Abstract: Disclosed herein is a compound having formula (I), wherein R.sub.1 represents a hydrogen atom or a C.sub.1-3 alkyl group; and R.sub.2 represents phenyl and furanyl group, or a group represented by the formula: --C(R.sub.a).dbd.C(R.sub.b)(R.sub.c), wherein R.sub.a, R.sub.b, and R.sub.c, being the same or different from each other, means hydrogen atom or methyl or phenyl group. The present invention further provides a method for preparing the compound (I) and a composition comprising as an active ingredient the compound (I). The compound (I) of the present invention can effectively inhibit the expression of enzymes involved in phase I reaction while activating the expression of enzymes involved in phase II reaction, thereby can be advantageously used to protect liver from being injured by various chemicals.