Improved separation of the curcuminoids, syntheses of their rare earth complexes, and studies of potential antiosteoporotic activity

•First binary rare earth curcuminoids ML3 (Eu(III), Gd(III), Lu(III)) are characterized.•Improved separation of curcumin, demethoxycurcumin and bisdemethoxycurcumin.•Toxicities of metal complexes and ligands investigated in osteoblast-like MG-63 cells.

The first reported homogenous rare earth curcumin (HCurc; ((1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione)) complexes with the formula ML3, where M3+ is Eu(III), Gd(III) or Lu(III), were synthesized and characterized by mass spectrometry, infrared spectroscopy and, in the case of the lutetium complex, 1H NMR spectroscopy. Most importantly an improved separation of the three curcuminoids, HCurc, HDMC ((1E,6E)-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) and HBDMC ((1E,6E)-1,7-bis(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) was realized using a combination of normal-phase column and phosphate-impregnated preparative-thin layer chromatographies. The toxicities of the metal curcumin complexes and ligands were investigated in MG-63 cells, an osteoblast-like cell line, for potential activity as antiosteoporotic agents.

Graphical abstractThe first binary rare earth curcumin ML3, where M3 + is Eu(III), Gd(III) or Lu(III), are reported and characterized, and an improved separation of the three curcuminoids, HCurc, HDMC ((1E,6E)-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) and HBDMC ((1E,6E)-1,7-bis(4-hydroxyphenyl)hepta-1,6-diene-3,5-dione) was realized. The toxicities of the metal curcumin complexes and ligands were investigated in MG-63 cells, an osteoblast-like cell line, for potential activity as antiosteoporotic agents.Figure optionsDownload full-size imageDownload as PowerPoint slide