2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/338Using a reasonably large chemical reaction network consisting of 421 species, we show that along with normal chemical evolution of molecular cloud during collapse and star formation, significant amount of adenine, a DNA base, may be produced after an evolution of 10^{6-7} years. This findings may shed light on whether life on earth had to begin from scratch or these molecules could have contaminated the earth from the beginning.4 pages including Figures; Accepted in Astronomy and Astrophysics LettersAstrophysicstext