In Vitro Inhibition Of Cancer Cells And Anti-inflammatory Activity Of Curcumin-loaded Zein Complex Nanoparticles

Among the many phytochemicals present in turmeric,curcumin is one of the most studied polyphenols.The health-promoting effects of curcumin are well recognized and have been practiced in traditional medicine since ancient times.However,the poor water solubility and stability of curcumin limits its bioavailability and affects its practical application.The application of nano-delivery systems to encapsulate curcumin can overcome multiple unfavorable conditions,and nano-delivery systems based on zein has been proved to be widely used.Our group has developed curcumin loaded zein/pectin nanoparticles(En-CUR)and explored its antioxidant capacity in vitro.Based on this,we investigated the bioactivity of loaded curcumin nanoparticles by probing the mechanism of cellular uptake of En-CUR,the inhibitory activity of En-CUR on hepatocellular carcinoma cells and the preventive protection against acute ulcerative colitis in mice.The main results are as follows:1.The uptake of En-CUR by Caco-2 cells increased with the increase of concentration,which was concentration dependent;the nanoparticles loaded with curcumin required energy during the internalization of the cells,and the uptake of En-CUR by Caco-2 cells was reduced by 62.23%at 4 °C compared to 37 °C.The cellular uptake after sucrose,nystatin,M-β-CD and Wortmannin treatment was significantly lower(p<0.0001)by 55.12%,48.78%,59.30% and 55.06%,respectively.It indicates that En-CUR can be internalized by cells through various pathways such as clathrin-dependent endocytosis,caveolin-mediated endocytosis pathway and macropinocytosis.2.En-CUR inhibited the viability of Hep G2 cells more effectively than free curcumin(CUR),and induced apoptosis in hepatocellular carcinoma cells.After treatment with En-CUR or CUR,the viability of hepatoma cells gradually decreased with increasing concentration.Cell viability decreased to 52.7% after 24 h treatment with En-CUR(15μg/m L),compared with 80.0% after treatment with CUR at the same concentration.The MMP levels of Hep G2 cells exposed to En-CUR or CUR showed a dose-dependent decrease.The apoptosis rate increased from 5.94%(control)to 56.01% after treatment with 15 μg/m L of En-CUR and to 32.20% after treatment with the same concentration of CUR.These results indicated that the ability of En-CUR to induce apoptosis of Hep G2 cells is stronger than CUR.Cell cycle arrest was observed in S-phase and G2/M-phase after En-CUR or CUR treatment of cells compared to control cells.But,after treatment of cells with En-CUR or CUR at a concentration of 10 μg/m L,cell cycle arrest was observed in the G2/M phase in En-CUR-treated cells,whereas this phenomenon was observed in the S phase in CUR-treated cells.Compared with control cells,the expression levels of apoptosis-related proteins such as Bax,cytochrome c,p53,cleaved caspase-3 and cleaved caspase-9 were upregulated in En-CUR-treated Hep G2 cells,and showed a dose-effect relationship with the treatment concentration.It showed that En-CUR could induce apoptosis in hepatocellular carcinoma cells more effectively through the mitochondrial apoptosis pathway.3.In the acute ulcerative colitis mice experiment,mice in the En-CUR group had a significantly decreased disease activity index compared to mice in the CUR group(p<0.05).Compared with the DSS group,the colonic tissue MPO activity was reduced by 91.0%(high-dose group)and 90.5%(low-dose group)in the En-CUR group,respectively,whereas it was reduced by only 22.3% in the CUR group.Colonic crypt damage,mucosal inflammation and cellular infiltration were significantly improved in the H-En-CUR group(p<0.05),and IL-6 levels in mice serum decreased by 37.14% compared to the DSS group.IL-10 levels in mice serum were increased by 19.65 in the L-En-CUR group compared to the DSS group.Compared with CUR,En-CUR was able to reduce the DAI score in mice with acute ulcerative colitis,effectively improve the degree of colon histopathology and protect the colon and spleen of mice.The high concentration of En-CUR significantly reduced the MPO activity in colon tissue and inhibited the level of inflammatory factors in serum,while the low concentration of En-CUR could increase the level of anti-inflammatory factors in serum,which played a role in the prevention and protection of acute ulcerative colitis in mice.