Pien Tze Huang (PZH), a common hepatoprotective Traditional Chinese Medicine that has been found to be an effective treatment for carbon tetrachloride‑induced hepatic damage, including liver fibrosis. Circular RNAs (circRNAs) serve a crucial role in regulating gene expression levels via circRNA/micro (mi)RNA/mRNA networks in several human diseases and biological processes. However, whether circRNAs are involved in the underlying mechanism of the therapeutic effects of PZH on liver fibrosis remains unclear.
View Article and Find Full Text PDFThis article describes the full details of our synthetic efforts toward the enantioselective total synthesis of the complex alkaloid methoxystemofoline. The enantioselective construction of the tetracyclic core features: (1) the Keck allylation at the -α bridgehead carbon to forge the tetrasubstituted stereocenter; (2) an olefin cross-metathesis reaction for the side-chain elongation that is amenable for the synthesis of congeners and analogues; and (3) a regioselective aldol addition reaction with methyl pyruvate that ensured the subsequent regioselective cyclization reaction to construct the fourth ring. Overman's method was employed to install the 5-(alkoxyalky1idene)-3-methyl-tetronate moiety.
View Article and Find Full Text PDFThe powerful insecticidal and multi-drug-resistance-reversing activities displayed by the stemofoline group of alkaloids render them promising lead structures for further development as commercial agents in agriculture and medicine. However, concise, enantioselective total syntheses of stemofoline alkaloids remain a formidable challenge due to their structural complexity. We disclose herein the enantioselective total syntheses of four stemofoline alkaloids, including (+)-stemofoline, (+)-isostemofoline, (+)-stemoburkilline, and (+)-(11S,12R)-dihydrostemofoline, in just 19 steps.
View Article and Find Full Text PDFThe annotation of six cluster N phages (Kevin1, Nenae, Parmesanjohn, ShrimpFriedEgg, Smurph, and SpongeBob) reveals regions of genomic diversity, particularly within the central region of the genome. The genome of Kevin1 includes two orphams (genes with no similarity to other phage genes), with one predicted to encode an AAA-ATPase.
View Article and Find Full Text PDFWe present here the first example of C(sp)-H activation directed by a sulfur atom. Based on this transformation catalyzed by Ru/C, we have developed a hydrogen isotope exchange reaction for the deuterium and tritium labelling of thioether substructures in complex molecules.
View Article and Find Full Text PDFThis work describes the first thermally activated delayed fluorescence material enabling circularly polarized light emission through chiral perturbation. These new molecular architectures obtained through a scalable one-pot sequential synthetic procedure at room temperature (83% yield) display high quantum yield (up to 74%) and circularly polarized luminescence with an absolute luminescence dissymmetry factor, |glum|, of 1.3 × 10(-3).
View Article and Find Full Text PDFThe first enantioselective total synthesis of (+)-methoxystemofoline (2) and (+)-isomethoxystemofoline (3) has been reported. The synthesis employed the halide-assisted bromotropanonation method that we developed recently to construct the core structure, and Overman's strategy for the implementation of the butenolide moiety. Through this work, the structure of methoxystemofoline was revised as with an E-alkene, and its absolute configuration was established.
View Article and Find Full Text PDFThe halo-assisted intramolecular addition of silyl enol ethers with in situ activated lactams yielded (hydroxylated) 1-halo-8-azabicyclo[3,2,1]octane and 1-halo-9-azabicyclo[3,3,1]nonane ring systems, which provided an easy enantioselective access to 6β-silyloxytropane-3-one, 3α,6β-dihydroxytropane, and pervilleine B. The absolute configuration of the natural (-)-pervilleine B was determined to be 1R,3R,5S,6R.
View Article and Find Full Text PDFThree keys to success: A concise method for the construction of a tricyclic substructure (2) of haliclonin A (1) in racemic form is described (see figure). This synthesis features a new Pd-mediated chemoselective carbonyl-enone coupling reaction, an organocatalytic reaction, and a ring-closing metathesis reaction for the construction of the macrocyclic ring as key steps.
View Article and Find Full Text PDF