Antibacterial activity of ethanolic and n-hexane extracts of Ruellia tuberosa leaves against Escherichia coli and Bacillus subtilis bacteria

Abstract

Abstract. Amijida H, Purwoko T, Susilowati A. 2019. Antibacterial activity of ethanolic and n-hexane extracts of Ruellia tuberosa leaves against Escherichia coli and Bacillus subtilis bacteria. Biofarmasi J Nat Prod Biochem 17: 69-80. Ruellia tuberosa L. has pharmacological activity, one of which is antibacterial. This study aimed to determine the antibacterial activity and the minimum inhibitory concentration (MIC) of pletekan leaf extract (R. tuberosa) against Escherichia coli and Bacillus subtilis and the chemical compounds contained in the leaves of R. tuberosa. This study used a completely randomized design with five treatments and three replications. Ruellia tuberosa leaf extract was obtained by extraction by maceration and reflux using ethanol and n-hexane as solvents. The concentrations of the R. tuberosa leaf extract used were: P1 (125 mg/mL), P2 (250 mg/mL), P3 (500 mg/mL), P4 (1000 mg/mL) and P5 (2000 mg/mL) with dimethylsulfoxide (DMSO) solvent. The positive control was in a 30 g chloramphenicol antibiotic disc, while the negative control used was DMSO solvent. The agar diffusion method used a paper disc to conduct the antibacterial activity test. The minimum inhibitory concentration of R. tuberosa leaf extract was determined using the dilution method. Identification of secondary metabolites was carried out using phytochemical screening. The data obtained were analyzed using the One-Way ANOVA test and if there was a significant difference, then continued with the Tukey test. Ruellia tuberosa leaf extract with ethanol solvent has better antibacterial activity against E. coli and B. subtilis than n-hexane. The minimum inhibitory concentration of R. tuberosa leaf ethanol extract against E. coli was 500 mg/mL with a 99.1% inhibition percentage. The minimum inhibitory concentration of R. tuberosa leaf ethanol extract against B. subtilis is 1,000 mg/mL with a 99% inhibition percentage. The ethanolic extract of R. tuberosa leaves contains alkaloids, flavonoids, tannins, saponins, and glycosides, while the n-hexane extract of R. tuberosa leaves contains terpenoids.