Biophysical properties of plumeria obtusa leaf extract for antimicrobial ability and antioxidant ability

Abstract

The crude extracts of Plumeria obtusa (P.O) in four different solvents as ethanol, petroleum ether, ethyl acetate and distilled water were prepared before starting. At first, these extracts were used at the concentration of 6 mg/ ml and 3 mg/ ml for the determination of total phenolic and flavonoid content respectively. These results rose from 37 to 68 mg GAE/g dried crude extract with the highest amount resulted from ethyl acetate extract. Antioxidant activity was evaluated at different concentrations ranging from 0.078 to 1.3 mg/ml using DPPH assay. The obtained results clearly indicated that the EtOH extract showed the strongest antioxidant activity in terms of DPPH free radical. The last results came from antimicrobial tests including Disc diffusion method and MIC value. The MIC values of each extracts for different species of bacteria were determined to be 2.50 mg/ml and 5.00 mg/ml for DW sample; 1.25 mg/ml and 2.50 mg/ml for EA and EtOH samples; and 1.25 mg/ml, 2.50 mg/ml and 5.00 mg/ml for the PE sample. The zone of inhibition recorded from EA sample revealed its well resistance to mostly all four species of bacteria while PE sample gave smaller zone compared to the others. Key words: Plumeria Obtusa, crude extract, antioxidant, antimicrobial.