Ultrasound-assisted synthesis of some curcumin analogs and their synergistic effect with ferulic acid on α-amylase inhibition

Three curcumin analogs of dimethylaminobenzaldehyde derivatives, i.e., A, B and C were synthesized using a green method using the ultrasound-assisted technique, and the process was compared to the conventional method. The improvements were achieved by decreasing the reaction time from hours to minutes and giving the higher yields of the products. The products were tested as an antidiabetic agent by treated them as an inhibitor for α-amylase activity. The result of α-amylase inhibition showed that curcumin analogs (A, B, C) have high inhibition (77.06; 76.59; 78.34) with IC50 value 23.64; 1.36; and 5.93 μg/mL, respectively. Meanwhile, the α-amylase inhibition of the combination between curcumin analog and ferulic acid showed that the curcumin analog C gave the highest inhibition level of 95.94 with IC50 13.38 μg/mL. The combination of curcumin analog A and ferulic acid has a strong synergistic effect with a combination index (CI) value of less than 1, i.e., 0.33. These curcumin analogs are quite potent in inhibiting the activity of α-amylase so that it can be a good candidate for antidiabetic drugs. © 2019 Trans Tech Publications Ltd, Switzerland.