Cyanide & Happiness: The mystery of its lethal poisoning …

Introduction

• What is Cyanide?

• A salt or ester of hydrocyanic acid, containing the anion CN− or the group −CN. The salts are generally extremely toxic.

• It’s most notable characteristic is its rapid effect. Cyanide’s drastic effects can be prominent only a few seconds after its inhalation.

• Cyanide is most dangerous when it is present in high concentrations in closed areas, unventilated areas, because it has a high diffusion rate, so it won’t have much effect if it were released in the open.

Structure & Types of Cyanide

1. KCN – Potassium Cyanide

A colourless crystalline compound ,

similar in appearance to sugar ,

highly soluble in water.

Most of KCN is used in gold mining,

organic synthesis, and electroplating.

The toxicity of potassium cyanide when ingested depends on the acidity of the stomach, because it must react with an acid to become hydrogen cyanide, the deadly form of cyanide.

• NaCN= Sodium Cyanide.

It is a white, water-solube solid

and has a high affinity for metals,

which means it reacts vigorously

with them.

• When it reacts with gas, it forms Hydrogen Cyanide.

• Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide.

• HCN = Hydrogen Cyanide or Hydrocyanic acid.

• It is a colorless gaseous inorganic compound, which may or may not have an odor. Its odor is usually “bitter almond”. Some people have the inability to taste it. ( Genetic trait ;) )

• It is sometimes called prussic acid.

• It is a linear, weakly acidic, and has a triple bond between Hydrogen and Nitrogen.

• Its is the most toxic type of all three types of Cyanides.

Mechanism of Action

• Cyanide is a lethal compound mainly because it inhibits cellular respiration through hampering mitochondrial cytochrome oxidase. It, also, blocks the transport electron chain, preventing the movement of electrons.

• Cyanide blocks the action of Cytochrome a3 at complex 4 in the mitochondria, and thus preventing the reduction of water as well as production of ATP.

• This blockage produces many problems, some of which are:• 1- High Oxygen concentration in the blood without

consumption.• 2- No production of ATP, energy, which affects mainly the

brain and heart.• 3- Lactic Acidosis as a result of using anaerobic

metabolism.

Effect of Cyanide on cells/muscles

• As mentioned before, Cyanide promotes metabolic acidosis and anaerobic respiration, especially in cells that require oxygen the most. As a result, heart muscles and brain cells are the first to be affected by Cyanide intoxication.

• The CNS which is very sensitive to the levels of Oxygen, is going to malfunction very early in the intoxication and cause respiratory dysfunction.

• Heart muscles are going to be oxygen-starved for a few moments and will use anaerobic metabolism, which cannot last for long before serious harm to the cells occur.

Effect on Complex IV

• Cytochrome c Oxidase is a membrane protein complex, complex IV, in the mitochondria, which consists of Cytochrome a and a3 as well as two copper centres.

• It is the last enzyme in the electron transport chain of mitochondria. It receives electrons from each four cytochrome c molecules and transfers them to a single molecule of Oxygen.

• Cyanide has high affinity for certain sulfur compounds as well as metallic complexes. The cyanide ion may very rapidly bind to the (Fe3

+)iron ion in cytochrome a3, which inhibits its effect and renders the Electron Transport Chain futile.

Dose of Death

• A dose of around 250 to 325 mg of potassium or sodium cyanide is lethal in humans, and a lethal case would have a blood level of around 1 mg mL1. A blood level of greater than 0.2 mg mL is toxic.

• Toxicity by cyanide is nominated – Histotoxic hypoxia-

Signs & Symptoms

• The symptoms of poisoning include headache, salivation nausea, anxiety, confusion, vertigo, convulsions, paralysis, unconsciousness coma, cardiac arrhythmias, hypotension, and respiratory failure.

• Both venous blood and arterial blood remain oxygenated, and hence the victim may appear pink.

Usage and Processing

• Cyanide is mainly produced during the mining of gold and silver. It helps dissolve these metals and their ores.

• Cyanide is also used in electroplating, where it stabilizes metal ions in the electrolyte solution prior to their deposition.

• Cyanide has also some medical uses, such as:• 1- Emergency situations ; to rapidly decrease

blood pressure.• 2- The cyanide compound sodium nitroprusside is

used mainly  to measure urine ketone bodies as a follow-up to both diabetic & renal failure patients.

• Cyanide can be found in many substances, natural and synthesized:• 1- Cigarettes.• 2- Synthesis & combustion of plastic.• 3- Flora such as bitter almond, apricot, stone of

peach.• 4-Cassava tuber• 5-Combustion polyurethane foam.

Thank You

Prepared by Amjad Shamsi Basha,

Edited by Mohammed Khalifa