Curcumin analogs: synthesis and biological activities

Curcumin has received great attention in the past three decades due to its versatile medicinal activities, which are attributed to the presence of certain functional groups in its structure. Despite this, the application of curcumin in therapy is limited by its poor aqueous solubility which results in low bioavailability, and also by its low chemical stability due to the keto-enol tautomerism. In this work, eight analogs of curcumin were synthesized starting from aminophenol to tackle these issues. Their chemical structures were characterized by detecting their IR, H-1-NMR, and C-13-NMR spectra. Biological studies were performed on the synthesized analogs using curcumin as a positive control. The tested activities included antioxidant capacity via DPPH and hydroxyl radical scavenging activity tests, preliminary antitumor activity by MTT test against MCF-7 and HeLa cancer cell lines, and antibacterial activity against Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonia using disk diffusion technique. The results of antioxidant activity showed that the SC50 values of the synthesized analogs are closely related to the control, the same finding is reported in the preliminary antitumor activity. In the testing of antibacterial activity, the synthesized analogs displayed variable activities with a superior effect attributed to chloride-based analogs. In the course of performing these tests, it could be deduced that both stability and solubility of the analogs were improved in comparison with curcumin. It is proposed that such analogs with improved aqueous solubility may be useful guides to improve the therapeutic applications of curcumin.