Yohimbine

Yohimbine is not a nutritional food source but rather a pharmacologically active indole alkaloid (chemically: 17α-hydroxy-yohimban-16α-carboxylic acid methyl ester, C21H26N2O3, MW ~354.44 g/mol) extracted primarily from the bark of Pausinystalia yohimbe (Rubiaceae family). Key bioactive compound details: • Yohimbine HCl is the principal active alkaloid, typically standardized at 2–10 mg per dose in supplement formulations; raw bark extracts may contain approximately 1–6% total alkaloids by weight, of which yohimbine constitutes roughly 10–15% of total alkaloid content (approximately 0.1–0.9% of bark dry weight). • Related minor alkaloids present in whole bark extracts include corynanthine (rauwolscine/alpha-yohimbine), ajmalicine, and other yohimbanoid alkaloids, which may modulate overall pharmacological activity. • Mechanism of action: selective alpha-2 adrenergic receptor antagonist (Ki ≈ 1–2 nM at α2-adrenoceptors), which increases norepinephrine release, promoting sympathetic nervous system activation, catecholamine-mediated lipolysis, and vasodilation relevant to erectile function. • No significant macronutrient content (no protein, carbohydrates, fats, or dietary fiber in purified form). • No meaningful vitamin or mineral content. • Bioavailability notes: Oral bioavailability of yohimbine HCl is estimated at approximately 20–33% due to extensive first-pass hepatic metabolism (primarily via CYP3A4 and CYP2D6); peak plasma concentrations (Tmax) are reached within approximately 45–60 minutes; plasma half-life is approximately 0.5–2.5 hours. Bioavailability is highly variable among individuals, influenced by CYP2D6 polymorphism status (poor metabolizers may experience significantly higher plasma levels and increased adverse effect risk). Whole bark extracts show less predictable pharmacokinetics due to variable alkaloid composition and potential matrix effects. • Solubility: Yohimbine HCl is water-soluble (~16 mg/mL); free base form is poorly water-soluble but soluble in ethanol and chloroform.