Extraction procedure and antibacterial activity in vitro of total phenol extract from Abutilon theophrasti Medic. Leaves

摘要

In this study, attempts were made to extract the total phenol from the leaves of Abutilon theophrasti Medic using ultrasound-assisted extraction, determine the content of the total phenol by Folin-Ciocalteu's reagent and evaluate antibacterial activities against 22 clinical E.coli and S.aureus, and two reference strains with broth microdilution method. The optimal extraction results were obtained when working at an ultrasonic frequency of 40 kHz, a power of 100 W, ethanol concentrations of 40% (v/v), a ratio of material to solvent of 1:30 (g/mL), an extraction time of 20 min, two cycles and at 60 degrees C. Spectrophotometric study of the phenolic compounds showed that the leaves of Abutilon theophrasti Medic. had more abundant total phenol content (9.76 GAE mg/g medicinal materials). Plant extracts had shown antibacterial activity against 24 test microorganisms. Minimum inhibitory concentrations (MICs) for the bacterial species ranged from 1.21-4.93 mg/mL. The results of this study suggest that the natural total phenol extract derived from the leaves of Abutilon theophrasti Medic. may have potential use in food, pharmaceutical and/or agro industries for preservatives or antimicrobial agents that require further investigation.