Spermidine is a

polyamine A polyamine is an organic compound having more than two amino groups. Alkyl polyamines occur naturally, but some are synthetic. Alkylpolyamines are colorless, hygroscopic, and water soluble. Near neutral pH, they exist as the ammonium derivatives. ...

compound () found in ribosomes and living tissues and having various metabolic functions within organisms. It was originally isolated from

semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. Semen i ...

Function

Spermidine is an

aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane, or ...

polyamine.

Spermidine synthase Spermidine synthase is an enzyme () that catalyzes the transfer of the propylamine group from ''S''-adenosylmethioninamine to putrescine in the biosynthesis of spermidine. The systematic name is S-adenosyl 3-(methylthio)propylamine:putrescine 3-a ...

(SPDS) catalyzes its formation from

putrescine Putrescine is an organic compound with the formula (CH2)4(NH2)2. It is a colorless solid that melts near room temperature. It is classified as a diamine. Together with cadaverine, it is largely responsible for the foul odor of putrefying flesh, b ...

. It is a precursor to other polyamines, such as

spermine Spermine is a polyamine involved in cellular metabolism that is found in all Eukaryote, eukaryotic cells. The precursor for synthesis of spermine is the amino acid ornithine. It is an essential growth factor in some Bacterium, bacteria as well. ...

and its structural

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

thermospermine A polyamine is an organic compound having more than two amino groups. Alkyl polyamines occur naturally, but some are synthetic. Alkylpolyamines are colorless, hygroscopic, and water soluble. Near neutral pH, they exist as the ammonium derivatives. ...

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

N-methyl-d-aspartate ''N''-methyl--aspartic acid or ''N''-methyl--aspartate (NMDA) is an amino acid derivative that acts as a specific agonist at the NMDA receptor mimicking the action of glutamate, the neurotransmitter which normally acts at that receptor. Unl ...

receptor (NMDA receptor), which has been associated with

nitric oxide synthase Nitric oxide synthases () (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine. NO is an important cellular signaling molecule. It helps modulate vascular tone, insulin secretion, airway tone, and p ...

(NOS) and cGMP/PKG pathway activation and a decrease of Na⁺,K⁺-ATPase activity in cerebral cortex synaptosomes. Spermidine is a

longevity The word " longevity" is sometimes used as a synonym for "life expectancy" in demography. However, the term ''longevity'' is sometimes meant to refer only to especially long-lived members of a population, whereas ''life expectancy'' is always d ...

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

Autophagy Autophagy (or autophagocytosis; from the Ancient Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent re ...

is the main mechanism at the molecular level, but evidence has been found for other mechanisms, including inflammation reduction, lipid metabolism, and regulation of cell growth, proliferation, and death. 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 A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

and

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

in plants. Spermidine has been tested and discovered to encourage hair shaft elongation and lengthen hair growth. Spermidine has also been found to “upregulate expression of the epithelial stem cell-associated keratins K15 and K19, and dose-dependently modulated K15 promoter activity ''in situ'' and the colony forming efficiency, proliferation and K15 expression of isolated human K15-GFP+ cells ''in vitro''.” Polyamine synthesis

Biochemical actions

Spermidine's known actions include: * Inhibits neuronal

(nNOS) * Binds and precipitates DNA * Polyamine plant growth regulator

Sources

Good dietary sources of spermidine are aged cheese, mushrooms, soy products, legumes, corn, and whole grains. Spermidine is plentiful in a

Mediterranean diet The Mediterranean diet is a diet inspired by the eating habits of people who live near the Mediterranean Sea. When initially formulated in the 1960s, it drew on the cuisines of Greece, Italy, France and Spain. In decades since, it has also incor ...

. For comparison: The spermidine content in human seminal plasma varies between approx. 15 and 50 mg/L (mean 31 mg/L). Note - spermidine content varies by source and age. See ref for details. In grains, the

endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the embryo and ...

contains most of the spermidine. One of the best known grain dietary sources is

wheat germ Cereal germ or Wheat germ: The germ of a cereal is the reproductive part that germinates to grow into a plant; it is the embryo of the seed. Along with bran, germ is often a by-product of the milling that produces refined grain products ...

, containing as much as 243 mg/kg.

Uses

* Spermidine can be used in

electroporation Electroporation, or electropermeabilization, is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs, electrode arrays or DNA to be introdu ...

while transferring the DNA into the cell under the electrical impulse. May be used for purification of DNA-binding proteins. * Spermidine is also used, along with calcium chloride, for precipitating DNA onto microprojectiles for bombardment with a

gene gun In genetic engineering, a gene gun or biolistic particle delivery system is a device used to deliver exogenous DNA (transgenes), RNA, or protein to cells. By coating particles of a heavy metal with a gene of interest and firing these micro-projec ...

. * Spermidine has also been reported to protect the heart from aging and prolong the lifespan of mice, while in humans it was correlated with lower blood pressure. It also was found to reduce the amount of aging in yeast, flies, worms, and human immune cells by inducing

autophagy Autophagy (or autophagocytosis; from the Ancient Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent re ...

. * Spermidine may play a role in male and female fertility. Fertile men have higher spermidine levels than men who are infertile, and spermidine supplementation has been shown to help maintain a healthy hormone balance and reduce oxidative stress. * Spermidine is commonly used for in vitro molecular biology reactions, particularly, in vitro transcription by phage RNA polymerases, ''in vitro'' transcription by human RNA polymerase II, and ''in vitro'' translation. *Spermidine increases specificity and reproducibility of Taq-mediated PCR by neutralizing and stabilizing the negative charge on DNA phosphate backbone. * Spermidine is, at physiological pH, a polycationic reagent that aids in enzyme digestion by forcing apart DNA molecules.

References

External links