Antioxidant and Antibacterial Activity against Food-borne Pathogens of Dyes Extracted from Turmeric, Butterfly-pea Flower and Pandan leaves

This study aimed to investigate the antioxidant and antibacterial activity against food-borne pathogens of dye extracted from turmeric (Curcuma longa Linn), butterfly–pea flower (Clitoria ternatea L.), and Pandan leaves (Pandanus amaryllifolius Roxb.) by 95% ethanol. The dye from turmeric can inhibit all bacteria tested: Staphylococcus aureus, Bacillus subtilis, Salmonella typhimurium and Escherichia coli. The MBC were 250 to 1000 mg/mL. This dye at 10 mg/mL showed the highest antioxidant activity against 2,2-diphenyl-1- picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical. The % inhibition was 58.87 ± 0.16 and 59.80 ± 1.01, respectively. Dye from butterfly–pea flower can inhibit only B. subtilis (MBC = 125 mg/mL) and its antioxidant activity against DPPH and ABTS radicals was 18.79 ± 2.18% and 49.92 ± 0.00%, respectively. However, dye from Pandan leaves cannot inhibit any bacteria tested and the antioxidant activities were lower than 40%.