Cooking enhances curcumin anti-cancerogenic activity through pyrolytic formation of “deketene curcumin”

• Cooking of curcumin increases hydrophilicity (HPLC data) and absorption of products.
• Pyrolysis of curcumin forms 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one.
• This curcumin derivative exhibits stronger anti-cancerogenic effects than curcumin.
• 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one induces G2 arrest in cancer.

Curcumin is widely used in traditional Asian kitchen as a cooking ingredient. Despite its low bioavailability, epidemiological data, on low cancer incidence in Asia, suggest beneficial health effects of this compound. Therefore, the question arose whether cooking modifies the anti-cancerogenic effects of curcumin. To evaluate this, we pyrolysed curcumin with and without coconut fat or olive oil, and analysed the products by high-performance liquid chromatography (HPLC). A number of more hydrophilic curcumin isoforms and decomposition products, including a compound later identified by nuclear magnetic resonance spectroscopy (NMR) as “deketene curcumin” (1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one), formerly described as a synthetic curcumin derivative, were detected. Additionally, we proved that deketene curcumin, compared to curcumin, exhibits higher toxicity on B78H1 melanoma cells resulting in G2 arrest. In conclusion, deketene curcumin is formed as a consequence of pyrolysis during common household cooking, showing stronger anti-cancer effects than curcumin. Moreover, we propose a chemical reaction-pathway for this process.