ABSTRACT
ObjectiveTo investigate the effect of microemulsion on the distribution of index components in different phases of Zexietang extract based on high performance liquid chromatography（HPLC） and phase separation process. MethodParticle size meter and transmission electron microscope were used to characterize the colloidal particles in blank microemulsion， aqueous extract of Zexietang and microemulsion extract of Zexietang. The phase separation process was established by high-speed centrifugation and dialysis， and based on this process， the aqueous extract and microemulsion extract of Zexietang were separated into the true solution phase， the colloidal phase and the precipitation phase， respectively. The contents of six components， including atractylenolide Ⅲ， atractylenolide Ⅱ， 23-acetyl alisol C， alisol A， alisol B and alisol B 23-acetate， were determined by HPLC with the mobile phase of water（A）-acetonitrile（B） for gradient elution（0-5 min， 40%-43%B； 5-20 min， 43%-45%B； 20-45 min. 45%-60%B； 45-75 min， 60%-80%B）. The solubility of the index components in water and microemulsion was determined by saturation solubility method. ResultThe colloidal particles in the aqueous extract， microemulsion extract and blank microemulsion were all spherical， and the particle size， polydispersity index（PDI） and Zeta potential of the colloidal particles were in the order of aqueous extract >microemulsion extract >blank microemulsion. The results of phase separation showed that the colloidal phase and the true solution phase could be completely separated by dialysis for 2.5 h， and the phase separation process was tested to be stable and feasible. Compared with the aqueous extract of Zexietang， the use of microemulsion as an extraction solvent could increase the contents of atractylenolide Ⅲ， 23-acetyl alisol C， atractylenolide Ⅱ ， alisol A， alisol B and alisol B 23-acetate by 3.75， 6.82， 35.47， 10.66， 35.41， 27.75-fold， and could increase the extraction efficiencies of the latter five constituents by 2.03， 1.15， 1.70， 6.43， 5.53 times. The solubility test showed that the microemulsion could significantly improve the solubility of atractylenolide Ⅱ， alisol A， alisol B and alisol B 23-acetate， but it had less effect on the solubility of atractylenolide Ⅲ and 23-acetyl alisol C. ConclusionMicroemulsion can improve the extraction efficiency and increase the distribution of the index components in the colloidal phase state of Zexietang to different degrees， providing a reference for the feasibility of microemulsion as an extraction solvent for traditional Chinese medicine.
ABSTRACT
This study focused on the separation, characterization, content determination, and antiviral efficacy research on colloidal particles with different sizes in Maxing Shigan Decoction(MXSG). The mixed colloidal phase of MXSG was initially separated into small colloidal particle segment(S), medium colloidal particle segment(M), and big colloidal particle segment(B) using ultrafiltration. Further fine separation was performed using size-exclusion chromatography. Dynamic light scattering(DLS) and transmission electron microscopy(TEM) were employed to characterize the size and morphology of the separated colloidal particles. UPLC-MS/MS was used to determine the content of ephedrine, amygdalin, glycyrrhizic acid, and the EDTA complexometric titration was used to measure the calcium(Ca~(2+)) content in different colloidal phases. Finally, a respiratory syncytial virus(RSV) infection mouse model was established using intranasal administration. The experimental groups included a blank group, a model group, a ribavirin group, an MXSG group, an S group, an M group, and a B group. Oral administration was given for treatment, and pathological changes in mouse lung tissue and organ indices were evaluated. The results of the study showed that the distribution of ephedrine, amygdalin, glycyrrhizic acid, and Ca~(2+) content was not uniform among different colloidal segments. Among them, the B segment had the highest proportions of the three components, except for Ca~(2+), accounting for 46.35%, 53.72%, and 92.36%, respectively. Size-exclusion chromatography separated colloidal particles with uniform morphology in the size range of 100-500 nm. Compared to the S and M segments, the B segment showed an increased lung index inhibition rate(38.31%), spleen index, and thymus index in RSV-infected mice, and it improved the infiltration of inflammatory cells and lung injury in the lung tissue of mice. The complex components in MXSG form colloidal particles of various sizes and morphologies through heating, and small-molecule active components such as ephedrine, amygdalin, glycyrrhizic acid, and Ca~(2+) participate in the assembly to varying degrees. The main material basis for the antiviral effect of MXSG is the colloidal particles with certain particle sizes formed by the assembly of active components during the heating process.