This study is to evaluate some biochemical characteristics and inhibitory effects against two phytopathogenic bacteria (Klebsiella variicola and Erwinia sp.) of methanolic and ethanolic crude extracts and their silica gel/ liquid-liquid fractions from five indigenous plants (Annona glabra, Passiflora foetida, Elaeocarpus hygrophilus Kurz., Phyllanthus amarus and Melastomas sp.) under in vitro conditions. High concentrations of total phenolic, flavonoid, tannin and alkaloid contents were found in all extracts. These extracts exhibited strong antioxidant activities through reducing power, H₂O₂ scavenging and DPPH scavenging assays. Using the agar well diffusion assay, all extracts showed the antibacterial activites against two tested bacteria. Amongst those, fraction from Annona glabra showed the highest activity against Klebsiella variicola and Erwinia sp. at the concentration of 150 mg/mL and 100 mg/mL respectively.

Key words: Antioxidant, antibacterial, fractions, phytopathogenic bacteria.