A small bottle of Brucine, something what I used a few years ago for chiral resolutions by making diastereomeric brucine salts.
Brucine is a bitter alkaloid closely related to strychnine, the only difference besides of the two methoxy groups on the molecule, it’s not as toxic. It occurs in several plant species and it’s really toxic.
You may ask, that if its not as toxic as strychnine, than why is that skull on the bottle? The problem comes when you accidentally eat a small amount of this compound. A human consuming over 2 mg (0,002 g) of pure brucine will almost certainly suffer symptoms resembling strychnine poisoning. How does it works? It’s a neurotoxin which acts as an antagonist of glycine and acetylcholine receptors. It primarily affects the motor nerves in the spinal cord which control muscle contraction. The minimal lethal dose in humans is low as 30 mg (0,03 g).
Important info for every chemist: Brucine was in fact, the first natural product used as an organocatalyst in a reaction resulting in a successful enantiomeric enrichment ( by Marckwald in 1904). He reported the synthesis of chiral l-valeric acid (α-methyl propanoic acid) from the pyrolysis of brucine salt of racemic α-methyl-α-ethylmalonic acid with a 10% enantiomeric excess.