Synthesis and assessment of the antioxidant and antitumor properties of asymmetric curcumin analogues

• 12 asymmetric curcumin analogues and 5 symmetric curcumin derivatives were synthesized.
• In the assays of DPPH, ABTS, TRAP, and NET, compounds 14–17, 19–20, 24–26 performed better antioxidant activities than VC.
• In antioxidant experiment, compound 14 exhibited a stronger activity than curcumin, compound 25 is similar to curcumin.
• Compound 25 performed the preferential cytotoxic activity against MCF-7 cells (25, IC50 = 9.11 μM, curcumin, IC50 = 70.2 μM).

In this study, 12 asymmetric curcumin (CUR) analogues and 5 symmetric curcumin derivatives were synthesized, the antioxidant activity of these derivatives were evaluated by radicals 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay, 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assay, ROO (TRAP) assay and O2− (NET) assay and anti-proliferative activities of these analogues were assessed against the human hepatoma cell line (SMMC-7721), the human breast cancer cell line (MCF-7) and the human prostate cancer cell lines (PC-3). Most of the asymmetric compounds showed stronger antioxidant activities than Vitamin C (Vc). Curcumin analogues reducing free radicals contain two reaction mechanisms: H-atom and electron transfer mechanisms. Compound 14 showed the most significant antioxidant activity compared with curcumin and other derivatives. Shorted the carbon chain of 14 can reduce the O–H bond dissociation enthalpy (BED) to improve the antioxidant activity. The antioxidant activity of 25 was similar to curcumin. All of the compounds performed better in an anti-proliferate assay than curcumin, especially compound 25, which exhibited the preferential cytotoxic activity against MCF-7 cells(25, IC50 = 9.11 μM, curcumin, IC50 = 70.2 μM). Considering these data, future studies should be performed to assess the therapeutic values of these asymmetric curcumin analogues.

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