Catalytic Asymmetric Synthesis of Atropisomers Bearing Multiple Chiral Elements: An Emerging Field

With the rapid development of asymmetric catalysis, the demand for the enantioselective synthesis of complex and diverse molecules with different chiral elements is increasing. Owing to the unique features of atropisomerism, the catalytic asymmetric synthesis of atropisomers has attracted a considerable interest from the chemical science community. In particular, introducing additional chiral elements, such as carbon centered chirality, heteroatomic chirality, planar chirality, and helical chirality, into atropisomers provides an opportunity to incorporate new properties into axially chiral compounds, thus expanding the potential applications of atropisomers. Thus, it is important to perform catalytic asymmetric transformations to synthesize atropisomers bearing multiple chiral elements. In spite of challenges in such transformations, in recent years, chemists have devised powerful strategies under asymmetric organocatalysis or metal catalysis, synthesizing a wide range of enantioenriched atropisomers bearing multiple chiral elements. Therefore, the catalytic asymmetric synthesis of atropisomers bearing multiple chiral elements has become an emerging field. This review summarizes the rapid progress in this field and indicates challenges, thereby promoting this field to a new horizon.

Organocatalytic Enantioselective Synthesis of Axially Chiral N,N'-Bisindoles

This study establishes the first organocatalytic enantioselective synthesis of axially chiral N,N'-bisindoles via chiral phosphoric acid-catalyzed formal (3+2) cycloadditions of indole-based enaminones as novel platform molecules with 2,3-diketoesters, where de novo indole-ring formation is involved. Using this new strategy, various axially chiral N,N'-bisindoles were synthesized in good yields and with excellent enantioselectivities (up to 87 % yield and 96 % ee). More importantly, this class of axially chiral N,N'-bisindoles exhibited some degree of cytotoxicity toward cancer cells and was derived into axially chiral phosphine ligands with high catalytic activity. This study provides a new strategy for enantioselective synthesis of axially chiral N,N'-bisindoles using asymmetric organocatalysis and is the first to realize the applications of such scaffolds in medicinal chemistry and asymmetric catalysis.

[Association of high-density lipoprotein cholesterol with risk of cardiovascular disease mortality]

Objective: To analyze the association between high density lipoprotein cholesterol (HDL-C) and the risk of cardiovascular disease mortality. Methods: A total of 71 618 residents aged over 18 years with complete baseline data, who were filed on the health information big data platform of Yinzhou district, Ningbo city, Zhejiang Province from 2009 to 2014, were selected as the research population. The research population were divided into four groups according to the level of HDL-C: low-level group (HDL-C<1.0 mmol/L), intermediate-level group (1.0 mmol/L≤HDL-C<1.5 mmol/L), medium-high-level group (1.5 mmol/L≤HDL-C<2.0 mmol/L) and high-level group (HDL-C≥2.0 mmol/L). Cox proportional hazard model was used to calculate the risk ratio of cardiovascular diseases mortality in different groups. Results: The study population was followed up for a total of 427 989.4 person-years, follow-up time of (5.98±1.04)years. During the follow-up period, there were 799 deaths due to cardiovascular diseases. After adjusting for confounding factors, compared with the medium-high-level group as the reference group, the HR (95%CI) for cardiovascular diseases mortality was 1.43 (1.13-1.82) in the low-level group and 1.22 (1.02-1.46) in the high-level group. Conclusion: The low level of HDL-C (<1.5 mmol/L) is associated with a higher risk of cardiovascular disease deaths. The level of HDL-C can be used as a biological indicator to monitor the development of cardiovascular diseases and guide treatment.

Brønsted Acid-Catalyzed (4 + 3) Cyclization of N, N'-Cyclic Azomethine Imines with Isatoic Anhydrides

A Brønsted acid-catalyzed (4 + 3) cyclization of N, N'-cyclic azomethine imines with isatoic anhydrides has been discovered, which constructs seven-membered nitrogenous heterocyclic frameworks with overall high yields (up to 98% yield). This reaction represents a rarely reported (4 + 3) cyclization of N, N'-cyclic azomethine imines, which involves the reassembly of a C-N bond. In addition, this reaction has also accomplished the unprecedented (4 + 3) cyclization of isatoic anhydrides.

Organocatalytic [4 + 2] cyclizations of para-quinone methide derivatives with isocyanates

The first [4 + 2] cyclizations of o-hydroxyphenyl-substituted p-quinone methide derivatives with isocyanates have been established under the catalysis of Brønsted acids or Brønsted bases, which efficiently constructed benzoxazin-2-one frameworks in generally high yields.

[Application and analysis of abdominal aortic branch malperfusion pattern in thoracic endovascular aortic repair for Stanford B aortic dissection]

OBJECTIVE

To evaluate the efficiency of thoracic endovascular aortic repair (TEVAR) in dealing with abdominal aortic branch malperfusion based on the analysis of aortic computed tomography angiography (CTA) images in pre- and post-TEVAR.

METHODS

Retrospective analysis from September 2015 to March 2016 in single institution to 32 patients, diagnosed as Stanford B aortic dissection with abdominal aortic branch malperfusion, CTA images in pre- and post-TEVAR were collected. Based on the aortic branch malperfusion pattern redefined by Nagamine, we identified and characterized branch malperfusion pattern for four abdominal aortic branches (celiac trunk, superior mesenteric artery, bilateral renal artery) in statistical analysis.

RESULTS

In the four abdominal aortic branches (total 128 branches), 86 branches (67.2%) expressed with Class I patterns, in which subtype I-b presented with 0.8%, subtype I-c with 5.5%; 14 branches (10.9%) expressed with Class II patterns, in which subtype II-b-1 with 3.9%, subtype II-b-2 with 3.1%; 16 branches (12.5%) expressed with Class III patterns, all with subtype III-a, no subtype III-b and III-c presented. The remaining 12 branches were normal. The 100% successful rate of TEVAR obtained in 32 patients performed. The mean following-up was 4 months. Aortic CTA showed that among the 14 "high-risk" abdominal aortic branch malperfusion, 13 (92.9%) with obvious branch malperfusion in post-TEVAR were observed to improve, and the remaining one branch malperfusion (7.1%) was observed to change from subtype I-b to I-c.

CONCLUSION

Few ratios in abdominal aortic branches suffered with obvious malperfusion complicated by Stanford B aortic dissection. For branches with "high-risk" malperfusion pattern, optimal changes were observed in abdominal aortic branch without revascularization in post-TEVAR, as well other branches with non-"high-risk" pattern perfusion were mostly stable in post-TEVAR. It could be of profound benefit to extend branch malperfusion patterns redefined by Nagamine in clinical practice to assess aortic dissection and in further guide for revascularization or not.

[Acute toxicity and bio-distribution of silver nitrate and nano-silver with different particle diameters in rats]

Objective: To explore the acute toxic effect and the cumulative target organ of silver nitrate and nano-silver with two different particle diameters in rats. Methods: Thirty-six adult SD rats were divided into small particle size nano-silver group (SNS), large particle size nano-silver group (LNS), silver nitrate group (SN), and control group (C) according to the random number table, with 9 rats in each group. The rats of the four groups were respectively injected with 10 mg/mL nano-silver solution (particle diameter of 20 nm, prepared by saline) in silver dose of 30 mg/kg by tail vein for once, 10 mg/mL nano-silver solution (particle diameter of 100 nm, prepared by saline) in silver dose of 30 mg/kg, 1.67 mg/mL silver nitrate solution (prepared by glucose solution) in silver dose of 3 mg/kg, and 30 mg/mL polyvinylpyrrolidone solution (prepared by saline) in dose of 90 mg/kg. (1) Toxicity test. The general observation was performed within 14 days after injection, and the deviation between value of body mass before injection and each of that on post injection day (PID) 1, 7, and 14 were respectively recorded. On PID 1, 7, and 14, 3 rats of each group were harvested for determination of serum content of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, and albumin by fully automatic biochemical analyzer. Then the rats were sacrificed immediately, and heart tissue, liver tissue, spleen tissue, lung tissue, kidney tissue, and brain tissue were collected to calculate the organ coefficient. Organ samples with obvious changes in organ coefficient were collected for histopathological observation by HE staining, with 3 samples in each group at each time point. (2) Bio-distribution. The specimens of heart, liver, spleen, lung, and kidney of rats from groups SNS, LNS, and SN were collected for detection of silver content by inductively coupled plasma mass spectrometry, with 3 samples in each group at each time point. Data were processed with analysis of variance of factorial design, LSD test, and Dunnett's T3 test. Results: (1) The general condition of rats in groups C and SN after injection were normal. The state of rats of groups SNS and LNS was poor with black secretion in the eye and other phenomena on PID 1, which recovered from PID 3 on. (2) The deviations between values of body mass before injection and that on PID 14 in rats of groups LNS and SN were significantly decreased as compared with deviation of group C (with P values below 0.01), but deviation of group SNS was not significantly changed (P>0.05). The deviations between values of body mass before injection and each of that on PID 1 and 7 in rats in the other three groups were similar to those in group C (with P values above 0.05). (3) Compared with those in group C, the serum content of total protein of rats in group SN on PID 1 was significantly decreased, and liver coefficient was significantly increased (with P values below 0.05). On PID 1, the serum content of ALT of rats in group LNS was (61.0±8.7) U/L, which was significantly higher than that in group C [(40.0±4.6) U/L, P<0.01]. Compared with those in group C [(126.0±3.5) U/L and 4.05±0.23], the serum content of AST of rats in groups SNS and LNS on PID 1[(249.7±107.2) and (237.0±38.3) U/L] was significantly increased, and liver coefficients (3.50±0.38 and 3.31±0.07) were significantly decreased, with P values below 0.05. Compared with those in group C [(69.2±4.8) U/L and 4.32±0.39], the serum content of AST of rats in groups SNS and LNS on PID 7 [(181.0±51.5) and (167.7±16.5) U/L] was also significantly increased, and liver coefficients (3.55±0.18 and 3.62±0.21) were also significantly decreased, P<0.05 or P<0.01. On PID 14, the four liver biochemical indexes in serum and all organ coefficients of rats in the other three groups were similar to those in group C (with P values above 0.05). (4) The liver of rats in group SN had slight degeneration on PID 1, the liver cells around the central vein of liver of rats in group SNS had slight degeneration on PID 7, and the liver cells got severely eosinophilic degeneration in liver of rats in group LNS on PID 7. There was no significant pathological change in the liver of rats in each group at the rest time points. (5) The silver content of lung and kidney in rats of group SNS on PID 1, that of spleen and kidney in rats of group LNS on PID 1, and that of heart and kidney in rats of groups LNS and SNS on PID 7 was significantly less than that of group SN (with P values below 0.05). The silver content of liver and spleen in rats of group SNS on PID 14 was significantly more than that of group SN (with P values below 0.05). Compared with that of group SN, the silver content of lung on PID 1 and liver on PID 7 in rats of group LNS was significantly increased (with P values below 0.05). On PID 14, there was no significant change in the silver content of all organs of rats between group SN and group LNS (with P values above 0.05). The silver content of heart, lung, and kidney on PID 1 and heart on PID 7 in rats of group LNS was significantly more than that of group SNS (with P values below 0.05). On PID 14, the silver content of each organ of rats in group SNS was close to that in group LNS (with P values above 0.05). Conclusions: Silver nitrate and nano-silver with two different particle diameters have a short acute toxic effect on the liver of rats, and the liver has certain ability of self-healing. Nano-silver is mainly accumulated in the liver. The distribution of nano-silver with large particle diameter in organs is more widely than that of nano-silver with small particle diameter.

Low-concentration capsaicin promotes colorectal cancer metastasis by triggering ROS production and modulating Akt/mTOR and STAT-3 pathways

Colorectal cancer (CRC), one of the most common human malignancies, is a major public health problem in the developed world. Capsaicin, widely used as a food additive and as an analgesic agent, is a major pungent ingredient of red pepper. Though capsaicin-induced apoptosis was previously reported in cancer cells, relatively little is known about the impact of capsaicin on other aspect of cancer cell behavior. In this study, we demonstrated that treatment with high-concentration of capsaicin (≥ 200 µM for SW480 and CT-26 cell lines; ≥ 25 µM for HCT116 cell line) inhibited CRC cell proliferation in a dose-dependent manner. In spite of no anti-proliferative effect, notably, low-concentration of capsaicin (100 µM for SW480 and CT-26 cell lines; 12.5 µM for HCT116 cell line) enhanced both migratory and invasive capability of these cells, which was validated by both in vitro and in vivo model. Further, we showed that 100 µM capsaicin induced epithelial-to-mesenchymal (EMT), up-regulated expression of MMP-2 and MMP-9, and activated Akt/mTOR and STAT-3 pathways in SW480 cells. Finally, we showed that capsaicin-induced metastasis of CRC cells was mediated by modulating reactive oxygen species (ROS) production. Our findings are considered a significant step toward a better understanding of capsaicin-associated regulatory network on CRC cells.

[Effects of polychlorinated biphenyl on bcl-2 and TGFbeta1 expression in rat testes]

OBJECTIVE

To study the effects of polychlorinated biphenyl (PCB) on bcl-2 and TGFbeta1 expression in rat testes.

METHODS

Forty male Wistar rats were divided into 4 groups at random: Group A (normal control), Group B (fed on 10(-8) mol/L PBC), Group C (feb on 10(-7) mol/L) and Group D (feb on 10(-6) mol/L). After three months, all the rats were killed, the animal model established, and observations made on the expression of bcl2 and TGFbeta1 in the rat testis using the optical microscope and immunohistochemical techniques.

RESULTS

The damage to the structure of the testis was related to the dosage of PCB: the higher the dodage, the more serious the damage. PCB induced the expression of bcl-2 and TGFbeta1. The TGFbeta1 expression was significantly higher in the highest dosage group than in others (P < 0.01 ), and the bcl-2 expression was dramatically higher in Group C than in other groups (P < 0.01).

CONCLUSION

PCB can cause injury in rat testes.

HNF1 and/or HNF3 may contribute to the tissue specific expression of glucokinase gene

A possible role of hepatocyte nuclear factor 1 (HNF1) or HNF3, a predominant trans-acting factors of hepatic or pancreatic beta-cells, was examined on the tissue specific interdependent expression of glucokinase (GK) in liver, H4IIE, HepG2, HIT-T15 and MIN6 cell line. The tissues or cell lines known to express GK showed abundant levels of HNF1 and HNF3 mRNA as observed in liver, H4IIE, HepG2, HIT-T15 and MIN6 cells, whereas they were not detected in brain, heart, NIH 3T3, HeLa cells. The promoter of glucokinase contains several HNF3 consensus sequences and are well conserved in human, mouse and rat. Transfection of the glucokinase promotor linked with luciferase reporter to liver or pancreatic beta cell lines showed high interacting activities with HNF1 and HNF3, whereas minimal activities were detected in the cells expressing very low levels of HNFs. The binding of HNF1 or HNF3 to the GK promoter genes was confirmed by electrophoretic mobility shift assay (EMSA). From these data, we propose that the expression of HNF1 and/or HNF3 may, in part, contribute to the tissue specific expression of GK

[Inhibitory effect of methanol extract of Boschniakia rossica Fedtsch. et Flerov on rat hepatic preneoplastic lesions induced by diethylnitrosamine]

OBJECTIVE

To investigate the inhibitory effect of Boschniakia rossica(BR) on hepatocarcinogenesis in rats.

METHOD

Based on immunohistochemistry techniques, the expression of placental form glutathione S-transferase(GST-P), mutant p53 and p21 protein were investigated in hepatic preneoplastic lesions induced by Solt-Farber protocol in the liver of rats that had been treated with the above method, administered with BR extract and of control group.

RESULT

The extract of BR(500 mg/kg) has inhibitory effect on the formation of diethylnitrosamine-induced GST-P-positive foci in F344 rat and the expression of mutant p53 and p21 protein was lower than that of hepatic preneoplastic lesions, and the increasing gamma-glutamyltranspeptidase(gamma-GT) activity in rat liver treated with Solt-Farber protocol was decreased by the extract of BR.

CONCLUSION

These results indicate that BR has inhibitory effect on DEN induced hepatic preneoplastic lesions in F344 rat.

p16INK4 and p15INK4B alterations in primary gynecologic malignancy

Chromosome 9 abnormalities have been found in primary tumors and cell lines from human gynecologic malignancy. Alterations of p16INK4 and p15INK4B genes mapped on the band p21 of chromosome 9 have been detected in various human tumors, but the role of these genes as tumor suppressors in vivo appear to be dependent on tumor type. Polymerase chain reaction (PCR)-based analysis was performed to search for lesions of these genes in 202 primary gynecologic malignancies. Homozygous deletions of p16INK4 were detected in 7 of 128 (5%) cervical, 1 of 41 (2%) endometrial, 2 of 27 (7%) ovarian, and 3 of 6 (50%) vulvar carcinomas, while homozygous deletions of p15INK4B were detected in 19 of 128 (15%) cervical, 1 of 41 (2%) endometrial, 9 of 27 (33%) ovarian, and 3 of 6 (50%) vulvar carcinomas, respectively. No mutations were found in exon 2 of p16INK4 from 161 cases of gynecologic malignancy without deletion of p16INK4. All 3 cases of vulvar carcinoma showing homozygous deletions of p16INK4 and p15INK4B were at advanced clinical stage (stage III-IV), while all 7 cases of cervical carcinoma and 2 cases of ovarian carcinoma showing homozygous deletion of p16INK4 were at early stage (stage I-II). The results indicate that homozygous deletions of p16INK4 and/or p15INK4B genes may play a role in a subset of primary gynecologic malignancy.

[The rapid effect of the iontophoretically applied cortisol on unit activity of neurons in three brain areas in rats]

The present study was undertaken to analyze whether the glucocorticoid (GC) effect was region specific in the brain. Na-cortisol-succinate (HC) was applied iontophoretically to cerebral cortex (CX), hippocampus (HPC) and PVN respectively and the effect on unit discharge rate in these three brain areas were compared. In cerebral cortex, the percentage of responsive neurons was only 8% (4/50), which was significantly lower than those in HPC (10/36, 27.8%) and PVN (9/35, 25.7%). The difference in the occurrence is paralleled with the known distribution of traditional GC cytosolic receptors in the brain. In all the three brain areas studied the main response to GC was inhibitory and the latencies of the responses were 9.6 +/- 6.5, 22.7 +/- 24.0, and 14.5 +/- 11.5 s and the durations of the after-effect were 74.8 +/- 66.5 (n = 4), 24.2 +/- 14.5 (n = 6) and 21.0 +/- 10.5 s (n = 9) respectively. The shortness of the latencies once again suggests that the mechanism involved is non-genomic. It is interest to note that in some HPC neurons the after-effect lasted for 1758 +/- 2148 s (n = 4). The results show that the rapid effect of GC on neurons is different in the three brain areas studied in regarding to the occurrence of responsive neurons and the duration of the after-effects.