Ribose Accumulation in Borate-Rich Prebiotic Environments.

Under the RNA first hypothesis for the origin of life, RNA that emerges from prebiotic chemistry performed both catalytic and informational roles. Ribose is the only sugar in RNA; thus, many have sought to understand how ribose might have emerged on a prebiotic Earth. Ribose can be formed from formaldehyde with small amounts of glycolaldehyde by formose-like processes. However, under the strongly alkaline conditions of the reaction, ribose is consumed as it is formed. Here, we show that borate significantly decreases the consumption of the ribose formed in the formose reaction, which results in higher amounts of ribose that remained as the reaction progressed. Given a longer timescale of prebiotic chemical reactions governed by geological processes, borate-rich environments could have contributed to accumulating ribose on prebiotic Earth. Borate could be available on proto-continents and is known to contribute to ribonucleoside synthesis, ribose 5-phosphate synthesis, and nucleoside phosphorylation. Therefore, such environments might have promoted chemical reactions to RNA.