Andrographolide is a group of diterpenoid lactone isolated from Andrographis paniculata (Burm. F.) NEES. One of the analogues is 19-O-triphenylmethylandrographolide (RSPP050) which possesses anticancer activity. In seeking to capitalise on the last property, we have investigated the in vitro tumour targeting capabilities and MRI imaging for hepatocellular carcinoma. In this study, we have designed galactose-targeted and non-targeted micelles comprised of poly(ethylene glycol)-b-poly(lactide) that enveloped RSPP050 as an anticancer agent and superparamagnetic iron oxide (SPIO) as a contrast agent. The targeting abilities were endeavored by examining the cellular uptake with MTT assay, fluorescence microscopy, Prussian blue staining, and in vitro MRI. Targeted SPIO micelles as a T2* contrast agent decreased the relative T2* MRI intensity at 3 h. Results revealed that galactose micelles displayed 10.91 ± 0.19% drug loading content, -37.17 ± 0.63 mV zeta potential, and these micelles at the concentration of 0.5 µg/ml exhibited higher cytotoxicity than non-targeted micelles and free RSPP050 after incubation for 24 h. Fluorescence microscopy and Prussian blue staining at 3 h demonstrated significant cellular uptake by HepG2 cells. Thus, anticancer activity of RSPP050 could be improved using galactose as a targeting ligand and theranostic function was achieved using SPIO.
Keywords: HepG2; RSPP050; SPIO micelles; galactose targeted micelles; in vitro MRI; in vitro anticancer.