<unk>  is a glycosaminoglycan (formerly called a mucopolysaccharide) found mostly in skin, but also in blood vessels, heart valves, tendons, and lungs.
It is also referred to as chondroitin sulfate B,  although it is no longer classified as a form of chondroitin sulfate by most sources.
Dermatan sulfate
Heparan sulfate
Chondroitin sulfate
Keratan sulfate
Sarcoglycan
Lecithin
Hyaluronic acid 
Pentosan polysulfate