Although identical in molecular formula and weight, curcumin and cyclocurcumin show remarkable differences in their reactivity. Both are natural compounds isolated from the rhizome of turmeric, the former is involved in the diketo/keto-enol tautomerism through the bis-α,β-unsaturated diketone unit according to the polarity of the solvent, while the latter could react by trans-cis isomerization due to the presence of the α,β-unsaturated dihydropyranone moiety. Even if curcumin is generally considered responsible of the therapeutical properties of Curcuma longa L. due to its high content, cyclocurcumin has attracted great interest over the last several decades for its individual behavior and specific features as a bioactive compound. Cyclocurcumin has a hydrophobic nature characterized by fluorescence emission, solvatochromism, and the tendency to form spherical fluorescent aggregates in aqueous solution. Molecular docking analysis reveals the potentiality of cyclocurcumin as antioxidant, enzyme inhibitor, and antiviral agent. Promising biological activities are observed especially in the treatment of degenerative and cardiovascular diseases. Despite the versatility emerging from the data reported herein, the use of cyclocurcumin seems to remain limited in clinical applications mainly because of its low solubility and bioavailability.
Keywords: bioavailability; biological activity; cyclocurcumin; docking analysis; fluorescence; photoisomerization; platelet aggregation; rheumatoid arthritis; solvatochromism.