Structure of saccharides

Standard monosaccharides are widely distributed in nature and easily obtained by degredation of polysaccharides or isolation from various materials for example plants, microorganisms, yeast, marine sources or milk. However, the structures of many sugars which are known today are different from the general formula Cn(H2O)n. They are modified by amino groups or deoxygenation to name but a few. Many of them have been given trivial names as they are frequently found as constituents of different classes of biologically active compounds such as hormones, alkaloids, antibiotics, or cardiac glycosides.