Yohimbe (Pausinystalia johimbe)

Yohimbe refers to the bark of Pausinystalia johimbe, a West‑African evergreen tree whose bark contains the alkaloid yohimbine. The extract is most often marketed as a dietary supplement and is principally used to modulate sympathetic nervous‑system activity, which can affect cardiovascular tone, blood flow, and sexual function.

Yohimbine (C₂₁H₂₆N₂O₃) is a indole alkaloid belonging to the β‑carboline family. IUPAC name: (2S,3R,12bR)-13‑Methoxy‑12‑hydroxy‑5,6‑dihydro‑2‑hydroxy‑1,3‑dihydro‑β‑carboline (common synonym: yohimbine hydrochloride when in salt form). The molecule features a fused indole‑pyridine core with a methoxy group at C‑13, a hydroxyl at C‑12, and a tertiary amine (pKa ≈ 9.5). The alkaloid is lipophilic (logP ≈ 2.5), poorly water‑soluble, and stable under acidic conditions but degrades in alkaline environments. The hydrochloride salt improves aqueous solubility for oral formulations.

Yohimbe bark is harvested from mature P. johimbe trees primarily in Cameroon, Gabon, and the Democratic Republic of Congo. Sustainable harvesting requires ≥30‑year‑old trees and a rotational harvest to avoid over‑exploitation. Extraction typically uses ethanol or methanol under controlled temperature to preserve yohimbine content (≈2–3 % w/w in raw bark). Commercial supplements use standardized extracts (10 % yohimbine HCl) produced via liquid‑liquid extraction and subsequent crystallization. Quality considerations include verifying yohimbine content by HPLC, testing for heavy metals, microbial contamination, and confirming botanical identity through DNA barcoding. Certified Good Manufacturing Practice (cGMP) facilities and third‑party testing (e.g., USP, NSF) are essential to ensure potency and safety.