Formal Synthesis of Ecteinascidin 743 via an Intramolecular Cascade Heck Reaction to Construct the Diazabicyclo[3.3.1]nonane Framework

A synthetic route to ecteinascidin 743 has been established via an intramolecular cascade Heck reaction to construct the diazabicyclo[3.3.1]nonane skeleton while controlling the two contiguous stereogenic centers. The strategically formed five-membered ring was oxidatively cleaved to generate a dialdehyde intermediate, from which the B ring of ecteinascidin 743 was constructed.

Synthetic Approach toward (–)-Tetrodotoxin via Construction of the Bicyclo[2.2.2]octane Skeleton

A synthetic approach toward (–)-tetrodotoxin (TTX) is described. Our approach features a stereoselective construction of the TTX core structure using the bicyclo[2.2.2]octane skeleton which was constructed via intramolecular Diels–Alder reaction of an o-quinone monoketal having the key functional groups. The robust asymmetric synthesis was achieved by an iridium-catalyzed dynamic kinetic resolution (DKR) of the aryl vinyl carbinol that could be easily prepared from a simple aromatic compound.

Total Synthesis of Haliclonin A

The total synthesis of haliclonin A was accomplished. Starting from 3,5-dimethoxybenzoic acid, a functionalized cyclohexanone fused to a 17-membered ring was prepared through a Birch reduction/alkylation sequence, ring-closing metathesis, intramolecular cyclopropanation, and stereoselective 1,4-addition of an organocopper reagent to an enone moiety. Reductive C-N bond formation via an N,O-acetal forged the 3-azabicyclo[3.3.1]nonane core. The allyl alcohol moiety was constructed by a sequence involving stereoselective α-selenylation of an aldehyde via an enamine, syn-elimination of a selenoxide, and allylation of the aldehyde with an allylboronate. Formation of the 15-membered ring containing a skipped diene was achieved by ring-closing metathesis, and final transformations led to the synthesis of haliclonin A.

Photo-oxygenation by a biocompatible catalyst reduces amyloid-β levels in Alzheimer's disease mice

Amyloid formation and the deposition of the amyloid-β peptide are hallmarks of Alzheimer's disease pathogenesis. Immunotherapies using anti-amyloid-β antibodies have been highlighted as a promising approach for the prevention and treatment of Alzheimer's disease by enhancing microglial clearance of amyloid-β peptide. However, the efficiency of antibody delivery into the brain is limited, and therefore an alternative strategy to facilitate the clearance of brain amyloid is needed. We previously developed an artificial photo-oxygenation system using a low molecular weight catalytic compound. The photocatalyst specifically attached oxygen atoms to amyloids upon irradiation with light, and successfully reduced the neurotoxicity of aggregated amyloid-β via inhibition of amyloid formation. However, the therapeutic effect and mode of actions of the photo-oxygenation system in vivo remained unclear. In this study, we demonstrate that photo-oxygenation facilitates the clearance of aggregated amyloid-β from the brains of living Alzheimer's disease model mice, and enhances the microglial degradation of amyloid-β peptide. These results suggest that photo-oxygenation may represent a novel anti-amyloid-β strategy in Alzheimer's disease, which is compatible with immunotherapy.

A novel translation inhibitor, mersicarpine, inhibits S-phase progression and induces apoptosis in HL60 cells

Mersicarpine is an aspidosperma alkaloid isolated from the Kopsia genus of plants. Its intriguing structural features have attracted much attention in synthetic organic chemistry, but no biological activity has been reported. Here, we report the effects of mersicarpine on human leukemia cell line HL60. At concentrations above 30 µm, mersicarpine reversibly arrested cell cycle progression in S-phase. At higher concentrations, it induced not only production of reactive oxygen species, but also apoptosis. Macromolecular synthesis assay revealed that mersicarpine specifically inhibits protein synthesis. These results suggest that mersicarpine is a novel translation inhibitor that induces apoptosis.

Total Synthesis of Lycoposerramine-R

A total synthesis of lycoposerramine-R was accomplished. The synthesis featured a Claisen–Ireland rearrangement to install a two-carbon unit, and a hetero-Diels–Alder reaction to form a cyclic enol ether that reacted with an ethynyl group to construct a cis-hydrindane core containing a quaternary carbon. A 2-pyridone synthesis using 2-(phenylsulfinyl)acetamide was used to complete the synthesis.

Synthesis of Cardiopetaline via a Wagner-Meerwein Rearrangement without Preactivation of the Pivotal Hydroxy Group

A synthesis of cardiopetaline has been accomplished via a Wagner-Meerwein rearrangement of a diol having the denudatine skeleton. The Wagner-Meerwein rearrangement could be facilitated simply by heating the diol with p-toluenesulfonic acid in pivalic acid, without preactivating the pivotal hydroxy group. This strategy does not require differentiation of several hydroxy groups in the substrate for the Wagner-Meerwein rearrangement and could be applied to the synthesis of more highly oxygenated aconitine-type diterpenoid alkaloids.

Synthetic Studies of Haliclonin A: Construction of the 3-Azabicyclo[3.3.1]nonane Skeleton with a Bridge that Forms the 17-Membered Ring

The core structure of haliclonin A, a 3-azabicyclo[3.3.1]­nonane with a bridge that forms a 17-membered ring, was constructed. The synthesis features a ring-closing metathesis that constructs the macrocyclic ring, the stereoselective introduction of carbon units via the intra­molecular cyclopropanation of a diazoester, the conjugate addition of an organocopper reagent, and the formation of 3-azabi­cyclo­[3.3.1]­nonane skeleton via an unexpected 1,5-hydride shift.

Synthesis of the [7-5-5] tricyclic core of Daphniphyllum alkaloids

The [7-5-5] tricyclic core of the Daphniphyllum alkaloids was constructed, featuring a Claisen-Ireland rearrangement to install the two contiguous stereogenic centers, E1cB elimination to form the tetrasubstituted C–C double bond, and a 2,3-Wittig rearrangement to construct the quaternary carbon.

High expression of ABCG2 induced by EZH2 disruption has pivotal roles in MDS pathogenesis

Both proto-oncogenic and tumor-suppressive functions have been reported for enhancer of zeste homolog 2 (EZH2). To investigate the effects of its inactivation, a mutant EZH2 lacking its catalytic domain was prepared (EZH2-dSET). In a mouse bone marrow transplant model, EZH2-dSET expression in bone marrow cells induced a myelodysplastic syndrome (MDS)-like disease in transplanted mice. Analysis of these mice identified Abcg2 as a direct target of EZH2. Intriguingly, Abcg2 expression alone induced the same disease in the transplanted mice, where stemness genes were enriched. Interestingly, ABCG2 expression is specifically high in MDS patients. The present results indicate that ABCG2 de-repression induced by EZH2 mutations have crucial roles in MDS pathogenesis.

Total Synthesis of Huperzine Q

The total synthesis of huperzine Q was accomplished. The synthesis features the construction of the cis-hydrindane skeleton via a Diels-Alder reaction and a ring contraction reaction of an epoxyketone.

Enantioselective Total Synthesis of (+)-Hinckdentine A via a Catalytic Dearomatization Approach

Optically pure hinckdentine A was synthesized on a 300 mg scale via an asymmetric catalysis-based strategy. The key steps to the first asymmetric synthesis involved (i) enantioselective dearomative cyclization of an achiral N-acyl indole that allowed for the efficient construction of the key polycyclic indoline intermediate with a crucial tetrasubstituted stereogenic carbon center, (ii) Beckmann fragmentation-mediated ring expansion, (iii) rearrangement-based introduction of an anilinic nitrogen atom, (iv) regioselective tribromination, and (v) final closure of the cyclic amidine moiety.

Eudistomin C, an Antitumor and Antiviral Natural Product, Targets 40S Ribosome and Inhibits Protein Translation

Eudistomin C (EudiC), a natural product, shows potent antitumor and antiviral activities, but the target molecule and the mechanism of action remain to be revealed. Here, we show that the 40S ribosome is the target in EudiC cytotoxicity. We isolated EudiC-resistant mutants from a multidrug-sensitive yeast strain, and a genetic analysis classified these YER (yeast EudiC resistance) mutants into three complementation groups. A genome-wide study revealed that the YER1-6 mutation is in the uS11 gene (RPS14A). Biotinylated EudiC pulled down Rps14p-containing complexes from 40S and 80S ribosomes, but not from the 60S ribosome. EudiC strongly inhibited translation of the wild-type strain but not of YER1-6 in cells and in vitro. These results indicate that EudiC is a protein synthesis inhibitor targeting the uS11-containing ribosomal subunit, and shows cytotoxicity by inhibiting protein translation.

Morphological Evaluation of Nonlabeled Cells to Detect Stimulation of Nerve Growth Factor Expression by Lyconadin B

The success of drug development is greatly influenced by the efficiency of drug screening methods. Recently, phenotype-based screens have raised expectations, based on their proven record of identifying first-in-class drugs at a higher rate. Although fluorescence images are the data most commonly used in phenotype-based cell-based assays, nonstained cellular images have the potential to provide new descriptive information about cellular responses. In this study, we applied morphology-based evaluation of nonlabeled microscopic images to a phenotype-based assay. As a study case, we attempted to increase the efficiency of a cell-based assay for chemical compounds that induce production of nerve growth factor (NGF), using lyconadin B as a model compound. Because the total synthesis of lyconadin B was accomplished very recently, there is no well-established cell-based assay scheme for further drug screening. The conventional cell-based assay for evaluating NGF induction requires two types of cells and a total of 5 days of cell culture. The complexity and length of this assay increase both the risk of screening errors and the cost of screening. Our findings show that analysis of cellular morphology enables evaluation of NGF induction by lyconadin B within only 9 h.

BIN1 regulates BACE1 intracellular trafficking and amyloid-β production

BIN1 is a genetic risk factor of late-onset Alzheimer disease (AD), which was identified in multiple genome-wide association studies. BIN1 is a member of the amphiphysin family of proteins, and contains N-terminal Bin-Amphiphysin-Rvs and C-terminal Src homology 3 domains. BIN1 is widely expressed in the mouse and human brains, and has been reported to function in the endocytosis and the endosomal sorting of membrane proteins. BACE1 is a type 1 transmembrane aspartyl protease expressed predominantly in neurons of the brain and responsible for the production of amyloid-β peptide (Aβ). Here we report that the depletion of BIN1 increases cellular BACE1 levels through impaired endosomal trafficking and reduces BACE1 lysosomal degradation, resulting in increased Aβ production. Our findings provide a mechanistic role of BIN1 in the pathogenesis of AD as a novel genetic regulator of BACE1 levels and Aβ production.

Total Synthesis of (-)-Cardiopetaline

The total synthesis of (-)-cardiopetaline, an aconitine-type natural product, has been accomplished. Our synthesis involved a Wagner-Meerwein rearrangement of a sulfonyloxirane that enabled, in a single step, the construction of the bicyclo[3.2.1] system in the aconitine skeleton and effective introduction of oxygen functional groups at the appropriate positions.

Total Synthesis of Lycopalhine A

The total synthesis of lycopalhine A has been accomplished. The synthesis features construction of the tricyclic system via cleavage of a cyclopropane ring and an ensuing intramolecular Michael addition, stereoselective introduction of a 2-aminoethyl moiety via a reaction of allyltrimethylsilane to a sulfonyliminium ion, and a stereoselective intramolecular aldol reaction.

Prospective and clinical validation of ALK immunohistochemistry: results from the phase I/II study of alectinib for ALK-positive lung cancer (AF-001JP study)

BACKGROUND

Anaplastic lymphoma kinase (ALK) fusions need to be accurately and efficiently detected for ALK inhibitor therapy. Fluorescence in situ hybridization (FISH) remains the reference test. Although increasing data are supporting that ALK immunohistochemistry (IHC) is highly concordant with FISH, IHC screening needed to be clinically and prospectively validated.

PATIENTS AND METHODS

In the AF-001JP trial for alectinib, 436 patients were screened for ALK fusions through IHC (n = 384) confirmed with FISH (n = 181), multiplex RT-PCR (n = 68), or both (n = 16). IHC results were scored with iScore.

RESULT

ALK fusion was positive in 137 patients and negative in 250 patients. Since the presence of cancer cells in the samples for RT-PCR was not confirmed, ALK fusion negativity could not be ascertained in 49 patients. IHC interpreted with iScore showed a 99.4% (173/174) concordance with FISH. All 41 patients who had iScore 3 and were enrolled in phase II showed at least 30% tumor reduction with 92.7% overall response rate. Two IHC-positive patients with an atypical FISH pattern responded to ALK inhibitor therapy. The reduction rate was not correlated with IHC staining intensity.

CONCLUSIONS

Our study showed (i) that when sufficiently sensitive and appropriately interpreted, IHC can be a stand-alone diagnostic for ALK inhibitor therapies; (ii) that when atypical FISH patterns are accompanied by IHC positivity, the patients should be considered as candidates for ALK inhibitor therapies, and (iii) that the expression level of ALK fusion is not related to the level of response to ALK inhibitors and is thus not required for patient selection.

REGISTRATION NUMBER

JapicCTI-101264 (This study is registered with the Japan Pharmaceutical Information Center).

Synthesis of the Common Core Structure of the Stemofoline Alkaloids

A novel synthetic route to the common core structural motif of the stemofoline alkaloids has been developed. The key transformations include (1) an intramolecular 1,3-dipolar cycloaddition reaction of a highly functionalized nitrone, (2) the subsequent formation of a caged structure via lithiated allylic sulfoxide, and (3) the concomitant sila-Pummerer reaction of α-silylalkenyl sulfoxide to prepare a thioester precursor. A series of stereochemistries on the highly caged core structure characteristic of the stemofoline alkaloids was successfully assembled.