Study on the Antibacterial Activity of Magnolol Co-Crystals
Objective To increase the antibacterial activity of magnolol(MAG).Methods Magnolol-L-proline(MAG-PRO)co-crystal and magnolol-betaine(MAG-BET)co-crystal were prepared by the grinding method.The co-crystals were identified by the powder X-ray diffraction(PXRD),thermogravimetric analysis(TG),differential scanning calorimetry(DSC),and Fourier transform infrared spectroscopy(FT-IR)methods.PXRD characterization was performed to observe the stability of co-crystals.The equilibrium solubilities of the MAG and its two co-crystals in four dissolution media[10 mL water,hydrochloric acid buffer(pH 2.0),phosphate buffer(pH 4.5,pH 6.8)]were determined by the high-performance liquid chromatography(HPLC)method.The antibacterial activity of the MAG and its two co-crystals at different mass concentrations(50,100,200 μg/mL)against Escherichia coli was detected by the broth microilution method.Results The co-crystals were confirmed by the above four identification methods.The PXRD characterization showed that the samples did not have any crystal form change and showed good stability.The equilibrium solubilities of MAG and its two co-crystals in four dissolution media were significantly different,with the highest in phosphate buffer(pH 6.8)and lowest in phosphate buffer solution(pH 4.5).At different concentrations of MAG,the antibacterial rate of co-crystals was higher than that of MAG;and when the concentration of MAG was 200 μg/mL,all MAG and its co-crystals showed antibacterial activity(antibacterial rate＞50％).Conclusion MAG-PRO and MAG-BET have higher antibacterial activity compared to monomer,which can provide a reference for further pharmaceutical research and development of MAG.
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