RESUMEN
ObjectiveTo evaluate some properties of scutellarin-phospholipid complex nanoemulsion（SCU-PC-NE）， such as release， cell uptake and tissue distribution， and to investigate its effect on ameliorating lipopolysaccharide（LPS）-induced vascular endothelial injury. MethodSCU-PC-NE was prepared by weighting SCU-PC， ethyl oleate， Kolliphor HS15， 1，2-propylene glycol（50， 400， 514.3， 85.7 mg）， respectively. And the appearance of SCU-PC-NE was observed by transmission electron microscope， the average paticle size and Zeta potential were measured by nanopotential particle size analyzer. The cumulative release of SCU-PC-NE in vitro was measured by dynamic dialysis， thiazolyl blue（MTT） colorimetric assay was used to investigate the effect of SCU-PC-NE on the viability of human umbilical vein endothelial cells（HUVECs）， the inverted fluorescence microscope and flow cytometry were used to investigate cell uptake of HUVECs by SCU-PC-NE in vitro using coumarin 6 as a fluorescent probe， the tissue distribution of DiR/SCU-PC-NE labeled by near infrared fluorescent dyes was obeserved by small animal in vivo imaging system. The inflammation injury model was established by co-incubation with LPS（1 mg·L-1） and HUVECs， the effect of SCU-PC-NE on the levels of interleukin（IL）-1β and IL-6 were determined by enzyme-linked immunosorbent assay（ELISA）， 18 Kunming male mice were randomly divided into blank group， model group， blank preparation group（equivalent to high dose group）， SCU group and SCU-PC-NE low and high dose groups（5， 10 mg·kg-1）， 3 mice in each group， and the drug administration groups were administered once in the tail vein at the corresponding dose every 48 h， equal volume of normal saline was given to the blank group and the model group， and the drug was administered for 4 consecutive times. Except for the blank group， the endothelial inflammatory injury was induced by intraperitoneal injection of LPS（10 mg·kg-1） at 12 h before the last administration in each group. Hematoxylin-eosin（HE） staining was used to investigate the effect of SCU-PC-NE on the histopathological changes in the thoracic aorta of mice. ResultThe appearance of SCU-PC-NE displayed pale yellow milky light， mostly spherical with rounded appearance and relatively uniform particle size distribution， with the average particle size of 35.31 nm， Zeta potential of 7.23 mV， and the encapsulation efficiency of 75.24%. The cumulative release in vitro showed that SCU-PC-NE exhibited sustained release properties compared with SCU. The cell viability of SCU-PC-NE was >90% at a concentration range of 1.05-8.4 mg·L-1. The results of cellular uptake experiments showed that the cellular uptake ability of SCU-PC-NE was significantly enhanced when compared with the SCU group（P<0.01）. Compared with normal mice， the results of tissue distribution showed that the fluorescence intensity of DiR/SCU-PC-NE was significantly enhanced in the spleen， kidney， brain and thoracic aorta of mice at different time points after intraperitoneal injection of LPS（P<0.05， P<0.01）， especially in thoracic aorta. ELISA results showed that the levels of IL-1β and IL-6 in the model group were significantly increased when compared with the blank group（P<0.05， P<0.01）， and compare with the model group， all administration groups significantly down-regulated IL-1β level， with the strongest effect in the SCU-PC-NE high-dose group（P<0.01）， and all administration groups significantly down-regulated IL-6 level， with the strongest effect in the SCU-PC-NE low-dose group（P<0.05）. Compare with the blank group， the results of HE staining showed that the endothelial cells were damaged， the elastic fibers were broken and arranged loosely in the model group， although similar vascular injury could be observed in the blank preparation group， SCU group and SCU-PC-NE low-dose group， the vascular endothelial damage was significantly reduced in the high-dose group of SCU-PC-NE， which had a better effect than that in the SCU group. ConclusionSCU-PC-NE can promote the uptake of drugs by endothelial cells and effectively enriched in the site of vascular endothelial injury caused by LPS， suggesting that it has a protective effect on vascular endothelial injury and is a good carrier of SCU.