Fast Dissolving Curcumin Cocrystals

Curcumin is the principal curcuminoid of the popular Indian spice turmeric. Despite the diverse pharmacological activities of this bioactive phenol, its application as a drug is severely limited by poor aqueous solubility. We report novel cocrystals of curcumin (1) with resorcinol and pyrogallol obtained by liquid-assisted grinding. Curcumin resorcinol (1a) (1:1) and curcumin pyrogallol (1b) (1:1) were characterized by X-ray diffraction, thermal analysis, FT-IR, FT-Raman, and solid-state C-13 NMR spectroscopy. The 1:1 cocrystal stoichiometry is sustained by O-H center dot center dot center dot O hydrogen bonds between the phenolic OH groups of the coformers to the carbonyl group of curcumin. The melting point of the cocrystals is in between that of curcumin and the coformer and the lower melting cocrystal 1b is more soluble than higher melting la. The dissolution rates of curcumin-resorcinol (1a) and curcumin-pyrogallol (1b) in 40% EtOH-water are similar to 5 and similar to 12 times faster than that for curcumin.