PROBLEM TO BE SOLVED : To provide use of extracts rich in N-acids of imino sugars (as opposed to neutral and basic imino sugars) and/or pipecolic acids obtainable from plant leaves of mulberry (Morus). SOLUTION : This invention relates to extracts rich in N-acids of imino sugars (as opposed to neutral and basic imino sugars) and/or pipecolic acids obtainable from plant leaves of mulberry (Morus). The extracts have been shown to have enzyme inhibition activity, so that extracts rich in these compounds and compounds isolated from these extracts are good candidates for use in treatment of diseases, particularly, but not exclusively, metabolic disorders, such as diabetes. SELECTED DRAWING : Figure 14 COPYRIGHT : (C)2019, JPO&INPIT