Effect of 3 delivery systems on the intracellular uptake of thymol in pathogenic bacteria
Objective To determine the effect of cationic-β-cyclodextrin(C-β-CD),hydroxypropyl-β-cyclodextrin(HP-β-CD)and 10％ethanol delivery systems on the absorption of thymol(THY)in Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).Methods The minimum inhibitory concentration(MIC)of C-β-CD-THY,HP-β-CD-THY inclusion complexes and 10％ethanol solution of THY were determined with the doubled-and-half dilution method.The bacteriostatic activity was determined with growth curve.The intracellular uptake of C-β-CD-THY,HP-β-CD-THY inclusion complexes and THY 10％ethanol solution by E.coli and S.aureus were determined by HPLC.Scanning electron microscopy was used to analyze the morphological changes of the two bacteria after the drug treatment.Results The MICs of THY 10％ethanol solution,C-β-CD-THY and HP-β-CD-THY against E.coli were 1.66,1.66,and 2.13 mmol·L-1,respectively,and the MICs against S.aureus were 0.83,0.83,and 1.66 mmol·L-1The intracellular uptake of C-β-CD-THY and HP-β-CD-THY by E.coli was 2.2 and 1.6 times higher than that of the THY water solution group.The intracellular uptake of C-β-CD-THY and HP-β-CD-THY by S.aureus was 6.5 and 5.5 times higher than that of the THY water solution group,respectively.Scanning electron microscopy revealed that C-β-CD-THY and HP-β-CD-THY treatment caused severe damage to the bacterial,resulting in crumpling and indentation and loss of cellular integrity.Conclusion Cyclodextrin inclusion complexes can disrupt bacterial cell membranes,increase the intracellular concentration of THY in E.coli and S.aureus,and enhance the bioavailability of THY.Cyclodextrins and their derivatives can be used as solubilizing excipients instead of ethanol to improve drug safety.The C-β-CD-THY inclusion complexes have better antimicrobial effect compared with HP-β-CD-THY,which can be used as an effective bacteriostatic agent in food and drugs.
cationic-β-cyclodextrinhydroxypropyl-β-cyclodextrinthymolinclusion complexdelivery system
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