Fast Dissolving Curcumin Cocrystals

Abstract

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 13C NMR spectroscopy. The 1:1 cocrystal stoichiometry is sustained by O–H···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 1a. The dissolution rates of curcumin–resorcinol (1a) and curcumin–pyrogallol (1b) in 40% EtOH–water are ∼5 and ∼12 times faster than that for curcumin.