Adenosine

A nucleoside combining adenine with ribose — synonym adenine riboside — and a constituent of nucleotides and nucleic acids at the heart of cellular energy transfer. In muscle foods it sits in the ATP breakdown cascade whose intermediates, especially inosine monophosphate, generate umami and meaty flavour during ageing. It is also a signalling molecule in its own right: caffeine’s stimulant effect works partly by blocking adenosine receptors in the brain, which is why this quiet metabolic intermediate also explains the wakefulness a cup of coffee delivers.