In vitro Antisalmonellal and Antioxidant Activities of Extracts and Fractions of Curcuma longa L. Rhizomes (Zingiberaceae)

Abstract

Typhoid fever is still a major public health problem in developing countries, where it remains endemic. With a view to searching for new antityphoid substances, Curcuma longa rhizome extracts and fractions were assessed for their antisalmonellal and antioxidant activities. The antisalmonellal efficacy in terms of minimum inhibitory concentrations (MICs) of the different extracts and fractions was determined using serial microdilution method. The antioxidant activity was determined by measuring FRAP (ferric reducing-antioxidant power), DPPH radical scavenging, nitric oxide (NO) radical scavenging, ferrous ion-chelating and hydroxyl radical scavenging activities. Total flavonoids and total phenolic contents were also evaluated. The results showed that the extracts and fractions of Curcuma longa were effective against all the bacteria tested with MICs ranging from 32 to 1024 µg/mL. These results also showed that MeOH/CH2Cl2 (v/v, 1:1) extract, residual and ethyl acetate fractions possessed strong antioxidant activities (IC50< 20 µg/mL). Phytochemical screening showed the presence of alkaloids, flavonoids, saponins and phenols in all the extracts and fractions. In the light of the foregoing, it was obvious that Curcuma longa contains antisalmonellal and antioxidant principles which could be developed for the treatment of enteric fevers (typhoid and paratyphoid fevers) and the management of oxidative stress induced by the salmonellal infections. These findings support the claim of the local community about the use of this plant for the treatment of typhoid fever.