In the comments, yesterday, we started talking about other retinoids a bit. We were talking about naturally occuring ones and close pharmaceutical analogues. I was racking my brain today trying to come up with one that didn’t follow the terpenoid/long chain of alternating double bonds pattern. I know of one that a friend targets for his research, but I can never remember the structure. Then I remembered another: adapalene!

Not very like retinoic acid (a vitamin A-related compound):

It is a topical acne drug. Many of the acne drugs, such as Accutane (isotretinoin) and Retin-A (tretinoin, just retinoic acid, above) target Vitamin A (really retinoic acid) receptors.

My favorite part about adapalene is that it has an adamantyl group:

Adamantane is named from Latin, from Greek, from adamas (”diamond,” or “invincible” depending whom you ask). This is because the 3-d structure of that ugly thing is actually very much like diamond. This has led into a bunch of research on diamondoids and molecular diamonds, which are kind of neat. Here, it is just a bulky alkyl group.

I think it’s 4-day weekend time. See you later.

Today’s molecule, canthaxanthin, is a member of the carotenoid family. This includes beta-carotene and lutein. These molecules are all strongly colored. This is a function of the degree of conjugation in the system.

A conjugated system has alternating double and single bonds, as you see in that long central chain. Small conjugated systems like benzene absorb in the UV, and larger conjugated systems, like our carotenes, absorb lower-energy light, yielding a visible color. For more information, see particle in a box (warning to the uninitiated: this ventures into quantum mechanics and gets a bit esoteric). Read the rest of this entry »

I was curious about this one after seeing it in the grocery and drugstore so many times. Docosanol, or Abreva, is apparently an effective treatment for herpes labialis (cold sores). It is one of the most boring structures you can imagine, and probably one of the only drugs to have its IUPAC name as its common generic name:

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Back tomorrow!

This one is obvious. It smells like, well, vanilla. Exactly like vanilla. Some people claim that it is a simplistic, cloying version of vanilla and you should always buy real vanilla extract instead of synthetic (which is mostly vanillin); I say these people are exaggerating. While you can definitely smell a difference, vanillin gets you 95% of the way there, and it isn’t a one-note wonder. If the smell weren’t so ubiquitous we’d find it much more amazing. Earthy and rich, yet spicy and vibrant, it really is a singular aroma. Read the rest of this entry »

I’ve mentioned this in the past as one of the canonical bitter compounds. It was originally extracted from the bark of the cinchona tree. It has been found useful in the treatment of malaria. The scope of malaria’s effects is both broad and amazing. According to a citation in Wikipedia, malaria infects 350-500M individuals annually - for reference, this is roughly 6-8% of the world! The vast majority of infections are in African children.

Antimalarial drugs, then, are a godsend. One of the most famous natural products ever, quinine was extracted from cinchona for years, and finally synthesized by Bob Woodward in 1944. The pharmaceutical and chemical industry would look incredibly different today if this man had never existed. You can see a picture of him at Dylan’s Tenderblog. He is the one on the right, smoking the cigarette next to the flask of the toxic and/or flammable chemicals. Amazingly, RB Woodward’s total synthesis of quinine takes up only one page in a journal. It would be slightly longer today. With more pictures. Here’s a picture:

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Even my peers make fun of me for this - it continually blows my mind that carbon dioxide is a part of a plastic. Logically, I know that there’s nothing special about a gas becoming incorporated into a nonvolatile chemical (ethylene, for example, is a gas and is incorporated into polyethylene, another plastic!). I think the idea has always rocked my world because CO₂’s so ubiquitous and comes out of things like you, me, and fire. CO₂, you see, can actually combine with a molecule of water to form carbonic acid:

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Here is one with which many readers will be acquainted first hand: nicotine. Named after Jean Nicot, tobacco booster extraordinaire, nicotine is an alkaloid that occurs in the whole nightshade family, of which tobacco is a member. Typically people will give the structure on the left, below.

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Sorry to punt again but I’m just getting home. Today’s molecule is carboxymethylcellulose. It is made from cellulose by its reaction with chloroacetic acid.

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Here’s a quickie. One of the earliest totally synthetic plastics (I don’t count cellulose derivatives since the work of polymerizing the stuff was already done by the tree) was Bakelite, a resin of formaldehyde and phenol (I show only the monomers here, that Wikipedia link will give you an idea of the kind of complex mixtures you get).

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