Phytother Res. 2001 Dec; 15(8): 676-80.

Isolation of an antimicrobial compound from Impatiens balsamina L. using bioassay-guided fractionation.

Yang X, Summerhurst DK, Koval SF, Ficker C, Smith ML, Bernards MA.

Department of Plant Sciences, University of Western Ontario, London, ON, Canada.

By using brine shrimp (Artemia salina) lethality test-guided fractionation, a single bioactive compound (LC(50)=26 ppm) was isolated from the 95% ethanol extract of the dried aerial parts of Impatiens balsamina L. and subsequently identified as 2-methoxy-1,4-naphthoquinone (MNQ). The structure of MNQ was confirmed by UV, FT-IR, MS, and 1-and 2-D NMR spectroscopy. The antimicrobial activity of MNQ was evaluated using 12 bacterial and eight fungal strains. Five gram-positive and two gram-negative bacteria as well as all eight fungi (including multi-drug resistant strains) tested were highly sensitive to MNQ. A tea prepared according to traditional methods was found to contain sufficient MNQ to account for its antimicrobial properties.Copyright 2001 John Wiley & Sons, Ltd.