Bipyridyl

Chemical Name

  • Bipyridyl
  • 2,2'-Bipyridyl

IUPAC / CAS

2,2'-Bipyridine /  366-18-7

Physical and Chemical Properties

Bipyridyls are white crystalline solids insoluble in water but soluble in organic solvents like diethyl ether and methanol.

Mode of Action

Bipyridyls compounds are known herbicides. Bipyridyls compounds act on the cell envelope and increase the permeability causing leaking of ions and hence cell death.

Activity Spectrum

Bipyridyls have good activity against gram-positive cocci like Staphylococcus aureus. Resistance to Bipyridyls has been reported in Methicillin Resistant S. aureus (MRSA) and gram negative bacilli especially Pseudomonas aeruginosa. One study has indicated that adding an efflux pump inhibitor like reserpine can reduce the resistance to the gram-positive group. Similarly adding a membrane permeabalising agent like sodium citrate also increases the susceptibility to Gram-negative bacilli.

Disadvantages

  • Too toxic for systemic use hence must be used locally
  • Cannot be used alone as a biocide as it does not have broad spectrum antimicrobial activity.

Toxicity and Side Effects in Humans

Bipyridyls when used as pesticides have shown to increase the risk of Parkinsonism. The postulated pathogenesis is the oxidative stress and proteosomal dysfunction involved in the dopaminergic neurons. Bipyridyl toxicity is mainly due to th ability of bipyridyl compounds to dissociate into free bipyridyl radicals. The release of superoxide radicals initiates the arachidonic acid cycle.

Regulatory Information

It has been classified as a hazardous substance by all the international regulatory bodies.

Safety Measures

Bipyridyls are very toxic compounds. They should be handled with all personal protective clothing like chemical protect gloves, aprons, face shields and goggles. Bipyridyl compounds must be stored in a cool dry, well-ventilated area, in airtight containers. It should be stored away from ignition sources and heat.

First Aid Treatment

  • Ingestion: Bipyridyls are very toxic compounds.Severe acute toxicity can cause death.It acts as an irritant to the gastrointestinal mucosa. Do not induce vomitting in such patients. Immediately seek medical help in such cases
  • Inhalation: Take the person away from the source to an area of fresh air. If there is persistent difficulty in breathing, seek medical help , respiratory support may be required.
  • Skin contact: Bipyridyl compounds are contact irritants. The area must be washed with plenty of cold water and mild soap. Use an emolient in that area. If the injury is extensive consult a dermatologist for further management.
  • Eye contact: Bipyridyls can induce chemical conjunctivitis and keratitis. Flush the eye immediately with plenty of warm water at the eyewash station, atleast for 15 minutes.
    In case of fire, use dry chemical agents or foam or fog to curtail the fire.

References

  1. Yang, Wonsuk, Tiffany-Castiglioni, Evelyn. The bipyridyl herbicide paraquat-induced toxicity in human neuroblastoma SH-SY5Y cells: relevance to dopaminergic pathogenesis. Journal of Toxicology and Environmental Health Part A 2005; 68 (26):1939-1961
  2. Denny BJ, Novotny L, PJW West, Blesova M, Zamocka J.Antimicrobial activity   
    of a series of 1- Alkyl ?2(4- pyridium) Pyridinium bromides against Gram Positive and gram negative bacteria. Med Princ Pract 2005; 14: 377 -381