D-Xylose A simple sugars, C4H9O4CHO formula. Xylose is a component of the composite wood, xylan exist widely in plant. Xylose also exist in animal heparin, cartilage element and glycoprotein, it is some glycoprotein sugar in chain and serine (or threonine) connection unit. In nature has yet been found the free state of xylose.