It is made up of seven carbon atoms, eight hydrogen atoms, four nitrogen atoms, and two oxygen atoms. Theobromine is very similar to caffeine but is ten times weaker. Caffeine has two more hydrogen atoms than theobromine. The structure of theobromine also contains two amide groups and three amine groups. Theobromine naturally occurs in cacao beans and is found in all chocolate products. It is what is toxic in chocolate to animals. Cardiac and central nervous system distress in dogs can be caused by 100-200 mg of theobromine per kg of the weight of the dog.
It is toxic because animals metabolize theobromine much slower than humans. Theobromine has a bitter flavor, therefore found in higher quantities in dark chocolate than milk chocolate. Theobromine also increases the excretion of water from bodies, relaxes, and stimulates. It can also be used to dilate blood vessels to lower blood pressure. There is no easily accessed evidence of the relationship between the structure and functionality of theobromine.