Wednesday, June 30, 2010

Palladium-Catalyzed Trifluoromethylation of Aryl Chlorides..

When I  was working with one of the leading agrochemicals company, I was using 4-chlorobenzotriflouride as starting material for my two projects (trifluralin and a pyrazole derivative with diflouromethyl substituted phnyl).  I know how difficult is to introduce the triflouromethyl group (use of anhydrous HF to convert CCl3 to CF3) and that is why we got the starting material imported. 

Now, MIT chemists have designed a new way to attach a trifluoromethyl group to certain compounds, which they believe could allow pharmaceutical companies to create and test new drugs much faster and potentially reduce the cost of drug discovery. 
MIT Chemistry Professor Stephen Buchwald, who led the research team, says achieving the synthesis has been a long-standing challenge for chemists. "Some people said it couldn't be done, so that's a good reason to try," says Buchwald, the Camille Dreyfus Professor of Chemistry at MIT.
With the new reaction, the CF3 group can be added at a much later stage of the overall drug synthesis. The reaction can also be used with a broad range of starting materials, giving drug developers much more flexibility in designing new compounds.  Though many groups are trying, the major challenge has been finding a suitable catalyst  to transfer the CF3 entity from another source to the carbon ring. 

CF3- (trifluoromethyl negative ion) tends to be unstable when detached from other molecules, so the catalyst must act quickly to transfer the CF3 group before it decomposes. The MIT team chose to use a catalyst built from palladium i.e., BrettPhos (see structure). MIT team is not the first to try palladium catalysis for this reaction, but the key to their success was the use of a ligand (a molecule that binds to the metal to stabilize it and hasten the reaction) called BrettPhos 2-(Dicyclohexylphosphino)-3,6-dimethoxy-2'-4'-6'-tri-i-propyl-1,1'-biphenylwhich they had previously developed for other purposes

During the reaction, a CF3 group is transferred from a silicon carrier to the palladium, displacing a chlorine atom. Subsequently, the aryl-CF3 unit is released and the catalytic cycle begins anew. The researchers tried the synthesis with a variety of aryl compounds and achieved yields ranging from 70 to 94 percent of the trifluoromethylated products. 

Researchers conclude that, in its current state the process is too expensive for manufacturing use. For drug discovery, however, it may lower overall costs because it streamlines the entire synthesis process.
"For discovery chemistry, the price of the metal is much less important," says Kinzel....

Ref :  http://www.sciencemag.org/cgi/content/abstract/328/5986/1679

Tuesday, June 29, 2010

Blueberry consumption is beneficial for hepatic diseases....

We know that blueberry has many chemicals such as anthocyanins, proanthocyanidins, resveratrol, flavonols and tannins and how blueberry inhibit mechanisms of cancer cell development and inflammation in vitro. Similar to red grape, some blueberry species contain in their skins significant levels of resveratrol a phytochemical. 

Now research team led by Ming-Liang Cheng, MD, from Department of Infectious Diseases, Guiyang Medical College, Guiyang,  have found that blueberries could reduce liver indices, serum levels of hyaluronic acid and alanine aminotransferase, and increase levels of superoxide dismutase and decrease levels of malondialdehyde in liver homogenates compared with the model group.  Meanwhile, the stage of hepatic fibrosis was significantly weakened. Blueberries increased the activity of glutathione-S-transferase in liver homogenates and the expression of Nrf2 and Nqo1 compared with the normal group, but there was no significant difference compared with the model group. 

The authors suggest that blueberry consumption is beneficial for hepatic diseases (including fibrosis)....

I read an article in the same lines, where in the  researchers from Miyazaki prefecture of southern Japan and University of Miyazaki, screened nearly 300 different agricultural products for potential compounds that suppress HCV replication and uncovered a strong candidate in the leaves of rabbit-eye blueberry (native to the southeastern US). They purified the compound and identified it as proanthocyandin (a polyphenol similar to the beneficial chemicals found in grapes and wine). While proanthocyandin can be harmful, Kataoka and colleagues noted its effective concentration against HCV was 100 times less than the toxic threshold. The researchers are  hoping to explore the detailed mechanisms of how this chemical stops HCV replication....

Ref :  http://www.biologynews.net/archives/2009/08/07/the_hepatitis_healing_power_of_blueberry_leaves.html

Monday, June 28, 2010

Liquid Crystals - A New Way to Better Data Storage ?

In continuation of my update on liquid crystals (after a long gap)....

As cell phones and computers continue to shrink, many companies are seeking better ways to store hundreds of gigabytes of data in small, low-power devices. A special type of liquid crystal (similar to those used in computer displays and televisions) offers a solution  and lasers can encode data throughout a liquid crystal known as holographic storage, the technique makes it possible to pack much more information in a tiny space.   

But attempts to use liquid crystals for data storage have had limited success. In order to reliably record and rewrite data, researchers must figure out a way to uniformly control the orientation of liquid crystal molecules as the most liquid crystal technologies currently rely on physical or chemical manipulation, such as rubbing in one direction, to align molecules in a preferred direction. 

In an important advance, scientists at the Tokyo Institute of Technology have created a stable, rewritable memory device that exploits a liquid crystal property called the "anchoring transition". Researchers  demonstrated memory and rewritable bistable devices based on an anchoring transition of a nematic liquid crystal on a perfluoropolymer surface. Spontaneous orientation changes between planar and homeotropic occur on cooling and heating with a large temperature hysteresis. Orientation switching also occurs by applying an electric field with a response time of several milliseconds depending on the field strength claims the researchers.

Using either a laser beam or an electric field, the researchers can align rod-like liquid crystal molecules in a polymer. Their tests show that the liquid crystal created by the team can store data, be erased and used again...
"This is the first rewritable memory device utilizing anchoring transition," said Hideo Takezoe, who led the research. And because the device is bi-stable -- the liquid crystals retain their orientation in one of two directions -- it needs no power to keep images, adds Takezoe.

 Ref : http://jap.aip.org/japiau/v107/i12/p123108_s1?isAuthorized=no

Saturday, June 26, 2010

Resveratrol in Red Wine Neutralizes Toxicity of Proteins Related to Alzheimer's

We know that, Resveratrol (found in the skin of red grapes and is a constituent of red wine, see structure)  (trans-resveratrol) is a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi.  And also it has been reported to possess diverse activities such as, anti-cancer, anti-inflammatory, blood-sugar-lowering and other beneficial cardiovascular effects in mouse and rat models of testings. In the only positive human trial, extremely high doses (3–5 g) of resveratrol in a proprietary formulation have been necessary to significantly lower blood sugar.Claims of anti-aging effects of the same compounds is to be still established.

Now researchers led by Rensselaer Professor Peter M. Tessier, have come up with an interesting finding i.e., resveratrol - has the ability to neutralize the toxic effects of proteins linked to Alzheimer's disease. 

As per the claims by the researchers, resveratrol picks out the clumps of peptides that are bad and leaves alone the ones that are benign, it helps us to think about the structural differences between the peptide isoforms (different packing arrangements of a particular peptide) Deformations of a particular peptide  the Aβ1-42 peptide,   have been linked to Alzheimer's disease. 

Improperly folded peptides have been shown to collect in accumulations called "plaques (often found near areas of cell death in diseased brain)" within the brain.

Researchers conclude that, though it is not clear that resveratrol is able to cross the blood-brain barrier. However, the molecule has garnered interest in recent years for its potential impact on cancer and aging...

Ref : http://www.jbc.org/content/early/2010/05/28/jbc.M110.133108....

Thursday, June 24, 2010

New use of old drugs (Metformin & AICAR ) in treating hepatitis C...

In continuation of my update on Metformin...

Researchers from  University of Leeds have found drugs such as antidiabetic  drug  Metformin  (right  structure)  and                AICAR, (5-Amino-4-imidazole carboxamide ribonucleotide) below right structure) used to combat obesity, can prevent the hepatitis C virus from replicating in the body.

Drugs such as Metformin and AICAR work by stimulating an enzyme called AMP kinase (AMPK) which regulates energy within our cells,  the very enzyme that hepatitis C virus represses to enable it to replicate. As per the claim by the researchers, the hepatitis C virus switches off AMPK so that the cell continues production of lipids and membranes, both of which are vital to its survival. 

AMPK's usual function is to conserve the energy balance in cells (it does by temporarily shutting down the production of lipids (fats) and membranes) when it senses an increase in energy requirements. Researchers  claim that, when a cell becomes infected by a virus,  AMPK gets activated and  shuts down certain functions of the cell temporarily until the cell's energy is rebalanced. 

Building on this finding, the research team were able to examine how cells would react when treated with common drugs that stimulate AMPK. They found that in infected cells, the drugs were able to halt virus replication, enabling cells to clear the infection...
"We're very excited about these findings," says Professor Mark Harris from the University's Faculty of Biological Sciences. "These drugs are already on the market, and whilst substantial clinical trials still need to take place before they can be used to treat hepatitis C infection, we think it could be an enormous step forward in the battle against the virus."  ....

Ref : http://www.leeds.ac.uk/news/article/825/new_use_for_old_drugs_in_treating_hepatitis_c?research

Wednesday, June 23, 2010

Crizotinib Shows Dramatic Results for Shrinking Tumors (lung cancer)....

Patients with a specific kind of lung cancer may benefit from a Phase III clinical trial offered by the Moores UCSD Cancer Center. The new drug, crizotinib (structure), under development by Pfizer, showed dramatic results in reducing lung cancer tumors in some patients during Phase I and II clinical trials.

"The results of the first two trials have been very encouraging," said Lyudmila Bazhenova, MD, assistant clinical professor at UC San Diego School of Medicine and a member of the Moores UCSD Cancer Center...

According to a preliminary study,  57% of patients had their tumors reduced and at eight weeks of the treatment, 87% showed disease stabilization.

The Phase III clinical trial will compare crizotinib with standard-of-care chemotherapy in the treatment of ALK-positive recurrent NSCLC. Through a randomized selection process, patients will either be treated with chemotherapy or crizotinib. If the patients who are given the chemotherapy do not respond to treatment, they will be given crizotinib at the end of the trial....

Ref : http://ucsdnews.ucsd.edu/newsrel/health/06-22ShrinkingTumors.asp

FDA approves Jevtana to treat men with prostate cancer

In continuation of my update on Cabazitaxel......

FDA approves Jevtana to treat men with prostate cancer

Tuesday, June 22, 2010

Synergistic activity of Sorafenib and Sulforaphane abolishes pancreatic cancer...

In continuation of my update on "Sorafenib", I find this info interesting to share with...

A team led by Professor Dr. Ingrid Herr, Head of the Department of Molecular Oncosurgery, a group of the Department of Surgery at Heidelberg University Hospital, have come up with an interesting finding, i.e.,  Sorafenib  (used for advanced liver and kidney cancer) also appears to be effective against cancer stem cells in pancreatic cancer. It inhibits resistant tumor stem cells and is also especially effective in combination with sulforaphane, an organic compound found in broccoli. 

In their tests on cancer cells and mice, the researchers showed that sorafenib inhibited typical properties of cancer stem cells from pancreas tumors and greatly reduced tumor growth. However, this effect lasted only for a short time and after four weeks, new colonies of cancer stem cells formed that no longer reacted to further treatment with sorafenib. The resistance is probably related to a certain metabolic pathway, the NF-kB pathway, that is activated by sorafenib, claims the researchers. 

Naturally occurring substance(s) e.g., sulforaphane (vegetables from the cruciferous family such as broccoli and cauliflower possess a high content of sulforaphane, an anti-cancer compound)  that block precisely this undesired NF-KB pathway and thus make the dangerous cells vulnerable.  The experiments show that sulforaphane prevents the activation of the NF-kB pathway by sorafenib and hence the combination treatment reinforces the effect of sorafenib without causing additional side effects. Researchers conclude that the invasive potential of cancer cells was prevented  and  metastasis was completely blocked in cell culture experiments
"We assume that nutrition may be a suited approach to break therapy resistance of cancer stem cells and thus make tumor treatment more effective," Professor Herr suggested....
Ref : http://cancerres.aacrjournals.org/content/70/12/5004