Application of in vitro Drug Metabolism Studies in Chemical Structure Optimization for the Treatment of Fibrodysplasia Ossificans Progressiva (FOP)

Currently no approved treatment exists for fibrodysplasia ossificans progressiva (FOP) patients, and disease progression results in severe restriction of joint function and premature mortality. LDN-193189 has been demonstrated to be efficacious in a mouse FOP disease model after oral administration. To support species selection for drug safety evaluation and to guide structure optimization for back-up compounds, in vitro metabolism of LDN-193189 was investigated in liver microsome and cytosol fractions of mouse, rat, dog, rabbit, monkey and human. Metabolism studies included analysis of reactive intermediate formation using glutathione and potassium cyanide (KCN) and analysis of non-P450 mediated metabolites in cytosol fractions of various species. Metabolite profiles and metabolic soft spots of LDN-193189 were elucidated using LC/UV and mass spectral techniques. The in vitro metabolism of LDN-193189 was significantly dependent on aldehyde oxidase, with formation of the major NIH-Q55 metabolite. The piperazinyl moiety of LDN-193189 was liable to NADPH-dependent metabolism which generated reactive iminium intermediates, as confirmed through KCN trapping experiments, and aniline metabolites (M337 and M380), which brought up potential drug safety concerns. Subsequently, strategies were employed to avoid metabolic liabilities leading to the synthesis of Compounds 1, 2, and 3. This study demonstrated the importance of metabolite identification for the discovery of novel and safe drug candidates for the treatment of FOP and helped medicinal chemists steer away from potential metabolic liabilities

Investigation of reduced reverse degree based polynomials & indices of gold crystals

Gold is widely recognized as a noble metal due to its inherent inertness in its bulk form. Nevertheless, gold exhibits reactivity in its ionic form. The inert qualities of bulk gold have led to its extensive recognition as a fundamental raw ingredient in several biomedical processes. These applications encompass drug delivery microchips, dental prostheses, reconstructive surgery, food additives, and endovascular stents. Gold in large amounts can be thought of as safe. Gold can also exist as molecules or ions, specifically gold ions, making it easier to make gold nanomaterials. The distinctive characteristics of gold set it apart from its molecular or bulk states, making its execution a very efficient instrument in the field of nanomedicine. Some of these traits are ease of synthesis, a higher ratio of surface area to volume, more reactive particles, the ability to withstand changes to the surface, and strong optical properties. The reduced reverse degree-based polynomials and topological descriptors of the molecular structure of the gold crystal are investigated in this manuscript. The numerical and graphical analysis of outcomes this study are also described.Full text license: CC BY 4.0;</p

Bioactivation of Lamotrigine in Vivo in Rat and in Vitro in Human Liver Microsomes, Hepatocytes, and Epidermal Keratinocytes: Characterization of Thioether Conjugates by Liquid Chromatography/Mass Spectrometry and High Field Nuclear Magnetic Resonance Spectroscopy

Previous studies suggested that lamotrigene (LTG) underwent bioactivation to a reactive aryl epoxide intermediate in rats. Nevertheless, definitive structures of these thioether conjugates, which are often needed to substantiate the mechanism of bioactivation and identity of reactive intermediate(s), were not fully established. In the present study, GSH, cysteinylglycine, and N-acetyl cysteine conjugates of LTG were isolated from bile of rats orally dosed with LTG (100 mg/kg), and their structures were fully elucidated by LC/MS and NMR. The definitive structural characterization of these metabolites provided evidence for the existence of a reactive aryl epoxide that was trapped as a GSH adduct. In vitro studies using various hepatic cellular and subcellular fractions obtained from human and rat were performed to demonstrate that LTG underwent bioactivation to form a GSH conjugate that was identical to the one initially characterized from in vivo studies. Human P450 2A6 and rat P450 2C11 appeared to be the primary enzymes activating LTG in human and rat liver microsomes, respectively. Interindividual variation in the bioactivation of LTG was demonstrated with 20 individual human liver microsomes. Furthermore, it was shown that human epidermal keratinocytes were capable of forming the same GSH conjugate, suggesting that LTG could be bioactivated in skin cells. The results from these studies suggest that LTG has the potential to undergo hepatic and nonhepatic bioactivation, leading to a reactive aryl epoxide intermediate in human. The bioactivation of LTG in epidermal cells provides a possible explanation for the idiosyncratic cutaneous reactions associated with LTG therapy