Convenient way of adding reagents-Dropping funnel

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>> Friday, January 29, 2010

Few days back, an undergraduate student had a query on how to add the reagent slowly (drop wise) into the reaction mixture over long period of time in a convenient way. I know most of the synthetic / medicinal chemists are aware of solution for this problem but might be new to freshmen. So I decided to introduce the simple dropping funnel, which can solve above mentioned problem.Dropping funnel, as shown in the picture, is a glass tube with stopcock at one end. The reagent is kept in the glass tube and its flow is controlled by the stopcock. There is a relief tube (by-pass) which allows the escape of gases evolved during the reaction.
"Simple equipments can make work easy and convenient"

Study of proton pump inhibitors as anti-allergic asthmatic agents

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>> Friday, January 22, 2010

Recently, Choi et. al. reported that proton pump inhibitors have potential as an anti-allergic asthmatic agents. Before going to the study, let me explain in brief about proton pump inhibitors and its mechanism of action.

omeprazole, pantoprazole
Proton pump inhibitors (PPIs) like Omeprazole and Pantoprazole are widely used in the treatment of peptic ulcer, gastroesophageal reflux diseases (GERD) and Zollinger-Ellison syndrome. They specifically inhibit the human gastric H+/K+-ATPase (proton pump), which is responsible for the secretion or release of H+ ions in the apical canaliculi of parietal cells. These released H+ ions can combine with Cl- ions to give HCl. So proton pump has been the key target of PPIs. Omeprazole is inactive at neutral pH, but at acidic pH it undergoes protonation to give sulphenic acid and active sulfonamide derivative which actively acts as H+/K+-ATPase inhibitor. As it inactivate the enzyme irreversibly, formation of new H+/K+-ATPase molecules is required for acid secretion.

Simple method of recording TLC data

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>> Saturday, January 16, 2010

Preserving TLC data is important for future record, no doubt. The common way is just by drawing the TLC plate in notebook. Today’s post will explain simple method of transferring the TLC data from glass plate to notebook using sellotape. This method is very simple. What you need is just a sellotape.
Procedure : Apply the sellotape over the TLC plate. Thereafter pull out slowly and carefully. You will find the TLC data attached to sellotape, which you can simply paste in the notebook.

This method is beneficial while recording the stained TLC plate. When you apply the staining agents, you will get different colors for different compounds on heating. If you use common method (sketching TLC plate), either color pen or words are necessary to denote the colors. Second method will easily solve this problem.

Small molecule inhibitors of HIF-I pathway

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>> Tuesday, January 12, 2010

Recently, researchers from National Institutes of health, Bethesda, US (Xia, M. et. al.,) has identified four promising lead compounds as hypoxia-inducible factor-I (HIF-I) signaling pathway inhibitors. These compounds selectively inhibited both HIF-I activity and vascular endothelia growth factor (VEGF) protein expression. From structure activity relationship study, it is revealed that thiophen-oxadiazole core, rather than the oxadiazole group alone is important for the HIF-I inhibitory activity. For this purpose, they have screened 73,000 compounds by quantitative high-throughput screening (qHTS) method.

Reawakening of human theta defensins (retrocyclin) against HIV-1

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>> Monday, January 04, 2010

Image source:Flickr

Defensins are the small cysteine-rich cationic antimicrobial peptides that contribute to the host defense against a broad spectrum of pathogens. Position of the cysteine and the disulfide bonding pattern determines the types of defensins as alpha, beta and theta-defensins.Theta defensins such as retrocyclin are the most recently identified defensin, isolated initially from white blood cells and bone marrow of Rhesus macaques. They were produced in Rhesus macaques by the post-translation ligation of two nonapeptides, each derived from a 12 residue precursor called as "demidefensin".                                                                                      

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