Source comparison
MOTS-c vs NR: Mechanism and Bioavailability
NR enters cells via nucleoside transporters, gets phosphorylated to NMN by nicotinamide riboside kinase (NRK), then converted to NAD+ by NMNAT enzymes. Each step requires functional enzymes and cofactors. MOTS-c binds directly to folate metabolism enzymes (MTH
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- NR enters cells via nucleoside transporters, gets phosphorylated to NMN by nicotinamide riboside kinase (NRK), then converted to NAD+ by NMNAT enzymes. Each step requires functional enzymes and cofactors. MOTS-c binds directly to folate metabolism enzymes (MTHFD1L specifically) and activates AMPK without intermediate conversions. The mechanistic simplicity matters. Fewer steps mean fewer points of failure.
- Bioavailability data shows significant differences. Oral NR undergoes first-pass metabolism in the gut and liver, where nicotinamidase enzymes cleave the riboside bond, converting much of the dose back to nicotinamide (NAM) before it reaches systemic circulation. A pharmacokinetic study in Nature Communications found only 15–25% of oral NR dose reached peripheral tissues as intact NR. The rest became NAM, which feeds the salvage pathway but at lower efficiency.
- MOTS-c administered subcutaneously bypasses gut metabolism entirely. Plasma half-life is approximately 2–3 hours, with tissue distribution studies showing preferential accumulation in skeletal muscle and liver. The two primary sites of metabolic dysfunction in aging and metabolic syndrome. The peptide structure (hydrophilic, positively charged at physiological pH) allows rapid cellular uptake without requiring active transport.
- NR requires daily dosing at 300–1000mg to maintain elevated NAD+ levels because the salvage pathway runs continuously. NAD+ is consumed constantly by sirtuins, PARPs, and CD38 enzymes. MOTS-c produces sustained AMPK activation with administration 2–3 times weekly in rodent longevity studies published in Cell Metabolism. The signaling cascade it triggers persists beyond the peptide's plasma clearance.