Amphipathic methoxypolyethylene glycol-curcumin conjugate as effective drug delivery system useful for colonic diseases

Recently, supramolecular self-assembled core–shell nanostructures have emerged as advanced and notable drug delivery vehicles in biomedical arena for human health. Here, we have modified curcumin via Michael addition reaction with 3-mercaptopropionic acid followed by preparation of an amphiphatic conjugate employing hydrophilic polyethylene glycol monomethyl ether (mPEG). The synthesized compounds, curcumin-S-propionic acid (Cur-S) and curcumin-S-propionoyl-mPEG (Cur-S-mPEG), were spectroscopically characterized. Self-assembly of Cur-S-mPEG into micellar nanostructures was monitored by dynamic light scattering, which revealed the size of these nanostructures in the range of ~ 104 nm. Transmission electron microscopic analysis showed the size of these nanostructures ~ 26 nm. These micelles with hydrophobic pockets were then demonstrated to entrap hydrophobic therapeutics, ornidazole (Oz) and sulfasalazine (Sz), successfully with high efficiency. Drug-loaded formulations, Cur-S-mPEG(Oz) and Cur-S-mPEG(Sz), showed sustained release of drugs over a longer duration, particularly, a higher release at neutral pH 7.2 displaying the usefulness of the nanocarrier for colonic delivery. MTT assay performed on HEK 293 and Hep G2 cells displayed the non-toxic nature of the nanocarrier on normal cells (HEK 293 cells) while toxic on cancer cells (Hep G2 cells).