Polyamines are the most basic (positively charged) organic small molecules in nature. They are ubiquitous in tissues in high concentrations and are thought to be involved in a variety of physiological processes related to cell proliferation and growth. In fact, polyamines act as growth factors and inhibitors of enzymes, including protein kinases, in cultured mammalian cells and bacteria.

The exact role of polyamines at the molecular level is still unknown in science, but they represent important biological compounds and are present in high concentrations in semen. Polyamines may affect the gating and transport of substances through membrane channels. From a clinical perspective, polyamines (spermidine and spermine) have been studied as markers for androgen deprivation therapy in men with advanced prostate cancer (Cipolla et al., 1994). Other researchers (Heston, 1991; Kadmon, 1992; Love et al., 1993; Madhubala and Pegg, 1992) investigated the role of polyamines in the pathophysiology of prostate cancer. The first and rate-limiting steps of prostatic polyamine synthesis are controlled by ornithine decarboxylase (ODC). ODC gene expression has been shown to increase in BPH tissues (Liu et al., 2002). ODC can be inhibited by difluoromethylornithine (DMFO) and thus inhibit polyamine synthesis. DMFO has been proposed as a chemoprophylaxis agent for prostate cancer (Kadmon, 1992).

Spermine levels in normal human spermine vary from 50 to 350mg/dL, mainly from the prostate, which is the richest source of spermine in the body. Spermidine [NH2 -- (CH2)3 -- NH -- (CH2)4 -- NH -- (CH2)3 -- NH2] is a kind of basic aliphatic polyamine, because it has four positive charges, so with acid or negatively charged molecules, such as phosphate ions, nucleic acids and phospholipids. When semen is left standing at room temperature, acid phosphatase enzymatically hydrolyzes semen phosphocholine to form free inorganic phosphate ions, which then interact with positively charged spermine to precipitate into large translucent spermine salt crystals. Polyamines can also form amide bonds and covalently add them to protein carboxyl groups (Williams-Ashman et al., 1975), a modification that may be associated with regulatory function.

Spermine and other related polyamines such as spermidine and putrescine are of great interest because of the rapid and dramatic changes in levels and ratios associated with the many cell types that have been induced to grow. Williams - Ashman, etc. (1969, 1972, 1975) studied in detail the biosynthesis and regulation of polyamines in the male reproductive tract and described enzymatic reactions from ornithine to putrescine to spermidine to spermidine.