Spermidine is a polyamine compound (C7H19N3) found in ribosomes and living tissues and having various metabolic functions within organisms.

Spermidine synchronizes an array of biological processes, (such as Ca2+, Na+, K+ -ATPase) thus maintaining membrane potential and controlling intracellular pH and volume.

Spermidine is a longevity agent in mammals due to various mechanisms of action, which are just beginning to be understood.

[2] Spermidine is known to regulate plant growth, assisting the in vitro process of transcribing RNA, and inhibition of NOS.

Also, spermidine is a precursor to other polyamines, such as spermine and thermospermine, some of which contribute to tolerance against drought and salinity in plants.