Abstract. Praptiwi, Sulistiarini D, Qodrie ENP, Sahroni D. 2021. Antibacterial activity, antioxidant potential, total phenolic and flavonoids of three plant species of Rubiaceae from Banggai Island, Indonesia. Biodiversitas 22: 2773-2778. The present study was carried out to study the antioxidant and antibacterial potential of different plant parts (stems, leaves, and fruit) of the family Rubiaceae (Timonius celebicus, Psychotria celebica, Gardenia mutabilis) collected from the Banggai Islands. Screening of antibacterial activity against Staphylococcus aureus and Escherichia coli and antioxidant potential was carried out by Thin Layer Chromatography- Bioautography. Determination of IC50 and Minimum Inhibitory Concentration (MIC) was carried out by microdilution in a 96-well microplate. Total phenolic and total flavonoid content was determined by the colorimetric method. Total phenolic (TPC) and total flavonoid content (TFC) was varied from 29.78-380.99 mg GAE/g extract and 105.61-841.18 mg QE/g extract, respectively. The antioxidant capacity of three plant species was varied from moderate to very strong. Antioxidant Activity Index (AAI) was found more affected by TFC than TPC. The antibacterial activity of the extract against E. coli was weak, while some extracts have moderate antibacterial activity against S. aureus

Endophytic fungus Fusarium sp. CSP-4 was isolated from the rhizome of Curcuma sumatrana Miq. The ethyl acetate extract of CSP-4 was fractionated by chromatographic column with silica as a stationary phase. The fractions were tested for antibacterial activity against S.aureus and E.coli by Thin Layer Chromatography (TLC)- bioautography. Determination of Minimum Inhibitory Concentration (MIC) was carried out by the microdilution method on a 96-microwell plate with the concentrations from 2 to 256 µg/ml. The results showed that fraction 15 and 11 were able to inhibit bacterial growth with the MIC values of 256 and> 256 μg / mL against S.aureus and>256 μg / mL against E.coli, respectively.The antibacterial activity of fractions 15 and 11 was weaker compared to the positive control of chloramphenicol with the MIC value of 4 µg/mL against S.aureus and E.coli. Based on the results obtained showed that the fractions of the methanol extract of endophytic fungus Fusarium sp. CSP-4 have weak antibacterial activity.