Effect of solvent extraction of Centella asiatica on antioxidant activity and antibacterial activity against Salmonella enterica Enteritidis

Abstract

Nowadays, there are increasing trends of using natural products. Interestingly herbs are considered to be one of the alternatives consumers choose to use. In Thailand, Centella asiatica can be found in local market and locally called Buabok. C. asiatica is famous in Ayurvedic medicine for the treatment of leprosy, insanity, asthma, ulcers, eczema, skin tuberculosis, wounds, stomach aches, arthritis, varicose veins and high blood pressure (Ariffin et al, 2011 and Hakono et al, 1999). Due to the benefits of C. asiatica and its easily accessible, this studied had been done to evaluate the effect of solvent extraction of C. asiatica on antibacterial activity against Salmonella enterica Enteritidis and found out that ethanol and chloroform showed highest antibacterial activity against S. Enteritidis (9.33 ± 0.5774 and 9.50 ± 0.5000 mm., respectively) while hexane extract showed lowest activity (6.67 ± 0.1443 mm.) The minimum inhibitory concentrations (MICs), using a broth dilution method, were found to be 8 mg/ml for ethanol and chloroform. While hexane extract was found to be 32 mg/ml. The minimum bactericidal concentrations (MBCs) were greater than 32 mg/ml. Similar results were found in the antioxidant activity of C. asiatica referring to the amount of phenolic content. Total phenolic contents using Folin-Ciocalteu method, found out that ethanol extract contains highest phenolic content followed by chloroform with slightly lower in phenolic content and the lowest phenolic content was hexane extract (23.8020 ± 0.5241, 22.1718 ± 0.1403 and 7.9612 ± 1.6350 µg GAE/mg, respectively). Ferric reducing antioxidant potential value of ethanolic extract was greater than those of chloroform and hexane extract (6.4008 ± 0.0393, 3.4779 ± 0.6744 and 1.7693 ± 0.1279 mmol Fe2+/mg, respectively). According to the results, different extraction solvents affected the amount of total phenolic compounds and FRAP value. The difference in the antibacterial activity was found when using different extraction solvents.