was 18.81mg/g, phenolic contents poorest in mineral ether extracts was 30.35mg/g. In reducing power, the antioxidant ability of endocarp was acetic ether extracts > n-butyl alcohol extracts > crude extracts >water extracts > mineral ether extracts; In DPPH·, the antioxidant ability of endocarp was acetic ether extracts > water extracts > crude extracts >n-butyl alcohol extracts > mineral ether extracts; In anti-oxidation capacity of lipid, the antioxidant ability of endocarp was crude extracts >water extracts > acetic ether extracts > n-butyl alcohol extracts > mineral ether extracts. In correlation analysis, phenolic contents showed an obvious relation with reducing power and DPPH·, R2=0.9624,R2=0.8218.Based on acetic ether extracts n-butyl alcohol extracts water extracts and crude extracts, we studied the inhibition effects of the four extracts above against five common microorganisms including Bacillus subtilis, Escherichia coli, Staphylococcus aureus, yeast and Aspergillus niger with Oxford cup method. The result showed that four different extracts displayed a better influence on three bacteria while they exerted a subtle influence on two fungi. Consequently, four different extracts had a greater inhibition effect on bacteria than fungi. In the light of inhibition effect, four different extracts had a good inhibition effect on Staphylococcus aureus and a bad inhibition effect on Aspergillus niger. In the light of MIC, acetic ether extracts showed an obvious inhibition effect on Staphylococcus aureus. Consequently, acetic ether extracts had a better inhibition effect than other three extracts.