Synthesis of quinoline derivatives of tetrahydrocurcumin and zingerone and evaluation of their antioxidant and antibacterial attributes.

Tetrahydrocurcumin (THC, 1) and zingerone (2) are biologically active molecules originating from the
important spices turmeric and ginger, respectively. Novel quinoline derivatives of THC and zingerone
have been synthesised by an efficient protocol involving their reaction with substituted 2-aminobenzophenones
and 2-aminoacetophenone. Radical-scavenging activities (RSA) of THC, zingerone and their
quinoline derivatives were evaluated. The amino-substituted quinoline derivative of THC, 1e, showed
antioxidant activity superior to those of 1 and 1a. Derivatives 1b, 1c, 1d and 1f exhibited relatively lower
RSA at equimolar concentrations (�50–55 lmol). A similar trend was also seen in zingerone (2) and its
derivatives (2a–2e), with 2e displaying the best RSA. Derivatives of THC (1a–1f) showed stronger antimicrobial
activity than THC (1) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Yersinia
enterocolitica. Also, derivatives of zingerone (2b–2e) exhibited lower minimum inhibitory concentrations
(MIC) values than zingerone (2) and its derivative, 2a for both Gram-positive and Gram-negative bacteria.
The molecules may have potential pharmacological applications.