Structural Relationship Between Curcumin and Calebin A

Figure 1 shows how a metabolic diversion through oxidation could give rise to Calebin A from Curcumin.

Figure 1: Chemical structural resemblances between Curcumin and Calebin A

Even though Calebin A and Curcumin originate from the same plant and co-occur in the rhizome, Calebin A has keto and ester group structural features whereas Curcumin has 1,3-diketonic structure nearly fully enolic form. Curcumin is highly conjugated with bright color but Calebin A is not. While Curcumin is unstable in higher pH environments, Calebin A is stable in alkaline conditions. Both the compounds are Michael acceptors. Both possess anti-inflammatory and antioxidant actions. Some of these differential features in the structure render Calebin A as more potent agent in the protection of PC12 cells from beta-amyloid toxicity, with higher growth inhibitory properties on human hepatoma cell line HepG2 and a potent material for alleviating metabolic syndrome risk factors inclusive of underlying weight control.