A crystalline polyamine compound, C10H26N4, present in ribosomes and found widely in living tissues along with spermidine. It was originally isolated from semen

a polyamine widely distributed in plants and animals that plays a critical role in maintenance and stabilization of DNA helical structure.

Spermine is a polyamine involved in cellular metabolism found in all eukaryotic cells. Formed from spermidine, it is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at physiological pH.