Uji Antibakteri Ekstrak Rosella (Hibiscus sabdariffa L.) terhadap Bakteri Escherichia coli

Abstract. Roselle flowers (Hibiscus sabdariffa L.) contain active secondary metabolites with potential antibacterial properties. This study aimed to evaluate the antibacterial activity of roselle extract against Escherichia coli. The dried plant material was analyzed for its chemical constituents through phytochemical screening. Extraction was carried out using the maceration method with a solvent mixture of 96% ethanol and water (1:1), with pH adjusted to 1 using tartaric acid. The resulting thick extract was characterized organoleptically and by measuring its specific gravity. Antibacterial activity was tested using the well diffusion method at concentrations of 10%, 20%, and 30% against E. coli, with chloramphenicol as a positive control and 5% DMSO as a negative control. Phytochemical screening revealed the presence of alkaloids, flavonoids, polyphenols, and tannins (positive FeCl₃ test). The yield of the extract was 66.33%. The extract was reddish-brown, thick in texture, had a distinct aroma, and a specific gravity of 0.8775 g/mL. The highest inhibition zone, 26.63 mm, was observed at the 30% concentration. These results indicate that roselle extract obtained through maceration possesses strong antibacterial activity against E. coli and has potential as a natural antibacterial agent. Abstrak. Bunga Rosella (Hibiscus sabdariffa L.) mengandung metabolit sekunder aktif yang berpotensi sebagai antibakteri. Penelitian ini bertujuan mengevaluasi aktivitas antibakteri ekstrak rosella terhadap Escherichia coli. Simplisia dianalisis kandungan senyawanya melalui skrining fitokimia. Ekstraksi dilakukan dengan metode maserasi menggunakan pelarut etanol 96% dan air (1:1), serta penyesuaian pH dengan asam tartrat hingga pH 1. Ekstrak kental kemudian dikarakterisasi secara organoleptis dan melalui pengukuran bobot jenis. Uji aktivitas antibakteri dilakukan dengan metode sumuran pada konsentrasi 10%, 20%, dan 30% terhadap E. coli, dengan kloramfenikol sebagai kontrol positif dan DMSO 5% sebagai kontrol negatif. Hasil skrining menunjukkan adanya senyawa alkaloid, flavonoid, polifenol, dan tanin (uji FeCl₃ positif). Rendemen ekstrak sebesar 66,33%. Ekstrak berwarna cokelat kemerahan, bertekstur kental, beraroma khas, dan memiliki bobot jenis 0,8775 g/mL. Zona hambat tertinggi sebesar 26,63 mm diperoleh pada konsentrasi 30%. Hasil ini menunjukkan bahwa ekstrak rosella yang diperoleh melalui maserasi memiliki aktivitas antibakteri kuat terhadap Escherichia coli dan berpotensi sebagai antibakteri alami.