Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein X1, X2, and X3 are each CR2 or N; R1, R2, and R3 are each H, C1-6 alkyl, C1-6 alkoxy, SH, OH, or NRbRc, wherein Rb and Rc are each H, C1-6 alkyl, or hydroxy-C1-6 alkyl, or NRbRc forms a saturated or unsaturated 5- or 6-membered hetero ring; and B is a substituted or unsubstituted pyrazole, imidazole, pyridine, or piperidine; with the proviso that at least one of R1, R3, R4, and R6 is a group other than C1-3 alkyl in the case where X1?X2?Y1?N and X3?CR2.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein, R1, R3, R4, and R6 are each independently C1-3 alkyl; and R2 and R5 are each independently a hydrogen atom or C1-3 alkyl.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein, R1, R3, R4, and R6 are each independently C1-3 alkyl; and R2 and R5 are each independently a hydrogen atom or C1-3 alkyl.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a heterocyclic compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein R1, R2, and R2? are each independently C1-3 alkyl; Y is S or O; and p is an integer of 0 to 3, wherein when p is 2 or 3, R1 may be the same or different.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a heterocyclic compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein R1, R2, and R2? are each independently C1-3 alkyl; Y is S or O; and p is an integer of 0 to 3, wherein when p is 2 or 3, R1 may be the same or different.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein, R1, R3, R4, and R6 are each independently C1-3 alkyl; and R2 and R5 are each independently a hydrogen atom or C1-3 alkyl.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein X1, X2, and X3 are each CR2 or N; R1, R2, and R3 are each H, C1-6 alkyl, C1-6 alkoxy, SH, OH, or NRbRc, wherein Rb and Rc are each H, C1-6 alkyl, or hydroxy-C1-6 alkyl, or NRbRc forms a saturated or unsaturated 5- or 6-membered hetero ring; and B is a substituted or unsubstituted pyrazole, imidazole, pyridine, or piperidine; with the proviso that at least one of R1, R3, R4, and R6 is a group other than C1-3 alkyl in the case where X1?X2?Y1?N and X3?CR2.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a heterocyclic compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein A is C1-6 alkyl, C5-6 cycloalkyl, benzyl, benzylcarbonyl, benzoyl, phenyl, pyridyl or pyrimidyl; Ra is H, C1-6 alkyl, or C2-6 alkenyl; “” represents a single bond or a double bond wherein n=1 or 2; Y is S or O; and R3 and R4 are each independently H, C1-6 alkyl, hydroxy-C1-6 alkyl, C2-7 acyl, phenyl, pyridyl, pyrimidyl, etc.;with the proviso that at least one R3 is a group other than C1-3 alkyl in the case where: the hetero ring containing Y is a thiazoline ring; R4?Ra?H; X1?X2?CH; and either p =0 or R5?C1-6 alkyl.

Abstract: The present invention provides a compound having an excellent inhibitory action on melanin production and being useful as a whitening agent, and a skin external preparation containing the compound. The whitening agent of the present invention comprises, as an active ingredient, a heterocyclic compound represented by formula (1) or a pharmacologically acceptable salt thereof: wherein R1, R2, and R2? are each independently C1-3 alkyl; Y is S or O; and p is an integer of 0 to 3, wherein when p is 2 or 3, R1 may be the same or different.