To obtain an antimicrobial agent useful for inhibiting propagation of injurious yeast in the field of food, medicaments, cosmetics, etc., by including a new substance having activity against yeast which is isolated from yucca extract as an effective ingredient.
This antimicrobial agent comprises at least one kind selected from saponins expressed by any of formulas I to IV, wherein one of R1 and R2 is H and the other is methyl; Glc is β-D-glucose residue; Gal is β-D-galactose residue; and Xyl is β-D-xylose residue as at least one effective ingredient. The saponin preferably is obtained from Yucca Schidigera. For example, parts of Yucca Schidigera both under and above ground may be employed as raw material for extraction, and it is preferable that they are crushed down to an adequate size and are immersed so as to be extracted in a hydrophilic organic solvent such as water or methanol or a mixture of them which are maintained at a temperature ranging from room temperature to the boiling point.
TAMURA KOKICHI
MIZUTANI KENJI
TANAKA OSAMU
