Patent: WO2019118839 A1 | Beigelman, Leonid et al. published a patent in 2019| cas: 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 has many industry uses as a solvent including in natural and synthetic resins, high polymers, fat oils, rubber, polymer. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Application In Synthesis of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

Preparation of cyclic dinucleotides as STING agonists was written by Beigelman, Leonid; Bignan, Gilles; Connolly, Peter J.; Edwards, James Patrick; Emanuel, Stuart; Laquerre, Sylvia; Richter, Mark; Schepens, Wim Gert Griet; Thatikonda, Santhosh Kumar; Thuring, Johannes Wilhelmus John Fitzgerald; Viellevoye, Marcel; Wang, Guangyi; Zhong, Minghong. And the patent was published on June 20,2019.Application In Synthesis of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol The following contents are mentioned in the patent:

Cyclic dinucleotides I, wherein B1 and B2 are independently nucleobase; R1a is H, OH, F, alkoxy; R1b is H, F, OH; provided that when R1b is F, R1a is H or F; R1c is H or Me; R2a is H,, OH, F, alkoxy; R2b is H, F, or OH; provided that when R2b is F, R2a is H or F; R2c is H, F, CH3, or CH2F; X1 and X2 are the group consisting of O, S, and CH2; Y and Y1 are each independently absent or O or NH; Z and Z1 are the group consisting of O and NH; M and M1 are independently SO2, substituted phosphate, substituted thiophosphate, were prepared and used for treating of diseases, syndromes, or disorders that are affected by the modulation of STING. Thus, cyclic dinucleotide II was prepared and used as antitumor and antiviral agent and vaccine. Cyclic dinucleotides are used for treating of diseases, syndrome, melanoma, colon cancer, breast cancer, prostate cancer, lung cancer, and fibrosarcoma, hepatitis B. 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: 550-33-4Application In Synthesis 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.Tetrahydrofuran has many industry uses as a solvent including in natural and synthetic resins, high polymers, fat oils, rubber, polymer. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Application In Synthesis of (2R,3S,4R,5R)-2-(Hydroxymethyl)-5-(9H-purin-9-yl)tetrahydrofuran-3,4-diol

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

Patent: US20110111016 A1 | Phillips, Nigel C. et al. published a patent in 2011| cas: 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 (THF), or oxolane, is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Synthetic Route of C10H12N4O4  

Non-DNA base-containing polynucleotide compositions and their use for the modulation of immune responses was written by Phillips, Nigel C.; Filion, Mario C.. And the patent was published on May 12,2011.Synthetic Route of C10H12N4O4   The following contents are mentioned in the patent:

The present invention provides compositions comprising synthetic non-DNA base-containing polynucleotide sequences of 3 to 30 bases in length comprising one or more non-DNA bases wherein the bases are nebularine, hypoxanthine, or uracil, or combinations of nebularine, hypoxanthine and uracil bases, in combination with a pharmaceutically acceptable vehicle, particularly one or more adjuvant vehicle, and one or more antigen. The present invention relates to methods of administering these compositions for inducing or modulating an immune response in vitro or in vivo, and particularly for activating antigen presenting cells. The present invention relates to compositions comprising synthetic non-DNA base-containing polynucleotides, a pharmaceutically acceptable vehicle and optionally one or more antigens, and their use to modulate immune responses. Several of the compositions of the present invention permit lower doses of antigen to be used in a vaccine formulation. 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: 550-33-4Synthetic Route 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. THF (Tetrahydrofuran) is also used as a starting material for the synthesis of poly(tetramethylene ether) glycol (PTMG), etc.Synthetic Route of C10H12N4O4  

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

Patent: WO2022108944 A1 | Frank, Joseph et al. published a patent in 2022| cas: 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. THF (Tetrahydrofuran) is a stable compound with relatively low boiling point and excellent solvency. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Recommanded Product: 550-33-4

Bioherbicides for controlling one or more plant species was written by Frank, Joseph; Shakeel, Ameer Hamza; Carballo, Sergio Madrigal; Zomorodi, Sepehr; Pourtaheri, Payam. And the patent was published on May 27,2022.Recommanded Product: 550-33-4 The following contents are mentioned in the patent:

The present disclosure provides compositions and methods for suppressing growth of various plant species with bioactive agents. Also, the present disclosure provides agricultural compositions and methods of using the formulations containing minicells and bioactive agents for targeted delivery and controlled release to enhance control of various plant species in a stable and scalable manner. 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: 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. THF (Tetrahydrofuran) is a stable compound with relatively low boiling point and excellent solvency. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Recommanded Product: 550-33-4

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

Patent: WO2013071079 A1 | Sliz, Piotr et al. published a patent in 2013| cas: 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. THF (Tetrahydrofuran) is a stable compound with relatively low boiling point and excellent solvency. 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.Related Products of 550-33-4

Lin28/let-7 crystal structures, purification protocols, and modified tumor suppressor hairpin oligonucleotides, suitable for use in Lin28 inhibitor screening assays and cancer therapy was written by Sliz, Piotr; Nam, Yunsun. And the patent was published on May 16,2013.Related Products of 550-33-4 The following contents are mentioned in the patent:

The invention provides oligonucleotides, compositions and methods for regulating let-7 microRNA biogenesis by inhibiting Lin28. The invention also relates to compositions and methods for screening inhibitors of Lin28 activity that increase the level of mature let-7 miRNA in a cell. The invention also relates to a method of treating or preventing cancer in a subject, using oligonucleotides to promote cellular processing of tumor suppressor miRNA in combination with other therapies. 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: 550-33-4Related Products 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. THF (Tetrahydrofuran) is a stable compound with relatively low boiling point and excellent solvency. 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.Related Products of 550-33-4

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

Patent: WO2010037001 A2 | Rao, Anjana et al. published a patent in 2010| cas: 67341-43-9

Uridine 5′-(trihydrogen diphosphate) P’-(2-deoxy-2-fluoro-α-D-glucopyranosyl) ester (cas: 67341-43-9) 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. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Category: tetrahydrofurans

TET proteins for selective oxidation of 5-methylcytosine and generation of human Foxp3+ T cells and TET protein inhibitors for production of induced pluripotent stem cells to treat degenerative diseases was written by Rao, Anjana; Tahiliani, Mamta; Koh, Kian Peng; Agarwal, Suneet; Iyer, Aravind. And the patent was published on April 1,2010.Category: tetrahydrofurans The following contents are mentioned in the patent:

The present invention provides for novel methods for regulating and detecting the cytosine methylation status of DNA. The invention is based upon identification of a novel and surprising catalytic activity for the family of TET proteins, namely TET1, TET2, TET3, and CXXC4. The novel activity is related to the enzymes being capable of converting the cytosine nucleotide 5-methylcytosine into 5-hydroxymethylcytosine by hydroxylation. This study involved multiple reactions and reactants, such as Uridine 5′-(trihydrogen diphosphate) P’-(2-deoxy-2-fluoro-α-D-glucopyranosyl) ester (cas: 67341-43-9Category: tetrahydrofurans).

Uridine 5′-(trihydrogen diphosphate) P’-(2-deoxy-2-fluoro-α-D-glucopyranosyl) ester (cas: 67341-43-9) 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. Oxidations have also proved to be valuable and efficient approaches to chiral tetrahydrofuran derivatives.Category: tetrahydrofurans

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

Patent: WO2010048139 A2 | Barnes, Jeffrey A. et al. published a patent in 2010| cas: 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

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

Patent: US8158770 B2 | Wedekind, Joseph E. et al. published a patent in 2012| cas: 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. 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

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

Mikolas, Lena A’s team published research in Journal of pharmacy practice in 2018-05-21 | 58-97-9

Journal of pharmacy practice published new progress about 58-97-9. 58-97-9 belongs to class tetrahydrofurans, and the molecular formula is C9H13N2O9P, HPLC of Formula: 58-97-9.

Mikolas, Lena A; Jacques, Kimberly; Huq, Mostaqul; Krasner, Charles; Mambourg, Scott E published the artcile< Utilizing Clinical Pharmacist Specialist to Manage Hepatitis C Virus Patients on Direct-Acting Antiviral Therapy.>, HPLC of Formula: 58-97-9, the main research area is direct-acting antivirals; hepatitis C virus infection; liver disease; sustained virologic response.

OBJECTIVES: To evaluate outcomes of a clinical pharmacist specialist (CPS)-managed hepatitis C virus (HCV) treatment clinic (HCVTC) in treating HCV-infected veterans with direct-acting antivirals (DAAs). METHODS: We established a CPS-managed HCVTC under a collaborative practice agreement with our infectious disease physician (IDP). A total of 132 veterans were treated between November 1, 2014, and November 30, 2015. The CPS engaged in pretreatment screening, drug selection, patient education, medication counseling, drug therapy monitoring, drug utilization review, addressing issues on drug adherence, and routine and posttreatment follow-up of patients to assess sustained virologic response (SVR) after 12 weeks of treatment. RESULTS: Of 132 patients managed by the CPS, 87 (66%) were treated with ledipasvir/sofosbuvir (LDV/SOF), 29 (22%) with paritaprevir/ritonavir/ombitasvir + dasabuvir (PrOD), and 16 (12%) with sofosbuvir (SOF)-based regimen. The corresponding regimens demonstrated a SVR rate of 92% (n = 80), 100% (n = 29), and 93.8% (n = 15), respectively. We achieved an SVR rate of 94% against HCV genotype 1 (GT-1) and 100% against GT-2 to GT-4. The overall SVR rate was 94% across regimens, showing 93% in treatment-naive patients and 96% in treatment-experienced patients, and 93% in noncirrhotic and 94% in compensated cirrhotic patients. The results were comparable to SVR data reported in pivotal trials for DAAs. CONCLUSION: The results suggest that CPS could be effectively utilized in drug therapy management of HCV-infected patients treated with DAAs.

Journal of pharmacy practice published new progress about 58-97-9. 58-97-9 belongs to class tetrahydrofurans, and the molecular formula is C9H13N2O9P, HPLC of Formula: 58-97-9.

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

Stucchi, Marta’s team published research in Catalysis Today in 2020-11-01 | 97-99-4

Catalysis Today published new progress about Binding energy. 97-99-4 belongs to class tetrahydrofurans, and the molecular formula is C5H10O2, Product Details of C5H10O2.

Stucchi, Marta; Alijani, Sharam; Manzoli, Maela; Villa, Alberto; Lahti, Riikka; Galloni, M. G.; Lassi, Ulla; Prati, Laura published the artcile< A Pt-Mo hybrid catalyst for furfural transformation>, Product Details of C5H10O2, the main research area is platinum molybdenum catalyst furfural hydrogenation.

Furfural is a high-value chem., being the precursor of compounds such as furfuryl alc. and tetrahydrofurfuryl alc. Pt is known as active for furfural hydrogenation, but the high price limits its exploitation and imposes the search for alternatives. Here we presented a Pt/Mo bimetallic system with enhanced catalytic activity for furfural hydrogenation. For comparison, monometallic Mo- and Pt-supported on activated carbon have been prepared by impregnation and sol-immobilization. The bimetallic Pt/Mo was prepared impregnating the Mo-AC catalyst with Pt, using Na2PtCl4 as a precursor, PVA, and NaBH4 as reducing agent. HR-TEM analyses on Pt/Mo catalyst showed Mo-containing agglomerates embedded in the carbon matrix, displaying diffraction fringes with spacing typical of Mo4O11 in the orthorhombic phase, as well as Pt nanoparticles more evenly dispersed in the Mo-AC system compared to bare AC. The Pt/Mo catalyst showed higher activity than both monometallic ones, and it converted 92% of furfural to furfuryl alc. and Et furfuryl ether with 20% and 80% selectivity, resp. However, despite a lower initial activity, the monometallic Mo/AC catalyst showed a complete selectivity to the ether.

Catalysis Today published new progress about Binding energy. 97-99-4 belongs to class tetrahydrofurans, and the molecular formula is C5H10O2, Product Details of C5H10O2.

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

Nakagawara, Kosuke’s team published research in Biochemistry and Biophysics Reports in 2022-09-30 | 58-97-9

Biochemistry and Biophysics Reports published new progress about Absorption. 58-97-9 belongs to class tetrahydrofurans, and the molecular formula is C9H13N2O9P, Product Details of C9H13N2O9P.

Nakagawara, Kosuke; Takeuchi, Chieri; Ishige, Kazuya published the artcile< 5 ′-CMP and 5 ′-UMP promote myogenic differentiation and mitochondrial biogenesis by activating myogenin and PGC-1α in a mouse myoblast C2C12 cell line>, Product Details of C9H13N2O9P, the main research area is cytidinemonophosphate uridinemonophosphate myogenin PGCalpha myoblast myogenic differentiation mitochondrial biogenesis; 5′-CMP, Cytidine-5′-monophosphate; 5′-UMP, Uridine-5′-monophosphate; BS, Bovine serum; Cytidine-5′-monophosphate; Endurance; FBS, Fetal bovine serum; MRF, Myogenic regulatory factor; Mitochondria; MyHC, Myosin heavy chanin; Myogenic differentiation; Nutrition; Uridine-5′-monophosphate.

Ribonucleotides are basic monomeric building blocks for RNA considered as conditionally essential nutrients. They are normally produced in sufficient quantity, but can become insufficient upon stressful challenges. The administration of pyrimidine nucleotides, such as cytidine-5′-monophosphate (5′-CMP) and uridine-5′-monophosphate (5′-UMP), enables rats to endure prolonged exercise. However, the underlying mechanisms have remained elusive. To investigate these mechanisms, we studied the effect of 5′-CMP and 5′-UMP on muscular differentiation and mitochondrial biogenesis in myoblast C2C12 cells. A 5′-CMP and 5′-UMP were found to increase the mRNA levels of myogenin, which is a myogenic regulatory protein expressed during the final differentiation step and fusion of myoblasts into myotubes. The 5′-CMP and 5′-UMP also promoted myoblast differentiation into myotube cells. The 5′-CMP and 5′-UMP further increased the mRNA levels of PGC-1α which regulates mitochondrial biogenesis and skeletal muscle fiber type. In addition, 5′-CMP and 5′-UMP increased mitochondrial DNA copy number and enhanced mRNA levels of slow-muscle myosin heavy chains. Moreover, cytidine and uridine, nucleosides corresponding to 5′-CMP and 5′-UMP, markedly promoted myotube formation in C2C12 cells. Considering the metabolism and absorption of nucleotides, the active bodies underlying the effects observed with 5′-CMP and 5′-UMP could be cytidine and uridine. In conclusion, our results indicate that 5′-CMP and 5′-UMP can promote myogenic differentiation and mitochondrial biogenesis, as well as increase slow-twitch fiber via the activation of myogenin and PGC-1α. In addition, 5′-CMP and 5′-UMP may be considered as safe and effective agents to enhance muscle growth and improve the endurance in skeletal muscles.

Biochemistry and Biophysics Reports published new progress about Absorption. 58-97-9 belongs to class tetrahydrofurans, and the molecular formula is C9H13N2O9P, Product Details of C9H13N2O9P.

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