Regioselective SmI2-Mediated Radical ipso-Substitution Cyclization for the Construction of Pyrrolophenanthridinone Skeletons: The Synthesis of Amaryllidaceae Alkaloids.

Here, we report a regioselective, samarium(II) diiodide mediated intramolecular radical ipso-substitution cyclization. Through the use of a methoxy group as a leaving group, it was possible to regulate the regioselectivity of the reaction by changing the temperature and additives. We applied the developed reaction to the synthesis of four Amaryllidaceae alkaloids and have shown that the present reaction successfully overcomes regioselectivity issues encountered with other cyclization methods.

Thermoresponsive mixed polymer brush to effectively control the adhesion and separation of stem cells by altering temperature.

During the last few decades, thermoresponsive materials for modulating cell adhesion have been investigated for the application of tissue engineering. In this study, we developed thermoresponsive mixed polymer brushes consisting of poly(N-isopropylacrylamide) (PNIPAAm) and poly(N,N-dimethylaminopropylacrylamide) (PDMAPAAm). The mixed polymer brushes were prepared on a glass substrate via the reversible addition-fragmentation chain transfer polymerization of DMAPAAm and subsequent atom transfer radical polymerization of NIPAAm. The mixed polymer brushes grafted to glass exhibited increased cationic properties by increasing the grafted PDMAPAAm length. The shrinking and extension of PNIPAAm exposed and concealed PDMAPAAm, respectively, indicating that the surface cationic properties can be controlled by changing the temperature. At 37 â€‹°C, the prepared mixed polymer brushes enhanced cell adhesion through their electrostatic interactions with cells. They also exhibited various thermoresponsive adhesion and detachment properties using various types of cells, such as mesenchymal stem cells. Temperature-controlled cell adhesion and detachment behavior differed between cell types. Using the prepared mixed polymer brush, we separated MSCs from adipocytes and HeLa cells by simply changing the temperature. Thus, the thermoresponsive mixed polymer brushes may be used to separate mesenchymal stem cells from their differentiated or contaminant cells by altering the temperature.

Thiophene Carboxamide Analogs with Long Alkyl Chains Comprising Ethylene Glycol Units Inhibit Glioblastoma Cell Proliferation by Activating AMPK.

Glioblastoma is a refractory malignant tumor that requires novel therapeutic strategies for effective treatment. We have previously reported that JCI-20679 (1), an analog of annonaceous acetogenins, shows potent antitumor activity against glioblastomas. However, the synthesis of 1 requires 23 steps, including 16 steps for the preparation of a tetrahydrofuran (THF) moiety. This study reports the design and synthesis of 11 analogs with a triethylene glycol moiety in place of the THF moiety in 1. Among these, the analog 2k with an n-decyl chain exhibited potent inhibitory activity against the growth of glioblastoma stem cells by inhibiting mitochondrial function and synergistically enhancing the effect of temozolomide (TMZ). Furthermore, 2k significantly suppressed tumor growth without critical toxicity in vivo. Hence, this study presents novel potential anticancer agents and a strategy for the development of these agents that can be produced easily.

Synthesis of Acetogenin Analogs Comprising Pyrimidine Moieties Linked by Amine Bonds and Their Inhibitory Activity against Human Cancer Cell Lines.

Here, we synthesized three acetogenin analogs containing pyrimidine moieties linked by amine bonds, which represent the skeleton structure of pyrimidifen, a mitochondrial complex I-inhibiting insecticide. Replacing the pyrimidine moiety linked by the amine bond remarkably enhanced growth-inhibitory activity of the analogs against several human cancer cell lines. Moreover, these analogs selectively and potently inhibited the growth of these human cancer cell lines regardless of the pyrimidine substituents. Furthermore, COMPARE analyses suggested that these analogs inhibited cancer growth by inhibiting mitochondrial complex I. Our study provides insights into the design of acetogenin analogs as novel antitumor agents.

Thermoresponsive block copolymer brush for temperature-modulated hepatocyte separation.

Hepatic tissue engineering may be an effective approach for the treatment of liver disease; however, its practical application requires hepatic cell separation technologies that do not involve cell surface modification and maintain cell activity. In this study, we developed hepatocyte cell separation materials using a thermoresponsive polymer and a polymer with high affinity to hepatocytes. A block copolymer of poly(N-p-vinylbenzyl-O-ß-D-galactopyranosyl-(1→4)-D-gluconamide) (PVLA) and poly(N-isopropylacrylamide) (PNIPAAm) [PVLA-b-PNIPAAm] was prepared through two steps of atom transfer radical polymerization. On the prepared PVLA-b-PNIPAAm brush, HepG2 cells (model hepatocytes) adhered at 37 °C and detached at 20 °C, attributed to the temperature-modulated affinity between PVLA and HepG2. Cells from the immortalized human hepatic stellate cell line (TWNT-1) did not adhere to the copolymer brush, and RAW264.7 cells (mouse macrophage; model Kupffer cells) adhered to the copolymer brush, regardless of temperature. Using the difference in cell adhesion properties on the copolymer brush, temperature-modulated cell separation was successfully demonstrated. A mixture of HepG2, RAW264.7, and TWNT-1 cells was seeded on the copolymer brush at 37 °C for adherence. By reducing the temperature to 20 °C, adhered HepG2 cells were selectively recovered with a purity of approximately 85% and normal activity. In addition, induced pluripotent stem (iPS) cell-derived hepatocytes adhered on the PVLA-b-PNIPAAm brush at 37 °C and detached from the copolymer brush at 20 °C, whereas the undifferentiated iPS cells did not adhere, indicating that the prepared PVLA-b-PNIPAAm brush could be utilized to separate hepatocyte differentiated and undifferentiated cells. These results indicated that the newly developed PVLA-b-PNIPAAm brush can separate hepatic cells from contaminant cells by temperature modulation, without affecting cell activity or modifying the cell surface. Thus, the copolymer brush is expected to be a useful separation tool for cell therapy and tissue engineering using hepatocytes.

Structure-antitumor activity relationship of hybrid acetogenins focusing on connecting groups between heterocycles and the linker moiety.

We studied hybrid molecules of annonaceous acetogenins and mitochondrial complex I-inhibiting insecticides to develop a novel anticancer agent. A structure-antitumor activity relationship study focusing on the connecting groups between the heterocycles and the linker moiety bearing the tetrahydrofuran moiety was conducted. Eleven hybrid acetogenins with 1-methylpyrazole instead of γ-lactone were synthesized and their growth inhibitory activities against 39 human cancer cell lines were evaluated. The nitrogen atom at the 2'-position of the linker moiety was essential for inhibiting cancer growth. The 1-methylpyrazole-5-sulfonamide analog showed potent growth inhibition of NCI-H23, a human lung cancer cell line, in a xenograft mouse assay without critical toxicity. Hence, the results of this study may pave the way for the development of novel anticancer agents, with both selective and broad anticancer activities.

JCI­20679 suppresses the proliferation of glioblastoma stem cells by activating AMPK and decreasing NFATc2 expression levels.

The prognosis of glioblastoma, which is the most frequent type of adult­onset malignant brain tumor, is extremely poor. Therefore, novel therapeutic strategies are needed. Previous studies report that JCI­20679, which is synthesized based on the structure of naturally occurring acetogenin, inhibits mitochondrial complex I and suppresses the growth of various types of cancer cells. However, the efficacy of JCI­20679 on glioblastoma stem cells (GSCs) is unknown. The present study demonstrated that JCI­20679 inhibited the growth of GSCs derived from a transposon system­mediated murine glioblastoma model more efficiently compared with the growth of differentiation­induced adherent cells, as determined by a trypan blue staining dye exclusion test. The inhibition of proliferation was accompanied by the blockade of cell­cycle entry into the S­phase, as assessed by a BrdU incorporation assay. JCI­20679 decreased the mitochondrial membrane potential, suppressed the oxygen consumption rate and increased mitochondrial reactive oxygen species generation, indicating that JCI­20679 inhibited mitochondrial activity. The mitochondrial inhibition was revealed to increase phosphorylated (phospho)­AMPKα levels and decrease nuclear factor of activated T­cells 2 (NFATc2) expression, and was accompanied by a decrease in calcineurin phosphatase activity. Depletion of phospho­AMPKα by knockdown of AMPKß recovered the JCI­20679­mediated decrease in NFATc2 expression levels, as determined by western blotting and reverse transcription­quantitative PCR analysis. Overexpression of NFATc2 recovered the JCI­20679­mediated suppression of proliferation, as determined by a trypan blue staining dye exclusion test. These results suggest that JCI­20679 inhibited mitochondrial oxidative phosphorylation, which activated AMPK and reduced NFATc2 expression levels. Moreover, systemic administration of JCI­20679 extended the event­free survival rate in a mouse model transplanted with GSCs. Overall, these results suggested that JCI­20679 is a potential novel therapeutic agent against glioblastoma.

JCI-20679 suppresses autophagy and enhances temozolomide-mediated growth inhibition of glioblastoma cells.

Glioblastoma, a type of brain cancer, is one of the most aggressive and lethal types of malignancy. The present study shows that JCI-20679, an originally synthesized mitochondrial complex I inhibitor, enhances the anti-proliferative effects of suboptimal concentrations of the clinically used chemotherapeutic drug temozolomide in glioblastoma cells. Analysis of the effects of temozolomide combined with JCI-20679 using isobologram and combination index methods demonstrated that the combination had synergistic effects in murine and human glioblastoma cells. We found that JCI-20679 inhibited the temozolomide-mediated induction of autophagy that facilitates cellular survival. The autophagy induced by temozolomide increased ATP production, which confers temozolomide resistance in glioblastoma cells. JCI-20679 blocked temozolomide-mediated increases in ATP levels and increased the AMP/ATP ratio. Furthermore, JCI-20679 enhanced the therapeutic effects of temozolomide in an orthotopic transplantation model of glioblastoma. These results indicate that JCI-20679 may be promising as a novel agent for enhancing the efficacy of temozolomide against glioblastoma.

Chemical structures and induction of cell death via heat shock protein inhibition of the prenylated phloroglucinol derivatives isolated from Hypericum erectum.

Four new prenylated phloroglucinol derivatives (+)-erectumol I (1a), (-)-erectumol I (1b), (-)-erectumol II (2a), and (+)-erectumol II (2b) were isolated from the methanol extracts of the whole plants of Hypericum erectum. These new compounds were isolated as a pair of enantiomers, respectively. The planar chemical structures and relative configurations of the new compounds were suggested by Cu-Kα X-ray diffraction analysis and been confirmed by high-resolution mass and 1D and 2D NMR spectroscopic data. The absolute configuration of the four new compounds were established by comparing the experimental and predicted electronic circular dichroism data. Isolated compounds 1b and 2b induced death of Adriamycin-treated HeLa cells. Their enantiomers 1a and 2a did not. In addition, the apparent mechanism of cell death of 1b was the inhibited expression of heat shock protein 105.

Construction of sulfur-containing compounds with anti-cancer stem cell activity using thioacrolein derived from garlic based on nature-inspired scaffolds.

Sulfur-containing compounds, such as cyclic compounds with a vinyl sulfane structure, exhibit a wide range of biological activities including anticancer activity. Therefore, the development of efficient strategies to synthesize such compounds is a remarkable achievement. We have developed a unique approach for the rapid and modular preparation of nature-inspired cyclic and acyclic sulfur-containing compounds using thioacrolein, a naturally occurring chemically unstable intermediate. We constructed thiopyranone derivatives through the regioselective sequential double Diels-Alder reaction of thioacrolein produced by allicin, a major component in garlic, and two molecules of silyl enol ether as the diene partner. The cytotoxicity toward cancer stem cells of the thiopyranones was equal to or higher than that of (Z)-ajoene (positive control) derived from garlic, and the thiopyranones had higher chemical stability than (Z)-ajoene.

Structure-Activity Relationships of Thiophene Carboxamide Annonaceous Acetogenin Analogs: Shortening the Alkyl Chain in the Tail Part Significantly Affects Their Growth Inhibitory Activity against Human Cancer Cell Lines.

In a previous study, we found that the thiophene carboxamide solamin analog, which is a mono-tetrahydrofuran annonaceous acetogenin, showed potent antitumor activity through the inhibition of mitochondrial complex I. In this study, we synthesized analogs with short alkyl chains instead of the n-dodecyl group in the tail part. We evaluated their growth inhibitory activities against human cancer cell lines. We found that the alkyl chain in the tail part plays an essential role in their activity.

Construction of Acyclic All-Carbon Quaternary Stereocenter Based on Asymmetric Michael Addition of Chiral Amine.

Acyclic asymmetric quaternary stereocenters, which are composed of four carbon-carbon bonds, were finely constructed by utilizing a face-selective alkylation of enolate intermediates derived from an asymmetric Michael addition reaction of a chiral lithium amide with trisubstituted (E)-α,ß-unsaturated esters. The present face-selective alkylation was able to employ diverse alkyl halides as an electrophile to afford various Michael adducts having an all-carbon quaternary stereocenter. With regard to the deprotection of the chiral auxiliary, N-iodosuccinimide used in our previous study did not work in the present cases; however, we found that pyridine iodine monochloride in the presence of H2O was effective to remove the bornyl group and the benzyl group on the amino group to provide the ß-amino ester derivative.

Cell death-inducing activities via Hsp inhibition of the sesquiterpenes isolated from Valeriana fauriei.

Three new sesquiterpenes, valerianaterpenes I-III, and eight known compounds have been isolated from the methanol extract of the rhizomes and roots of Valeriana fauriei. The chemical structures of the three new sesquiterpenes were elucidated based on chemical and spectroscopic evidence. The absolute stereochemistry of valerianaterpene I was determined using X-ray crystallography. The cell death-inducing activity of isolated compounds alone or combination with Adriamycin (ADR) was observed by time-lapse cell imaging. Although the isolated compounds did not affect the number of mitotic entry cells and dead cells alone, kessyl glycol, kessyl glycol diacetate, and iso-teucladiol significantly increased the number of dead cells on ADR treated human cervical cancer cells. One of the mechanisms of cell death-inducing activity for the kessyl glycol acetate was suggested to be the inhibition of heat-shock protein 105 (Hsp105) expression level. This paper first deals with the naturally occurring compounds as Hsp105 inhibitor.

Reaction of 3-Oxa-2-oxobicyclo[4.2.0]oct-4-ene-1-carboxylate with Dimethylsulfoxonium Methylide.

We have been interested in the reactivities of small-ring compounds and have reported reactions that proceed through cyclopropane intermediates starting from coumarin derivatives bearing an electron-withdrawing group at the 3-position or 2-oxo-2H-pyran-3-carboxylate derivatives and dimethylsulfoxonium methylide. This time, the reaction between 3-oxa-2-oxobicyclo[4.2.0]oct-4-ene-1-carboxylate and dimethylsulfoxonium methylide has been investigated. 3a,4,5,7a-Tetrahydro-7-hydroxybenzofuran-6-carboxylate and/or 2-hydroxybicyclo[4.1.0]hept-2-ene-3-carboxylate were obtained. The compounds were characterized using various spectral and X-ray crystallographic techniques. A plausible reaction mechanism has been discussed. This reaction was applied to some 3-oxa-2-oxobicyclo[4.2.0]oct-4-ene-1-carboxylate derivatives to clarify the generality.

Syntheses of C2'-Fluorinated Analogs of Solamin.

The details of the total syntheses of C2'-fluorinated analogs of solamin, an antitumor annonaceous acetogenin, are described. Fluorine was enantioselectively introduced at the C2'-position by organocatalytic α-fluorination of the aldehyde according to a previously reported method. C2'-fluorinated solamin and its C2'-diastereomer were synthesized by the Sonogashira coupling of a tetrahydrofuran fragment and fluorine-containing γ-lactone fragments.

Chemical structures and cytotoxic activities of the constituents isolated from Hibiscus tiliaceus.

Five new cadinene-type sesquiterpenes, hibiscusterpenes I-V (1-5), and six known compounds (6-11) have been isolated from the methanol extract of the stems and the twigs of Hibiscus tiliaceus. The structures of the new compounds were elucidated based on chemical and spectroscopic evidence. The absolute stereochemistry of hibiscusterpene I (1) was determined using X-ray crystallography. For hibiscusterpene III (3), the absolute configuration was established upon comparison of the experimental and predicted electronic circular dichroism (ECD) data. Among the isolated compounds, hibiscone C (7) and syriacusin A (11) showed cytotoxic activity in HeLa cells. In addition, their cell death-inducing activity was observed using time-lapse cell imaging.

A Facile and Convenient Synthesis of Trisubstituted (E)-α,ß-Unsaturated Esters by Tandem Acetylation-E1cB Reaction.

A facile and convenient synthesis of trisubstituted (E)-α,ß-unsaturated esters was developed by improving our previously established method. The new method circumvented the separation of the intermediates, which have an activating group of the hydroxyl group in ß-hydroxy esters, furnishing α,ß-unsaturated esters in shorter steps than the previous method: an acetylation of ß-hydroxy group and subsequent E1cB reaction proceeded in tandem. In addition, the new method can not only employ a diastereomeric mixture of the substrate for the E1cB reaction, it has a wide substrate scope as well, which would enable the synthesis of various trisubstituted (E)-α,ß-unsaturated esters.

Chemical Structures of Novel Maillard Reaction Products under Hyperglycemic Conditions.

Two novel and two known compounds, 4-quinolylaldoxime and indole-3-aldehyde, were isolated from a reaction mixture consisting of D-glucose and L-tryptophan at physiological temperature and pH. The chemical structures of the two novel compounds were elucidated by spectroscopic analysis such as X-ray crystallography. One of the novel compound and the indole-3-aldehyde showed mutagenicity toward Salmonella typhimurium YG1024 with S9 mix. Furthermore, 4-quinolylaldoxime was detected from streptozotocin-induced diabetic rat plasma by LC-MS/MS analysis; however, the isolated compounds were not detected in rat diet extracts. To our knowledge, this is the first report in which 4-quinolylaldoxime was detected in rat plasma. These results suggest that amino-carbonyl reaction products may be formed in diabetic condition and induce genetic damage.

A simple and rapid LC-MS/MS method for quantitation of luseogliflozin in rat plasma and its application to a PK study.

AIM: Luseogliflozin is a novel sodium-dependent glucose cotransporter-2 inhibitor for the treatment of Type 2 diabetes mellitus. To assist pharmacokinetic and toxicodynamic studies, a rapid LC-MS/MS method were developed and validated for the quantitation of luseogliflozin in rat plasma. RESULTS: Sample preparation was carried out using simplified protein precipitation and liquid-liquid extraction procedures, and the run time was only 4 min. Extraction recovery was 92.9 to 95.3%, and the method was validated over the range 0.5 to 500 ng/ml for luseogliflozin with acceptable specificity, accuracy and precision. CONCLUSION: The validated method is considered suitable to quantify luseogliflozin in pharmacokinetic and pharmacodynamic/toxicodynamic studies in rats.

Reaction of 2a,8b-Dihydrobenzo[b]cyclobute[d]pyran-3-ones with Dimethylsulfoxonium Methylide.

Using dimethylsulfoxonium methylide as the methylene transfer reagent, 2a,8b-dihydrobenzo[b]cyclobute[d]pyran-3-ones were converted into 2,2'-biphenol derivatives as major products and dihydrodibenzofurans as minor products. The reaction mechanism was extrapolated from a deuteration experiment with CD2=S(O)(CD3)2.