Spermidine, also known as spermidine dihydrochloride, is a type of polyamine. Widely distributed in organisms, it is biosynthesized by putrescine (butylamine) and adenosylmethionine. Spermidine can inhibit neuronal synthase, bind and precipitate DNA; It can also be used to purify DNA binding proteins and stimulate T4 polynucleotide kinase activity. On September 1, 2013, scientists from Germany and Austria collaborated to study that spermidine may prevent the onset of Alzheimer's disease.