Uji Efektivitas Antibakteri dari Ekstrak Etanol Kulit Buah Jeruk Purut (Citrus Hysrix Dc.) terhadap Escherichia Coli

Abstract

Escherichia coli infections continue to represent an important public health concern, particularly with the increasing occurrence of antibiotic resistance. This situation has encouraged the exploration of natural sources that may provide alternative antibacterial agents. Kaffir lime (Citrus hystrix DC.) peel contains several bioactive constituents, including flavonoids, tannins, limonoids, and essential oils, which have been associated with antibacterial activity. This study aimed to assess the antibacterial activity of an ethanolic extract of kaffir lime peel against E. coli and to identify the extract concentration producing the greatest inhibitory effect. A laboratory-based experimental study was conducted using a post-test only control group design. Kaffir lime peel was extracted through maceration using 70% ethanol. Antibacterial activity was determined by the disc diffusion method on Mueller-Hinton Agar (MHA). Four extract concentrations were evaluated, namely 5%, 10%, 20%, and 40%. Chloramphenicol 30 µg served as the positive control, while 5% DMSO served as the negative control. The inhibition zones were measured following 24 hours of incubation at 37°C. Statistical analysis included the Shapiro-Wilk test, Levene's test, One-Way ANOVA, and Tukey HSD post hoc analysis. The mean inhibition zones were 6.11 ± 0.51 mm, 6.24 ± 0.10 mm, 6.85 ± 0.24 mm, and 7.52 ± 0.55 mm for extract concentrations of 5%, 10%, 20%, and 40%, respectively. The positive control produced an inhibition zone of 32.59 ± 0.67 mm, whereas no inhibition was observed in the negative control. One-Way ANOVA indicated a statistically significant difference among treatment groups (p = 0.008). These findings demonstrate that the ethanolic extract of kaffir lime peel has antibacterial activity against E. coli, with the 40% concentration showing the strongest inhibitory effect.