Alendronate-monoethyl adipate-(hydrazone)-doxorubicin conjugate (ALN-MA-hyd-DOX) was synthesized to specifically deliver doxorubicin (DOX) to bone tumor tissue. The binding kinetics of ALN-MA-hyd-DOX with hydroxyapatite (HA) and natural bone were detected by using spectrophotometer. Cytotoxicity of ALN-MA-hyd-DOX on tumor cells was determined by MTT [3-(4,5-dimethylthiaol-2-yl)-2,5-diphenyl-tetrazolium bromide] method. The cellular uptake of ALN-MA-hyd-DOX was observed by using fluorescence microscopy. The in vivo antitumor activity of ALN-MA-hyd-DOX was investigated by using tumor-bearing nude mice model. The results indicated that ALN-MA-hyd-DOX was able to quickly bind with HA and natural bone. ALN-MA-hyd-DOX immobilized on the natural bone released more DOX in pH 5.0 medium than that in pH 6.0 or 7.4 medium. The cytotoxicity of ALN-MA-hyd-DOX toward A549 cells and MDA-MB-231/ADR cells was greater than DOX. ALN-MA-hyd-DOX was rapidly uptaken by A549 cells and MDA-MB-231/ADR cells. Compared with the same dose of free DOX, ALN-MA-hyd-DOX significantly decreased tumor volume of tumor-bearing nude mice. DOX mainly distributed in bone tumor tissue after ALN-MA-hyd-DOX was intravenously administered to tumor-bearing nude mice, whereas DOX distributed through the whole body after DOX was intravenously administered to tumor-bearing nude mice. These findings implied that the ALN-MA-hyd-DOX was a promising bone-targeted conjugate for treating bone neoplasms. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:2293–2303, 2015

Folate–aminocaproic acid–doxorubicin (FA–AMA–DOX) was synthesized and characterized by H NMR spectroscopy and mass spectrometry. Cytotoxicity and cellular uptake experiments were performed in KB and HepG2 cells, which express folic acid receptor, and the cell line A549, which does not express folic acid receptor. Cytotoxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and cellular uptake was monitored using fluorescence microscopy. The amount of DOX released from FA–AMA–DOX was much greater at pH 5.0 than that at pH 6.5 or 7.4. The cytotoxicity of FA–AMA–DOX toward KB and HepG2 cells was greater than that of DOX or AMA–DOX at the same concentrations, and cytotoxicity could be attenuated by FA in a dose-dependent manner. On the contrary, the cytotoxicity of FA–AMA–DOX and AMA–DOX toward A549 cells was lower than that of DOX at the same concentration, and cytotoxicity could not be reduced by FA. Compared with FA–AMA, FA–AMA–DOX increased the intracellular accumulation of DOX in KB cells. These results suggested that FA–AMA–DOX have suitable attributes for the active targeting of folate-receptor-positive tumor cells and for releasing the chemotherapeutic agent, DOX, in situ; it therefore has potential as a novel cancer therapeutic. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:530–540, 2013