Antimicrobial Activity of Eucosterol Oligosaccharides Isolated from Bulb of Squill (Scilla scilloides)

Antimicrobial activity of methanol extract from bulb of Scilla scilloides as well as the purified eucosterol oligosaccharides (EOs) against bacteria, fungi and alga was evaluated in vitro using paper disc bioassay. EOs including scillascilloside E-1, E-2, E-3 and G-1 were isolated from the bulbs by methanol extraction, gel filtration on Sephadex LH-20 and preparative HPLC. The metabolites were identified by MS (HR-FAB-MS) and 1H- and 13C-NMR spectral data analyses. Methanol (MeOH) extract and purified compounds, EOs showed a selective inhibitory activity against eukaryotic cells including fungal species such as Aspergillus flavus, Candida albicans, Pyricularia oryzae and an alga such as Chlorella regulsris at the concentration of 200 μg/paper disc, but little active against bacteria. Out of four EO compounds, Scilla-scilloside E-3 revealed the highest activity. These results show that the MeOH extract and EOs from the medicinal plant, S. scilloides, may be applied as a natural fungicide or a food preservative for control of molds.