China
Africa
Explore chapters and articles related to this topic
Extraction and Chemistry of Rubber Allergens
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
Similarly, during thiazole accelerated vulcanization 2-2'-dithiobisbenzothiazole disulfide (MBTS) is reduced to MBT during the formation of the thiazole pendant group on a rubber polymer. Two MBT molecules can react forming additional MBTS molecules. Sulfenamide accelerators will also form MBT and MBTS during the vulcanization process.29 Thus, due to the multitude of accelerator chemical reactions that occur during the production of rubber products, the residual accelerator(s) found in rubber gloves may be different from that added and declared by the glove manufacturer.
Evaluation of Anti-ulcer Potential of Sphenodesme involucrata var. paniculata (C.B. Clarke) Munir Leaves on Various Gastric Aggressive Factors
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
P. S. Sreeja, K. Arunachalam, Parimelazhagan Thangaraj
In addition, another class of drugs that was introduced include the proton pump inhibitors (inhibits H+, K+-ATPase pathway in parietal cells) represented by omeprazole, lansoprazole, rabeprazole, pantoprazole, and omeprazole. These drugs were considered as effective in minimizing acid secretion and cellular restitution during the treatment of gastric ulcers (Palileo and Kaunitz 2011). The process for decreasing acid in the gastric environment by these drugs occurs through the acid secretory canaliculi of the parietal cell. By this action, the inactivation of the proton pump occurs via the formation of disulfide bonds between the structure of the drugs and the protein structure of said pump. Its active form, cyclic sulfenamide or sulfenic acid, reacts by covalently binding to the sulfhydryl group of the proton pump extracellular domain cysteine, which enables the inhibition of the hydrochloric acid secretion. However, this type of drug therapy causes side effects, such as lower vitamin B12 and iron absorption, hypergastrinemia, thrombocytopenia, risk of pneumonia, headaches, nausea, weakness, diarrhea, and gastric cancer, as well as a greater susceptibility to bone fractures (Dacha et al. 2015; Singh et al. 2018).
Mechanisms of action
Published in Fazal-I-Akbar Danish, Ahmed Ehsan Rabbani, Pharmacology in 7 Days for Medical Students, 2018
Fazal-I-Akbar Danish, Ahmed Ehsan Rabbani
Proton Pump Inhibitors (PPIs): These drugs are given orally in the form of capsules in which enteric-coated granules are enclosed to protect them from HCl destruction in the stomach. In intestines, shell is dissolved and granules are liberated. They are highly lipid-soluble and absorbed completely and rapidly from the intestines. Through blood, they reach their site of action, i.e. gastric canaliculi lined by parietal cells. Since the fluid in the gastric canaliculi is acidic and PPIs are basic in nature, the latter get ionised/protonated and trapped in the canaliculi, leading to a 1000-fold rise in their concentration. They are pro-drugs. They are activated into sulfenamide and sulfenic acid, which are interconvertable. These inhibitors combine with H+/K+-ATPase proton pump (via the SH-group of cysteine amino acids in the extracellular domain of the proton pump) thus inhibiting it. This leads to total inhibition of HCl synthesis (called anacidity).
Exploiting drug delivery systems for oral route in the peptic ulcer disease treatment
Published in Journal of Drug Targeting, 2021
Larissa Spósito, Giovanna Capaldi Fortunato, Bruna Almeida Furquim de Camargo, Matheus Aparecido dos Santos Ramos, Maurício Palmeira Chaves de Souza, Andréia Bagliotti Meneguin, Taís Maria Bauab, Marlus Chorilli
The PPIs promote a reduction of up to 95% in the daily production of hydrochloric acid (HCl) [22]. They are synthesised as prodrugs and require an acidic environment to be converted into their active form. Drugs of this class enter the oxyntic cell through the bloodstream and are concentrated in the secretory canaliculi, where they are activated by a process catalysed by protons, which leads to the formation of sulfenamide or thiophilic sulfenamide [23,24]. Once activated, they form a covalent bonding with the sulfhydryl group of the extracellular cysteines of the H+, K+ ATPase, which are essential for the inhibition of acid production. In general, PPIs are quickly absorbed and normally well tolerated. However, PPIs interact with certain microsomal cytochrome enzymes P450, resulting in the reduction of catabolism of certain drugs such as phenytoin and warfarin [25,26].
Repurposing of rabeprazole as an anti-Trypanosoma cruzi drug that targets cellular triosephosphate isomerase
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Itzhel García-Torres, Ignacio De la Mora-De la Mora, Gabriel López-Velázquez, Nallely Cabrera, Luis Antonio Flores-López, Ingeborg Becker, Juliana Herrera-López, Roberto Hernández, Ruy Pérez-Montfort, Sergio Enríquez-Flores
In a first attempt to evaluate the best PPI as an anti-trypanosomatid drug, we performed assays with all PPIs at increasing concentrations in the recombinant TcTIM, demonstrating that Rbz inactivated efficiently this enzyme, this effect of Rbz was similar at neutral and acidic conditions (Supplementary Figure S1). Our results contrast with other reports that argue that PPIs must be activated by acidic pH to achieve their effectiveness. Some examples of this include the report where it was shown that esomeprazole inhibited the proliferation of melanoma cells in vitro and induced cytotoxicity in a pH-dependent manner, obtaining the most potent anticancer effect at pH 6.065; and the work of Li et al., which demonstrated that the synergistic effect of pantoprazole and vitamin C was pH-dependent due to pantoprazole was more effective at a slightly acidic pH66. However, there are reports of the action of these drugs in conditions that commonly show neutral pH. For example, it has been demonstrated that omeprazole inhibits cell proliferation in Barrett’s oesophagus cells at neutral pH conditions67; in another report, it has been shown that omeprazole inhibits melanogenesis by blocking ATP7A trafficking in the same pH conditions68. Despite the reports that show sulfenamide formation in different pH values are few, Kromer since 199869 demonstrated that PPIs can be activated at different pH values with a differential rate. Therefore, it is reasonable that the PPIs can react with thiols of Cys residues in proteins at neutral pH. Taking into consideration the aforementioned, we evaluated the effect of Rbz at pH 7.4 based on its efficacy in killing T. cruzi epimastigotes. Our study points to the fact that this drug inhibits the activity of cellular triosephosphate isomerase of this parasite, suggesting it as a therapeutic target.