The purpose of the present invention is to provide a charge control agent for polymerized toners and particularly for color toners, which has a large charge amount and environmentally stable charging characteristics. Since a charge control agent including a pyrazolone derivative represented by a general formula (1) or a salt of the derivative as an active ingredient has a large charge amount and excellent environmental stability of charging, it has an excellent charge-imparting effect for use in polymerized toners and particularly in color toners: ##STR00001##
in the formula, R.sub.1, R.sub.2, and R.sub.3 each independently represent a substituted or unsubstituted C1 to C20 linear or branched alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group.

The purpose of the present invention is to provide a charge control agent for polymerized toners and particularly for color toners, which has a large charge amount and environmentally stable charging characteristics. Since a charge control agent including a pyrazolone derivative represented by a general formula (1) or a salt of the derivative as an active ingredient has a large charge amount and excellent environmental stability of charging, it has an excellent charge-imparting effect for use in polymerized toners and particularly in color toners: ##STR00001##
in the formula, R.sub.1, R.sub.2, and R.sub.3 each independently represent a substituted or unsubstituted C1 to C20 linear or branched alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted condensed polycyclic aromatic group.

[Object] The purpose of the present invention is to provide a charge control agent for polymerized toners and particularly for color toners, which has a large charge amount and environmentally stable charging characteristics.

[Solving Means] Since a charge control agent including a pyrazolone derivative represented by a general formula (1) or a salt of the derivative as an active ingredient has a large charge amount and excellent environmental stability of charging, it has an excellent charge-imparting effect for use in polymerized toners and particularly in color toners. (in the formula, R.sub.1, R.sub.2, and R.sub.3 each independently represent a substituted or unsubstituted C1 to C20 linear or branched alkyl group, a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted condensed polycyclic aromatic group.)

The present invention relates to pyrazolidine derivatives and related compounds, methods of preparing said compounds, pharmaceutical compositions and combinations comprising said compounds and the use of such compounds and pharmaceutical compositions for the prophylaxis and treatment of medical conditions that can be affected by inhibiting lactate dehydrogenase (LDH), in particular LDHA and/or LDHB.