Extraction,Identification And Action Mechanism Of Antifungal Constituents From Cynanchum Atratum Bunge

Nowsdays,we all acvocate green consumption,so developing green and security citrus preservatives is great significance.This paper through studying the extraction process,isolation identification and antimicrobial mechanism of antibacterial substance from Cynanchum atratum,layed the foundation for later development of C.atratum.The main results were as follows:1.In this paper,C.atratum was used as material,the diameter of inhibition zone and Penicillium italicum worked as an indicator and bacterial strain in this experiment respectively,beside these ultrasound-assisted extraction was used to antibacterial material from C.atratum.On the basis of single factor tests,the method of response surface methodology was used to optimize ultrasound-assisted extraction of antibacterial material form C.atratum.The result indicated that the optimal conditions to extract antibacterial material from C.atratum were that ethanol concentration was 50%,extraction time was 2hours,liquid-to-material ratio was 31 and extraction temperature was 69 ℃.Under these conditions,the inhibitory effect against P.italicum by C.atratum extracts was 40.58 mm,close to the theoretically predicted value of 40.81 mm.2.Through the method of antibacterial activity tracking,separation and purification were carried out by extraction,macroporous resin,silica gel chromatography,reversed phased silica gel chromatography and preparative liquid phase technology,combined with nuclear magnetic resonance(NMR),mass spectrometer(MS)and related database,literature material,identified an effective monomer compound ——7-Demethoxylophorine(DEM);In addition,the diameter of inhibition zone of 500 μg/mL DEM to P.italicum was36.5 mm,showed that the DEM has strong inhibitory effect on P.italicum.3.Study the effects of DEM with different concentrations on antibacterial activity.Based on these,take the minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MFC)as a reference to determine the DEM on spore germination,hyphal morphology,plasma membrane permeability,malate dehydrogenase(MDH)and succinate dehydrogenase(SDH)activity of P.italicum.The result shows that the MIC and MFC of DEM on antibacterial activity of P.italicum was 1.5625?μg/mL and6.25?μg/m L.The inhibition rate of spore germination was strengthened with the increasing of DEM concentrations and the inhibition rate reached to 95.39% when the concentration of DEM was 6.25?μg/mL.Additionally,DEM could lead to twist,break,lysis of mycelial morphology and increase plasma membrane permeability of mycelial,at the same time the MDH and SDH activity was decreased.So,DEM disrupting P.italicum gets normal growth by inhibiting spore germination,destroying hyphal morphology,changing theplasma membrane permeability,and inhibiting MDH and SDH activity of mycelial.