Uji Efek Antibakteri Ekstrak Batang Akar Kuning (Arcangelisia Flava Merr.) Terhadap Bakteri Staphylococcus Aureus Dan Escherichia Coli

: Indonesia has a high diversity of flora and fauna in the world. Many types of plants can be used as a medicinal plant; one of them is yellow root (Arcengelisia flava Merr.) which has been known empirically by the Dayak community in Central Kalimantan as natural herbs to treat jaundice. This study aimed to determine the antibacterial effect of the yellow root bark extract against Staphylococcus aureus and Escherichia coli. This study was conducted in the Laboratory of Pharmacology and the Laboratory of Microbiology Faculty of Medicine University of Sam Ratulangi. This was an experimental laboratory study using the Kirby-Bauer modified technique. Yellow root bark extract was obtained from maceration process using ethanol 96%. The antibacterial effect was tested by using the well diffusion method. The results showed that distilled water, the negative control, did not generate inhibition zone around the wells. Ciprofloxacin, the positive control, had the greatest diameter of inhibitory zone. The average diameter of inhibition zone generated by ciprofloxacin was 39.23 mm against Staphylococcus aureus and 40.95 mm against Escherichia coli. Meanwhile, yellow root extract generated an average diameter inhibition zone of 12.27 mm against Staphylococcus aureus and 14.44 mm against Escherichia coli. Conclusion: Yellow root bark extract potentially had antibacterial effect against Staphylococcus aureus and Escherichia coli