What is the pharmacological and structural difference between teophylline and theobromine?
I'm not sure that I am able to give any good up to date peer-reviewed literature on this, since most of what I know about these chemicals I know from medical and chemistry textbooks.
First, both theophylline and theobromine belong to a class of agents called methylxanthines (along with caffeine). A methylxanthine is a derivative of xanthine. For some pictures of Xanthine, I recommend Wikipedia: http://en.wikipedia.org/wiki/Xanthine to get a picture of a xanthine.
Both theophylline and theobromine have a methylgroup hanging off of one of the Nitrogens in the double ring Xanthine structure, the difference is which Nitrogen the methyl group is attached to. (see wikipedia page for a nice picture of what I don't think is well explainable in words)
Pharmacologically, methyl-xanthines have two important mechanisms:
1. They are phosphodiesterase inhibitors (if you recall phosphodiesterase breaks down cAMP, which is a second messenger in many cell receptors), so they actually have many different pharmacologic effects - this is responsible for many adrenergic effects in the cardiovascular and pulmonary system. (though effect 2 below probably also affects heart rate)
2. They are inhibitors of adenosine receptors - this is largely responsible for neurostimulant effects (though effect 1 is probably also important).
Now to leave the basic science, clinically what are they good for -
Theophylline is particular useful for the treatment of pulmonary function. It is a bronchodilator and also has some anti-inflammatory effects. For this reason it is used in the treatment of asthma (but because of its side effects and the need for close monitoring is usually a 3rd or 4th line agent). It is also used in the treatment of spinal cord-injured patients, especially those who continue to rely on a tracheostomy for either respiration or for maintenance of the respiratory tract (or if they are having difficulty weaning form a ventilator).
Theobromine as far as I know is not routinely being used clinically (at least not in the US), but the most practical clinical use that I know of it is as a cough suppressant.
Not sure if this is what you were looking for, but I hope that this gets you off to a start in the right direction.
Theobromine, is a plant alkaloid bitter cocoa. It is found in chocolate, as well as a number of other foods, including the leaves of the tea plant, and the kola nut. It is in a class of chemical compounds methylxanthine, which also includes similar compounds theophylline and caffeine.
Theobromine is a slightly water-soluble powder, crystalline, bitter, the color has been listed as white or colorless. Has a smaller similar effect, but the caffeine in the human nervous system, making it less counterpart. Theobromine is an isomer of theophylline. Theobromine is classified as dimethyl xanthine.
Theobromine was first discovered in 1841 in cacao beans by Russian chemist Alexander Voskresensky. Theobromine was first synthesized from xanthine by Hermann Emil Fischer.
The methylxanthines or alkylxanthines are nitrogen containing molecules; they comprise caffeine (3-methyl groups – trimethyl xanthine; present in coffee and tea), theophylline (2 methyl groups - dimethylxanthine; present in tea, one mg in a 5 oz cup of tea) and theobromine (2 methyl groups – dimethylxanthine- present in cocoa). Tablets used to treat asthma contain 100 - 400 mg of theophylline. The xanthine structure in caffeine, theophylline and theobromine are made up of six and five membered rings containing nitrogen plus the oxygen atoms, while methyl (CH3) groups are distributed at different positions of the two rings. Methylxanthines are related to purines, which are nitrogenous bases, found in nucleic acids. Adenosine (adenine base and a sugar) is an example; adenosine bound to three phosphate groups is ATP (adenosine triphosphate); adenine is a nucleotide (base, sugar and phosphate).
Most of the caffeine consumed is extensively and rapidly metabolized in humans, and after a few hours, only about 2% of unchanged caffeine is found in urine. Adenosine acts as a cell protective - cytoprotective - modulating molecule, which responds to stress in organs and tissues. It is very short lived in circulation. Despite this fact, it activates four subtypes of adenosine receptors (ARs). Caffeine and theophylline are prototypes of antagonists of ARs, and their stimulant actions occur primarily through this mechanism. Caffeine is metabolized by different forms (isozymes) of cytochrome P450 enzymes in tissues. Potential interactions of caffeine with different and diverse drugs influence its metabolism. Genetic polymorphisms of these enzymes have important effects on caffeine metabolism and disposition. Caffeine might have an action related to liver damage, as a result of its AR antagonistic activity. The effect of caffeine on tumor T cells has been proposed to confer antitumor activity.
Phosphodiesterase is a ubiquitously distributed enzyme that catalyzes the hydrolysis of phosphodiester bonds in nucleotides. It is responsible for the hydrolysis of cyclic 3,5- adenosine monophosphate (cAMP) and 3,5- cyclic guanosine monophosphate (cGMP). Drugs which inhibit the action of phosphodiesterase, consequently decreasing the breakdown of cAMP, have a potential therapeutic action on the heart, lung, and vascular systems. This effect can extend to platelet function and inflammatory cascades. Caffeine and theophylline are weak non-specific inhibitors of phosphodiesterase activity.
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