Benzamidine hydrochloride
[CAS# 1670-14-0]

Identification

• Classification: Chemical reagent >> Organic reagent >> Imine, amidine
• Name: Benzamidine hydrochloride
• Molecular Formula: C₇H₈N₂.HCl
• Molecular Weight: 156.61
• CAS Registry Number: 1670-14-0
• EC Number: 216-795-4
• SMILES: C1=CC=C(C=C1)C(=N)N.Cl

Properties

• Melting point: 169 - 173 °C (Expl.)
• Solubility: water: soluble (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

Benzamidine hydrochloride is an organic compound widely recognized for its role as a reversible serine protease inhibitor. It is the hydrochloride salt of benzamidine, whose structure consists of a benzene ring attached to an amidine functional group (–C(=NH)NH₂). The hydrochloride form, with the molecular formula C₇H₉ClN₂, enhances the compound’s water solubility and stability, making it suitable for use in biochemical and pharmaceutical contexts.

The discovery of benzamidine dates back to early 20th-century synthetic organic chemistry, where the amidine group was investigated for its basicity and biological activity. The compound gained importance in biochemistry due to its potent inhibitory activity against serine proteases such as trypsin, thrombin, and plasmin. It mimics the natural substrates of these enzymes by binding to the active site and blocking catalytic function, thereby preventing proteolytic cleavage.

In laboratory research, benzamidine hydrochloride is commonly used to inhibit protease activity during protein purification procedures. Proteases released during cell lysis can degrade target proteins, complicating purification and downstream analysis. By adding benzamidine hydrochloride to extraction buffers, researchers can protect proteins of interest from degradation, improving yield and quality. Its effectiveness is most pronounced against serine proteases, and it is often used alongside other inhibitors to achieve broad-spectrum protection.

Beyond its application as a laboratory reagent, benzamidine and its derivatives have been explored in drug discovery as starting points for the design of anticoagulants and antiprotease agents. Structural modification of the benzamidine core has yielded more selective and potent inhibitors with improved pharmacokinetic profiles. Benzamidine analogs have been studied as potential treatments for thrombosis, pancreatitis, and inflammatory diseases where protease activity is a pathological factor.

Crystallographic studies have also utilized benzamidine as a ligand in structural biology. It has been used to identify and characterize active sites of serine proteases through co-crystallization. These structural insights have guided the design of novel inhibitors for therapeutic applications.

Toxicologically, benzamidine hydrochloride is generally regarded as having low acute toxicity at concentrations used in laboratory settings. However, due to its biological activity, care must be taken to avoid inhalation or ingestion, and appropriate personal protective equipment should be used when handling the compound. It should also be stored in a dry, cool environment to maintain stability.

In summary, benzamidine hydrochloride is a well-established serine protease inhibitor with extensive use in protein biochemistry, enzyme studies, and drug development. Its reversible binding to enzyme active sites makes it a valuable tool for protecting proteins during extraction and purification, and its chemical structure has inspired the development of therapeutic inhibitors targeting serine proteases.

References

2024. Recent progress in the application of amidines for the synthesis of N-heterocyclic compounds. Monatshefte für Chemie - Chemical Monthly.
DOI: 10.1007/s00706-024-03180-w

2024. Synthesis of 2-arylquinazolines by Chan-Evans-Lam coupling of 2-formylphenylboronic acids with amidines. Chemistry of Heterocyclic Compounds.
DOI: 10.1007/s10593-024-03314-2

1955. The synthesis of some 4‐carbobenzoxy‐3‐alkoxy benzamidine hydrochlorides and other amidines. Journal of the American Pharmaceutical Association, 44(10).
DOI: 10.1002/jps.3030441002