Category: alkaloid
Aliases: α-Yohimbine, alpha-Yohimbine, Isoyohimbine, Corynanthidine
A minor indole alkaloid of yohimbe bark (Pausinystalia johimbe) and a diastereomer of yohimbine on the pentacyclic yohimban skeleton. It is a selective α₂-adrenoceptor antagonist, markedly more α₂- than α₁-selective (PMID:6142941); across human α₂ subtypes its affinity ranks α₂C > α₂A ≈ α₂B (GtoPdb), and it also antagonises 5-HT₂B (it serves as the radioligand [³H]rauwolscine for that receptor). Widely used as a pharmacological α₂-antagonist tool and sold in supplements as "α-yohimbine".
PubChem CID 643606 (C21H26N2O3, MW 354.4). Present in yohimbe bark: PMID:26391406 quantifies it as one of three P. johimbe alkaloids in US supplements. PubChem synonyms confirm α-yohimbine / isoyohimbine / corynanthidine (NB: "corynanthidine" = rauwolscine, distinct from the separate alkaloid corynantheidine).