Extracts rich in N-acids of imino sugars (as opposed to neutral and basic imino sugars) and/ or pipecolic acids obtainable from the plant leaves of mulberry (Morus). The extracts have been shown to have enzymatic activities making extracts rich in these compounds, and the compounds isolated from these extracts, good candidates for use in the treatment of diseases, in particular, but not exclusively, metabolic disorders, such as diabetes.