LOGANIACEAE

The Loganiaceae or logania family consists of approximately 500+ species of tropical herbs, shrubs, climbers and trees. They have opposite leaves, small showy flowers, and fruit in the form of berry, capsule, or drupe. The most poisonous species belong to the genus Strychnos, with some 100+ species of tropical climbers and trees. The South Asian Strychnos nux-vomica and Strychnos ignatii contain two highly toxic indole alkaloids, strychnine and brucine, which are most concentrated in the seed and bark. Both alkaloids induce fatal convulsions, as little as 0.1 grams is fatal to an adult human. Strychnine poisoning is very suffering, victims exhibit involuntary muscle spasms so severe, the face becomes rigid, the jaws locks, the eyes protrude, and the neck and back arch backwards into a bridge (ophistonous). This is followed by seizure and death due to respiratory failure. Nux-vomica seeds were used  by the ancient Chinese as torture poison!

Despite its high toxicity, strychnine is a chemical molecule with tremendous contribution to science. It has a complex chemical structure which was once thought to be unsolvable. The total synthesis (make in the lab from scratch) of strychnine is the greatest achievement of modern organic chemistry, culminating in two Nobel prizes and thousands of scientific publications even  to this day.

The South American Strychnos toxifera (calabash curare) is also deadly poisonous, it is used by aboriginal hunters as arrow poison. This is due to the presence of toxiferine, a neurotoxic indole alkaloid. Toxiferine paralyses voluntary muscles, but does not enter the brain. Victims become ‘locked-in’ their own body, but remain fully conscious. Death is due to respiratory failure.

Another genus of poisonous Loganiaceae is the Spigelia, with some 60+ species of tropical herbs. The West Indian Spigelia anthelmia contains diterpene alkaloids of the ryanodine skeleton. S. anthelmia induces paralysis and disturbance to the heart rhythm. It is used traditionally to treat intestinal worms, or as a rat poison. Ryanodine is highly toxic to insects, it inspired chemists to develop a novel class of insecticides called the ryanoids. Ryanodine has also  elucidated a new mechanism of nervous transmission of the human body. The associated receptors are called ryanodine receptors. 

 

Pinkroot (Spigelia anthelmia.

Strychnine tree (Strychnos nux-vomica).

 

 

 

 

 

Strychnos nux-vomica seeds. Fatal dose to an adult human is probably 2–3 seeds (chewed).