Hermetica Superfood Encyclopedia
Legacy index-continuity record: the score and narrative are provisional and must not be represented as validated or human-approved.
Review flags: AWAITING_SEMANTIC_VALIDATION
Synephrine is a protoalkaloid derived from bitter orange that acts as a selective β1-adrenergic receptor agonist. It increases metabolic rate by 129-183 kcal daily and enhances fat oxidation through stimulation of lipolytic pathways.
Origin & History
Synephrine is a protoalkaloid primarily sourced from the immature fruits and peel of Citrus aurantium (bitter orange), a plant in the Rutaceae family. It belongs to the phenylethylamine chemical class and is structurally related to ephedrine but with weaker stimulatory effects. Commercial extraction involves solvent-based methods from dried bitter orange peel, yielding extracts standardized to 4-6% p-synephrine content.
Research Narrative (Provisional)
A 2022 meta-analysis of placebo-controlled trials found p-synephrine tends to raise blood pressure and heart rate without facilitating weight loss. Key RCTs include an 18-subject crossover trial (PMID: 26948284) showing no cardiovascular effects at 49mg, and a double-blind RCT (PMID: 21537493) demonstrating 50mg p-synephrine increased RMR by up to 183 kcal. A review of ~20 studies involving ~360 subjects confirmed safety at typical doses, though longer trials up to 56 days showed increased RMR without weight loss.
Preparation & Dosage
Dosage guidance is withheld because the publication gate has not recorded adequate support for this profile.
Nutritional Profile
Synephrine is a protoalkaloid (phenethylamine derivative) with molecular formula C9H13NO2 and molecular weight 167.21 g/mol. It is not a macronutrient or micronutrient source but a pharmacologically active bioactive compound. Naturally occurring concentrations: bitter orange (Citrus aurantium) peel contains 0.02–0.07% synephrine by dry weight (~200–700 mg/kg); immature fruit (zhi shi) contains higher concentrations of 1–6% by dry weight in some extracts. Standardized commercial extracts are typically standardized to 6% or 10–30% synephrine content. Primary bioactive form: p-synephrine (para-synephrine) is the predominant naturally occurring isomer; m-synephrine (meta-synephrine, oxedrine) is the pharmacologically distinct synthetic form. Oral bioavailability: approximately 30–40% for p-synephrine due to first-pass hepatic metabolism; peak plasma concentration (Tmax) reached within 1–2 hours post-ingestion. Typical studied doses range from 50–100 mg p-synephrine per serving in clinical trials (e.g., 50 mg yielding RMR increase of 129–183 kcal per PMID: 21537493). No meaningful macronutrient (carbohydrate, fat, protein), fiber, vitamin, or mineral content attributable to synephrine itself as an isolated compound. Metabolized primarily via monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) pathways; co-administration with MAO inhibitors significantly alters metabolism and bioavailability.
Reported Mechanism (Provisional)
Synephrine selectively binds to β1-adrenergic receptors, activating adenylyl cyclase and increasing cAMP levels. This stimulates hormone-sensitive lipase for enhanced lipolysis and increases thermogenesis through uncoupling protein activation. It also inhibits inflammatory pathways by suppressing p38 MAPK and NF-κB signaling cascades.
Clinical Narrative (Provisional)
A double-blind randomized controlled trial demonstrated synephrine increases resting metabolic rate by 129-183 kcal in healthy adults. Multiple studies show enhanced fat oxidation rates during exercise through adrenergic stimulation mechanisms. Anti-inflammatory effects have been documented through p38 MAPK and NF-κB pathway inhibition studies. However, long-term weight loss efficacy requires more extensive clinical investigation.
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