Tag Archives: organic chemistry

The Yew Tree: From Foe to Friend

For thousands of years, people have used the poisonous materials from the yew tree to fight their battles. Ancient people used the extract from the bark to coat the tips of their war arrows, rendering them deadly. The Romans used the same substance to assassinate political leaders. In the modern era, the yew tree is fighting a new opponent: cancer. A chemical, Taxol, which is derived from the plant is one of the most prevalent chemotherapeutic agents used today to battle cancer.

roman-eating

The poisonous properties of the yew have been known for thousands of years Source: Wikimedia Commons

Taxol, or paclitaxel, is toxic to cells because it disrupts the mitosis process. Mitosis is when a cell splits into two identical daughter cells. It is essential to maintain an healthy and growing organism. When the yew plant is ingested, cells cannot divide because of the these anti-mitotic properties of paclitaxol. Division halts and the cells die, which can eventually result in the death of the whole organism. These anti-mitotic properties are why Taxol works as an agent against cancer. This is because cancerous cells have mutated so that they divide uncontrollably. As Taxol disturbs cell division, it can efficiently kill certain types of cancerous cells such as breast and ovarian cancer.

yew_berries

The Yew Tree                                                           Source: Wikimedia Commons

The yew tree still holds some secrets: unlike many drugs originally derived from plant sources, there is no entirely synthetic pathway that reproduces the naturally derived compound. That is to say, for this chemotherapy to have full effect, it still needs materials acquired from yew trees. As the National Cancer Institute reports, a manufacturing technique has been developed recently which combines synthetic compounds and the chemicals from the yew bark. This has made the drug more accessible and affordable, but Taxol currently used in cancer treatment is still plant-based.

With a chemotherapeutic drug like Taxol, doctors scientists use the same properties of the substance that has been killing us for thousands of years to kill the enemy within us: cancer.

How Taxol Works (Source: Cancer quest)

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-Megan Wolf

If Organic Molecules Were Human: NanoPutians

Although killer clown sightings are the main topic of discussion these past few weeks, there is one thing aspect in chemistry that is just as weird and creepy (because it is Halloween month): NanoPutians. NanoPutians were first introduced to me in my Chem 218 class and are defined as synthetic organic molecules that resemble human forms which include but are not limited to: athletes, monarchs, bakers, and chefs.

The process begins with the synthesis of a NanoKid which provides the structural backbone for the various forms of NanoPutians. This is carried out in two multistep reactions with the upper portion which includes the head and body and the lower portion which includes the waist and legs synthesized separately as shown (1):

nanoputian-upper-body

nanoputian-lower-body

The upper and the lower portions are then joined via a Pd/Cu catalyzed coupling reaction to yield the NanoKid as shown (1):

nanokid

Microwave radiation, in the presence of a 1,2 or a 1,3 diol, is the methodology for the “head-conversion reaction” of a NanoKid to yield the series of NanoPutians (1). Depending on the reaction conditions, the NanoPutian could resemble that of an athlete (NanoAthlete), a pilgrim (NanoPilgrim), a Green Beret (NanoGreenBeret), a jester (NanoJester), a monarch (NanoMonarch), a Texan (NanoTexan), a scholar (NanoScholar), a baker (NanoBaker), or a chef (NanoChef) as shown (1):

nanokid-conversion-reaction

Furthermore, if you are not satisfied with the diversity, miscellaneous reactions that do not implement a NanoKid backbone can yield NanoToddlers and NanoBalletDancers. A NanoPutian Chain can also be synthesized, with modifications to the synthesis of the upper portion of the NanoPutian to yield an AB polymer configuration, to resemble individual NanoPutians “holding hands” and to symbolize multinanolism and peace on NanoEarth (okay I’ll admit I made that up) as shown (1):

nanoputian-chain

Now you may ask yourself: “Who funds this kind of research?”, “Why would anyone invest their time on this?”, or “What is the significance in learning about NanoPutians to the scientific community?”. Truth be told, there is no known significance (yet), in terms of chemical and practical applications, which may explain the limited research in this area (2). However, the synthesis of NanoPutians contributes a significant role in aspiring the younger generations in science and more specifically, the field of chemistry (2). And sometimes, we tend to forget how important that really is. If scientific advancements are to be made in the future (and one can only predict what the future will look like), the younger generations must be inspired by science and motivated to learn more in order to solve the problems and answer the questions, that we could not, about the world we live in.

-Andrew Siu

Chem 300 Section 109

References

Chanteau, S., Tour, J. Synthesis of Anthropomorphic Molecules: The NanoPutians. Journal of Organic Chemistry 2003, 68, 8750.

NanoPutians. Wikipedia. https://en.wikipedia.org/wiki/NanoPutian (accessed Oct. 8, 2016).

 

 

 

 

 

 

The Defense Mechanism of Plants

Close your eyes and imagine your sun soaked skin embracing the warmth Vancouver has finally blessed you with, the gentle cool breeze dancing through your hair, and your feet standing on top of a luscious, emerald lawn. Go ahead, take a deep breath, the smell of freshly cut grass. The scent of summer.

Why is the scent of freshly cut lawns so pleasant? The answer is pheromones. Plants are able to communicate with each other by sending out pheromones—chemical messengers. Plant cells synthesize these chemical compounds and then release them into the environment to elicit a response in the times of distress.

One of the key chemicals that elicits the defense response in plants is Jasmonic Acid. This organic compound activates the production of other genes for defense.

Methyl Jasmonic Acid is a derivative of jasmonic acid; its role is to regulate the developmental process and defense responses of plants when stress is detected. Part of the defence mechanism is releasing pheromones into the air warning plants around them that danger is near. These pheromones released are organic volatile substances known as Green Leaf Volatile (GLV). They have aldehydes, alcohols, and ester functional groups, which produces that fragrant aroma that people so often associate with summer.

Volatile Organic Compounds       Credit: Materic, D. et al. phys.org

Methyl Jasmonic acid is synthesized through the octadecanoid pathway. The picture below shows a detailed reaction pathway to this compound.

meja

Biosynthesis of Methyl Jasmonic Acid        Credit: Cheong, J.J. and Choi, Y.D. , Trends in Genetics

Although these volatiles may come from the same or entirely different species, the presence of these chemicals increase defence compounds. When cell membrane receptors detect these volatile chemicals, it activates self-defence by producing toxins, such as proteinase inhibitor. Furthermore, some of these pheromones produced by plants are able to attract insects to help defend themselves. For example, some plants release a certain type of pheromones to attract wasps. These wasps lay their eggs in caterpillars and when these eggs are hatched, the larvae eat the caterpillar from inside out.

I find this defense mechanism of plants absolutely fascinating. Plants are able to defend themselves in certain ways humans and animals cannot. While animals have physical features such as sharp talons or claws, speed, enhanced senses, and humans have martial arts and the sympathetic nervous system that elicits the fight-or-flight response as a form to defense mechanisms, plants defend themselves with the power of chemistry!

So the next time you’re out on a stroll enjoying that summer evening and you hear the roar of your neighbour’s lawnmower, you now know that the fragrant cut grass scent that follows is actually their distress signal. While releasing a series of organic molecules into the air to warn their plant friends and neighbours, it serves as an aromatic treat for us humans.

This video provides a more general explanation of this topic:

Resources:

Reece, J.B. et al. Fundamental of Physiology, 2nd ed.; Pearson: Canada, 2014; pp 237-238.

Cheong, J.J.; Choi, Y.D. Methyl jasmonate as a vital substance in plants. TRENDS in Genetics. [Online] 2013, 7. 409-412. http://www.cell.com/trends/genetics/pdf/S0168-9525(03)00138-0.pdf (accessed Sept 23, 2016)

Phys.org. De-mystifying the Study of Volatile Organic Plant Compounds. http://phys.org/news/2016-01-de-mystifying-volatile-compounds.html (accessed: Sept 24, 2016)