Study of corrosion inhibition performance of volatile and non-volatile Curcuma longa L. extracts complemented with antioxidants and antibacterial assays

Abstract

The evaluation of antioxidant activity of volatile (essential oil) and non-volatile extracts of Curcuma longa L. was carried out by the DPPH free radical reduction method.The results obtained revealed strong antioxidant activities of non-volatile extracts rich in phenolic compounds such as ethyl acetate extract (IC50=11.86g/mL) and ethanolic extract (IC50=13.41g/mL) against an IC50=7.75g/mL for ascorbic acid L. In contrast, the essential oil showed modest antioxidant activity.The antibacterial activity of the various extracts of turmeric (Curcuma longa L.) revealed an activity of the essential oil, relatively small compared to the non-volatile extracts.The ethanol extract, tested on the different species of Gram-positive and Gram-negative bacteria, shows an extraordinary antibacterial activity which exceeds that of two antibiotics, Streptomycin and Ampicillin.Its minimum inhibitory concentration (MIC) ranges from 70 to 140 g/mL and its MBC (minimum bactericidal concentration) ranges from 140 to 280 g/mL.Curcuma longa L. essential oil exhibited good inhibitory efficacy which reached approximately 95% at a concentration of 0.6 g/L.On the other hand, the non-volatile extracts (aqueous and ethanolic extract) showed an inhibitory efficiency of approximately 80% at a concentration of 0.1 g/L.