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(ted)Are life-saving medicines hiding in

2023-05-26 20:54 作者:努力考研的二十八  | 我要投稿

For many people, you know, spending time in a dreamy location looks like this. But for me it looks like this.

00:09

(Laughter)

00:11

As a natural product chemist, I have always been inspired by those wonderful chemical substances we found in nature, especially the chemicals that are made by living organisms from cold environments. And today, I want to bring you along on my incredible journey into discovering the molecular treasure hiding in plants and other organisms thriving in the cold.

00:41

OK. Now I know what you might be thinking. "Norman, this just isn't for me. Chemistry was my worst subject in school, and I hate being cold. Why on Earth should I keep listening?”

00:55

(Laughter)

00:56

To which I say, stay with me. Because I’m convinced that there’s some amazing chemicals hiding in the north, which perhaps means that the next wonder drug to treat some of the nasty diseases that plague us humans is just waiting to be discovered. But we might not discover it without your help. Are you intrigued now?

01:21

(Audience) Yes!

01:22

Good. But before we go on with the chemistry, I want to give you a quick geography lesson. When we talk about the Canadian north, we talk about the land which is north of the 55th parallel. This includes most of the parts of Nunavik and Nunavut. And this land is really famous for beautiful landscape. It's famous for polar bears. It's famous for northern lights and it’s famous for ... Santa Claus.

01:54

(Laughter)

01:56

But despite these famous icons, the great white snowy North is still largely unexplored. And that's especially true at the molecular level. And my team and I hypothesize that the northern ecosystem must be producing fantastic unknown chemicals with fascinating properties. Why? Because of the harsh conditions and the unique stresses plants, fungi and other organism are experiencing in the north. They must produce chemicals to protect themselves from these stresses.

02:39

For example, imagine the sunburn you would get sunbathing for over 20 hours a day for a month. Well, to survive, you would need a tremendously good sunscreen. That's exactly what lichens have in the northern ecosystem. To protect themselves from UV radiation, they fabricate a defense chemical that blocks UV rays with an outstanding efficiency. And that's only one of the defense chemicals we know about. And we believe that there are many, many more hiding up there.

03:18

A couple of years ago, my group and I began our endeavors to prove this. Now, let me bring you to Umiujaq, Nunavik, a small Inuit village on the coast of the Hudson Bay. And we were interested there, we collected and we looked at the grayish lichens that have been very scarcely investigated, Stereocaulon paschale. Now this lichen is found only in ecosystems with very harsh climate conditions. And almost nothing was known at that time on its chemical content. So we thought it was a great species to investigate. So even though Stereocaulon paschale is quite abundant in Nunavik, we always try to minimize our footprint. So we sampled only 100 gram of the lichens and we brought it back to our lab at Université Laval in Quebec City. There we cleaned it and then we crushed it at -190 degree Celsius, using liquid nitrogen. And this step is essential to release the natural substances within the lichen cell.We then transformed the sample in the form of pulp using different solvents in a process called maceration. And after we filtered the sample and evaporated the solvents, we obtained what we call a crude lichen extract. And for a natural product chemist, that's when the fun starts.

04:56

(Laughter)

04:58

Through careful chromatographic separation and many other techniques, and years of work, we've been able to separate, purify and identify for the first time ever 13 natural substances in Stereocaulon paschale.

05:18

Now, I know, your minds are exploding right now.

05:22

(Laughter)

05:25

But wait, there's more.

05:26

(Laughter)

05:28

From these 13 natural substances, turned out that 11 had already been identified in other lichens, but two of the substances turned out to be unique in the world. Think about it for a moment. From over 340,000 natural chemical substances known on the planet, Stereocaulon paschale from Nunavik is producing two unique substances, a clear demonstration that organisms experiencing stresses in the northern ecosystem produce unique chemicals.

06:10

Now what are the properties of these chemicals, of these natural substances? We don't know at this point. This is still under investigation. And to me, and I hope to you now, this is the exciting part. Who knows if the next generation of much needed anti-inflammatory agent or cancer fighting drug or even cure for Alzheimer will be inspired by a chemical substance from Nunavik lichens. Wow.

06:44

Let me bring you now further north. In Nunavut, on the beautiful Baffin Island. And here the story began when a group of Canadian microbiologists identified for the first time ever in the sediment of the beautiful, cold Frobisher Bay, a microscopic fungus. Well, the fungus was part of the genus of what we call Mortierella. And so they called it, with not much originality, Mortierella species.

07:22

(Laughter)

07:23

But they also discovered that this weird-looking fungus is synthesizing unique natural substances, mortiamides. Now why a rather strange-looking fungus is producing these natural substances is still a mystery. However, this sparked our curiosity. From past research investigation, we knew that natural substances that share some of the similarities with the mortiamide, compounds isolated from the jatropha plants from Africa had antimalaria properties because they were able to neutralize the parasite responsible for the majority of malaria cases. Could the mortiamides possess the same properties? Well, to find out, we went back into the lab and we synthesized sufficient quantity of all the mortiamides. And we studied their antimalarial activity. And guess what? One of the substances, the mortiamide D,efficiently neutralized the parasite of malaria. But that's not the end of the story. It's even better. It was able to neutralize a strain of the parasite that is resistant to many, many malaria drugs currently use in clinics. Isn't that amazing? You get the natural substances coming out from, produced by a microscopic fungus isolated from the sediment of the icy cold Frobisher Bay in the great white, snowy north that could provide an answer to one of the most terrible tropical infections. It's a small world after all.

09:16

(Laughter)

09:17

Isn't it? (Audience) Yes!

09:19

Well, it's time to talk about the scary news. The north, unfortunately, is undergoing transformation at an alarming pace. It is warming up faster than anywhere else on the planet. And this leads to a phenomenon called the greening of the northern ecosystem. And this is particularly true with Nunavik.There's a shrub called Betula glandulosa that is progressing north very rapidly. Now one of the immediate consequences of this rapid shrub growth is that it decreases the daylight on the lower plants and lichen. This is altering the complete food chain, and it’s altering also the traditional way of living of the Indigenous community. And, unavoidably, this will lead to loss of biodiversity. And one of the hidden consequences of losing biodiversity is the loss of chemodiversity. It is my great fear that with the loss of plants, lichen and fungi, some unknown, fascinating natural substances and potentially wonder drugs could be lost, too.

10:50

Now, this is why we think our work is important. And timely. And this is why I hope by now you're convinced that you have a good reason to help protect the great white, snowy north. For my part, I'm going to continue to search for molecular treasures in the north in the hope of finding novel argumentsto provide stakeholders and politicians with good arguments for enforcing stronger and immediate measures to mitigate climate change. For your part, remember the story of mortiamide D, and how a discovery in the north could save lives in the tropics? We're all in this together. And no matter what corner of the planet you lived in, you must do your part to save Mother Earth one molecule at the time.

11:51

Merci beaucoup. Thank you.

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