The semester only started about the month ago and I’m already relying on caffeine more and more to get me through the week. With midterms starting up, I’m sure a lot of you feel the same way! Since I spend most of my time with a cup of coffee or a Diet Coke in my hand, I thought it was time to learn the actual mechanism of caffeine.
Caffeine is a stimulant of the central nervous system. In plants, it’s synthesized from AMP, GMP, and IMP. It’s then converted to xanthosine and then theobromine, which is then converted to caffeine. In the body, it counteracts adenosine, which reduces neural activity. Caffeine is able to easily cross the blood-brain barrier because of its small size and solubility in both water and lipids. It also inhibits phosphodiesterase and activates protein kinase A. It’s also a little basic, with a pKa of around 0.6.
Apparently, it’s also fairly toxic in doses above about 500 mg at a time (which is probably a good thing for me to remember right about now.)
Additionally, because of its structure, caffeine is able to bind to the adenosine receptor (they both have two connected rings with nitrogen with several O atoms). However, unlike adenosine, caffeine speeds up the rate that neurons fire and causes the pituitary gland to increase production of adrenaline.