Abstract: An insoluble cell fraction obtained from plant cells cultured in a suspension composed entirely of natural molecules for the treatment of primary and recurrent Clostridium difficile infections is provided. A process for the preparation of the insoluble cell fraction is also provided.

Abstract: The present invention provides a Dpp4 inhibitor which comprises a leucine derivative of the following formula (1) or a methionine derivative of the following formula (2): wherein each R1 and R3 represents a hydrogen atom (H) and an L-amino acid residue; R2 represents a hydroxyl group (OH), alkoxy group having 1 to 6 carbon atoms, amino group (NH2), alkylamino group having 1 to 6 carbon atoms, glycine residue, ?-alanine residue, L-amino acid (except for proline, alanine and phenylalanine) residue or L-amino-acid amide (except for proline amide, alanine amide and phenylalanine amide) residue; and R4 represents a hydroxyl group (OH), alkoxy group having 1 to 6 carbon atoms, amino group (NH2), alkylamino group having 1 to 6 carbon atoms, glycine residue, ?-alanine residue, L-amino acid (except for proline and alanine) residue or L-amino-acid amide (except for proline amide and alanine amide) residue. These derivatives also act as autophagy regulators.