Chemical Evolution from Hydrogen Cyanide: Photochemical Decarboxylation of Orotic Acid and Orotate Derivatives

Abstract

Irradiation of solutions at pH 7 to pH 8.5 of orotic acid, orotidine, and orotidine 5'-phosphate with light at 254 nanometers yields the corresponding uracil derivative via the singlet excited state. This reaction completes a plausible prebiotic synthesis of uracil and its derivatives starting from HCN as the only carbon source.

Prebiotic synthesis of orotic acid parallel to the biosynthetic pathway

“…According to Horowitz's hypothesis (Horowitz, 1945), some of the contemporary biosynthetic pathways might reflect the corresponding prebiotic organic synthesis during chemical evolution. However, such a parallelism has not been found as yet, although a partial similarity has been mentioned (Ferris and Joshi, 1978a). We report here a possible prebiotic synthesis of orotic acid from aspartic acid and urea in aqueous solution.…”

Prebiotic-chemistry inspired polymer coatings for biomedical and material science applications

“…Matthew's and Ferris' separate studies of HCN polymerization chemistry, as well as Sagan's and Khare's study of tholins, also involved the facile production of complex, highly colored organic polymers. [7][8][9][10][11][12][13][14][15] They have also been considered as a potential source of amino acids, nucleobases and peptides on earth and appear to be common throughout our solar system. For example, these materials have been proposed to be the source of the distinctive orange, redbrown and black colors of comets and the atmosphere of planets and moons such as Saturn, Jupiter and Titan and carbonaceous meteorites, indicating their abundance in our solar system and the universe, respectively.…”

“…20 AMN, along with iminoacetonitrile, has received attention as an intermediate in the polymerization of hydrogen cyanide as well as a highly reactive synthon in heterocyclic organic synthesis. 7,11,13,[21][22][23] It is formally a trimer of hydrogen cyanide and spontaneously polymerizes when commercially available p-toluenesulfonate is neutralized (Figure 1b). 24 It allows easy access to HCN polymers under very mild and controllable conditions without the need to use HCN itself.…”

Orotidine‐Containing RNA: Implications for the Hierarchical Selection (Systems Chemistry Emergence) of RNA

“…Only orotic acid has that “privilege”, and is synthesized from aspartic acid and converted to orotidine by reaction with a ribose–phosphate derivative (Figure ) . Furthermore, the facile (abiotic) photochemical decarboxylative conversion of orotidine‐5′‐phosphate to uridine‐5′‐phosphate, is taken as a support for “transition from prebiology to biology”, pointing to the close similarity between the prebiotic and contemporary biotic pathways . In such cases, it has been proposed that slow non‐enzymatic reactions may have been improved by proteins at a later stage …”