Ricinine (Castor Bean Pyridine Alkaloid · Ricin Biomarker · Informational Reference)
| Compound | Ricinine |
| Chemical class | Alkaloid — Pyridine (2-Methoxy-1-methyl-4-pyridone; N-methylnicotinoylmorpholine) |
| CAS | 524-40-3 |
| Primary source | Ricinus communis (castor bean seeds and leaves) — minor alkaloid alongside ricin |
| Key applications | Informational reference — castor bean alkaloid; mild neurotoxic; mildly insecticidal; forensic marker |
| Claim strength | Emerging (entomological context); Informational only (supplement) |
| Typical form | Not a supplement ingredient; forensic marker compound for Ricinus exposure |
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Name origin: From Ricinus (castor bean genus, from Latin ricinus = tick, referring to the seed’s appearance). Ricinine is a pyridone alkaloid — the only alkaloid typically found in Ricinus communis alongside the infamous non-alkaloid toxin ricin. Important distinction: ricin (a ribosome-inactivating protein toxin — 6,000× more toxic than cyanide by weight, a potential bioweapon) and ricinine (a mild pyridine alkaloid) are completely different molecules from the same plant. Pharmacology and toxicity: Ricinine is mildly neurotoxic in animals at high doses (convulsions via GABA receptor modulation in some models). It has mild insecticidal properties and has been studied as a potential natural pesticide. The toxicity of ricinine is far below that of ricin and is not a practical poison at any likely dietary or environmental exposure. Forensic significance: Ricinine is used as a biomarker to detect Ricinus communis exposure or ricin poisoning — urine and plasma ricinine levels can confirm exposure to castor plant materials in forensic and toxicological investigations. Commercial importance: Castor oil (from Ricinus communis seeds) is a major industrial raw material (lubricants, bioplastics, cosmetics) and pharmaceutical excipient (castor oil is used in injectable formulations). The oil extraction process removes ricin and reduces ricinine; commercial castor oil is safe. Supplement status: Not a supplement ingredient. Castor oil (de-toxified) has cosmetic and pharmaceutical excipient applications.
Ricinine — Toxicological and Commercial Context
Differentiation from ricin (critical): Ricin is a ribosome-inactivating protein (RIP) — a lectin consisting of two chains (A-chain: N-glycosidase that depurinates 28S rRNA; B-chain: galactose-binding lectin for cell entry). It is one of the most toxic naturally occurring substances known. Ricinine is a small molecule pyridine alkaloid with none of ricin’s cytotoxic mechanism. The two co-occur in castor seeds but are chemically, mechanistically, and toxicologically completely distinct. Any formulator working with castor-derived ingredients must understand this distinction. Critical safety reference.
Forensic biomarker application: Ricinine is stable in human urine and can be quantified by LC-MS/MS at very low concentrations (ng/mL). Following ricin poisoning (or any Ricinus exposure), ricinine appears in urine before clinical symptoms develop, providing early diagnostic confirmation. CDC protocols for ricin exposure investigation use ricinine as the primary urinary biomarker. This application makes ricinine analytically important in forensic toxicology. Forensic reference.
Castor oil safety and commercial applications: Cold-pressed castor oil (the commercial product) contains negligible ricin (ricin is in the press cake, not the oil) and low levels of ricinine. Commercial castor oil is safe for: cosmetic use (hair conditioning, skin moisturising), pharmaceutical excipient (solubiliser, surfactant in injectable formulations including Cremophor EL® for paclitaxel), and industrial applications. The castor oil press cake (ricin-containing) requires safe disposal — it cannot be used as animal feed. Commercial reference for formulators.
This compound is documented for research and formulator education purposes. For commercially available botanical ingredients, explore the HerbIQ Compound Index →
Frequently Asked Questions — Ricinine
What is the difference between ricin and ricinine?
Ricin is a large protein toxin (66 kDa) consisting of two polypeptide chains that kills cells by irreversibly inactivating ribosomes. It is classified as a potential bioweapon and is extremely toxic (estimated lethal dose in humans is approximately 1–10 micrograms/kg). Ricinine is a small molecule pyridine alkaloid (163 Da) with mild and poorly characterised toxicity at high doses in animals. The two are completely different molecules that happen to co-occur in Ricinus communis seeds.
Is castor oil safe to use in supplements or cosmetics?
Yes — commercial castor oil (cold-pressed or expeller-pressed) is safe. The oil extraction process does not extract ricin (a protein that stays in the press cake) and contains very low ricinine levels. Castor oil is approved by FDA as a GRAS ingredient for food applications and as a pharmaceutical excipient (Category I drug excipient). In cosmetics, castor oil is a common hair conditioning and skin-moisturising ingredient. The key commercial distinction is: castor oil = safe; castor seed powder/meal/press cake = contains ricin and is not safe for food or supplement use.
Can ricinine exposure from castor oil be detected in urine?
At commercial castor oil use levels (cosmetic or pharmaceutical excipient doses), urinary ricinine levels are typically below detection limits of standard forensic methods. Detectable urinary ricinine generally indicates significant Ricinus plant material exposure (seeds, leaves) rather than castor oil use. In a forensic context, measurable urinary ricinine would raise concern about potential ricin exposure warranting investigation.
What are the insecticidal applications of ricinine?
Ricinine has documented contact insecticidal activity against several agricultural pest species at concentrations achievable from castor plant preparations. It has been explored as a potential natural pesticide alternative in integrated pest management. However, commercial development is limited by the regulatory complexity of any Ricinus-derived agricultural product (due to ricin co-occurrence) and by the availability of more potent and better-characterised botanical insecticides (pyrethrin, azadirachtin, rotenone).
Related compounds: Amygdalin, Senecionine, Coniine, Nicotine
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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