Cephaeline (Ipecac Isoquinoline · Emetic · Amoebicidal Reference)

Compound	Cephaeline (O-Demethylemetine; Cephaelis isoquinoline alkaloid)
Class	Alkaloid — Isoquinoline (Emetane-type BBIQ)
CAS	483-17-0
Molecular formula	C₂₈H₃₈N₂O₄
Primary sources	Cephaelis ipecacuanha (ipecacuanha root), Cephaelis acuminata
Plant part	Roots
Claim strength	Moderate
Key applications	Emetic; amoebicidal; antiviral research; informational-only (cardiotoxic)
Buy from Herbuno	Informational reference — see HerbIQ Compound Index →

Name origin: Cephaeline is named after Cephaelis ipecacuanha — the plant genus from which it is one of the two primary alkaloids (the other being emetine). Structurally, cephaeline is emetine's 6′-O-demethyl analogue — one methoxy group less than emetine on the B-ring benzyl isoquinoline portion. Traditional use: Ipecacuanha root has been used since the 17th century — first by Brazilian indigenous peoples, then introduced to European medicine — as a powerful emetic and amoebicide. Cephaeline is present at approximately 30–50% of the total ipecac alkaloid fraction alongside emetine (50–60%) and minor alkaloids (psychotrine, O-methylpsychotrine). Both emetine and cephaeline contribute to ipecac's emetic and amoebicidal activities. Research trajectory: Cephaeline has attracted COVID-19 antiviral research interest alongside emetine — cell-based studies showing SARS-CoV-2 inhibition at concentrations overlapping with cytotoxic concentrations, limiting therapeutic applicability. Structure-activity studies in the emetane series confirm that the 6′-methoxy group of emetine slightly reduces potency relative to cephaeline for some antiprotozoal activities. Safety context: Cephaeline, like emetine, is cardiotoxic at doses approaching amoebicidal concentrations — QT prolongation, myocarditis, and cardiac arrest are documented at suprapharmacological doses. Not a supplement ingredient.

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Pharmacological Profile of Cephaeline

Emetic activity: Cephaeline and emetine produce emesis via two mechanisms: peripheral gastric irritation (direct mucosal action) and central stimulation of the chemoreceptor trigger zone (area postrema) and vomiting centre in the medulla. Both mechanisms are operative with ipecac syrup; the central mechanism requires sufficient alkaloid absorption, explaining the 15–30 minute latency of ipecac-induced emesis. Cephaeline's emetic potency is approximately equivalent to emetine. Claim strength: High (pharmacological).

Amoebicidal activity: Cephaeline inhibits protein synthesis in Entamoeba histolytica via 60S ribosomal subunit interaction — the same mechanism as emetine. In vitro antiprotozoal IC₅₀ values for cephaeline are in the low nanomolar range, making it potent but with a narrow therapeutic index due to mammalian cell cross-toxicity. The structural difference from emetine (one fewer methoxy group) produces subtle but measurable differences in cell selectivity ratios. Claim strength: Moderate.

Antiviral activity (COVID-19 and HIV): Cephaeline shows SARS-CoV-2 inhibition in Vero cell assays at sub-micromolar concentrations — slightly more potent than emetine in some screens. Both inhibit viral protein synthesis via the shared ribosomal mechanism. However, therapeutic concentrations overlap with cytotoxic concentrations, and cardiovascular risk precludes clinical application. Claim strength: Emerging (in vitro only).

Cardiotoxicity: Cephaeline and emetine cause QT interval prolongation, impaired myocardial contractility, and at higher doses irreversible myocarditis. The cardiotoxicity is dose-dependent and cumulative — chronic low-dose exposure causes progressive myocardial damage. This is the primary safety concern limiting any pharmaceutical development of emetane alkaloids. Claim strength: High (toxicology).

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Frequently Asked Questions — Cephaeline

How does cephaeline compare to emetine in pharmacological activity?
Cephaeline is emetine's 6′-O-demethyl analogue — one fewer methoxy group. For emetic activity, both are approximately equivalent. For amoebicidal activity, cephaeline is slightly more potent than emetine in some assays (the 6′-OH group may interact favourably with the ribosomal binding site). For antiviral screening, cephaeline often shows marginally better potency than emetine. Both share the same cardiotoxicity mechanism and safety limitations.

What happened to ipecac syrup in household poisoning management?
Ipecac syrup was withdrawn from household poisoning first aid recommendations in 2003–2004 by the American Academy of Pediatrics, American Association of Poison Control Centers, and equivalent bodies internationally. Evidence showed induced emesis with ipecac does not reduce toxin absorption, delays effective treatment (activated charcoal), and increases aspiration risk. Ipecac syrup sales fell precipitously after these recommendations; it is no longer commercially available in most markets as a household product.

Is there any current medical use for cephaeline or emetine?
Emetine hydrochloride (injectable) retains use in some developing-country contexts for severe amoebic dysentery and liver abscess where metronidazole is unavailable or has failed. It requires hospitalisation and cardiac monitoring. Cephaeline has no current clinical drug application. The emetane alkaloid class is effectively a historical pharmaceutical category superseded by metronidazole, nitazoxanide, and other safer amoebicides.

Why does the HerbIQ index document cephaeline given it has no supplement use?
The HerbIQ Compound Index provides complete pharmacological reference for all significant plant secondary metabolites, including pharmaceutical, controlled, and toxic compounds. Cephaeline is pharmacologically and historically important — it is part of one of the most clinically significant alkaloid families in the history of tropical medicine. The informational-only designation clearly designates no sourcing intent; the entry serves formulator education on the full chemical diversity of Cephaelis/Carapichea botanicals including the ipecacuanha Oil Soluble Extract in Herbuno's catalogue.

Related compounds: Psychotrine, Emetine, Sanguinarine, Chelidonine

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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