Minggu, 07 Juli 2013

Glutamate — From Discovery To Global Product


Glutamate — From Discovery To Global Product

Author: ChemViews

Published Date: 19 July 2011

Source / Publisher: Chemistry - An Asian Journal/Wiley-VCH

Copyright: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

In 1908 Professor Kikunae Ikeda (1864—1936), College of Science, Tokyo Imperial University, Japan, isolated glutamate, one of the natural amino acids, from seaweed broth. 2300 years before this, Aristotle described the four tastes: sweet for sugar, salty for sodium chloride, sour for acid, and bitter for alkaloids. The fifth taste, the unami taste, is the indicator for proteins and nucleic acids.
Two other umami compounds were isolated later in Japan.
Ikeda found that humans can sense glutamate at a concentration as low as 0.01 % in water—far lower than the detection limit of sodium chloride and sugar—and that it is essential for a meal to taste good. He also found that sodium glutamate and sodium chloride synergistically enhance the taste of a meal.
Parmigiano reggiano contains a large amount (1.7 wt %) of glutamate, matured tomato > 2 % of its dry weight, and half of the amino acid content in human breast milk is glutamate. Today it is known that humans have a glutamate-receptor protein on the surface of their tongue and stomach.
In 1909, in collaboration with Ikeda, Saburosuke Suzuki started producing a seasoning on a commercial basis. A century later “Ajinomoto” has developed into a global product, and is now used by 800 million people in about 100 countries.

From Radicals to γ-Lactones


From Radicals to γ-Lactones

Author: Theresa Kueckmann

Published Date: 08 May 2012

Source / Publisher: Chemistry An Asian Journal/Wiley-VCH

Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Volatile γ-lactones are popular components of flavorings and fragrances, but their synthesis from O-allyl-α-haloesters by radical cyclization is hindered by slow conformational equilibration.

Fabrice Dénès and co-workers, Université de Nantes, France, have shown that α-bromo aluminum acetals, prepared from the corresponding α-bromo esters using diisobutylaluminum hydride (also known as DIBAL-H) can be cyclized at low temperature under reducing conditions. They report that this method can be combined in a one-pot sequence with subsequent Oppenauer oxidation to prepare the desired γ-lactones. This process enables straightforward access to γ-lactones from easily available precursors. The efficiency of the methodology was illustrated by synthesis of optically enriched (–)-trans-cognac lactone (pictured).

Nanomaterials and Chocolate – Interview with Luisa De Cola


Nanomaterials and Chocolate – Interview with Luisa De Cola


Author: Vera Köster

Published Date: 02 October 2012

Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Professor Luisa De Cola did post-doctoral research in the USA, has held positions at universities in Italy, The Netherlands, Germany, and France, as well as having guest professorships in Switzerland, Belgium, and Spain, and she has been a visiting scientist in Japan.
She talks in an interview for ChemViews magazine to Dr. Vera Koester about teaching in these varied countries and the increasing role of the internet in teaching, how she chose the interdisciplinary area of nanomaterials as her research field, and a topic close to her heart: chocolate.



You have a truly international biography and have now moved from the University of Münster, Germany, to the ISIS in Strasbourg, France. Which languages do you speak?
I speak a little bit of German; I speak Italian, English, and a little bit of Spanish.


What does your research focus on?
My research deals with different types of nanomaterials. In particular we are interested in porous materials that could be rigid or soft, crystalline or amorphous, and in materials able to emit light under different stimuli.

We are interested in the interactions of nanosystems with living cells. In particular we are interested in their toxicity, and in their potential use for imaging and therapy.

Also, we are interested in soft self-assembly systems and, especially, in the luminescence of assembled molecules. Soft scaffolds, in which the emission can be modulated upon the assembly process, are in my opinion a very interesting class of systems and their use can be extended from biology to optoelectronics.


How did you become interested in Chemistry?
This is indeed a very interesting story, because first I did not want to study chemistry. I started my career studying biology. And then during my first year in biology, I got very interested in chemistry, so I switched faculty. It was a difficult choice, because I liked almost any science. I also was interested in physics. But another love is cinema and I wanted to become a film director. – My niece is an actress, so somehow it is in the blood of the family.


So you often go to the cinema?
Yes, I do, I love movies.


How did you find your research topic?
I was trained as a physical chemist. I studied in Messina, Italy. Then I went to the US where I started to do synthesis. I was a Postdoc funded by the National Institutes of Health (NIH), so I started to be interested in molecules that could be functional, and we were using phosphorescent molecules. In particular we were using luminescent lanthanide compounds. And because I started with luminescent molecules, I got in contact with Professor Balzani, University of Bologna, Italy. After I finished my Postdoc, I went back to Italy to his lab. I stayed in Bologna for twelve years and really enjoyed my time there, because I learned the photophysics of metal complexes, but also how to run a group. I consider Professor Balzani to be my scientific father.

From there I went on to more applied research. So at least something that could be used, though doing new science. And I started to work on the creation of molecules to be used as materials for optoelectronics, in particular for organic light emitting diodes for TV screens or computers. This was a very successful part of my research. I was in Amsterdam, The Netherlands, at the time and had a wonderful collaboration with Philips.

And from there, of course, we started to look at the properties of materials and realized that with some modification these metal complexes could also be used for diagnostics. And this is how I started this bio- and biomedical area, which is now an important part of my research area. Also, because I received the ERC advanced grant in 2010, this area is at the moment very much at the forefront of my research group.

From simple molecules we progressed to work with the scaffold-like silica or alumina silicate, but we are also looking at soft molecular containers and at hybrid systems. The dynamic behavior of molecules versus rigid scaffold could lead to properties which can be switched on and off, such as emission or toxicity and, of course, this could open interesting approaches for the design of labels or multifuntional systems.


You received the 2011 Distinguished Woman in Chemistry or Chemical Engineering award. Are differences between women and men in sciences a big topic for you?
This depends a little bit on the country. In places like Italy and France there are many women in sciences and the society somehow is structured so that women can work until late in the afternoon, for instance. In Germany to be a woman scientist is more problematic, because the society is not organized to have women working full time. This is the reason why not so many women in Germany hold high level positions in the universities and also in industry. This is true also in the Netherlands or in Switzerland.

I do not think that there is a real discrimination. I mean I don’t think that the men discriminate against women for positions or important tasks. It is just a matter of being good. If a man is better, then they should take the man, not a woman just because she is a woman. However, the fact that the woman can become a mother, and therefore be less present at work, is a factor of discrimination. Combining family and profession is not easy ...

I strongly believe women should be encouraged to do science, because it is important for society and also because I feel that women are very much into sciences. I notice very often, even with my students, that women often have the possibility to look for a different strategy. While men maybe stick to a single approach or a single vision, women are more open to a new way of thinking and able to connect things. In my experience, women are very successful when they are really committed.


During your career you have taught students from lots of different countries. Is studying chemistry getting more international or is it still that every country has its own way of teaching?
First of all, I like all my students no matter of skin or religion or habits or whatever.
Of course, there are schools that are better than others. And also some countries are more advanced in terms of the technology and techniques that the students learn compared with less rich or developed countries. It is obvious that a poor country cannot have the equipment and facilities that we have in Germany or the US, for example. But I think this will not hinder a brilliant student. An intelligent and creative student can catch up with technology much better than, let’s say, a not so bright or motivated student living in a highly technological country. So I think it is a matter of intelligence, motivation, interest, and curiosity. I consider these as very important ingredients for a student to be successful.

In general, I would say education is not so different anymore. I mean everybody studies from the same books and reads the same papers everywhere in the world. So I think they are exposed to the same type of science. It is more related maybe to the quality of teaching (labs and computers, facilities) which differs in different schools.


Do you see that students use the internet more to learn?
Yes, the students use the internet much more than before. And it is good because if you look at the internet, that means you are curious about things and this kind of curiosity is good to have.

I notice, for example, that my young nieces use the internet in a very smart way. As a scientist, looking at ChemistryViews or an interview or at recordings from conferences is very, very nice, because sometimes you cannot attend a conference and the students have no money to attend. The experience of viewing the speaker, the author of a paper we have read, is completely different to reading the paper. It is a much easier way of, let’s say, getting an overview and a first feeling if you like that field or research or not. Of course, to go deeper you have to read the papers, it is not enough to listen, and you have to digest the knowledge yourself.

However, sometimes people learn only from Wikipedia and this is not what is desirable. The students tend to accept everything they read without being critical, without recognizing mistakes. This is where, of course, the teachers and the professors have an important role in the student’s life. They should guide them, force them to read more widely, and also make them more critical towards what they are reading. So I don’t think the role of the professor will disappear. Wikipedia will not suppress our teaching system.

On the other hand, I find the videos and in general many of the tools from the internet very, very important for spreading the sciences. Especially I would say at school level this is very nice. I hope and I wish that the teachers of high and middle schools would use more of these tools than they do.


What else do you like besides sciences?
I have a big love that is chocolate.


Ah, so do I.
I give seminars on chocolate. I gave one in Strasbourg, France, recently for the International Year of Chemistry (IYC). So this is kind of another research topic for me. I am a pure experimentalist there. That means I try new chocolates all the time.


What kind of talk did you give?
I talked about the history of chocolate, how cocoa reached Europe, for instance, and then about the processes that transform the beans into the bar of chocolate you eat. The chemistry of some of the molecules contained in chocolate is fascinating and I try to discuss some of it.
I also showed the way you should eat chocolate. There is a special way – like for wine – to appreciate the taste, the smell, and the melting of the chocolate.


Can everybody attend these seminars?
Sure, these are open to the public. So in Strasbourg, for instance, there were tele videos in different rooms and they told me that more than 700 people listened to my talk! In the room there were about 200 people. And more than 100 were high school kids. So this was quite an experience.


This sounds very interesting! I would like to attend one of these.
I think there is one you can find on the internet. (www.canalc2.tv/video.asp?idEvenement=603)


Now that you have moved to Strasbourg you are in the right town, because there is so much chocolate over here.
Yes. This will be a disaster for me in terms of diet ...
The good thing in Germany is, of course, you can get any type of chocolate there, but the Germans are not really producing as much chocolate as the French or the Swiss.


Thank you very much for the interview.

Chemistry – Our Life, Our Future


Chemistry – Our Life, Our Future

Author: Sabine Wiederhold

Published Date: 31 December 2011

Copyright: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

An unmistakable sign of the approaching New Year's Eve are the annual end-of-year reviews. The oversupply of shows and articles may have already spoiled the mood for another review. Nevertheless, it is worth looking back on 2011 from the perspective of chemistry this time, as 2011 was the International Year of Chemistry (IYC 2011). Under the theme “Chemistry – our life, our future” the UNESCO and IUPAC coordinated worldwide events to celebrate the achievements of chemistry and to indicate the importance for future development.

The global campaign aimed at not only rectify the – due to accidents like Seveso or Bhopal – tarnished image of chemistry and show that chemical research is crucial for future technologies and sustainable development, but also encourage interest in chemistry among young people. Finally, the best car paint is useless, if the engine does not run. To promote science, education in the STEM fields should be strengthened, e.g., by means of simple experiments for kindergarten children and elementary school pupils. In this sense, various competitions and events were organized for all ages during the IYC. One major activity was certainly the Global Water Experiment that offered students the possibility to participate in what was probably the biggest chemistry experiment ever. Also addressed to young people, but to all others as well, is a touring exhibition dedicated to sustainable chemistry, which was opened in Bremen, Germany. Interactive exhibits about important issues like climate change and water recycling allow a playful approach to chemistry beyond the IYC.

And what about the success of the IYC? How sustainable is the effect on the image and the promotion of young talents in chemistry? As yet, no final conclusion has been drawn and whether the image has been permanently improved can only be evaluated in a few years. But people are definitively interested in chemistry. One of the IYC´s highlights in Germany was certainly the open house with, according to the VCI (German chemical industry association), more people visiting the participating chemical companies and academic institutions than attending the eight soccer matches of the first and second German Soccer Leagues on the same day. Without doubt, this is a respectable achievement in a soccer-loving country like Germany.

Finally, a glance into the future shows that in 2012 we can expect many highlights as well. First of all – in the case of chemical engineering – the ACHEMA in Frankfurt, Germany, deserves a special mention where the issues of energy and resource changes will be represented in special shows.
We will be curious to see what else is to come.

Mixing Water and Oil: A Magic Process


Mixing Water and Oil: A Magic Process

Author: Angewandte Chemie International Edition

Published Date: 15 May 2013

Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH

Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Making Emulsions

A new process for generating nanometer-scale oil droplets in water has been reported in the journal Angewandte Chemie by Japanese researchers, who have developed a technique they named MAGIQ (monodisperse nanodroplet generation in quenched hydrothermal solution). Under standard conditions, hydrocarbons and water do not mix; however, at high temperatures and high pressures near the critical point of water, they freely mix. Quenching homogeneous solutions of dodecane and water under these conditions in the presence of a detergent produces nanoemulsions in just ten seconds.

Oil and water are not miscible but can form emulsions in which tiny droplets of one component are dispersed in the other. Milk, face creams, and printer’s ink are examples of emulsions. Nanoemulsions with droplets that have diameters in the 20 to 200 nm range have recently attracted more attention. Because of their small droplet size, they are transparent or translucent and are much slower to separate. In addition, there are potentially interesting new applications for them, either in pharmaceutical or cosmetic formulations that are easier to absorb, or as “nanoreactors” for the production of nanomaterials.

Homogenous Solution of Oil and Water
Emulsions are usually made by a “top-down” process. Mixtures of water, oil, and surfactant are subjected to external forces, such as vigorous stirring, to break up larger drops into smaller ones. This becomes harder as the droplets get smaller, so this method has inherent limits. In contrast, solid nanoparticles are usually produced in a “bottom-up” process. This begins with a homogeneous solution. The dissolved molecules aggregate to make nanoparticles. This could also be a possible method to make nanodroplets. The problem is that water and oil would have to form a homogeneous solution to start from, but they are not miscible.

Shigeru Deguchi and Nao Ifuku at the Japan Agency for Marine-Earth Science and Technology in Yokosuka have now found a way around this with their new MAGIQ process. When water is heated under pressure it reaches its critical point at 374 °C and 22.1 MPa. At this point there is no longer a difference between the liquid and gas phases. The water no longer dissociates and no clusters of water molecules can form. At this point, the properties of the water are like those of an oil—the researchers used dodecane in this case—and the two can be freely mixed together. When this homogeneous solution is quenched with cold water, a very rapid phase separation occurs, resulting in extremely small droplets in less than ten seconds. Addition of a detergent stabilizes the nanoemulsion. The researchers developed an apparatus in which they can carry out their “magic” technique in a constant flow process. The cooling temperature and speed, the ratio of water to dodecane in the mixture, and the concentration of detergent determine the—very uniform—size of the droplets.


Vitamin C Goes Astray

Vitamin C Goes Astray

Author: Angewandte Chemie International Edition

Published Date: 03 April 2013

Source / Publisher: Angewandte Chemie International Edition/Wiley-VCH

Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Degradation of Vitamin C

Vitamin C is found in many foods, and, among other things, is used to prolong shelf life. However, it is not stable in air or at room temperature. Cut fruits turn brown and the tastes of foods change. In the journal Angewandte Chemie, German researchers have now presented a systematic study of the processes that occur during the degradation of vitamin C.

Vitamin C, ascorbic acid, is a reducing carbohydrate and can react with amino acids, peptides, and proteins. These types of reactions between carbohydrates (sugars) and proteins belong to a class of reactions known as Maillard reactions, which are named after the man who discovered them, Louis Camille Maillard. Maillard reactions are ubiquitous: They make our toast crispy, are responsible for the smell of browning meat, and give roast potatoes their aroma.

However, the Maillard reactions of vitamin C are less pleasant. They are involved in the browning of cut fruit and can cause changes in the flavor of foods. In addition, the Maillard degradation of vitamin C in the body may be involved in clouding the lenses of the eyes and in the age-related loss of elasticity in the skin and sinews.

Identifying the End-Products of Vitamin C Maillard Systems
The process of vitamin C degradation has previously not been truly understood. Marcus A. Glomb and Mareen Smuda at the Martin Luther University of Halle-Wittenberg, Germany, have now comprehensively studied the amine-catalyzed degradation of vitamin C in a model system. By using vitamin C molecules marked in various places with 13C isotopes, they were able to trace the products of the Maillard reaction back to their original positions in the vitamin C structure. They also carried out experiments under an atmosphere of 18O2 isotopes and quantified all of the primary fragmentation products. This allowed them to clarify about 75 % of the Maillard-induced degradation reactions of vitamin C: the end products are carbonyl and dicarbonyl compounds, carboxylic acids, and amides.

Among other compounds, the researchers identified N6-xylonyl lysine, N6-lyxonyl lysine, and N6-threonyl lysine as unique characteristic end-products of vitamin C Maillard systems. In the future, identification of these compounds will make it possible to differentiate between vitamin C related Maillard reaction products and those stemming from other reducing carbohydrates like glucose.

The insights gained from this model system help to clarify the changes that occur in vitamin C containing foods during storage and preparation, even though the reaction pathways in real systems are naturally far more complex. These experiments also lay the groundwork for a better understanding of the negative effects of vitamin C degradation in the body.