scholarly journals Star-shaped Triazine-derivatives: would they crossbind SARS-CoV-2 spike helices?

2021 ◽  
Author(s):  
julio coll
Keyword(s):  
Neural Network ◽  
Severe Acute Respiratory Syndrome ◽  
Chemical Synthesis ◽  
Building Blocks ◽  
Water Soluble ◽  
Fusion Inhibition ◽  
Host Membrane ◽  
Bottom Cavity ◽  
Triazine Derivatives

This work describes synthesizable water-soluble Triazine-derivatives computationally crossbinding the S spike helices of Severe Acute Respiratory Syndrome coronavirus (SARS)-CoV-2. The "spring-loaded switch-folding” (S-SLSF) α-helices included in the S homotrimer top-to-bottom cavity and implicated in viral-host membrane fusion were targeted by star-shaped Trihydroxyl-Triphenyl-Triazines (TTT) leads at subnanomolar binding-scores. Exploration of in silico leads among millions of molecular candidates, included several similar searches, core-replacement, fragment extensions, or convolutional neural network deep-screening combined with hundreds of water-soluble lead-derivatives identified by manual iterations and commercially available building-blocks for chemical synthesis. The lead-derivatives are briefly discussed for in vitro validation and possibilities of fusion inhibition substituting mutations.

scholarly journals Would It Be Possible to Stabilize Prefusion SARS-COV-2 Spikes with Ligands?

2020 ◽  
Author(s):  
Julio Coll
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Membrane Fusion ◽  
Experimental Validation ◽  
Wild Type ◽  
Native Conformation ◽  
Enveloped Viruses ◽  
Computational Screening ◽  
Host Membrane ◽  
Nm Range

The<i> </i>infection by Severe Acute Respiratory Syndrome coronavirus (SARS)-CoV2 could be inhibited <i> in vitro </i>by mutations stabilizing their spike (S) native conformation in prefusion states, as reported by several authors. However, the possible S stabilization by binding-ligands, rather than by mutations, have not been computationally explored, nor it is known if that will be possible. Therefore, to first explore these possibilities, a binding target for predictive programs was focused to where the inhibiting mutations were described in the S coronavirus protein, in particular to the “spring-loaded switch-folding” (SLSF) segment of the S2 subunit, whose prefusion unfolding/refolding is required for viral/host membrane fusion. Similar SLSF prefusion mechanisms have been described in many other enveloped viruses. Results of a double computational screening of hundred of thousands of natural compounds for binding to wild-type SLSF conformer, predicted more leads in the low nM range for trimers than for monomers. Further ranked by the number of bound SLSF-conformers, some of the derived top-leads were predicted that may deserve experimental validation. Additionally, thousands of drugs were also included into the screening, resulting in a few top-lead drugs predicted to bind SLSF targets in the low nM range. All these potentially interacting S-ligands, similar structures and/or chemically improved designs, could be used to experimentally find out whether it will be possible to use them for inhibiting fusion and infection, offer new tools to investigate prefusion mechanism(s) and may contribute to therapeutic purposes.

Would It Be Possible to Stabilize Prefusion SARS-COV-2 Spikes with Ligands?

2020 ◽  
Author(s):  
Julio Coll
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Membrane Fusion ◽  
Experimental Validation ◽  
Wild Type ◽  
Native Conformation ◽  
Enveloped Viruses ◽  
Computational Screening ◽  
Host Membrane ◽  
Nm Range

The<i> </i>infection by Severe Acute Respiratory Syndrome coronavirus (SARS)-CoV2 could be inhibited <i> in vitro </i>by mutations stabilizing their spike (S) native conformation in prefusion states, as reported by several authors. However, the possible S stabilization by binding-ligands, rather than by mutations, have not been computationally explored, nor it is known if that will be possible. Therefore, to first explore these possibilities, a binding target for predictive programs was focused to where the inhibiting mutations were described in the S coronavirus protein, in particular to the “spring-loaded switch-folding” (SLSF) segment of the S2 subunit, whose prefusion unfolding/refolding is required for viral/host membrane fusion. Similar SLSF prefusion mechanisms have been described in many other enveloped viruses. Results of a double computational screening of hundred of thousands of natural compounds for binding to wild-type SLSF conformer, predicted more leads in the low nM range for trimers than for monomers. Further ranked by the number of bound SLSF-conformers, some of the derived top-leads were predicted that may deserve experimental validation. Additionally, thousands of drugs were also included into the screening, resulting in a few top-lead drugs predicted to bind SLSF targets in the low nM range. All these potentially interacting S-ligands, similar structures and/or chemically improved designs, could be used to experimentally find out whether it will be possible to use them for inhibiting fusion and infection, offer new tools to investigate prefusion mechanism(s) and may contribute to therapeutic purposes.

Design of an in vitro biocatalytic cascade for the manufacture of islatravir

Science ◽  
2019 ◽  
Vol 366 (6470) ◽  
pp. 1255-1259 ◽  
Author(s):  
Mark A. Huffman ◽  
Anna Fryszkowska ◽  
Oscar Alvizo ◽  
Margie Borra-Garske ◽  
Kevin R. Campos ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Directed Evolution ◽  
Building Blocks ◽  
Hiv Treatment ◽  
Pharmaceutical Manufacturing ◽  
Enzymatic Reactions ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Enzyme-catalyzed reactions have begun to transform pharmaceutical manufacturing, offering levels of selectivity and tunability that can dramatically improve chemical synthesis. Combining enzymatic reactions into multistep biocatalytic cascades brings additional benefits. Cascades avoid the waste generated by purification of intermediates. They also allow reactions to be linked together to overcome an unfavorable equilibrium or avoid the accumulation of unstable or inhibitory intermediates. We report an in vitro biocatalytic cascade synthesis of the investigational HIV treatment islatravir. Five enzymes were engineered through directed evolution to act on non-natural substrates. These were combined with four auxiliary enzymes to construct islatravir from simple building blocks in a three-step biocatalytic cascade. The overall synthesis requires fewer than half the number of steps of the previously reported routes.

Controlled Release of Metformin Hydrochloride I. In vitro Release from Physical Mixture Containing Xanthan Gum as Hydrophilic Rate Retarding Polymer

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Mashkura Ashrafi ◽  
Jakir Ahmed Chowdhury ◽  
Md Selim Reza
Keyword(s):  
Controlled Release ◽  
Xanthan Gum ◽  
In Vitro Release ◽  
Correlation Coefficients ◽  
High Ratio ◽  
Water Soluble ◽  
Metformin Hydrochloride ◽  
Model Drug ◽  
Very High

Capsules of different formulations were prepared by using a hydrophilic polymer, xanthan gum and a filler Ludipress. Metformin hydrochloride, which is an anti-diabetic agent, was used as a model drug here with the aim to formulate sustained release capsules. In the first 6 formulations, metformin hydrochloride and xanthan gum were used in different ratio. Later, Ludipress was added to the formulations in a percentage of 8% to 41%. The total procedure was carried out by physical mixing of the ingredients and filling in capsule shells of size ‘1’. As metformin hydrochloride is a highly water soluble drug, the dissolution test was done in 250 ml distilled water in a thermal shaker (Memmert) with a shaking speed of 50 rpm at 370C &plusmn 0.50C for 6 hours. After the dissolution, the data were treated with different kinetic models. The results found from the graphs and data show that the formulations follow the Higuchian release pattern as they showed correlation coefficients greater than 0.99 and the sustaining effect of the formulations was very high when the xanthan gum was used in a very high ratio with the drug. It was also investigated that the Ludipress extended the sustaining effect of the formulation to some extent. But after a certain period, Ludipress did not show any significant effect as the pores made by the xanthan gum network were already blocked. It is found here that when the metformin hydrochloride and the xanthan gum ratio was 1:1, showed a high percentage of drug release, i.e. 91.80% of drug was released after 6 hours. But With a xanthan gum and metformin hydrochloride ratio of 6:1, a very slow release of the drug was obtained. Only 66.68% of the drug was released after 6 hours. The percent loading in this case was 14%. Again, when Ludipress was used in high ratio, it was found to retard the release rate more prominently. Key words: Metformin Hydrochloride, Xanthan Gum, Controlled release capsule Dhaka Univ. J. Pharm. Sci. Vol.4(1) 2005 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

NGHIÊN CỨU ẢNH HƯỞNG CỦA CHITOSAN HOÀ TAN TRONG NƯỚC ĐẾN NẤM Colletotrichum musae D1 GÂY BỆNH THÁN THƯ TRÊN CHUỐI Ở ĐIỀU KIỆN IN VITRO

2016 ◽  
Vol 119 (5) ◽  
Author(s):  
Lê Thanh Long ◽  
Nguyễn Văn Toản ◽  
Nguyễn Văn Huế ◽  
Trang Sĩ Trung ◽  
Vũ Ngọc Bội
Keyword(s):  
Water Soluble ◽  
28S Rrna ◽  
Colletotrichum Musae

Chủng D1 phân lập từ các mẫu chuối có vết bệnh thán thư điển hình được sử dụng để nghiên cứu khả năng kháng nấm của chitosan hoà tan trong nước (Water-soluble chitosan_WSC) ở điều kiện in vitro. Kết quả phân tích trình tự gen mã hoá 28S rRNA của chủng D1 cho thấy tương đồng trình tự cao với các trình tự tương ứng của loài Colletotrichum musae và được ký hiệu là Colletotrichum musae D1. Kết quả các thí nghiệm đều cho thấy C. musae D1 rất nhạy cảm với WSC, hiệu lực ức chế tăng khi tăng nồng độ WSC xử lý ở điều kiện in vitro. Trên môi trường PDA, nồng độ 1,6% WSC ức chế hoàn toàn sự sinh trưởng của sợi nấm C. musae D1, nồng độ ức chế 50% (PIRG50) và nồng độ ức chế tối thiểu 90% (MIC90) tương ứng với nồng độ WSC 0,28% và 0,88%. Trong môi trường PDB, giá trị IC50 và MIC90 tương ứng là 0,11% và 0,43% và sự phát triển của sợi nấm C. musae D1 bị ức chế hoàn toàn ở nồng độ 0,8%. WSC không chỉ ức chế sự nảy mầm mà còn gây biến đổi bất thường bào tử nấm khi quan sát trên kính hiển vi.

Fenofibrate Solid Dispersion for Improving Oral Bioavailability: Preparation, and Characterization and in vivo Evaluation

2020 ◽  
Vol 13 (5) ◽  
pp. 5102-5109
Author(s):  
Venu Madhav K ◽  
Somnath De ◽  
Chandra Shekar Bonagiri ◽  
Sridhar Babu Gummadi
Keyword(s):  
Oral Bioavailability ◽  
Oral Delivery ◽  
Solid Dispersions ◽  
In Vitro Release ◽  
Aqueous Solubility ◽  
Water Soluble ◽  
Scanning Calorimetry ◽  
In Vivo Evaluation

Fenofibrate (FN) is used in the treatment of hypercholesterolemia. It shows poor dissolution and poor oral bioavailability after oral administration due to high liphophilicity and low aqueous solubility. Hence, solid dispersions (SDs) of FN (FN-SDs) were develop that might enhance the dissolution and subsequently oral bioavailability. FN-SDs were prepared by solvent casting method using different carriers (PEG 4000, PEG 6000, β cyclodextrin and HP β cyclodextrin) in different proportions (0.25%, 0.5%, 0.75% and 1% w/v). FN-SDs were evaluated solubility, assay and in vitro release studies for the optimization of SD formulation. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) analysis was performed for crystalline and morphology analysis, respectively. Further, optimized FN-SD formulation evaluated for pharmacokinetic performance in Wistar rats, in vivo in comparison with FN suspension.  From the results, FN-SD3 and FN-SD6 have showed 102.9 ±1.3% and 105.5±3.1% drug release, respectively in 2 h. DSC and PXRD studies revealed that conversion of crystalline to amorphous nature of FN from FT-SD formulation. SEM studies revealed the change in the orientation of FN when incorporated in SDs. The oral bioavailability FN-SD3 and FN-SD6 formulations exhibited 2.5-folds and 3.1-folds improvement when compared to FN suspension as control. Overall, SD of FN could be considered as an alternative dosage form for the enhancement of oral delivery of poorly water-soluble FN.

Solubility Enhancement of Poorly Water-Soluble Antifungal Drug Acyclovir by Nanocrystal Formulation Approach

2018 ◽  
Vol 11 (2) ◽  
pp. 4036-4042
Author(s):  
Prakash Goudanavar ◽  
Ankit Acharya ◽  
Vinay C.H
Keyword(s):  
Chemical Interaction ◽  
Research Work ◽  
Antiviral Drug ◽  
In Vitro Release ◽  
Oral Route ◽  
Water Soluble ◽  
Precipitation Method ◽  
Dsc Studies ◽  
Ft Ir

Administration of an antiviral drug, acyclovir via the oral route leads to low and variable bioavailability (15-30%). Therefore, this research work was aimed to enhance bioavailability of acyclovir by nanocrystallization technique. The drug nanocrystals were prepared by anti-solvent precipitation method in which different stabilizers were used. The formed nanocrystals are subjected to biopharmaceutical characterization including solubility, particle size and in-vitro release. SEM studies showed nano-crystals were crystalline nature with sharp peaks. The formulated drug nanocrystals were found to be in the range of 600-900nm and formulations NC7 and NC8 showed marked improvement in dissolution velocity when compared to pure drug, thus providing greater bioavailability. FT-IR and DSC studies revealed the absence of any chemical interaction between drug and polymers used. 

Formulation and Evaluation of Orally Disintegrating Tablets of Lamotrigine

2015 ◽  
Vol 8 (2) ◽  
pp. 2881-2888
Author(s):  
Sudarshan Singh ◽  
S S Shyale ◽  
P Karade
Keyword(s):  
Drug Release ◽  
Water Soluble ◽  
In Vitro Dissolution ◽  
Disintegration Time ◽  
Orally Disintegrating Tablet ◽  
Drug Content ◽  
Weight Variation ◽  
Wetting Time ◽  
Croscarmellose Sodium

The aim of this study was to design orally disintegrating tablet (ODT) of Lamotrigine. It is an Antiepileptic drug which is widely used in epilepsy. It is also used in simple and complex partial seizures and secondary generalized tonic-clonic seizures. It is poorly water soluble drug (0.46 mg/ml). Thus, an attempt was made to enhance the water solubility by complexation with β-cyclodextrin (1:1 molar ratios). The orally disintegrating tablet of lamotrigine was prepared by direct compression method using different concentration of superdisintegrants such as Sodium starch glycollate, croscarmellose sodium by sublimating agent such as camphor. The formulations were evaluated for weight variation, hardness, friability, drug content, wetting time, in vitro disintegration time and in vitro dissolution studies. The prepared tablets were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The disintegration time for the complexed tablets prepared by different concentration of superdisintegrants was found to be in range of 32.54 ± 0.50 to 55.12 ± 0.57 sec and wetting time of the formulations was found to be in range of 28.47 ± 0.67 to 52.19 ± 0.72 sec. All the formulation showed almost 100 percent of drug release within 15 min. Among all the formulation F6 and F7 prepared with 18% croscarmellose sodium and camphor shows faster drug release, respectively 10 min, F6 gives good result for disintegration time, drug release, wetting time and friability. Further formulations were subjected to stability testing for 30 days at temperature of 40 ± 5 ºC/75 ± 5 %RH. Tablets showed no appreciable changes with respect to physical appearance, drug content, disintegration time and dissolution profiles. Results were statistically analyzed by one-way ANOVA at a p < 0.05. It was found that, the data at any point of time are significant at p < 0.05.

Development of Strategies for Glycopeptide Synthesis: An Overview on the Glycosidic Linkage

2020 ◽  
Vol 24 (21) ◽  
pp. 2475-2497
Author(s):  
Andrea Verónica Rodríguez-Mayor ◽  
German Jesid Peralta-Camacho ◽  
Karen Johanna Cárdenas-Martínez ◽  
Javier Eduardo García-Castañeda
Keyword(s):  
Chemical Synthesis ◽  
Solid Phase ◽  
Building Blocks ◽  
Heterogeneous Environments ◽  
Phase Synthesis ◽  
Low Concentrations ◽  
Biological Sources ◽  
Synthetic Routes ◽  
The Impact ◽  
Potential Use

Glycoproteins and glycopeptides are an interesting focus of research, because of their potential use as therapeutic agents, since they are related to carbohydrate-carbohydrate, carbohydrate-protein, and carbohydrate-lipid interactions, which are commonly involved in biological processes. It has been established that natural glycoconjugates could be an important source of templates for the design and development of molecules with therapeutic applications. However, isolating large quantities of glycoconjugates from biological sources with the required purity is extremely complex, because these molecules are found in heterogeneous environments and in very low concentrations. As an alternative to solving this problem, the chemical synthesis of glycoconjugates has been developed. In this context, several methods for the synthesis of glycopeptides in solution and/or solid-phase have been reported. In most of these methods, glycosylated amino acid derivatives are used as building blocks for both solution and solid-phase synthesis. The synthetic viability of glycoconjugates is a critical parameter for allowing their use as drugs to mitigate the impact of microbial resistance and/or cancer. However, the chemical synthesis of glycoconjugates is a challenge, because these molecules possess multiple reaction sites and have a very specific stereochemistry. Therefore, it is necessary to design and implement synthetic routes, which may involve various protection schemes but can be stereoselective, environmentally friendly, and high-yielding. This review focuses on glycopeptide synthesis by recapitulating the progress made over the last 15 years.

The Potential Migrated Mechanism of Water-Soluble Components in Pellets Prepared by Wet Extrusion/Spheronization: Effect of Drying Rate

2020 ◽  
Vol 17 ◽  
Author(s):  
Bingwei Wang ◽  
Jianping Liu ◽  
Zhenghua Li ◽  
Yulong Xia ◽  
Shuangshuang Zhang ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Soluble ◽  
In Vitro Dissolution ◽  
Drying Rate ◽  
Scanning Calorimetry ◽  
Drying Temperature ◽  
Wet Extrusion ◽  
Extrusion Spheronization ◽  
Soluble Components

Background: At present, there were numerous researches on the migration of components in tablets and granules, the investigation in the pharmaceutical literatrue concerning the effect of drying rate on the migration of water-soluble components of pellets was limited. Temperature and relative humidity (RH) were crucial parameters during the drying process which was an essential step in the preparation of pellets via wet extrusion/spheronization. To quantify these variables, the water loss percentage of pellets per minute was defined as drying rate. Objective: The study aimed to investigate the influence of drying rate on the migration of water-soluble components in wet pellets and the potential migrated mechanism. Methods: The pellets containing tartrazine as a water-soluble model drug and microcrystalline cellulose as a matrix former were prepared by extrusion/spheronization and dried at four different drying temperature and relative humidity. Afterward, the extent of migrated tartrazine was assessed regarding appearance, in-vitro dissolution test, Differential Scanning Calorimetry, X-Ray Powder Diffraction, Attenuated total reflectance Fourier transform infrared spectroscopy and Confocal Raman Mapping. Results: Results demonstrated that red spots of tartrazine appeared on the surface of pellets and more than 40% tartrazine were burst released within 5 minutes when pellets dried at 60℃/RH 10%. While pellets dried at 40℃/RH 80%, none of these aforementioned phenomena was observed. Conclusion: In conclusion, the faster drying rate was, the more tartrazine migrated to the exterior of pellets. Adjusting drying temperature and relative humidity appropriately could inhibit the migration of water-soluble components within wet extrusion/spheronization pellets.

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