Antibacterial activity of sugar maple autumn‐shed leaf extract: Identification of the active compound

Abstract

AbstractEthanolic crude extract prepared from autumn‐shed leaves of sugar maple (Acer saccharum Marsh.) was recently shown to have antibacterial activity against Pseudomonas cichorii and Xanthomonas campestris pv. vitians, two bacteria causing diseases in lettuce production. In this study, antibacterial activity of sugar maple autumn‐shed leaves (SMASL) extract was further investigated. SMASL ethanolic crude extract was fractionated using HPLC system and geraniin was identified as the antibacterial compound by UPLC/Q‐Tof‐MS system. Geraniin, an ellagitannin, was then purified from SMASL crude extract using a glass chromatographic C18‐reversed phase silica gel column (purification Step 1) and a semi‐preparative HPLC system equipped with 5 μm XTerra Prep MS C18 column (purification Step 2). Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of purified geraniin (purity of 96%) against P. cichorii and X. campestris pv. vitians were determined. X. campestris pv. vitians (MIC of 0.024 mg ml−1 and MBC of 3.125 mg ml−1) was more sensitive to geraniin than P. cichorii (MIC of 0.781 mg ml−1 and MBC of 6.25 mg ml−1). In the present study, geraniin is reported for the first time as the main antibacterial compound present in SMASL.