Antioxidant and antibacterial assay against fish pathogen bacteria of Kjellbergiodendron celebicum (Koord.) merr. leaf extract

Introduction: Kjellbergiodendron celebicum (Koord.) Merr. (local name: tombe uwa) is a plant endemic to Sulawesi, Indonesia, and grows around lakes or aquatic environments where fish live. Based on phytochemical screening in previous studies, i.e. methanol extract and ethyl acetate fraction from the leaves of Kjellbergiodendron celebicum (Koord.) Merr., the methanol extract gives positive results containing polyphenol compounds in the flavonoid group which have been known to have strong antioxidant and antibacterial properties. Objective: To test the effectiveness of the comparison of the natural content in the compounds (antibacterial and antioxidant properties) and the total content of phenol in Kjellbergiodendron celebicum (Koord.) Merr., which was extracted using two methods, i.e. maceration and Ultrasonic-Assisted Extraction (UAE), in fish-disease bacteria. Method: The leaves were separated to be extracted with two different methods: maceration and Ultrasound-Assisted Extraction (UAE). Extracts were first screened qualitatively for antioxidant activity and then quantified with respect to in vitro antioxidant activity using the 2.2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and the ferric-reducing antioxidant power (FRAP) assay. Antibacterial activity was determined by the paper disc diffusion method and microdilution. Results: 70% Ethanol in leaves extract of Kjellbergiodendron celebicum (Koord.) Merr. The extract which has the highest activity based on the DPPH test and FRAP test is the extract from UAE extraction with IC₅₀ value of 9.81512 μg/mL and ferrous equivalent antioxidant capacity (FeEAC) value of 1.661.3 μmol/gr. UAE method also has a higher potential in antibacterial activity based on the diffusion method of paper discs and microdilution with the MIC obtained as much as 390.6 μg/mL. Conclusion: the UAE extraction method is better at scanning polyphenol compounds compared to the conventional maceration extraction method. Therefore, the results of the antioxidant and antibacterial activity using the UAE method are better than the maceration method.