Ricin

1
Ricin

• Drew Thompson

2
The Big Picture

• Ricin derived from castor bean
• Beans have been known since 4000 BC when they
  were worshiped by the Egyptians
• Widely cultivated for the production of
  castor-oil
• Fabled panacea of many cultures oil and bean
  used to treat bronchitis, leprosy, syphilis, bone
  disorders, etc.

3
Ricin as a Medicine

• Used in cell surface property studies
• Currently being investigated for AIDS and cancer
  therapies when conjugated with mono- and
  polyclonal antibodies
• Used to selectively kill neurons for neuronal and
  brain research

4
What happened to Molecules of Death?

• Pound for pound, ricin is twice as toxic as adult
  cobra venom.
• About 4 beans contains enough to kill a human,
  1 10mg/kg if ingested
• If injected, toxicity drastically increases .3
  3µg/kg
• Average adult fatal dose can be as low as 25µg

5
How does ricin kill you?

• Two subunits A chain and B chain B-chain binds
  to cell surface to facilitate A-chain entry into
  cell
• A-chain travels through golgi, ER, lysomes into
  cytosol inactivates 60S ribosomal subunit

6
So what? I have lots of ribosomes

• A single A-chain can inactivate 1500
  ribosomes/min
• Only one A-chain molecule is needed to kill a
  single cell.
• In 25µg there are about 9,393,939,393,939,393,000
  molecules of ricin
• You don't have that many ribosomes, or cells

7
What if I eat the beans instead?

• Don't chew them, breaking the protective coat
  around the bean will release the ricin
• But the beans taste like hazelnuts
• First symptoms may take anywhere from an hour to
  several days to appear
• Will include severe dehydration, gastrointestinal
  bleeding, diarrhea, vomiting and fever
• Death is due to hypovolemic shock, caused by
  reduction in blood volume

8
There's an Antidote right?

• There is no antidote for ricin
• If ricin poisoning occurs from ingestion,
  vomiting can be induced, and administering
  activated charcoal as well as treating the
  dehydration
• If poisoning occurs via injection...you're
  basically dead.

9
People who've died

• Georgi Markov, Bulgarian dissident journalist in
  1978
• Vladimir Kostav, Bulgarian dissident living in
  Paris
• Ricin is schedule 1 in the Chemical Weapons
  Convention
• Has been used for attempted suicide and actual
  suicide

10
In Summary

• Ricin is one of the most toxic poisons found in
  nature
• It has fairly high potential for use in
  bioterrorism and chemical warfare
• If you have to eat a castor bean, don't chew it
• Children are most affected by this form of
  accidental poisoning, keep castor beans away from
  them