Uncaria gambir Roxb Flavonoid Extraction, Antibacterial Assessment Against Escherichia coli, and Bio-Nanoparticle Preparation

Background: One of medicinal plants which has long been utilized by the Dayak tribes, indigenous to the Indonesian island of Borneo as a traditional medicine to treat diarrhea, open wounds, and cancer is Bajakah Kalalawit (Uncaria gambier Roxb.). This inspired our scientific exploration into the extraction of flavonoids from Uncaria gambier Roxb. (UGR) as a potential antibacterial agent against Escherichia coli ATCC 11229 (E. coli). Method: The concentration of flavonoid was determined using the aluminum chloride (AlCl3) colorimetric assay and visible spectrophotometry and found to be (31.55 ±0.29) mg QE/g, which was much higher than that of 30 Indonesian, 21 Indian, and 93 Chinese medicinal plants. The antibacterial activities of flavonoid at three different concentrations (10 ppm, 20 ppm, and 30 ppm) were assessed using the Kirby-Bauer method. Both their efficacy and development of resistance were compared to chloramphenicol as positive control. Results: Comparison at the same concentration (5%) showed that flavonoid produced efficacy 134.9 times than that of chloramphenicol. E. coli showed relatively weak resistance development to chloramphenicol after 39 hours. However, it did not show any resistance to flavonoid up to the last measurement at 75 hours. In addition, the success of synthesis flavonoid bio-nanoparticles opens the opportunity to combine chemical and physical antibacterial agents in a single product to combat stronger and more resistant bacteria. Conclusion: The findings underline medicinal plant UGR as a promising source of flavonoid which was proven to have very high efficacy against Escherichia coli and to have power to prevent bacterial resistance.