l-LSD, also known as (âÂÂ)-LSD or (5S,8S)-LSD, as well as l-lysergic acid diethylamide or l-lysergide, is a lysergamide and one of four possible stereoisomers of the lysergic acid diethylamide (LSD) molecule (with the psychedelic drug actually being the enantiopure d-isomer).
The LSD molecule has two chiral centers at carbons 5 and 8 of the ergoline ring system and hence there are four possible enantiomeric stereoisomers of LSD. l-LSD, also known as (âÂÂ)-LSD or (5S,8S)-LSD, is one of four possible stereoisomers. The other isomers are LSD (d-LSD, (+)-LSD, or (5R,8R)-LSD), iso-LSD (d-iso-LSD, (+)-iso-LSD, or (5R-8S)-LSD), and l-iso-LSD ((âÂÂ)-iso-LSD or (5S,8R)-iso-LSD). None of them are known to have significant psychoactivity in humans besides LSD.
l-LSD showed only 0.06% of the antiserotonergic activity of LSD in the isolated rat uterus. Hence, it was more than 1,000-fold less potent than LSD in this assay and was regarded as essentially inactive. In subsequent receptor binding studies, l-LSD showed 2,000- to 10,000-fold lower affinity for serotonin receptors than LSD.
l-LSD showed no psychedelic effects in humans at a dose of up to 10mg orally or up to 400times the minimum effective dose of LSD (~25üg). However, Albert Hofmann reported that although l-LSD produced no LSD-like effects, it caused "very slight drowsiness" at doses above 500üg.
l-LSD was first described in the scientific literature by at least the 1950s.