What hordenine does to monoamine oxidase
Hordenine is an N,N-dimethyl derivative of tyramine found in barley, bitter orange, and some cacti. In laboratory and animal work it has been reported to inhibit monoamine oxidase, the enzyme that breaks down trace amines and catecholamines. By slowing that breakdown, the idea is that signalling molecules such as phenylethylamine (PEA) and noradrenaline persist a little longer at the synapse.
It is worth being precise about the evidence: most hordenine MAO data come from in vitro and animal models rather than controlled human trials, and inhibition is generally modest and reversible rather than the strong, sustained block seen with pharmaceutical MAO inhibitors. Treat the diagram as a mechanistic sketch, not a measured human dose-response.
Why it appears alongside PEA in pre-workout blends
PEA is degraded so quickly by MAO-B that swallowed PEA on its own produces only a fleeting effect. Pairing it with a putative MAO inhibitor such as hordenine is the rationale behind some pre-workout stacks: the inhibitor is meant to extend PEA's window. Human evidence that this combination meaningfully improves performance or mood is limited.
Combining substances that affect monoamine breakdown carries real interaction risk, particularly with prescription MAO inhibitors, certain antidepressants, and tyramine-rich foods, where blood pressure spikes are a recognised danger. This page is general educational information, not medical advice; anyone considering these supplements, especially alongside medication, should consult a qualified healthcare professional first.