<![CDATA[Abstract: Lactobacillus acidophilus is a Gram-positive bacterium that causes caries. It is known that natural ingredients of red pomegranate peel extract (Punica granatum L.) have antibacterial effect. This study aimed to determine the effectiveness of red pomegranate peel extract in inhibiting the growth of Lactobacillus acidophilus. This was a laboratory and experimental study using a post-test only design with a control group design. Samples were Lactobacillus acidophilus bacteria. Sample size was determined using the Federer's formula, and five repetitions were obtained for each group. Data were analyzed with One Way ANOVA and Post Hoc LSD tests. The results showed that the average diameters of the inhibition zones of red pomegranate peel extract (Punica granatum L.) at concentrations of 25%, 50%, 75%, and 0.2%, chlorhexidine (positive control), and DMSO (negative control) on the growth of Lactobacillus acidophilus were 16.08±1.16 mm, 17.66 ±0.60 mm, 18.76±0.54 mm, 14.04±0.90 mm, and 0 mm. Statistic tests showed significant differences between various concentrations of red pomegranate peel extract and the positive control (p<0.05). The secondary metabolite compounds contained in red pomegranate peel extract (Punica granatum L.) were saponins, flavonoids, tannins, triterpenoids, and glycosides. In conclusion, various concentrations of red pomegranate peel extract (Punica granatum L.) have antibacterial effect to inhibit the growth of Lactobacillus acidophilus. Keywords: Lactobacillus acidophilus; red pomegranate peel; antibacterial effect Abstrak: Lactobacillus acidophilus merupakan bakteri Gram positif penyebab terjadinya karies. Bahan alami dari ekstrak kulit buah delima merah (Punica granatum L.) telah dikenal memiliki efek antibakteri. Penelitian ini bertujuan untuk mengetahui efektivitas ekstrak kulit buah delima merah dalam menghambat pertumbuhan Lactobacillus acidophilus. Metode penelitian ialah eksperimental laboratorium dengan post-test only with control group design dengan menggunakan sampel bakteri Lactobacillus acidophilus. Penentuan besar sampel menggunakan rumus Federer dan diperoleh lima kali pengulangan tiap kelompok. Analisis data menggunakan uji One Way ANOVA dan Post Hoc LSD. Hasil penelitian mendapatkan rerata diameter zona hambat pada ekstrak kulit buah delima merah konsentrasi 25%, 50%, 75%, chlorhexidine 0,2% (kontrol positif) dan DMSO terhadap pertumbuhan Lactobacillus acidophilus ialah 16,08±1,16 mm; 17,66± 0,60mm; 18,76±0,54 mm; 14,04±0,90 mm; dan 0 mm. Uji statistik menunjukkan perbedaan bermakna antara ekstrak kulit buah delima merah berbagai konsentrasi dengan kontrol positif (p<0,05). Kandungan senyawa metabolit sekunder yang terdapat pada ekstrak kulit buah delima merah yaitu saponin, flavonoid, tanin, triterpenoid, dan glikosida. Simpulan penelitian ini ialah ekstrak kulit buah delima merah berbagai konsentrasi memiliki kemampuan antibakteri untuk menghambat pertumbuhan Lactobacillus acidophilus. Kata kunci: Lactobacillus acidophilus; kulit buah delima merah; efek antibakteri]]>
