An iminosugar, also known as an iminosaccharide, is any analog of a sugar where a nitrogen atom has replaced the oxygen atom in the ring of the structure. Iminosugars are common components of plants and may be responsible for some of their medicinal properties. The first iminosugar to be isolated from a natural source, 1-deoxynojirimycin (DNJ), found in Mulberry, was reported in 1976, but few others were discovered until many years later.