Imidazoles-derivatives

Formulation development of oral liquisolid systems of poorly water-soluble drug, hydrochlorothiazide, using mixed solvency concept and their evaluations was written by Wadhwani, Harshal;Maheshwari, R. K.. And the article was included in International Journal of Pharmacy and Pharmaceutical Research in 2021.Recommanded Product: 145040-37-5 This article mentions the following:

The present work is aimed to enhance the drug loading capacity in a liquisolid system, decreasing the required volume of nonvolatile solvent due to enhanced solubility of a drug in nonvolatile solvent using the mixed solvency concept. Hydrochlorothiazide was selected as a model poorly water-soluble drug for exploring the mixed solvency concept to enhance the solubility and hence to enhance the release rate of the drug. The proposed formulation is aimed to enhance the solubility of hydrochlorothiazide by employing the mixed solvency concept and to develop the fast-release capsule of hydrochlorothiazide using the liquisolid technique. The prepared liquisolid dosage form was tested for flow properties, thin layer chromatog., drug excipient interaction studies, drug content determination, disintegration time study, and dissolution studies. The comparative dissolution studies were performed and it was observed that the formulated capsule containing liquisolid formulation released 81.09% of the drug within 10 min, and only 56.25% drug was released from the marketed tablet formulation within 10 min. In the experiment, the researchers used many compounds, for example, 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5Recommanded Product: 145040-37-5).

1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5) belongs to imidazole derivatives. Among the different heterocyclic compounds, imidazole is better known due to its broad range of chemical and biological properties. Imidazole has become an important synthon in the development of new drugs. Imidazole is incorporated into many important biological compounds. The most pervasive is the amino acid histidine, which has an imidazole side-chain. Histidine is present in many proteins and enzymes, e.g. by binding metal cofactors, as seen in hemoglobin.Recommanded Product: 145040-37-5

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

4-Aminoimidazole-5-carboxamide, precursor of the purines in E. coli was written by Ben-Ishai, Ruth;Volcani, Benjamin;Bergmann, Ernst D.. And the article was included in Archives of Biochemistry and Biophysics in 1951.Reference of 26832-08-6 This article mentions the following:

In the presence of only 4 γ/cc. of any of the purine bases, which by themselves gave only 30% growth, 4-aminoimidazole-5-carboxamide (I) (30γ) gave full growth. p-Aminobenzoic acid (0.1 γ/cc.) and 0.005 γ/cc. folic acid had no effect on the rate at which I was utilized but B₁₂ (0.0002 γ/cc.) increased the rate of utilization. B₁₂ had no effect in media containing adenine or other purine bases. The formyl derivative of I was more effective than I. In the experiment, the researchers used many compounds, for example, 1H-Imidazole-4-carboxamide (cas: 26832-08-6Reference of 26832-08-6).

1H-Imidazole-4-carboxamide (cas: 26832-08-6) belongs to imidazole derivatives. Imidazole is a heterocyclic compound with a five-membered planar ring. It is amphoteric and highly polar. The pharmacophore of imidazole exists in bioactive compounds including amino acids, plant growth regulators and therapeutic agents.n increase of the alkyl chain length of the alcohols. Reference of 26832-08-6

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

DNA-Based Asymmetric Inverse Electron-Demand Hetero-Diels-Alder was written by Mansot, Justine;Lauberteaux, Jimmy;Lebrun, Aurelien;Mauduit, Marc;Vasseur, Jean-Jacques;Marcia de Figueiredo, Renata;Arseniyadis, Stellios;Campagne, Jean-Marc;Smietana, Michael. And the article was included in Chemistry – A European Journal in 2020.Quality Control of 1-(1-Methyl-1H-imidazol-2-yl)ethanone This article mentions the following:

While artificial cyclases hold great promise in chem. synthesis, this work presents the first example of a DNA-catalyzed inverse electron-demand hetero-Diels-Alder (IEDHDA) between dihydrofuran and various α,β-unsaturated acyl imidazoles. The resulting fused bicyclic O,O-acetals containing three contiguous stereogenic centers I (R = Me, c-hexyl, Ph, etc.) are obtained in high yields (up to 99%) and excellent diastereo- (up to >99:1 dr) and enantioselectivities (up to 95% ee) using a low catalyst loading. Most importantly, these results show that the concept of DNA-based asym. catalysis can be expanded to new synthetic transformations offering an efficient, sustainable, and highly selective tool for the construction of chiral building blocks. In the experiment, the researchers used many compounds, for example, 1-(1-Methyl-1H-imidazol-2-yl)ethanone (cas: 85692-37-1Quality Control of 1-(1-Methyl-1H-imidazol-2-yl)ethanone).

1-(1-Methyl-1H-imidazol-2-yl)ethanone (cas: 85692-37-1) belongs to imidazole derivatives. Among the different heterocyclic compounds, imidazole is better known due to its broad range of chemical and biological properties. Imidazole has become an important synthon in the development of new drugs. Imidazole based anticancer drug find applications in cancer chemotherapy. It is used as buffer component for purification of the histidine tagged recombinant proteins in immobilized metal-affinity chromatography (IMAC).Quality Control of 1-(1-Methyl-1H-imidazol-2-yl)ethanone

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Molybdenum(II) Complexes with α-Diimines: Catalytic Activity in Organic and Ionic Liquid Solvents was written by Saraiva, Marta S.;Nunes, Carla D.;Felix, Vitor;Ribeiro, Ana P. C.;de Castro, Carlos Nieto;Calhorda, Maria Jose. And the article was included in European Journal of Inorganic Chemistry in 2018.Quality Control of 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide This article mentions the following:

The new [MoX(η³-C₃H₅)(CO)₂(α-diimine)] complexes with: (i) X = Br or triflate and α-diimine = 1,10-phenanthroline (phen) and dipyridophenazine (dppz); and (ii) X = Br and α-diimine = phen and dppz, with several substituents, are synthesized and characterized. The structures of [MoBr(η³-C₃H₅)(CO)₂(Cl-phen)] and [Mo(CF₃SO₃)(η³-C₃H₅)(CO)₂(dppz)] are determined by using single-crystal X-ray diffraction. These and three complexes of 2,2′-bipyridyl (bpy), and its two derivatives with Me and ^tBu substituents, are tested in the homogeneous catalytic epoxidation of several olefins in dichloromethane, exhibiting, in general, a good selectivity towards the resp. epoxide and relatively low TOFs. For the first time, the oxidation of cis-cyclooctene with some of these catalysts is also conducted in a variety of room-temperature ionic liquids (RTILs). In the presence of [MoBr(η³-C₃H₅)(CO)₂(phen)], the conversions, in general, increase, compared with the reactions in organic solvents. Interestingly, different chemoselectivity is found when [C₆mim][Ntf₂] and [C₂mim][FAP] are used with diol (24-26 %). On the other hand, [MoBr(η³-C₃H₅)(CO)₂(L)] (L = Me-phen or dppz) exhibits much lower conversions in the RTILs tested than in common organic solvents. In the experiment, the researchers used many compounds, for example, 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide (cas: 404001-48-5Quality Control of 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide).

3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide (cas: 404001-48-5) belongs to imidazole derivatives. Many natural products, especially alkaloids, contain the imidazole ring. These imidazoles share the 1,3-C3N2 ring but feature varied substituents. The pharmacophore of imidazole exists in bioactive compounds including amino acids, plant growth regulators and therapeutic agents.n increase of the alkyl chain length of the alcohols. Quality Control of 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Imidazolium Ionic Liquids as Potential Anti-Candida Inhibitors: QSAR Modeling and Experimental Studies was written by Hodyna, Diana;Kovalishyn, Vasyl;Rogalsky, Sergiy;Blagodatnyi, Volodymyr;Metelytsia, Larisa. And the article was included in Current Drug Discovery Technologies in 2016.Recommanded Product: 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide This article mentions the following:

Quant. structure-activity relationships (QSAR) of imidazolium ionic liquids (ILs) as inhibitors of C. albicans collection strains (IOA-109, KCTC 1940, ATCC 10231) have been studied. Predictive QSAR models were built using different descriptor sets for a set of 88 ionic liquids with known min. inhibitory concentrations (MIC) against C. albicans. We applied the state-of-the-art QSAR methodologies such as WEKA Random Forest (RF) as a binary classifier, Associative Neural Networks (ASNN) and k-Nearest Neighbors (k-NN) to build continuum non-linear regression models. The obtained models were validated using a 5-fold cross-validation approach and resulted in the prediction accuracies of 80% ± 5.0 for the classification models and q2 = 0.73-0.87 for the non-linear regression models. Biol. testing of newly synthesized 1,3-dialkylimidazolium ionic liquids with predicted activity was performed by disco-diffusion method against C. albicans ATCC 10231 M885 strain and clin. isolates C. albicans, C. krusei and C. glabrata strains. The high percentage of coincidence between the QSAR predictions and the exptl. results confirmed the high predictive power of the developed QSAR models within the applicability domain of new imidazolium ionic liquids In the experiment, the researchers used many compounds, for example, 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide (cas: 404001-48-5Recommanded Product: 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide).

3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide (cas: 404001-48-5) belongs to imidazole derivatives. Many natural products, especially alkaloids, contain the imidazole ring. These imidazoles share the 1,3-C3N2 ring but feature varied substituents. Imidazole also acts as a microtubule destabilizing agents and inhibits topoisomerase and Cytochrome P450 Family 26 Subfamily A Member 1 (CYP26A1) enzymes.Recommanded Product: 3-Dodecyl-1-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Chelated Assisted Metal-Mediated N-H Bond Activation of β-Lactams: Preparation of Irida-, Rhoda-, Osma-, and Ruthenatrinems was written by Casarrubios, Luis;Esteruelas, Miguel A.;Larramona, Carmen;Muntaner, Jaime G.;Olivan, Montserrat;Onate, Enrique;Sierra, Miguel A.. And the article was included in Organometallics in 2014.Safety of 1-Methyl-1H-benzo[d]imidazole-2-carbaldehyde This article mentions the following:

2-Azetidinones substituted with pyridine (2a), quinoline (2b), isoquinoline (2c), imidazole (2d), and benzimidazole (2e) at the 4-position of the four-membered ring have been prepared in order to synthesize tribactams containing a transition metal and its associated ligands, L_nM, at the 2-position of the tricyclic skeleton. The developed procedure is compatible with a wide range of transition-metal starting complexes. Thus, the iridium and rhodium dimers [M(η⁵-C₅Me₅)Cl₂]₂ react with 2a–e, in the presence of sodium acetate, to afford irida- and rhodatrinems (1a–j) containing the half-sandwich d⁶ metal fragments M(η⁵-C₅Me₅)Cl (M = Ir, Rh). The reactions of [M(μ-OMe)(η⁴-COD)]₂ (M = Ir, Rh) with 2a lead to irida- and rhodatrinems (1k,l) with the d⁸ moieties M(η⁴-COD). The coordination sphere and oxidation state of the metal center in these compounds can be modified, without affecting the 2-azetidinone backbone, by substitution and oxidative addition reactions. As a proof of concept, metallatrinems with the M(CO)₂ (M = Ir (1m), Rh (1n)) and Ir(Me)I(CO)₂ (1o) units are also reported. Osmatrinems 1p,q containing the d⁴ metal fragment OsH₃(PⁱPr₃)₂ have been obtained starting from the d² hexahydride OsH₆(PⁱPr₃)₂, by reaction with 2a,b, whereas the treatment of the tetrahydroborate complexes MH(η²-H₂BH₂)(CO)(PⁱPr₃)₂ (M = Os, Ru) with 2a yields osma- and ruthenatrinems (1r,s) containing six-coordinate bis(phosphine) d⁶ metal fragments. The IR stretching frequency of the lactamic carbonyl, the bent angle between the five- and four-membered rings of the tricycle, and the N-CO bond length in the lactamic ring are clearly influenced by the L_nM fragment. In the experiment, the researchers used many compounds, for example, 1-Methyl-1H-benzo[d]imidazole-2-carbaldehyde (cas: 3012-80-4Safety of 1-Methyl-1H-benzo[d]imidazole-2-carbaldehyde).

1-Methyl-1H-benzo[d]imidazole-2-carbaldehyde (cas: 3012-80-4) belongs to imidazole derivatives. 1H-imidazole is an imidazole tautomer which has the migrating hydrogen at position 1. It is a conjugate base of an imidazolium cation. It is a conjugate acid of an imidazolide. It is a tautomer of a 4H-imidazole. The pharmacophore of imidazole exists in bioactive compounds including amino acids, plant growth regulators and therapeutic agents.n increase of the alkyl chain length of the alcohols. Safety of 1-Methyl-1H-benzo[d]imidazole-2-carbaldehyde

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

110th Anniversary: Properties of Imidazolium-Based Ionic Liquids Bearing Both Benzylic and n-Alkyl Substituents was written by Bara, Jason E.;Finotello, Alexia;Magee, Joseph W.;Qian, Shuai;O’Harra, Kathryn E.;Dennis, Grayson P.;Noble, Richard D.. And the article was included in Industrial & Engineering Chemistry Research in 2019.Safety of 1-Octyl-1H-imidazole This article mentions the following:

Reports of imidazolium ionic liquids (ILs) with at least one benzylic substituent bound to the imidazolium cation are far less common than the ubiquitous 1-alkyl-3-methylimidazolium ILs ([C_nmim][X]). Yet, there is significant motivation to determine structure-property relationships for imidazolium-based ILs with at least one benzylic substituent. Not only are these ILs just as straightforward to synthesize as [C_nmim][X] ILs, but ILs with benzylic substituents are also representative segments of poly(ILs) and ionenes where imidazolium cations with benzylic groups are commonly found. This report focuses on the effects of benzyl and methylbenzyl substituents on the d. and viscosity of a series of imidazolium cations paired with bis[(trifluoromethyl)sulfonyl]imide (more commonly known as bistriflimide) ([Tf₂N]^–) anions. Furthermore, the solubility of CO₂ in 1-benzyl-3-methylimidazolium bistriflimide [Bnmim][Tf₂N] (CAS: 433337-24-7) was measured at 303.15, 318.15, 333.15, and 348.15 K at pressures in the range of 1-9 bar. In the experiment, the researchers used many compounds, for example, 1-Octyl-1H-imidazole (cas: 21252-69-7Safety of 1-Octyl-1H-imidazole).

1-Octyl-1H-imidazole (cas: 21252-69-7) belongs to imidazole derivatives. 1H-imidazole is an imidazole tautomer which has the migrating hydrogen at position 1. It is a conjugate base of an imidazolium cation. It is a conjugate acid of an imidazolide. It is a tautomer of a 4H-imidazole. Many drugs contain an imidazole ring, such as certain antifungal drugs, the nitroimidazole series of antibiotics, and the sedative midazolam.Safety of 1-Octyl-1H-imidazole

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Enhanced SIA-chemiluminescence probes for angiotensin II receptor antagonist detection using silver and gold nanoparticles: applications in pharmaceutical formulations was written by Alarfaj, N. A.;Altamimi, S. A.;El-Tohamy, M. F.;Almahri, A. M.. And the article was included in New Journal of Chemistry in 2018.Application of 145040-37-5 This article mentions the following:

The present work describes three different sequential injection chemiluminescence (SIA-CL) systems (luminol-ferricyanide(III), Ce(IV)-Na₂SO₃ and luminol-H₂O₂) for the detection of some angiotensin II receptor antagonists, such as candesartan cilexetil (CDC), valsartan (VAL) and telmisartan (TEL), in their pharmaceutical formulations. Under optimal conditions, CL detection was conducted by measuring the high catalytic potential of silver and gold nanoparticles (AgNPs and AuNPs) in CL oxidation reactions. It was found that the increase in CL signals is proportional to the concentration of the target analytes. The calibration graphs cover linear concentration ranges of 0.001-1000, 0.005-2000 and 0.002-40 ng mL^-1 for CDC, VAL and TEL in the presence of AgNPs, resp., and 0.005-500, 0.05-1000 and 0.5-120 ng mL^-1, resp. for the previously mentioned drugs in the presence of AuNPs. The influence of possible interfering species such as common cations, amino acids, sugars and coformulated additives was tested. The proposed methods were validated in accordance with the ICH guidelines. The suggested SIA-CL systems were successfully applied to determine the investigated drugs in pure and pharmaceutical dosage forms. The obtained results were in good agreement with those obtained by other reporting methods. In the experiment, the researchers used many compounds, for example, 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5Application of 145040-37-5).

1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5) belongs to imidazole derivatives. Imidazole derivatives generally have good solubility in protic solvents. Simple imidazole derivatives, such as 1H-imidazole, 2-methyl-1H-imidazole, and 1,2-dimethylimidazole, have very high solubility in water. Imidazole is incorporated into many important biological compounds. The most pervasive is the amino acid histidine, which has an imidazole side-chain. Histidine is present in many proteins and enzymes, e.g. by binding metal cofactors, as seen in hemoglobin.Application of 145040-37-5

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Drug repurposing for identification of potential spike inhibitors for SARS-CoV-2 using molecular docking and molecular dynamics simulations was written by Lazniewski, Michal;Dermawan, Doni;Hidayat, Syahrul;Muchtaridi, Muchtaridi;Dawson, Wayne K.;Plewczynski, Dariusz. And the article was included in Methods (Amsterdam, Netherlands) in 2022.Safety of 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate This article mentions the following:

For the last two years, the COVID-19 pandemic has continued to bring consternation on most of the world. According to recent WHO estimates, there have been more than 5.6 million deaths worldwide. The virus continues to evolve all over the world, thus requiring both vigilance and the necessity to find and develop a variety of therapeutic treatments, including the identification of specific antiviral drugs. Multiple studies have confirmed that SARS-CoV-2 utilizes its membrane-bound spike protein to recognize human angiotensin-converting enzyme 2 (ACE2). Thus, preventing spike-ACE2 interactions is a potentially viable strategy for COVID-19 treatment as it would block the virus from binding and entering into a host cell. This work aims to identify potential drugs using an in silico approach. Mol. docking was carried out on both approved drugs and substances previously tested in vivo. This step was followed by a more detailed anal. of selected ligands by mol. dynamics simulations to identify the best mols. that thwart the ability of the virus to interact with the ACE2 receptor. Because the SARS-CoV-2 virus evolves rapidly due to a plethora of immunocompromised hosts, the compounds were tested against five different known lineages. As a result, we could identify substances that work well on individual lineages and those showing broader efficacy. The most promising candidates among the currently used drugs were zafirlukast and simeprevir with an average binding affinity of -22 kcal/mol for spike proteins originating from various lineages. The first compound is a leukotriene receptor antagonist that is used to treat asthma, while the latter is a protease inhibitor used for hepatitis C treatment. From among the in vivo tested substances that concurrently exhibit promising free energy of binding and ADME parameters (indicating a possible oral administration) we selected the compound BDBM50136234. In conclusion, these mols. are worth exploring further by in vitro and in vivo studies against SARS-CoV-2. In the experiment, the researchers used many compounds, for example, 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5Safety of 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate).

1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate (cas: 145040-37-5) belongs to imidazole derivatives. 1H-imidazole is an imidazole tautomer which has the migrating hydrogen at position 1. It is a conjugate base of an imidazolium cation. It is a conjugate acid of an imidazolide. It is a tautomer of a 4H-imidazole. The pharmacophore of imidazole exists in bioactive compounds including amino acids, plant growth regulators and therapeutic agents.n increase of the alkyl chain length of the alcohols. Safety of 1-(((Cyclohexyloxy)carbonyl)oxy)ethyl 1-((2′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem

Magnetic ionic liquids based on transition metal complexes with N-alkylimidazole ligands was written by Chand, Deepak;Farooq, Muhammad Qamar;Pathak, Arjun K.;Li, Jingzhe;Smith, Emily A.;Anderson, Jared L.. And the article was included in New Journal of Chemistry in 2019.Recommanded Product: 21252-69-7 This article mentions the following:

In this study, magnetic ionic liquids (MILs) consisting of Ni(II), Co(II), and Mn(II) and paired with the bis[(trifluoromethyl)sulfonyl]imide [NTf₂^–] anion were synthesized from their water soluble chloride intermediates. The MILs feature low viscosity, high hydrophobicity, and hydrolytic stability making them attractive candidates for a number of highly interdisciplinary applications. In the experiment, the researchers used many compounds, for example, 1-Octyl-1H-imidazole (cas: 21252-69-7Recommanded Product: 21252-69-7).

1-Octyl-1H-imidazole (cas: 21252-69-7) belongs to imidazole derivatives. Imidazole is a heterocyclic compound with a five-membered planar ring. It is amphoteric and highly polar. This ring system is present in important biological building blocks, such as histidine and the related hormone histamine.Recommanded Product: 21252-69-7

Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem