RESUMEN
OBJECTIVE: To study the distribution of folate receptor targeted ursolic acid liposomes and evaluate its antitumor effects on human epidermoid carcinoma xenografts in nude mice. METHODS: Folate derivative was used as targeting molecule and conjugated with mPEG-DSPE for obtaining liposome with long circulation features. This novel targeted agent was prepared by a thin-film dispersion method and ursolic acid was loaded into the liposomes as the anticancer drugs. Tissue distribution of liposomes in heart, liver, spleen, stomach, kidney and tumor were investigated. The antitumor effect of the targeted ursolic acid liposomes (F-PEG-L-UA) on human epidermoid carcinoma xenografts in nude mice was also studied. RESULTS: Compared with free ursolic acid liposome, UA liposome was slowly removed from blood circulation and the concentration of F-PEG-L-UA in liver, kidney and tumor tissue is significantly higher than other groups. The growth speed of tumor in the group of F-PEG-L-UA was significantly slowed down compared with other groups. The tumor volume in F-PEG-L-UA group was about 50% reduction compared with PBS-treated mice (P<0.05). CONCLUSION: A novel targeted ursolic acid compound is synthesized as the folate receptor targeting functional material. It has obvious inhibitory effect on human epidermoid carcinoma xenografts and it might be an effective antitumor drug delivery system.
RESUMEN
Objective: Lethocerus indicus salivary venom characterization and evaluation of extracellular degradation activity and cytotoxic effect against native human collagen type 1 and epidermoid carcinoma cell, A431. Method: Salivary venom extract was collected from adult insects by injecting 2% pilocarpine of 50 μml. Enzyme presence was detected by the apiZYM assay. The proteolytic activity was tested by the photometric and zymogram methods using specific fluorescent substrates and inhibitors. The cytotoxic activity was determined by the MTT assay and Trypan blue exclusion method. Apoptosis induction was observed using AO/EB staining solution. Digestion of extracellular matrix protein was detected against native human type I collagen. Result: L. indicus salivary venom presents amylases, proteases, carbohydrases, phosphatases and lipases. Among them, protease enzyme showed highest composition. The highest rate of proteolytic activity observed at pH 8 in 35ºC (100 %). Serine proteases present predominantly in salivary venom. Cysteine and metalloproteases are also detected. The activation energy of salivary venom is 49.86 kJ. Use of serine inhibitor, PMSF inhibited 92.77% which indicated that the maximum activity was due to serine protease. Detection of trypsin-like protease was confirmed by using PMSF and TLCK with specific substrate, BApNA. It shows significant inhibitions, 82% and 78% respectively suggesting maximum influence in salivary venom. Degradation of the fibrillar native state collagen Type I into 8 smaller peptide bands showed it importance in medical application. IC50 concentration of venom that induces cytotoxicity in epidermoid carcinoma cells, A431was 2.3 μg/ml only. It gives prominent apoptotic features such as cytoplasmic membrane blebbing, nuclear contraction, nuclear fragmentation and contact inhibition. Conclusion: We suggest that further investigation of the venom will lead to identification of active compound in L. indicus salivary venom for its potential use in therapeutic application.