Tag: 200-300

Structure-Activity Relationships of Synthetic Cordycepin Analogues as Experimental Therapeutics for African Trypanosomiasis was written by Vodnala, Suman K.; Lundbaeck, Thomas; Yeheskieli, Esther; Sjoeberg, Birger; Gustavsson, Anna-Lena; Svensson, Richard; Olivera, Gabriela C.; Eze, Anthonius A.; de Koning, Harry P.; Hammarstroem, Lars G. J.; Rottenberg, Martin E.. And the article was included in Journal of Medicinal Chemistry on December 27,2013.Recommanded Product: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol The following contents are mentioned in the article:

Novel methods for treatment of African trypanosomiasis, caused by infection with Trypanosoma brucei are needed. Cordycepin (3′-deoxyadenosine, 1a) is a powerful trypanocidal compound in vitro but is ineffective in vivo because of rapid metabolic degradation by adenosine deaminase (ADA). The authors elucidated the structural moieties of cordycepin required for trypanocidal activity and designed analogs that retained trypanotoxicity while gaining resistance to ADA-mediated metabolism 2-Fluorocordycepin (2-fluoro-3′-deoxyadenosine) was identified as a selective, potent, and ADA-resistant trypanocidal compound that cured T. brucei infection in mice. 2-Fluorocordycepin is transported through the high affinity TbAT1/P2 adenosine transporter and is a substrate of T. b. brucei adenosine kinase. 2-Fluorocordycepin has good preclin. properties suitable for an oral drug, albeit a relatively short plasma half-life. The authors present a rapid and efficient synthesis of 2-halogenated cordycepins, also useful synthons for the development of addnl. novel C2-substituted 3′-deoxyadenosine analogs to be evaluated in development of exptl. therapeutics. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Recommanded Product: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Solid acid catalysis, and the advantages often associated with their use, have been proved equally efficient for the synthesis of tetrahydrofurans or furans. Commercial tetrahydrofuran contains substantial water that must be removed for sensitive operations, e.g. those involving organometallic compounds. Although tetrahydrofuran is traditionally dried by distillation from an aggressive desiccant, molecular sieves are superior.Recommanded Product: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

550-33-4;(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol;The future of 550-33-4;New trend of C10H12N4O4  ;function of 550-33-4

A Method for the Reductive Scission of Heterocyclic Thioethers was written by Graham, Thomas H.; Liu, Wensheng; Shen, Dong-Ming. And the article was included in Organic Letters on December 2,2011.Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol The following contents are mentioned in the article:

A mild, chemoselective, and generally high-yielding method for the reductive scission of heterocyclic thioethers is described. Suitable heterocycles have a thioether substituent at the 2-position relative to a ring heteroatom. The convenient and straightforward method is demonstrated with reactants which are not compatible with the standard Raney nickel conditions such as sulfides, sulfones, and thiophenes. In addition, benzyl esters, benzyl amides, and benzyl carbamates are tolerated by the reductive reaction conditions. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Tetrahydrofurans and furans are important oxygen-containing heterocycles that often exhibit interesting properties for biological applications or applications in the cosmetic industry. It is more basic than diethyl ether and forms stronger complexes with Li+, Mg2+, and boranes. It is a popular solvent for hydroboration reactions and for organometallic compounds such as organolithium and Grignard reagents.Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

550-33-4;(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol;The future of 550-33-4;New trend of C10H12N4O4  ;function of 550-33-4

Inhibition of Trypanosoma cruzi growth in mammalian cells by purine and pyrimidine analogs was written by Nakajima-Shimada, Junko; Hirota, Yumiko; Aoki, Takashi. And the article was included in Antimicrobial Agents and Chemotherapy on November 30,1996.Application of 13146-72-0 The following contents are mentioned in the article:

Trypanosoma cruzi, the causative agent of Chagas’ disease, exhibits two different developmental stages in mammals, the amastigote, an intracellular form that proliferates in the cytoplasm of host cells, and the trypomastigote, an extracellular form that circulates in the bloodstream. We have already established an in vitro culture system using mammalian host cells (HeLa) infected with T. cruzi in which the time course of parasite growth is determined quant. We adopted this system for the screening of anti-T. cruzi agents that would ideally prove to be effective trypanosomes with no toxicity to the host cell. Of the purine analogs tested, allopurinol markedly inhibited the growth of amastigotes in a dose-dependent manner, with no lethal effect on trypomastigotes. 3′-Deoxyinosine and 3′-deoxyadenosine also suppressed T. cruzi growth inside the host cell, with the concentrations causing 50% growth inhibition being 10 and 5 μM, resp., in contrast to a concentration causing 50% growth inhibition of 3 μM for allopurinol. Among the pyrimidine analogs examined, 3′-azido-3′-deoxythmidine (zidovudine) significantly reduced the growth of the parasite at concentrations as low as 1 μM. The anti-human immunodeficiency virus agents 2′,3′-dideoxyinosine and 2′,3′-dideoxyadenosine caused a decrease in amastigote growth, while 2′,3′-dideoxycytidine and 2′,3′-dideoxyuridine had no inhibitory effect. When Swiss 3T3 fibroblasts were used as host cells, allopurinol, 3′-deoxyinosine, 3′-deoxyadenosine, and 3′-azido-3′-deoxythymidine also markedly inhibited T. cruzi proliferation. These results indicate that our culture system is useful as a primary screening method for candidate compounds against T. cruzi on the basis of two criteria, namely, intracellular replication by the parasite and host-cell infection rate. This study involved multiple reactions and reactants, such as 9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0Application of 13146-72-0).

9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0) belongs to tetrahydrofuran derivatives. Tetrahydrofuran (THF), or oxolane, is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Application of 13146-72-0

13146-72-0;9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol;The future of 13146-72-0;New trend of C10H12N4O4 ;function of 13146-72-0

Impact of Base Analogues within a CpG Dinucleotide on the Binding of DNA by the Methyl-Binding Domain of MeCP2 and Methylation by DNMT1 was written by Lao, Victoria Valinluck; Darwanto, Agus; Sowers, Lawrence C.. And the article was included in Biochemistry on November 30,2010.Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol The following contents are mentioned in the article:

The epigenetic control of transcription requires the selective recognition of methylated CpG dinucleotides by methylation-sensitive sequence-specific DNA binding proteins. In order to probe the mechanism of selective interaction of the methyl-binding protein with methylated DNA, we have prepared a series of oligonucleotides containing modified purines and pyrimidines at the recognition site, and we have examined the binding of these oligonucleotides to the methyl-binding domain (MBD) of the methyl-CpG-binding protein 2 (MeCP2). Our results suggest that pyrimidine 5-substituents similar in size to a Me group facilitate protein binding; however, binding affinity does not correlate with the hydrophobicity of the substituent, and neither the 4-amino group of 5-methylcytosine (mC) nor Watson-Crick base pair geometry is essential for MBD binding. However, 5-substituted uracil analogs in one strand do not direct human DNA methyltransferase 1 (DNMT1) methylation of the opposing strand, as does mC. Important recognition elements do include the guanine O6 and N7 atoms present in the major groove. Unexpectedly, removal of the guanine 2-amino group from the minor groove substantially enhances MBD binding, likely resulting from DNA bending at the substitution site. The enhanced binding of the MBD to oligonucleotides containing several cytosine analogs observed here is better explained by a DNA-protein interface mediated by structured water as opposed to hydrophobic interactions. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Tetrahydrofuran and dihydrofuran form the basic structural unit of many naturally occurring scaffolds like gambieric acid A and ciguatoxin, goniocin, and some biologically active molecules. Tetrahydrofuran (THF) is primarily used as a precursor to polymers including for surface coating, adhesives, and printing inks.Name: (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

550-33-4;(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol;The future of 550-33-4;New trend of C10H12N4O4  ;function of 550-33-4

The Chemoenzymic Synthesis of 2-Chloro- and 2-Fluorocordycepins was written by Denisova, Alexandra O.; Tokunova, Yulia A.; Fateev, Ilja V.; Breslav, Alexandra A.; Leonov, Vladimir N.; Dorofeeva, Elena V.; Lutonina, Olga I.; Muzyka, Inessa S.; Esipov, Roman S.; Kayushin, Alexey L.; Konstantinova, Irina D.; Miroshnikov, Anatoly I.; Stepchenko, Vladimir A.; Mikhailopulo, Igor A.. And the article was included in Synthesis on November 30,2017.Electric Literature of C10H12N4O4  The following contents are mentioned in the article:

Two approaches to the chemoenzymic synthesis of 2-fluorocordycepin and 2-chlorocordycepin were studied: (i) the use of 3′-deoxyadenosine (cordycepin) and 3′-deoxyinosine (3’dIno) as donors of 3-deoxy- D-ribofuranose in the transglycosylation of 2-fluoro- ( 2FAde) and 2-chloroadenine ( 2ClAde) catalyzed by the recombinant E. coli purine nucleoside phosphorylase (PNP), and (ii) the use of 2-fluoroadenosine and 3′-deoxyinosine as substrates of the cross-glycosylation and PNP as a biocatalyst. An efficient method for 3′-deoxyinosine synthesis starting from inosine was developed. However, the very poor solubility of 2ClAde and 2FAde is the limiting factor of the first approach. The second approach enables this problem to be overcome and it appears to be advantageous over the former approach from the viewpoint of practical synthesis of the title nucleosides. The 3-deoxy-α- D-ribofuranose-1-phosphate intermediary formed in the 3’dIno phosphorolysis by PNP was found to be the weak and marginal substrate of E. coli thymidine (TP) and uridine (UP) phosphorylases, resp. Finally, one-pot cascade transformation of 3-deoxy-D-ribose in cordycepin in the presence of adenine and E. coli ribokinase, phosphopentomutase, and PNP was tested and cordycepin formation in ca. 3.4% yield was proved. This study involved multiple reactions and reactants, such as 9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0Electric Literature of C10H12N4O4 ).

9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0) belongs to tetrahydrofuran derivatives. THF (Tetrahydrofuran) is water-miscible and has a low viscosity making it a highly versatile solvent used in a variety of industries. THF can also be synthesized by catalytic hydrogenation of furan. This allows certain sugars to be converted to THF via acid-catalyzed digestion to furfural and decarbonylation to furan, although this method is not widely practiced. THF is thus derivable from renewable resources.Electric Literature of C10H12N4O4 

13146-72-0;9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol;The future of 13146-72-0;New trend of C10H12N4O4 ;function of 13146-72-0

Method development and validation for the analysis of didanosine using micellar electrokinetic capillary chromatography was written by Mallampati, Swapna; Leonard, Stefanie; De Vulder, Sabine; Hoogmartens, Jos; Van Schepdael, Ann. And the article was included in Electrophoresis on November 30,2005.Synthetic Route of C10H12N4O4  The following contents are mentioned in the article:

A selective MEKC method was developed for the anal. of didanosine in bulk samples. Successful separation of didanosine from 13 of its potential impurities, derived from the various synthetic preparation procedures, was achieved. As CZE gave poor separation selectivity, MEKC was preferable. The use of EKC allowed achievement of the separation in a significantly shorter time than conventional HPLC. An anionic long-chain surfactant, lithium dodecyl sulfate (LiDS), was used as the pseudostationary phase and sodium tetraborate buffer as the aqueous phase. To obtain the optimal conditions and to test the method robustness, a central composite response surface modeling experiment was performed. The optimized electrophoretic conditions include the use of an uncoated fused-silica capillary with a total length of 40 cm and an ID of 50 μm, a BGE containing 40 mM sodium tetraborate and 110 mM LiDS at pH 8.0, an applied voltage of 18.0 kV, and the capillary temperature maintained at 15°C. The method was found to be robust. The parameters for validation such as linearity, precision, and sensitivity are also reported. Three com. bulk samples were analyzed with this system. This study involved multiple reactions and reactants, such as 9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0Synthetic Route of C10H12N4O4 ).

9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0) belongs to tetrahydrofuran derivatives.Tetrahydrofuran has many industry uses as a solvent including in natural and synthetic resins, high polymers, fat oils, rubber, polymer. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Synthetic Route of C10H12N4O4 

13146-72-0;9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol;The future of 13146-72-0;New trend of C10H12N4O4 ;function of 13146-72-0

Identification and characterization of new impurity in didanosine was written by Rao, D. V. N. Srinivasa; Srinivas, N.; Bharathi, Ch.; Prasad, Ch. S.; Dandala, Ramesh; Naidu, A.. And the article was included in Journal of Pharmaceutical and Biomedical Analysis on November 5,2007.Product Details of 13146-72-0 The following contents are mentioned in the article:

Didanosine is an antiviral drug. During the preparation of didanosine in our lab, six process related known impurities and one unknown impurity were detected in HPLC anal. at levels ranging from 0.05 to 0.8%. The same unknown impurity was also observed in com. batches. This new impurity was isolated by preparative HPLC and co-injected with didanosine sample to confirm the retention times in HPLC. This impurity was characterized as, 9-(2,3,5-trideoxy-β-D-glycero-pentofuranosyl)-9H-purin-6-one (2′,3′,5′-trideoxyinosine). Structural elucidation of this impurity by spectral data (1H NMR, 13C NMR, MS, and IR) has been discussed. This study involved multiple reactions and reactants, such as 9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0Product Details of 13146-72-0).

9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol (cas: 13146-72-0) belongs to tetrahydrofuran derivatives. Tetrahydrofurans and furans are important oxygen-containing heterocycles that often exhibit interesting properties for biological applications or applications in the cosmetic industry. THF can also be synthesized by catalytic hydrogenation of furan. This allows certain sugars to be converted to THF via acid-catalyzed digestion to furfural and decarbonylation to furan, although this method is not widely practiced. THF is thus derivable from renewable resources.Product Details of 13146-72-0

13146-72-0;9-((2R,3R,5S)-3-Hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-ol;The future of 13146-72-0;New trend of C10H12N4O4 ;function of 13146-72-0

Metabolomic analysis of the effects of omeprazole and famotidine on aspirin-induced gastric injury was written by Takeuchi, Kenichiro; Ohishi, Maki; Endo, Keiko; Suzumura, Kenichi; Naraoka, Hitoshi; Ohata, Takeji; Seki, Jiro; Miyamae, Yoichi; Honma, Masashi; Soga, Tomoyoshi. And the article was included in Metabolomics on October 31,2014.Computed Properties of C10H12N4O4   The following contents are mentioned in the article:

Gastric mucosal ulceration and gastric hemorrhage are frequently associated with treatment by non-steroid anti-inflammatory drugs (NSAIDs); however, no convenient biomarker-based diagnostic methods for these adverse reactions are currently available, requiring the use of endoscopic evaluation. We recently reported five biomarker candidates in serum which predict gastric injury induced by NSAIDs in rats, but were unable to clarify the mechanism of change in the levels of these biomarker candidates. In this study, we performed capillary electrophoresis-mass spectrometry-based metabolomic profiling in stomach and serum from rats in which gastric ulcer was induced by aspirin and prevented by co-administration of omeprazole and famotidine. Results showed drug-induced decreases in the levels of citrate, cis-aconitate, succinate, 3-hydroxy butanoic acid, and O-acetyl carnitine in all animals administered aspirin. In contrast, aspirin-induced decreases in the level of 4-hydroxyproline were suppressed by co-administration of omeprazole and famotidine. We consider that these changes were due to the prevention of gastric ulcer and decrease in the amount of collagen in stomach tissue by omeprazole and famotidine, without prevention of the NSAID-induced depression of mitochondrial function. In addition, the decreases in 4-hydroxyproline in the stomach was also detectable as changes in the serum. While further study is needed to clarify limitations of indications and extrapolation to humans, this new serum biomarker candidate of gastric injury may be useful in the monitoring of NSAID-induced tissue damage. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Computed Properties of C10H12N4O4  ).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Tetrahydrofuran (THF), or oxolane, is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent. Tetrahydrofuran can also be produced, or synthesised, via catalytic hydrogenation of furan. This process involves converting certain sugars into THF by digesting to furfural. An alternative to this method is the catalytic hydrogenation of furan with a nickel catalyst.Computed Properties of C10H12N4O4  

550-33-4;(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol;The future of 550-33-4;New trend of C10H12N4O4  ;function of 550-33-4

Content dependent inhibitors of cytidine deaminases and uses thereof was written by Wedekind, Joseph E.; Smith, Harold C.. And the patent was published on April 17,2012.Safety of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol The following contents are mentioned in the patent:

This invention relates to cytidine deaminase inhibitors (Cytidine deaminase inhibitors) of cytidine deaminases and uses thereof. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Safety of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Solid acid catalysis, and the advantages often associated with their use, have been proved equally efficient for the synthesis of tetrahydrofurans or furans. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Safety of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

Referemce:
Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem

Copper cleaning and protection formulations was written by Barnes, Jeffrey A.; Benac, Brian; Boggs, Karl E.; Feng, Lin; Liu, Jun; Petruska, Melissa A.; Yan, Xiaodong; Zhang, Peng. And the patent was published on April 29,2010.Product Details of 550-33-4 The following contents are mentioned in the patent:

Disclosed is a cleaning composition and process for cleaning post-chem. mech. polishing (CMP) residue and contaminants from a microelectronic device having said residue and contaminants thereon. The cleaning compositions include novel corrosion inhibitors. The composition achieves highly efficacious cleaning of the post-CMP residue and contaminant material from the surface of the microelectronic device without compromising the low-k dielec. material or the copper interconnect material. This study involved multiple reactions and reactants, such as (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4Product Details of 550-33-4).

(2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol (cas: 550-33-4) belongs to tetrahydrofuran derivatives. Tetrahydrofuran and dihydrofuran form the basic structural unit of many naturally occurring scaffolds like gambieric acid A and ciguatoxin, goniocin, and some biologically active molecules. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Product Details of 550-33-4

Referemce:
Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem