[Preparation of hydrophilic Indigo Naturalis based on polyethylene glycol( PEG) surface film-forming method and...

Polyethylene glycol (PEG) surface film-forming method was used to prepare hydrophilic Indigo Naturalis decoction pieces with stable effect.The preparation process of modified Indigo Naturalis was optimized and its microscopic properties,hydrophilicity,antipyretic efficacy,and safety were systematically evaluated.With equilibrium contact angle as assessment index,the influence of modifier type,modifier dosage,dispersant dosage,and co-grinding time on water solubility of Indigo Naturalis was investigated by single factor test.The results showed that the optimal preparation process was as follows.The 6%PEG6000 is dissolved in 10%anhydrous ethanol solution by sonification and then the mixture is ground with Indigo Naturalis for 2 min.The resultant product is dried on a square tray in an oven at 60℃to remove ethanol and thereby the PEG-modified hydrophilic Indigo Naturalis decoction pieces are yielded.The morphological observation under scanning electron microscope (SEM) indicated that the modified Indigo Naturalis had smoother surface than Indigo Naturalis,and energy spectrometer measurement showed that the nitrogen (N),calcium(Ca),oxygen (O),and silicon (Si) on the surface of modified Indigo Naturalis powder were less than those of Indigo Naturalis powder.Modified Indigo Naturalis had the equilibrium contact angle 18.96°smaller,polar component 22.222 m J·m~(-2)more,and nonpolar component 7.277 m J·m~(-2)smaller than the Indigo Naturalis powder.Multiple light scattering technique was employed to evaluate the dispersion in water and the result demonstrated that the transmittance of Indigo Naturalis and modified Indigo Naturalis was about85%and 75%,respectively,suggesting the higher dispersity of modified Indigo Naturalis.The suspension rate of modified Indigo Naturalis in water was determined by reflux treatment.The result showed that 57%of Indigo Naturalis was not wetted after refluxing for1 h,while the modified Indigo Naturalis was all wetted and dispersed into water.The dissolution of indigo and indirubin of modified Indigo Naturalis increased and the process was more stable.Then,rats were randomized into the blank group,model group,acetaminophen group,Indigo Naturalis group,and hydrophilic Indigo Naturalis group.The temperature changes of rats were observed after administration and the concentration of IL-1βand TNF-αin serum and IL-1βand PGE_2in hypothalamus was measured.The results indicated that the temperature of Indigo Naturalis group and hydrophilic Indigo Naturalis group dropped and the IL-1βlevel of the hydrophilic Indigo Naturalis group decreased (P<0.05) as compared with those in the model group.Thus,both Indigo Naturalis and hydrophilic Indigo Naturalis had antipyretic effect,particularly the hydrophilic Indigo Naturalis.The acute toxicity test of hydrophilic Indigo Naturalis verified that it had no toxicity to rats.In this study,the hydrophilic Indigo Naturalis decoction pieces were prepared with the PEG surface film-forming method,and the antipyretic efficacy and safety were evaluated,which expanded the technological means of powder modification for Chinese medicine and provided a method for clinical use of Chinese medicine.