Teaching old drugs new tricks

Thalidomide. If you studied chemistry to A level you will know that this is the name of a drug which was once prescribed as a sedative and to pregnant women to prevent morning sickness in the 1950s. It was, however, banned for use because of a property of thalidomide that was, at the time, overlooked – its stereochemistry (the way its atoms are arranged in 3D space).

The chemical structure of Thalidomide. For those unfamiliar with stick drawings, every corner is a carbon.

The image above shows thalidomide’s structure. The wiggly line between the carbon on the 6-membered ring and the nitrogen on the 5-membered ring indicates that there are two ways to arrange the molecule in 3D space, i.e. if the 5-membered ring is in the plane of your computer screen, the 6-membered ring could either be seen to be angled into or out of the screen. It was discovered that one of these arrangements was responsible for birth defects amongst children whose mother had taken the drug during pregnancy.

BUT it has recently been discovered that combining thalidomide with a yellow pigment from turmeric (curcumin) produces a molecule which can kill multiple myeloma cells – the second most common blood cancer! The curcumin section (which also shows anti-cancer properties) ensures that the thalidomide section doesn’t degrade in the body, and the thalidomide section makes the curcumin section more water soluble. The hybrid compound has higher toxicity against cancer cells than thalidomide or curcumin alone or any combination of the two.

The new hybrid compounds have not yet reached human clinical trials,  but have shown promising activity against myeloma and prostate cancer in animal models.

One of the cucumin-thalidomide hybrids which have shown promising anticancer results

One of the cucumin-thalidomide hybrids which has shown promising anticancer results

Reference: Org. Biomol. Chem., 2013, 11, 4757-4763. DOI: 10.1039/C3OB40595H

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Golden Balls

Can’t find your condom? No problem! Researchers in China have developed a new type of contraceptive! All you need to do is inject your testicles with gold nanorods and irradiate them with infrared light… Sounds pleasant!

The treatment works in a similar way to your microwave. A microwave works by using radiation of a certain frequency to make the water molecules in your food vibrate and generate heat. Infrared radiation would cause the ‘hairs’ on the nanorods vibrate, producing enough heat to kill off our little soldiers (if you know what I mean!) and the cells in the glands that produce them.

nanorods

Rod shaped gold particles covered in ‘hairs’ which vibrate when exposed to infrared light

Research has only been carried out so far on mice, but there are plans to extend the treatment into the canine and feline worlds as an alternative to surgical neutering. There are talks, however, of one day applying the treatment to humans!

With a shorter exposure to infrared light, it is possible to ensure that the testes’ temperature doesn’t climb too high, and that the infertility would only be temporary – a week or so. The paper seems to imply that this could be an alternative to using condoms, but I personally doubt that it will catch on – what sane man would let anyone go near his gonads with a needle!

Reference: Wen-qing Li et al., Nano Letters, 13 (6), p2477 (DOI: 10.1021/nl400536d)

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Why being a masters student is a type of slavery

Slave to science

Obviously the title of this post is a vast overstatement, and this is probably one of the biggest first world problems out there, but sometimes it really does feel that way! Okay, slaves don’t get paid for all their hard work and have no rights, but masters students pay thousands of pounds to do a year’s worth of hard work which often doesn’t get credited.

Undergraduate chemists are taught lies about how easy reactions are to carry out, and how reliably everything works if you follow the instructions properly. Experiments in undergraduate teaching labs have been tried and tested literally millions of times around the world, so you have to be a really bad practical chemist to go drastically wrong (I still managed it once or twice, though). The reality is that molecules are massively unpredictable, and when you start doing novel research, nothing tends to work!

Just today I finished a reaction with high hopes of finally getting the molecule I’ve been trying to make for about six months, only to find that no reaction had actually occurred, despite me having followed the protocol to the bone, and all I can do for now is move on and try to use another method. At least if a slave cleans the floor, the end result is that the floor is clean, not that it is just as dirty as it was at the start.

Despite this, though, when things do work in research, the overwhelming feeling of “Take that science! I beat you!!” is strong enough to give you false hope and make you keep going. That is the reason why, despite the challenges I’ve faced doing research this year, I still love chemistry and why I still want to carry on doing research as a PhD student.

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Discreet Meat Deceit

As you’re probably aware, horse meat has been found in many of the UK’s cheaper ‘beef’ products. This led to an investigation which discovered that this is happening all over Europe, including Sweden, Switzerland, Germany and France. Personally, I don’t mind, but a lot of people are creating a lot of noise about it, so it must be pretty important. I think maybe its the fact that people have been mislead. But how was the horse meat initially discovered in these products?

Image

Corse or How?

Some of the products tested showed a positive result for equine DNA – but if DNA is, at the end of the day, made of exactly the same building blocks in every living species on earth, how can you identify horse DNA from cow DNA from human DNA? Every individual living thing on the earth has their own unique DNA sequence (except identical twins) otherwise we’d all be clones of each other, and there are certain genes that must be present in each species in order to make them look how they do. An example would be the genes that give horses a single hoof and cows a cloven hoof on each foot, or the genes that give the horse one stomach chamber but the cow four.

The DNA sequences of many, many animals have been catalogued, and so if a sample of meat is subjected to a DNA test, you can compare the genetic material in the meat to the ‘generic’ horse genome, and if horse meat is present, you know you have it in your sample!

Image

DNA

So, what are the implications of having horse meat in our burgers, lasagnes, etc? Horse meat is cheaper than beef in some countries, so using it can drive the price of products down. Horses are also fed a drug called bute as an anti-inflammatory, but it is actually lethal to humans at high enough concentrations, but you’d have to have a lot of it to kill you (it is still used as a last resort for extreme cases of spinal arthritis in humans – but only a last resort as the side effects are quite serious).

My opinion is that horse meat is leaner, apparently more succulent than beef, and is considered a delicacy in many countries, so maybe we should start too? Don’t forget to check out the other science blogs at http://www.sciencebrainwaves.com/

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Ultra-Ever Dry

I was recently offered a place at the Molecular Scale Engineering Centre for Doctoral Training based between Sheffield and Leeds universities, which I was more than happy to accept. Given that I will have a choice about what I’ll be doing, it got me thinking about the types of chemistry done at the centre and the applications that they have in real life. The popularity of surface modification chemistry is growing – I’m even doing some for my fourth year project – and it seems as though this area has almost limitless potential. For example, have a look at this video…

How awesome is that?! The secret to this kind of technology is to change the properties of the surface to make it hydrophobic (hydro = water, phobic = fear, i.e. hydrophobic things repel water). The Ultra-Ever Dry website claims that the hydrophobic surface creates a barrier of air to stop itself from getting wet… but what does this mean?

The hydrophobicity of a surface (how hydrophobic it is) can be calculated using the contact angle it makes with a droplet of water. The contact angle is the angle between a surface and a fluid at their interface, illustrated below. Ultra-Ever Dry say that surfaces coated with their material have a contact angle of around 170 degrees, making them ultrahydrophobic. This is pretty impressive considering that a contact angle of 180 degrees would make the surface perfectly non-wetting.

UED

Hydrophilic (water loving) surfaces have much lower contact angles than hydrophobic ones. Ultrahydrophobic surfaces have contact angles bigger than 150 degrees.

But not only do Ever Dry coated things repel water, they also repel fats and oils (making it oleophobic). If you’ve ever tried to mix water and oil, you’ll know they don’t mix, and this is because they have completely different properties – so how can this material repel both? I’ve contacted the company to see if they will reveal any more information about how it works, but it’s not likely that they will share very much.

My guess is that the molecules deposited onto the material interact so strongly with oxygen in the air that anything else that tries to reach the surface can’t get past the oxygen molecules. I’ve done my best to explain that using a crudely drawn diagram here…

How I think Ever Dry works

My best guess on how I think Ever Dry might work based on my knowledge of chemistry now and what is said on the product’s official website

If representatives from the company ever get back to me to reveal their trade secrets, I will let you know! If you’re interested in reading other science blogs, check out the Science Brainwaves site where I publish my material along with other science students!

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Heart attacks and hard ons

Would you believe me if I told you that the enzyme that can prevent heart attacks is almost identical to the enzyme that gives men erections? So much so, that in 1985 during clinical trials for a drug designed to relieve high blood pressure, male patients displayed one particularly surprising side effect, and this drug went on to be one of the world’s highest grossing drugs as a cure for erectile dysfunction. That’s right – I’m talking about the little blue pill – Viagra.

Molecular structure of sildenafil

Sildenafil

Viagra (or sildenafil) was designed to inhibit (block) an enzyme called phosphodiesterase (PDE for short). There are several strains of this enzyme, each located in different areas of the body, and this drug was designed to inhibit the PDE enzyme in the walls of blood vessels resulting in their vasodilation (dilation of vessels), lowering blood pressure, and reducing strain on the heart.

Instead, the drug targeted the PDE enzyme located in the smooth muscle of the penis (PDE-5). To get to grips with how the drug works, you first need to know what an erection is (chemically speaking). Erections arise due to the build up of the molecule called cGMP in the smooth muscle of the penis. PDE-5 catalyses the conversion of cGMP to GMP to terminate the erection. Men with erectile dysfunction have over active PDE-5 enzymes and Viagra competitively inhibits PDE-5 so that the erection can be maintained.

The chemistry of an erection

The chemistry of an erection. Instead of PDE-5 converting cGMP back to GMP, sildenafil occupies the enzyme’s active site so that it can no longer do its job. Guanylate cystase is the enzyme that can catalyse the conversion of GMP to cGMP in the presence of nitric oxide.

Interestingly, there is a phosphodiesterase enzyme in the retina of the eye (PDE-6), which sildenafil can also inhibit, and This is potentially why some men observe visual side effects after taking Viagra.

There are some difficult concepts in this post that non-chemists might not understand. Please let me know and I will try and explain if you don’t get it. Thanks for reading x

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Rebranding

So, although my meaning for my previous title ‘chem face’ was in the About page, I thought it was probably a little cryptic to most of the people who visit and don’t bother reading that part… Coming up with a good name for a chemistry blog is hard, though! I hope this one is a little better. I changed it to Chemistry Matters because chemistry is the study of matter, and I want to make it matter!

Anyway, hopefully more posts about science soon x

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