Assessing target engagement using proteome-wide solvent shift assays

Recent advances in mass spectrometry (MS) have enabled quantitative proteomics to become a powerful tool in the field of drug discovery, especially when applied toward proteome-wide target engagement studies. Similar to temperature gradients, increasing concentrations of organic solvents stimulate unfolding and precipitation of the cellular proteome. This property can be influenced by physical association with ligands and other molecules, making individual proteins more or less susceptible to solvent-induced denaturation. Herein, we report the development of proteome-wide solvent shift assays by combining the principles of solvent-induced precipitation (Zhang et al., 2020) with modern quantitative proteomics. Using this approach, we developed solvent proteome profiling (SPP), which is capable of establishing target engagement through analysis of SPP denaturation curves. We readily identified the specific targets of compounds with known mechanisms of action. As a further efficiency boost, we applied the concept of area under the curve analysis to develop solvent proteome integral solubility alteration (solvent-PISA) and demonstrate that this approach can serve as a reliable surrogate for SPP. We propose that by combining SPP with alternative methods, like thermal proteome profiling, it will be possible to increase the absolute number of high-quality melting curves that are attainable by either approach individually, thereby increasing the fraction of the proteome that can be screened for evidence of ligand binding.

Assessing target engagement using proteome-wide solvent shift assays

Recent advances in mass spectrometry (MS) have enabled quantitative proteomics to become a powerful tool in the field of drug discovery, especially when applied toward proteome-wide target engagement studies. Similar to temperature gradients, increasing concentrations of organic solvents stimulate unfolding and precipitation of the cellular proteome. This property can be influenced by physical association with ligands and other molecules, making individual proteins more or less susceptible to solvent-induced denaturation. Herein, we report the development of proteome-wide solvent shift assays by combining the principles of solvent-induced precipitation (Zhang et al., 2020) with modern quantitative proteomics. Using this approach, we developed solvent proteome profiling (SPP), which is capable of establishing target engagement through analysis of SPP denaturation curves. We readily identified the specific targets of compounds with known mechanisms of action. As a further efficiency boost, we applied the concept of area-under the-curve analysis to develop solvent proteome integral solubility alteration (solvent-PISA) and demonstrate that this approach can serve as a reliable surrogate for SPP. We propose that by combining SPP with alternative methods, like thermal proteome profiling, it will be possible to increase the absolute number of high-quality melting curves that are attainable by either approach individually thereby increasng the fraction of the proteome that can be screened 1 for evidence of ligand binding.

A Review on Precipitation inhibitors in supersaturable self emulsifying drug delivery system

The super saturable formulation has been widely used as an effective method to improve solubility and oral absorption of poorly aqueous-soluble drugs. When the super saturable formulation comes in contact with gastrointestinal fluids, its drug concentration goes over the equilibrium solubility, but this state does not exist for too long, the drug may precipitate before being absorbed, which minimizes the efficacy and bioavailability of the drug. Therefore, it is necessary to inhibit or retard the precipitation of drugs to achieve the maximum benefits of the super saturable formulation. Polymers (watersoluble and insoluble) are the commonly used excipients to inhibit precipitation. Cyclodextrins and surfactants are the other two excipients used as precipitation inhibitors. In some of the cases, even solid carriers can effectively retard precipitation. The precipitation inhibitors (PI) have the capacity to maintain a super saturable state of the formulation in GI for a particular time period. Therefore, it is important to properly select the precipitation inhibitor; too frequently used methods to select precipitation inhibitor are casting film method and solvent-shift method. Such selected and successfully used precipitation inhibitors are HPMC E5LV, PVP K17, HPMC E5, soluplus, poloxamer 407, HPMCAS, maltodextrin (mal) and microcrystalline cellulose (mcc). Since the super saturable technique has been widely used for delivering poorly water-soluble drugs like ezetimibe, indirubin, feno fibrate, butyl paraben and rosu vastatin calcium. There is a necessity for bio relevant evaluation of supersaturation/precipitation because simple methods like dissolution tests cannot be bio relevant in a supersaturation/precipitation context. Some of the important factors like sink versus non-sink conditions, hydrodynamic, medium selection and temperature play a vital role in the evaluation of in-vitro supersaturation

Multimodal cellular redox nanosensors based on self-doped polyaniline nanocomposites

We have successfully fabricated a nanocomposite, which is composed of polyaniline (PAni) and pyrene butyric acid (Pyba) via a solvent shift method, which was self-doped at a neutral pH value.

Hypsochromic solvent shift of the charge separation band in ionic donor–acceptor Li+@C60⊂[10]CPP

Photoinduced electron transfer in CPP-based donor–acceptor complexes C60⊂[10]CPP and Li+@C60⊂[10]CPP was studied using DFT/TDDFT. Unusual blue shift of charge separated states for Li+@C60⊂[10]CPP complexes in the polar medium is predicted.

The Influence of Polymers on the Supersaturation Potential of Poor and Good Glass Formers

The increasing number of poorly water-soluble drug candidates in pharmaceutical development is a major challenge. Enabling techniques such as amorphization of the crystalline drug can result in supersaturation with respect to the thermodynamically most stable form of the drug, thereby possibly increasing its bioavailability after oral administration. The ease with which such crystalline drugs can be amorphized is known as their glass forming ability (GFA) and is commonly described by the critical cooling rate. In this study, the supersaturation potential, i.e., the maximum apparent degree of supersaturation, of poor and good glass formers is investigated in the absence or presence of either hypromellose acetate succinate L-grade (HPMCAS-L) or vinylpyrrolidine-vinyl acetate copolymer (PVPVA64) in fasted state simulated intestinal fluid (FaSSIF). The GFA of cinnarizine, itraconazole, ketoconazole, naproxen, phenytoin, and probenecid was determined by melt quenching the crystalline drugs to determine their respective critical cooling rate. The inherent supersaturation potential of the drugs in FaSSIF was determined by a solvent shift method where the respective drugs were dissolved in dimethyl sulfoxide and then added to FaSSIF. This study showed that the poor glass formers naproxen, phenytoin, and probenecid could not supersaturate on their own, however for some drug:polymer combinations of naproxen and phenytoin, supersaturation of the drug was enabled by the polymer. In contrast, all of the good glass formers—cinnarizine, itraconazole, and ketoconazole—could supersaturate on their own. Furthermore, the maximum achievable concentration of the good glass formers was unaffected by the presence of a polymer.

Modeling the absorption spectrum of the permanganate ion in vacuum and in aqueous solution

The absorption spectrum of MnO4− in vacuum and aqueous solution is modeled using the range-separated complete active space short-range density functional theory method (CAS-srDFT) combined with either implicit (PCM) or explicit (PE) solvent models. The experimental vacuum-to-water solvent shift of the lowest intense transition is reproduced by PE-CAS-srDFT.