Importance of a Fluorine Substituent for the Preparation of meta- and para-Pentafluoro-λ(6) -sulfanyl-Substituted Pyridines.

Although there are ways to synthesize ortho-pentafluoro-λ(6) -sulfanyl (SF5 ) pyridines, meta- and para-SF5 -substituted pyridines are rare. We disclose herein a general route for their synthesis. The fundamental synthetic approach is the same as reported methods for ortho-SF5 -substituted pyridines and SF5 -substituted arenes, that is, oxidative chlorotetrafluorination of the corresponding disulfides to give pyridylsulfur chlorotetrafluorides (SF4 Cl-pyridines), followed by chloride/fluoride exchange with fluorides. However, the trick in this case is the presence on the pyridine ring of at least one fluorine atom, which is essential for the successful transformation of the disulfides into m-and p-SF5 -pyridines. After enabling the synthesis of an SF5 -substituted pyridine, ortho-F groups can be efficiently substituted by C, N, S, and O nucleophiles through an SN Ar pathway. This methodology provides access to a variety of previously unavailable SF5 -substituted pyridine building blocks.

Recharacterization of RSL3 reveals that the selenoproteome is a druggable target in colorectal cancer.

Ferroptosis is a non-apoptotic form of cell death resulting from the iron-dependent accumulation of lipid peroxides. Colorectal cancer (CRC) cells accumulate high levels of intracellular iron and reactive oxygen species (ROS) and are thus particularly sensitive to ferroptosis. The compound (S)-RSL3 ([1S,3R]-RSL3) is a commonly used ferroptosis inducing compound that is currently characterized as a selective inhibitor of the selenocysteine containing enzyme (selenoprotein) Gluathione Peroxidase 4 (GPx4), an enzyme that utilizes glutathione to directly detoxify lipid peroxides. However, through chemical controls utilizing the (R) stereoisomer of RSL3 ([1R,3R]-RSL3) that does not bind GPx4, combined with inducible genetic knockdowns of GPx4 in CRC cell lines, we revealed that GPx4 dependency does not always align with (S)-RSL3 sensitivity, questioning the current characterization of GPx4 as the central regulator of ferroptosis. Utilizing affinity pull-down mass spectrometry with chemically modified (S)-RSL3 probes we discovered that the effects of (S)-RSL3 extend far beyond GPx4 inhibition, revealing that (S)-RSL3 is a broad and non-selective inhibitor of selenoproteins. To further investigate the therapeutic potential of broadly disrupting the selenoproteome as a therapeutic strategy in CRC, we employed additional chemical and genetic approaches. We found that the selenoprotein inhibitor auranofin, an FDA approved gold-salt, chemically induced oxidative cell death and ferroptosis in both in-vitro and in-vivo models of CRC. Consistent with these data, we found that AlkBH8, a tRNA-selenocysteine methyltransferase required for the translation of selenoproteins, is essential for the in-vitro growth and xenograft survival of CRC cell lines. In summary, these findings recharacterize the mechanism of action of the most commonly used ferroptosis inducing molecule, (S)-RSL3, and reveal that broad inhibition of selenoproteins is a promising novel therapeutic angle for the treatment of CRC.

Pictet-Spengler condensations using 4-(2-aminoethyl)coumarins.

Androgen-deprivation therapy (ADT) is only a palliative measure, and prostate cancer invariably recurs in a lethal, castration-resistant form (CRPC). Prostate cancer resists ADT by metabolizing weak, adrenal androgens to growth-promoting 5α-dihydrotestosterone (DHT), the preferred ligand for the androgen receptor (AR). Developing small-molecule inhibitors for the final steps in androgen metabolic pathways that utilize 17-oxidoreductases required probes that possess fluorescent groups at C-3 and intact, naturally occurring functionality at C-17. Application of the Pictet-Spengler condensation to substituted 4-(2-aminoethyl)coumarins and 5α-androstane-3-ones furnished spirocyclic, fluorescent androgens at the desired C-3 position. Condensations required the presence of activating C-7 amino or N,N-dialkylamino groups in the 4-(2-aminoethyl)coumarin component of these condensation reactions. Successful Pictet-Spengler condensation, for example, of DHT with 9-(2-aminoethyl)-2,3,6,7-tetrahydro-1H,5H,11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one led to a spirocyclic androgen, (3R,5S,10S,13S,17S)-17-hydroxy-10,13-dimethyl-1,2,2',3',4,5,6,7,8,8',9,9',10,11,12,12',13,13',14,15,16,17-docosahydro-7'H,11'H-spiro-[cyclopenta[a]phenanthrene-3,4'-pyrido[3,2,1-ij]pyrido[4',3':4,5]pyrano[2,3-f]quinolin]-5'(1'H)-one. Computational modeling supported the surrogacy of the C-3 fluorescent DHT analog as a tool to study 17-oxidoreductases for intracrine, androgen metabolism.

Effect of the o-Acetamido Group on pH-Dependent Light Emission of a 3-Hydroxyphenyl-Substituted Dioxetane Luminophore.

A pioneering chemiluminescent molecule reported by Schaap and co-workers, 3-(2'-spiroadamantane)-4-methoxy-4-(3″-hydroxy)phenyl-1,2-dioxetane (AMPD), does not require enzymatic activation but is unsuitable for use under physiological conditions. To overcome this limitation, we have developed a new AMPD derivative that contains an acetamido group at the ortho position of the hydroxy group as an intramolecular hydrogen-bonding site in order to lower the p Ka value. This compound exhibits a superior chemiluminescence response to AMPD in the physiologically relevant pH range.

A small-molecule inhibitor of SOD1-Derlin-1 interaction ameliorates pathology in an ALS mouse model.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder. Despite its severity, there are no effective treatments because of the complexity of its pathogenesis. As one of the underlying mechanisms of Cu, Zn superoxide dismutase (SOD1) gene mutation-induced ALS, SOD1 mutants (SOD1mut) commonly interact with an endoplasmic reticulum-resident membrane protein Derlin-1, triggering motoneuron death. However, the importance of SOD1-Derlin-1 interaction in in vitro human model and in vivo mouse model remains to be elucidated. Here, we identify small-molecular-weight compounds that inhibit the SOD1-Derlin-1 interaction by screening approximately 160,000 compounds. The inhibitor prevents 122 types of SOD1mut from interacting with Derlin-1, and significantly ameliorates the ALS pathology both in motoneurons derived from patient induced pluripotent stem cells and in model mice. Our data suggest that the SOD1-Derlin-1 interaction contributes to the pathogenesis of ALS and is a promising drug target for ALS treatment.

2',6'-Dihalostyrylanilines, pyridines, and pyrimidines for the inhibition of the catalytic subunit of methionine S-adenosyltransferase-2.

Inhibition of the catalytic subunit of the heterodimeric methionine S-adenosyl transferase-2 (MAT2A) with fluorinated N,N-dialkylaminostilbenes (FIDAS agents) offers a potential avenue for the treatment of liver and colorectal cancers where upregulation of this enzyme occurs. A study of structure-activity relationships led to the identification of the most active compounds as those with (1) either a 2,6-difluorostyryl or 2-chloro-6-fluorostyryl subunit, (2) either an N-methylamino or N,N-dimethylamino group attached in a para orientation relative to the 2,6-dihalostyryl subunit, and (3) either an N-methylaniline or a 2-(N,N-dimethylamino)pyridine ring. These modifications led to FIDAS agents that were active in the low nanomolar range, that formed water-soluble hydrochloride salts, and that possessed the desired property of not inhibiting the human hERG potassium ion channel at concentrations at which the FIDAS agents inhibit MAT2A. The active FIDAS agents may inhibit cancer cells through alterations of methylation reactions essential for cancer cell survival and growth.