Spermidine solution is widely used in cell culture and molecular biology research due to its role in promoting cell growth, proliferation, and autophagy. It is commonly added to culture media to support the growth of certain mammalian cells and microorganisms that require polyamines for optimal development. In aging and longevity studies, spermidine is applied to investigate its potential to extend cellular lifespan by enhancing autophagy, a process that clears damaged cellular components. This makes it a key compound in neurodegenerative disease research, including Alzheimer’s and Parkinson’s, where impaired autophagy contributes to disease progression. Spermidine solution is also used in epigenetic studies, as it influences chromatin structure and gene expression. It stabilizes DNA and can modulate the activity of enzymes involved in histone modification. Additionally, it is utilized in cosmetic formulations for its purported skin-rejuvenating properties, supporting cell renewal and protecting against oxidative stress. In agriculture, spermidine is studied for its ability to enhance plant stress tolerance and improve crop yield under adverse conditions.