Strychnin (19-13-9) Physical and Chemical Properties
Strychnin
A naturally occurring indole alkaloid typically supplied as a crystalline solid and used as an analytical reference and research reagent for method development and toxicology studies.
| CAS Number | 19-13-9 |
| Family | Indole alkaloids |
| Typical Form | Crystalline solid (powder) |
| Common Grades | EP |
Strychnin is a polycyclic indole alkaloid belonging to the class of plant-derived natural products. Structurally it is a highly bridged, rigid heterocycle containing an indole core fused to multiple nitrogen- and oxygen-containing rings; the molecular formula is \(\ce{C21H22N2O2}\). The scaffold contains tertiary nitrogen centers and a lactam (14-one) functionality, yielding limited hydrogen-bond donation (no H–bond donors) but several acceptor sites (three H–bond acceptors). Conformational flexibility is very low (rotatable bond count = 0) and multiple undefined stereocenters are reported, consistent with a complex stereochemical topology.
Electronically and physicochemically, strychnin exhibits moderate lipophilicity (XLogP ≈ 1.9) with a modest topological polar surface area (TPSA = 32.8 Å2), implying reasonable membrane permeability for an alkaloid of its size. The free base is poorly ionized under strongly basic conditions but will form more water-soluble salts with strong acids; this salt-form behaviour is commonly used to manipulate aqueous solubility in formulation and analytical workflows. Pharmacologically and toxicologically it is a potent neuroactive alkaloid that antagonizes inhibitory glycine-mediated chloride conductance in the central nervous system, producing convulsant effects; this bioactivity underpins its historical use as a vertebrate pesticide and its continued relevance in pharmacology research.
Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Melting Point
No experimentally established value for this property is available in the current data context.
Boiling Point
No experimentally established value for this property is available in the current data context.
Vapor Pressure
No experimentally established value for this property is available in the current data context.
Flash Point
No experimentally established value for this property is available in the current data context.
Chemical Properties
Solubility and Phase Behavior
Strychnin in its free-base form is relatively lipophilic (XLogP = 1.9) and shows limited aqueous solubility at neutral pH; conversion to an acid salt (e.g., hydrochloride) markedly increases aqueous solubility and is the standard approach for preparing solutions for biological testing or analytical work. The molecule’s low TPSA (32.8 Å2) and absence of H-bond donors favor partitioning into organic phases and facilitate passage across lipid membranes. Solid-state behaviour is typical of rigid alkaloid solids (non-volatile, crystalline or amorphous solids depending on provenance and preparation), but no specific solubility or phase-transition data are provided here.
Reactivity and Stability
As a complex polycyclic tertiary-amine lactam, strychnin is chemically stable under ambient laboratory conditions but may be sensitive to strong oxidizing agents and extreme pH. Acidic treatment converts the free base to soluble salts; strong hydrolytic conditions (highly acidic or strongly basic, elevated temperature) could potentially hydrolyze labile amide/lactam functionality, though no experimental hydrolysis rates are reported here. Storage in the dark, under dry conditions and away from oxidizers is standard practice for similar alkaloid compounds.
Thermodynamic Data
Standard Enthalpies and Heat Capacity
No experimentally established value for this property is available in the current data context.
Molecular Parameters
Molecular Weight and Formula
- Molecular formula: \(\ce{C21H22N2O2}\)
- Molecular weight: 334.4
- Exact mass: 334.168127949
- Monoisotopic mass: 334.168127949
LogP and Polarity
- Computed XLogP3: 1.9
- Topological polar surface area (TPSA): 32.8 Å2
- Hydrogen bond donors: 0
- Hydrogen bond acceptors: 3
These parameters indicate moderate lipophilicity combined with low H-bond donor capacity, consistent with membrane-permeable but not highly polar small-molecule alkaloids.
Structural Features
- Heavy atom count: 25
- Rotatable bond count: 0 (rigid polycyclic framework)
- Complexity: 689
- Formal charge: 0
- Defined atom stereocenter count: 0; undefined atom stereocenter count: 6
The structure is a highly bridged, seven- or more–ring heterocycle incorporating an indole substructure, tertiary amine centers and a lactam carbonyl. The multiple undefined stereocenters indicate stereochemical complexity—conformer generation for full 3D enumeration may be constrained by undefined stereochemistry.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 19-13-9
- InChI: InChI=1S/C21H22N2O2/c24-18-10-16-19-13-9-17-21(6-7-22(17)11-12(13)5-8-25-16)14-3-1-2-4-15(14)23(18)20(19)21/h1-5,13,16-17,19-20H,6-11H2
- InChIKey: QMGVPVSNSZLJIA-UHFFFAOYSA-N
- SMILES: C1CN2CC3=CCOC4CC(=O)N5C6C4C3CC2C61C7=CC=CC=C75
- Other identifiers present in descriptive metadata: AIDS Number 578164; ChEMBL ID CHEMBL1609139; HMDB ID HMDB0251975; NSC Number 5365; Wikidata Q104667372.
Note: SMILES, InChI and InChIKey are provided as machine-readable identifiers for structure-based workflows.
Synonyms and Structural Names
Depositor-supplied and commonly encountered synonyms appearing in the descriptive metadata include: Strychnin, Strychnine, Vauquline, NSC5365, NSC 5365, CHEMBL1609139, QMGVPVSNSZLJIA-UHFFFAOYSA-N, BBL033983, MFCD00005941, STL372869, AKOS025247982, UN 1692, NCGC00167847-01, VS-12360, DB-050083, WLN: T6 G656 B7 C6 E5 D 5ABCEF A& FX MNV QO VN SU AHT&&TTTTJ, and several systematic IUPAC-style names (e.g., 4a,5,5a,7,8,13a,15,15a,15b,16-decahydro-2H-4,6-methanoindolo[3,2,1-ij]oxepino[2,3,4-de]pyrrolo[2,3-h]quinolin-14-one). The list above reproduces names present in the available metadata.
Industrial and Commercial Applications
Representative Uses and Industry Sectors
Strychnin is a plant-derived alkaloid historically and currently used as a vertebrate pesticide for the control of small mammals and birds. Its potent neurotoxic action on inhibitory neurotransmission is the mechanistic basis for this use. The compound also appears in research and analytical contexts as a reference standard or pharmacological tool compound for studies of inhibitory glycine receptor function.
Commercial grades: EP.
Role in Synthesis or Formulations
The compound’s role in commercial formulations is primarily as an active biocidal ingredient in pesticide products where permitted. In synthetic chemistry and medicinal chemistry contexts it serves as a structurally complex scaffold and a benchmark neuroactive molecule; however, specific synthetic intermediates, formulation concentrate percentages or product specifications are not provided here. No concise application summary beyond the above is available in the current data context.
Safety and Handling Overview
Acute and Occupational Toxicity
Strychnin is a high-potency convulsant alkaloid; exposure by ingestion or dermal contact can produce severe muscular convulsions escalating to death by asphyxia or exhaustion. Mechanistically it is an antagonist at the strychnine-sensitive glycine receptor (a ligand-gated chloride channel) in the spinal cord and brain.
Reported acute toxicity metrics (as provided):
- LD50: 2350 \(\mathrm{\mu g}\,\mathrm{kg}^{-1}\) (Oral, Rat) (T14)
- LD50: 1100 \(\mathrm{\mu g}\,\mathrm{kg}^{-1}\) (Intraperitoneal, Rat) (T14)
- LD50: 1200 \(\mathrm{\mu g}\,\mathrm{kg}^{-1}\) (Subcutaneous, Rat) (T14)
- LD50: 582 \(\mathrm{\mu g}\,\mathrm{kg}^{-1}\) (Intravenous, Rat) (T14)
Acute management of suspected poisoning includes gastrointestinal decontamination (activated charcoal where appropriate) and aggressive control of seizures using anticonvulsants (e.g., barbiturates, benzodiazepines) and muscle relaxants; supportive respiratory care may be required.
Storage and Handling Considerations
Handle strychnin as a highly toxic alkaloid: minimize exposure by using appropriate engineering controls (fume hood, enclosed handling), wear personal protective equipment (chemical-resistant gloves, eye protection, lab coat), and prevent ingestion or dermal contact. Control dust and aerosols during weighing and transfer. Store in tightly closed, labeled containers in a cool, dry, well-ventilated area away from oxidizers and strong acids or bases. For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
