 So let me show you a couple of small drugs that are actually on the market and being used to treat disease. There are five of them, I think, yes. All of these are small, quite hydrophobic drugs, there are some aromatic rings in all of them. There are hydrogen bond donors here, some NH groups, and acceptors, that's the oxygen. All of these have chemical names that don't tell us a whole lot, but for some of them I'll tell you the marketing names too. Agonine is a so-called neuropharmacological drug that is something that's treating our nervous system, in this case schizophrenia, the so-called indication. This particular one is an antagonist that's targeting a whole range of receptors in the nervous system. Pelocarbin is another, this is an agonist instead of an antagonist. It's interesting because it's 100 years old. I'll come back to that on the next slide, but it's related to where do we find these drugs in the first place. This one occurred in nature, it's used to treat glaucoma in your eyes. If you've ever had a runny nose, you might have taken the small drug autravene, right? Autravene on the bottle, that's just a marketing name for Xeulomethasoline. Again, nasal decongestion is the indication, and this targets adrenergic receptors. It's an agonist too. And then we have two more here, Symmetidine and Cypracidone. Symmetidine is targeting ulcer or heartburn, just like AstraZeneca's locik drug, and Cypracidone is another drug targeting the nervous system. In this case, use is an anti-psychotic, and both of them are antagonists, just to give you some taste of it. Historically, the usual place for us to find drugs was simply nature, even rainforests. And this could be that either folklore or indigenous population or something, they knew that if you're having a bit of pain or something, you should usually eat a bit of this drug and then it goes away. That's how we discovered cocaine, for instance, that the Indians would eat cocaine when they were tired or something. They would chew the leaves of the cocoa bush, right? And then eventually we were able to purify that and get the compound cocaine in pure form. There are several examples of that. Turbicurine is a muscle relaxant, Cortison is used for birth control, Quinine is used for malaria. I could probably find 20 more if I looked them up. But the one on the previous slide, Pillow Carpene is fun. So over a hundred years ago, people realized that a certain plant had the property that it helps against glaucoma in the eyes. I think it was in 18, let's see, yes, 1874 this was isolated from the small plant called Pillow Carpese, and that's what it looks like. And of course, since then, today we know what the structure of the receptor is. We know exactly how it's worked molecularly and everything. The patents on this drug has long since expired. It's an example that today we understand the molecular basis, while 100 years, 150 years ago, even things were more phenomenological. Understanding the molecular basis is good in many ways, but it also means that we tend to have much higher requirements that it can't be toxic and it must be efficient today, which poses some challenges for us.