Hexoses, such as the ones illustrated here, have the molecular formula C6H12O6. German chemist Emil Fischer (1852-1919) identified the stereoisomers for these aldohexoses in 1894. He received the 1902 Nobel Prize for chemistry for his work.
that have opposite configurations of a hydroxyl group at only one position, such as glucose and mannose, are called epimers. Glucose, also called dextrose, is the most widely distributed sugar in the plant and animal kingdoms and it is the sugar present in blood as “blood sugar”. The chain form of glucose is a polyhydric aldehyde, meaning that it has multiple hydroxyl groups and an aldehyde group. Fructose, also called levulose or “fruit sugar”, is shown here in the chain and ring forms. Fructose and glucose are the main carbohydrate constituents of honey.