Huperzine-A is a compound extracted from the herbs of the Huperziceae family. It is known as an acetylcholinesterase inhibitor, which means that it stops an enzyme from breaking down acetylcholine which results in increases in acetylcholine.
Acetylcholine is known as the learning neurotransmitter, and is involved in muscle contraction as well. Increasing levels of acetylcholine is routinely used as a technique amongst weight-lifters and scholars.
Huperzine-A appears to be a relatively safe compound from animal studies of toxicity and studies in humans showing no side-effects at dosages routinely supplemented with. Huperzine-A is in preliminary trials for usage in fighting Alzheimer's Disease as well.