Structural features localizing the ferroptosis inhibitor GIF-2197-r to lysosomes.

We previously reported that N,N-dimethylaniline derivatives are potent ferroptosis inhibitors. Among them, the novel aminoindan derivative GIF-2197-r (the racemate of GIF-2115 (R-form) and GIF-2196 (S-form)) is effective at a concentration of 0.01 µM due to its localization to lysosomes and ferrous ion coordination capacity. The current study demonstrates that the aliphatic tertiary amine moiety of GIF-2197-r is responsible for lysosomal localization. Although N,N-dimethylaniline derivatives cannot form chelate structures with Fe2+, density functional theory computation demonstrates that they can form stable monodentate complexes with a hydrated ferrous ion, likely due to the highly electron-rich nature of the (dialkylamino)phenyl ring. Furthermore, the results suggest that the aliphatic tertiary amine moiety contributes to stabilizing the complexation. These findings could prove useful for developing improved lysosomotropic ferroptosis inhibitors for neurodegenerative diseases.

The Effect of γ Phosphate Modified Deoxynucleotide Substrates on PCR Activity and Fidelity.

Controlling PCR fidelity is an important issue for molecular biology and high-fidelity PCR is essential for gene cloning. In general, fidelity control is achieved by protein engineering of polymerases. In contrast, only a few studies have reported controlling fidelity using chemically modified nucleotide substrates. In this report, we synthesized nucleotide substrates possessing a modification on Pγ and evaluated the effect of this modification on PCR fidelity. One of the substrates, nucleotide tetraphosphate, caused a modest decrease in Taq DNA polymerase activity and the effect on PCR fidelity was dependent on the type of mutation. The use of deoxyadenosine tetraphosphate enhanced the A : T→G : C mutation dramatically, which is common when using Taq polymerase. Conversely, deoxyguanosine tetraphosphate (dG4P) suppressed this mutation but increased the G : C→A : T mutation during PCR. Using an excess amount of dG4P suppressed both mutations successfully and total fidelity was improved.

Enantioselective aromatic Claisen rearrangement of allyl 2-naphthyl ethers catalyzed by π-Cu(ii) complexes.

The first catalytic enantioselective aromatic Claisen rearrangement of allyl 2-naphthyl ethers using 5-10 mol% of π-copper(ii) complexes is reported. A Cu(OTf)2 complex with an l-α-homoalanine amide ligand gave (S)-products in up to 92% ee. Conversely, a Cu(OSO2C4F9)2 complex with an l-tert-leucine amide ligand gave (R)-products in up to 76% ee. Density-functional-theory (DFT) calculations suggest that these Claisen rearrangements proceed stepwise via tight-ion-pair intermediates, and that (S)- and (R)-products are enantioselectively obtained via the staggered transition states for the cleavage of the C-O bond, which is the rate-determining step.

Quercetin and resveratrol inhibit ferroptosis independently of Nrf2-ARE activation in mouse hippocampal HT22 cells.

Oxidative stress is the central pathomechanism in multiple cell death pathways, including ferroptosis, a form of iron-dependent programmed cell death. Various phytochemicals, which include the inducers of the nuclear factor erythroid-2-related factor 2-antioxidant response element (Nrf2-ARE) transcription pathway, prevent ferroptosis. We recently reported that several compounds, such as the potent Nrf2-ARE inducer curcumin, protect mouse hippocampus-derived HT22 cells against ferroptosis independently of Nrf2-ARE activity. The present study characterized the anti-ferroptotic mechanisms of two additional Nrf2-ARE inducers, quercetin and resveratrol. Both compounds prevented erastin- and RSL3-induced ferroptosis of wild-type HT22 cells, and also blocked the exacerbated erastin- and RSL3-induced ferroptosis of Nrf2-knockdown HT22 cells. In both HT22 cells, quercetin and resveratrol blocked erastin- and RSL3-induced elevation in reactive oxygen species. These results suggest that the Nrf2-ARE pathway does protect against ferroptosis, but quercetin and resveratrol act by reducing oxidative stress independently of Nrf2-ARE induction. Quercetin and resveratrol also reduced Fe2+ concentrations in HT22 cells and in cell-free reactions. Thus, quercetin and resveratrol likely protect against erastin- and RSL3-induced ferroptosis by inhibiting the iron-catalyzed generation of hydroxyl radicals. Unlike quercetin, resveratrol cannot form a chelate structure with Fe2+ but the density functional theory computation demonstrates that resveratrol can form stable monodentate complexes with the alkene moiety and the electron-rich A ring.

One-Pot O2-Oxidation and the Horner-Wadsworth-Emmons Reaction of Primary Alcohols for the Synthesis of (Z)-α,ß-Unsaturated Esters.

We developed one-pot oxidation/olefination procedures of primary alcohols giving Z-α,ß-unsaturated esters 3. TEMPO-(CuCl or CuBr2)-(2,2'-bipyridine) (1:1:1) catalyzed O2 oxidation of primary alcohols in the presence of Z-selective Horner-Wadsworth-Emmons reagent 1b and K3PO4 or NaH gave 3 with Z/E = 84:16 to 96:4 in high yields. A stepwise reaction was also developed. After TEMPO-CuBr2-(2,2'-bipyridine)-K3PO4 (1:1:1:1) catalyzed O2 oxidation of alcohols in MeCN, the resulting mixture was treated with a THF solution of 1b and t-BuOK at -78 °C to 0 °C, giving 3 with higher selectivity (Z/E = 91:9 to 99:1).

Synthesis of Truncated Carbocyclic Nucleosides Using 5'-Deoxy-5'-Heteroarylsulfonylnucleosides.

This article describes the detailed protocol for the synthesis of "truncated" carbocyclic nucleosides with a cyclopentene core and without a 4'-hydroxymethyl group. The synthesis was performed using 5'-deoxy-5'-heteroarylsulfonylnucleosides, which were prepared by the 5'-O-mesylation of the appropriately protected nucleosides, followed by a nucleophilic substitution with heteroarylthiols and the oxidation of the resulting 5'-S-heteroaryl-5'-thionucleosides. The treatment of the 5'-deoxy-5'-heteroarylsulfonylnucleosides with 1,8-diazabicyclo[5.4.0]undec-7-ene affords the truncated carbocyclic nucleosides, presumably via a domino reaction involving the α-deprotonation of the heteroarylsulfone, elimination of the nucleobase, formation of an α,ß-unsaturated sulfone, Michael addition of the nucleobase to the α,ß-unsaturated sulfone, and an intramolecular Julia-Kocienski reaction. This protocol would be useful for the short-step synthesis of biologically active carbocyclic nucleosides. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Preparation of 5'-deoxy-5'-heteroarylsulfonylnucleosides Basic Protocol 2: Synthesis of truncated carbocyclic nucleosides.

Diastereoselective Addition of Prochiral Nucleophilic Alkenes to α-Chiral N-Sulfonyl Imines.

The Lewis-acid-promoted addition of prochiral E- and Z-allyl nucleophiles to chiral α-alkoxy N-tosyl imines is described. Alkene geometry is selectively transferred to the newly formed carbon-carbon bond, resulting in stereochemical control of C1, C2, and C3 of the resulting 2-alkoxy-3-N-tosyl-4-alkyl-5-hexene products. A computational analysis to elucidate the high selectivity is also presented. This methodology was employed in the synthesis of two naturally occurring isomers of clausenamide.

Synthesis of xanthosine 2-phosphate diesters via phosphitylation of the carbonyl group.

O2-Phosphodiesterification of xanthosine has been achieved by a one-pot procedure consisting of the phosphitylation of the 2-carbonyl group of appropriately protected xanthosine derivatives using phosphoramidites and N-(cyanomethyl)dimethylammonium triflate (CMMT), oxidation of the resulting xanthosine 2-phosphite triesters, and deprotection. In addition, a study on the hydrolytic stability of a fully deprotected xanthosine 2-phosphate diester has revealed that it is more stable at higher pH.

Serendipitous One-Step Synthesis of Cyclopentene Derivatives from 5'-Deoxy-5'-heteroarylsulfonylnucleosides as Nucleoside-Derived Julia-Kocienski Reagents.

A serendipitous one-step transformation of 5'-deoxy-5'-heteroarylsulfonylnucleosides into cyclopentene derivatives is reported. This unique transformation likely proceeds via a domino reaction initiated by α-deprotonation of the heteroaryl sulfone and subsequent elimination reaction to generate a nucleobase and an α,ß-unsaturated sulfone that contains a formyl group. The Michael addition of the nucleobase to the α,ß-unsaturated sulfone and the subsequent intramolecular Julia-Kocienski reaction eventually generate the cyclopentene ring. Heteroarylthio and acylthio groups can be incorporated into the cyclopentene core in place of the nucleobase by conducting this reaction in the presence of a heteroarylthiol and a thiocarboxylic acid, respectively. cis,cis-Trisubstituted cyclopentene derivatives are obtained as a single stereoisomer from ribonucleoside-derived Julia-Kocienski sulfones.

Stereoselective Installation of Five Contiguous Stereogenic Centers in a Double Aldol-Tishchenko Cascade and Evaluation of the Key Transition State through DFT Calculation.

The stereoselective formation of 5 contiguous chiral centers in a single pot reaction is demonstrated using an aldol, aldol-Tishchenko reaction of N-tert-butyl sulfinimines. One diastereoisomer (from 32 possibilities) predominates, and a series of cyclic and acyclic 3-amino-1,5-diol derivatives are synthesized in good yields (up to 80%) and excellent diastereoselectivities (up to >98:2 dr). Investigations support two reversible aldol steps, and multiple intermediates which are funnelled through a remarkably selective, irreversible, Tishchenko reduction, in a Curtin-Hammett phenomenon. DFT calculations using a disolvated (THF) model reveal the factors controlling stereoselectivity in the final irreversible Tishchenko step.

Odontogenic keratocysts are an important clue for diagnosing basal cell nevus syndrome.

Basal cell nevus syndrome (BCNS) is an autosomal dominant skin disorder characterized by multiple basal cell nevi. Patients with BCNS tend to develop basal cell carcinoma (BCC) and frequently show skeletal abnormalities. Most cases of BCNS are caused by mutations in patched 1 (PTCH1). PTCH1 encodes a transmembrane receptor protein for the secreted molecule sonic hedgehog, which plays a key role in the development of animals ranging from insects to mammals. We analyzed two Japanese BCNS patients from two independent families. Both of our patients had multiple jaw keratocysts. In one patient, these were the key to noticing his BCNS, as he had no skin tumors. The early detection of PTCH1 mutations would enable BCNS patients to be carefully followed up for the occurrence of BCC. The diagnosis of BCC at the early stage leads to prompt surgical treatments, resulting in a good prognosis. The present cases suggest that keratocysts of the jaw might be an important clue for diagnosing BCNS.

One-Pot Preparation of (E)-α,ß-Unsaturated Aldehydes by a Julia-Kocienski Reaction of 2,2-Dimethoxyethyl PT Sulfone Followed by Acid Hydrolysis.

(E)-α,ß-Unsaturated aldehydes were synthesized by the Julia-Kocienski reaction of 2,2-dimethoxyethyl 1-phenyl-1H-tetrazol-5-yl (PT) sulfone 3 with various aldehydes, followed by acid hydrolysis. The reaction could be carried out in one pot, and various (E)-α,ß-unsaturated aldehydes were obtained in a short time and with high yields.

Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines.

Density functional theory computations have elucidated the mechanism and origins of stereoselectivity in McGlacken's aldol-Tishchenko reaction for the diastereoselective synthesis of 1,3-amino alcohols using Ellman's t-butylsulfinimines as chiral auxiliaries. Variations of stereochemical outcome are dependent on the nature of the ketone starting materials used, and the aspects leading to these differences have been rationalized. The intramolecular hydride transfer step is the rate- and stereochemistry-determining step, and all prior steps are reversible.

Genetic characterization of melon accessions in the U.S. National Plant Germplasm System and construction of a melon core collection.

Melon (C. melo L.) is an economically important vegetable crop cultivated worldwide. The melon collection in the U.S. National Plant Germplasm System (NPGS) is a valuable resource to conserve natural genetic diversity and provide novel traits for melon breeding. Here we use the genotyping-by-sequencing (GBS) technology to characterize 2083 melon accessions in the NPGS collected from major melon production areas as well as regions where primitive melons exist. Population structure and genetic diversity analyses suggested that C. melo ssp. melo was firstly introduced from the centers of origin, Indian and Pakistan, to Central and West Asia, and then brought to Europe and Americas. C. melo ssp. melo from East Asia was likely derived from C. melo ssp. agrestis in India and Pakistan and displayed a distinct genetic background compared to the rest of ssp. melo accessions from other geographic regions. We developed a core collection of 383 accessions capturing more than 98% of genetic variation in the germplasm, providing a publicly accessible collection for future research and genomics-assisted breeding of melon. Thirty-five morphological characters investigated in the core collection indicated high variability of these characters across accessions in the collection. Genome-wide association studies using the core collection panel identified potentially associated genome regions related to fruit quality and other horticultural traits. This study provides insights into melon origin and domestication, and the constructed core collection and identified genome loci potentially associated with important traits provide valuable resources for future melon research and breeding.

Stereoselective Synthesis of Ribofuranoid exo-Glycals by One-Pot Julia Olefination Using Ribofuranosyl Sulfones.

One-pot Julia olefination using ribofuranosyl sulfones is described. The α-anomers of the ribofuranosyl sulfones were synthesized with complete α-selectivity via the glycosylation of heteroarylthiols using ribofuranosyl iodides as glycosyl donors and the subsequent oxidation of the resulting heteroaryl 1-thioribofuranosides with magnesium monoperphthalate (MMPP). The Julia olefination of the α-ribofuranosyl sulfones with aldehydes proceeded smoothly in one pot to afford the thermodynamically less stable (E)-exo-glycals with modest-to-excellent stereoselectivity (up to E/Z = 94:6) under the optimized conditions. The E selectivity was especially high for aromatic aldehydes. In contrast, the (Z)-exo-glycal was obtained as the main product with low stereoselectivity when the corresponding ß-ribofuranosyl sulfone was used (E/Z = 41:59). The remarkable impact of the anomeric configuration of the ribofuranosyl sulfones on the stereoselectivity of the Julia olefination has been rationalized using density functional theory (DFT) calculations. The protected ribose moiety of the resulting exo-glycals induced completely α-selective cyclopropanation on the exocyclic carbon-carbon double bond via the Simmons-Smith-Furukawa reaction. The 2-cyanoethyl group was found to be useful for the protection of the exo-glycals, as it could be removed without affecting the exocyclic C═C bond.

Stereoselective Synthesis of Trisubstituted (Z)-Alkenes from Ketones via the Julia-Kocienski Olefination Using 1-Methyl- and 1-tert-Butyl-1H-tetrazol-5-yl Alkyl Sulfones.

1-Methyl-1H-tetrazol-5-yl (MT) alkyl sulfones 1b, 3b, and 7b react with various unsymmetrical ketones in the presence of LiHMDS in THF at low temperature to give trisubstituted (Z)-alkenes in good yields stereoselectively (Z/E = 91:9 to 99:1). For sterically less demanding ketones, olefination using t-Bu reagents 1d and 3d generated (Z)-alkenes with higher stereoselectivity (93:7-99:1).

Methylenation for Aldehydes and Ketones Using 1-Methylbenzimidazol-2-yl Methyl Sulfone.

The methylenation reagent 1-methylbenzimidazol-2-yl methyl sulfone 2 reacts with various aldehydes and ketones in the presence of t-BuOK (room temperature, 1 h) in dimethylformamide to give the corresponding terminal alkenes generally in high yields. For sensitive substrates, the reaction is better carried out at low temperature using sodium hexamethyldisilazide in 1,2-dimethoxyethane. The byproduct is easily removed from the products, and the reaction conditions are mild and practical. Reagent 2 can be easily prepared from commercially available 2-mercaptobenzimidazole 5 in 95% yield without any expensive reagents.

Identification of a radical SAM enzyme involved in the synthesis of archaeosine.

Archaeosine (G+), 7-formamidino-7-deazaguanosine, is an archaea-specific modified nucleoside found at the 15th position of tRNAs. In Euryarchaeota, 7-cyano-7-deazaguanine (preQ0)-containing tRNA (q0N-tRNA), synthesized by archaeal tRNA-guanine transglycosylase (ArcTGT), has been believed to be converted to G+-containing tRNA (G+-tRNA) by the paralog of ArcTGT, ArcS. However, we found that several euryarchaeal ArcSs have lysine transfer activity to q0N-tRNA to form q0kN-tRNA, which has a preQ0 lysine adduct as a base. Through comparative genomics and biochemical experiments, we found that ArcS forms a robust complex with a radical S-adenosylmethionine (SAM) enzyme named RaSEA. The ArcS-RaSEA complex anaerobically converted q0N-tRNA to G+-tRNA in the presence of SAM and lysine via q0kN-tRNA. We propose that ArcS and RaSEA should be considered an archaeosine synthase α-subunit (lysine transferase) and ß-subunit (q0kN-tRNA lyase), respectively.

Introgression of a Novel Ug99-Effective Stem Rust Resistance Gene into Wheat and Development of Dasypyrum villosum Chromosome-Specific Markers via Genotyping-by-Sequencing (GBS).

Dasypyrum villosum is a wild relative of common wheat (Triticum aestivum L.) with resistance to Puccinia graminis f. tritici, the causal agent of stem rust, including the highly virulent race TTKSK (Ug99). In order to transfer resistance, T. durum-D. villosum amphiploids were initially developed and used as a bridge to create wheat-D. villosum introgression lines. Conserved ortholog set (COS) markers were used to identify D. villosum chromosome introgression lines, which were then subjected to seedling P. graminis f. tritici resistance screening with race TTKSK. A COS marker-verified line carrying chromosome 2V with TTKSK resistance was further characterized by combined genomic in situ and fluorescent in situ analyses to confirm a monosomic substitution line MS2V(2D) (20″ + 1' 2V[2D]). This is the first report of stem rust resistance on 2V, which was temporarily designated as SrTA10276-2V. To facilitate the use of this gene in wheat improvement, a complete set of previously developed wheat-D. villosum disomic addition lines was subjected to genotyping-by-sequencing analysis to develop D. villosum chromosome-specific markers. On average, 350 markers per chromosome were identified. These markers can be used to develop diagnostic markers for D. villosum-derived genes of interest in wheat improvement.