Regioselective construction of pyridazine and tetrahydrocinnoline derivatives via [4 + 2] cycloaddition–elimination with α-halogeno hydrazones and enaminones

Herein, we report the de novo construction of pyridazine scaffolds via a [4 + 2] cycloaddition–elimination reaction with α-halogeno hydrazones and enaminones.

Distinctive and Pervasive Alterations of Functional Brain Networks in Cerebral Small Vessel Disease with and without Cognitive Impairment

OBJECTIVE

To explore the within- and between-network patterns of the default mode network (DMN), the frontoparietal control network (FPCN), and the dorsal attention network (DAN) in cerebral small vessel disease (CSVD) with and without cognitive impairment (CI).

METHODS

Twenty CSVD with CI subjects, 21 CSVD without CI subjects, and 25 healthy elderly controls were recruited. The within- and between-network patterns of the networks were identified based on resting-state functional magnetic resonance imaging data.

RESULTS

Compared with the control group, both the CSVD with CI group and the CSVD without CI group displayed decreased within-network function of the DMN and lower negative connectivity between the DMN and other networks (i.e., DMN and DAN, DMN and FPCN), whereas the CSVD with CI group additionally showed within- and between-network alterations of the FPCN (i.e., increased within-network function of the FPCN and lower negative connectivity between the FPCN and the DMN). Furthermore, these alterations of the FPCN were correlated with the cognitive function of CSVD subjects. Interestingly, the between-network connectivity of the FPCN and the DMN was negatively correlated with deep white matter hyperintensities (DWMH) volume in CSVD subjects.

CONCLUSION

These findings suggest that cognitive alterations of CSVD subjects may be mainly regulated by the FPCN that correlates with DWMH burden, and shed light on the investigation of surrogate markers of CSVD.

The Altered Reconfiguration Pattern of Brain Modular Architecture Regulates Cognitive Function in Cerebral Small Vessel Disease

Background: Cerebral small vessel disease (SVD) is a common cause of cognitive dysfunction. However, little is known whether the altered reconfiguration pattern of brain modular architecture regulates cognitive dysfunction in SVD.

Methods: We recruited 25 cases of SVD without cognitive impairment (SVD-NCI) and 24 cases of SVD with mild cognitive impairment (SVD-MCI). According to the Framingham Stroke Risk Profile, healthy controls (HC) were divided into 17 subjects (HC-low risk) and 19 subjects (HC-high risk). All individuals underwent resting-state functional magnetic resonance imaging and cognitive assessments. Graph-theoretical analysis was used to explore alterations in the modular organization of functional brain networks. Multiple regression and mediation analyses were performed to investigate the relationship between MRI markers, network metrics and cognitive performance.

Results: We identified four modules corresponding to the default mode network (DMN), executive control network (ECN), sensorimotor network and visual network. With increasing vascular risk factors, the inter- and intranetwork compensation of the ECN and a relatively reserved DMN itself were observed in individuals at high risk for SVD. With declining cognitive ability, SVD-MCI showed a disrupted ECN intranetwork and increased DMN connection. Furthermore, the intermodule connectivity of the right inferior frontal gyrus of the ECN mediated the relationship between periventricular white matter hyperintensities and visuospatial processing in SVD-MCI.

Conclusions: The reconfiguration pattern of the modular architecture within/between the DMN and ECN advances our understanding of the neural underpinning in response to vascular risk and SVD burden. These observations may provide novel insight into the underlying neural mechanism of SVD-related cognitive impairment and may serve as a potential non-invasive biomarker to predict and monitor disease progression.

Total Syntheses of Echitamine, Akuammiline, Rhazicine, and Pseudoakuammigine

Echitamine (1) and akuammiline (2) are representative members of a fascinating class of monoterpenoid indole alkaloids. We report the syntheses of 2 and its congener deacetylakuammiline (3). The azabicyclo[3.3.1]nonane motif was assembled through silver-catalyzed internal alkyne cyclization, and one-pot C-O bond cleavage/C-N bond formation furnished the pentacyclic scaffold. Compound 3 then served as a common intermediate for preparing a series of structurally diverse and synthetically challenging congeners including 1. A position-selective Polonovski-Potier reaction followed by formal N-4 migration built the core of N-demethylechitamine (4) and 1. An alternative route featuring Meisenheimer rearrangement gave 4 as well. Oxidation of the alcohol within 3 gave rhazimal (5), which underwent tandem indolenine hydrolysis, hemiaminalization, and hemiketalization to form rhazicine (6). A sequence of N,O-ketalization and reductive amination secured the chemoselectivity of N-methylation, leading to pseudoakuammigine (7).

Structural Revision of Macropodumine A and Structure of 2-Deoxymacropodumine A, Daphniphyllum Alkaloids with 11-Membered Macrolactone Rings

An unusual Daphniphyllum alkaloid, 2-deoxymacropodumine A (1), possessing an 11-membered macrolactone ring, was obtained from an extract of the stems of Daphniphyllum angustifolium. The structure of 1 was elucidated by 1D and 2D NMR spectroscopic methods and chemical calculations. Based on a comparison of the experimental and calculated NMR data, the structure of macropodumine A (2'), an analogue of 1, was also revised.

Design and Synthesis of Matrine Derivatives as Novel Anti-Pulmonary Fibrotic Agents via Repression of the TGFβ/Smad Pathway

A total of 18 matrine derivatives were designed, synthesized, and evaluated for their inhibitory effect against TGF-β1-induced total collagen accumulation in human fetal lung fibroblast MRC-5 cell lines. Among them, compound 3f displayed the most potent anti-fibrotic activity (IC₅₀ = 3.3 ± 0.3 μM) which was 266-fold more potent than matrine. 3f significantly inhibited the fibroblast-to-myofibroblast transition and extracellular matrix production of MRC-5 cells. The TGF-β/small mothers against decapentaplegic homologs (Smad) signaling was also inhibited by 3f, as evidenced by inhibition of cytoplasm-to-nuclear translocation of Smad2/3 and suppression of TGF-β1-induced upregulation of TGF-β receptor type I (TGFβRI). Additionally, 3f exhibited potent inhibitory effects against TGF-β1-induced fibroblasts migration. These data suggested that 3f might be a potential agent for the treatment of idiopathic pulmonary fibrosis via repression of the TGFβ/Smad signaling pathway.

The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles

In the present work, an efficient regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported.

[Effects of glycyrrhizic acid on ERK1/2 and p38 MAPK signaling pathway in a murine model of asthma]

Objective: To explore the effects of glycyrrhizic acid (GA) on Extracellular regulated protein kinases (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK) signaling pathways in a murine model of asthma. Methods: Sixty female BALB/c mice were randomly divided into 6 groups (n=10 each): a control group, an asthmatic group, two treatment groups with low and high doses of GA, U0126 group and SB203580 group. Within 24 hours after the last OVA challenge, histological studies of lung were conducted with the hematoxylin and eosin staining (HE) and alcian blue-periodic acid-Schiff (AB-PAS), the relative protein expression of ERK1/2 and p38 MAPK were detected by immunohistochemistry and Western blotting in vivo. CD4(+) T cells were purified from spleens of OVA-sensitized and challenged mice by using the Mouse CD4 Cell Positive Isolation Kit and incubated with anti-CD3 mAb (1 μg/ml) in the presence of various concentrations of GA (10 and 100 μg/ml), U0126 (10 μmol/L) or SB203580(10 μmol/L). After 72 h of incubation, the relative protein expression of ERK1/2 and p38 MAPK of CD4(+) T cells were detected by Western blotting in vitro. Results: The asthmatic mice induced infiltration of inflammatory cells around airways and blood vessels, airway goblet cell hyperplasia and mucus production. Administration of GA at a dose of 100 mg/kg, U0126 or SB203580 significantly reduced the infiltration of inflammatory cells in the peribronchial areas and goblet cell hyperplasia compared with the asthmatic mice. The protein expressions of p-ERK1/2 were lower in GA at a dose of 100 mg/kg (0.090±0.022) and U0126 group (0.072±0.017) than those in asthmatic group (0.143±0.022) (all P<0.05). The protein expressions of p-p38 MAPK were lower in GA at a dose of 100 mg/kg (0.072±0.019) and SB203580 group (0.061±0.015) than those in asthmatic group (0.121±0.022) (all P<0.05) by immunohistochemistry. Compared with asthmatic group (0.783±0.133, 0.649±0.095), the protein expressions of p-ERK1/2 and p-p38 MAPK in GA at a high dose group (0.385±0.186, 0.275±0.089) and in U0126 group (0.117±0.051) or in SB203580 group (0.108±0.043) were decreased by Western blotting (all P<0.05). The expressions of p-ERK1/2 in CD4(+) T cells after 72 h incubation were lower in 100 μg/ml concentrations of GA (0.579±0.184) and group U0126 (0.249±0.082) and the expressions of p-p38 MAPK were much lower in 100 μg/ml concentrations of GA (0.445±0.081) and group SB203580 (0.249±0.082) compared with those in group CD3 (1.028±0.147, 0.902±0.107) (all P<0.05). Conclusion: ERK1/2 and p38 MAPK signaling pathways are activated in asthmatic mice and GA may negative regulate this activation.

Palladium-catalyzed difluoromethylation of heteroaryl chlorides, bromides and iodides

A palladium-catalyzed difluoromethylation of a series of heteroaryl chlorides, bromides and iodides under mild conditions is described. A wide range of heteroaryl halides such as pyridyl, pyrimidyl, pyrazyl, funanyl, thienyl, pyazolyl, imidazolyl, thiazolyl, and oxazolyl halides were efficiently difluoromethylated, thus providing medicinal chemists an alternative choice for the preparation of drug candidates with the difluoromethylated heteroarene unit.

Design, Synthesis, and Biological Activities of Spirooxindoles Containing Acylhydrazone Fragment Derivatives Based on the Biosynthesis of Alkaloids Derived from Tryptophan

On the basis of the biosynthesis of alkaloids derived from tryptophan and considering the wide use of spirooxindole in drug molecular design, a series of novel spirooxindole derivatives containing an acylhydrazone moiety were designed, synthesized, and first evaluated for their biological activities. The results of bioassays indicated that the target compounds possessed good activities against tobacco mosaic virus (TMV); especially compound 4, containing a tert-butyl at the benzene ring, exhibited the best antiviral activity in vitro and inactivation, curative, and protection activities in vivo (48.4%, 58 ± 0.4, 55.2 ± 2.3, and 49.7 ± 1.1% at 500 μg/mL, respectively) compared with ribavirin (38.2, 36.4 ± 0.2, 37.5 ± 0.2, and 36.4 ± 0.1% at 500 μg/mL, respectively) and harmine (44.6, 40.5 ± 0.2, 38.6 ± 0.8, and 42.4 ± 0.6% at 500 μg/mL, respectively). At the same time, these compounds exhibited fungicidal activity selectively against certain fungi; most of these derivatives exhibited >60% fungicidal activity against Physalospora piricola at 50 mg/kg. Additionally, compounds 25 and 14 displayed excellent insecticidal activities (60% motality against C. pipiens pallens at 0.25 mg/kg) even at very low concentrations.

Distribution and Characteristics of Colletotrichum spp. Associated with Anthracnose of Strawberry in Hubei, China

Anthracnose caused by Colletotrichum spp. is a serious disease of strawberry. The etiology of anthracnose of strawberry is complex, and several Colletotrichum spp. have been regarded as causal agents. In the present study, multilocus (actin, β-tubulin, calmodulin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase) phylogenetic analysis revealed that 100 isolates of Colletotrichum associated with anthracnose of strawberry in central China belong to five species. In total, 97 isolates were identified belonging to the Colletotrichum gloeosporioides species complex, with C. murrayae, C. gloeosporioides, C. fructicola, and C. aenigma accounting for 81, 8, 4, and 4% of the total isolates, respectively. Three isolates belonging to the C. acutatum complex were identified as C. nymphaeae. On inoculated strawberry plants, isolates of C. fructicola and C. murrayae species showed strong pathogenicity to both leaves and petioles of strawberry, with plant mortality 30 days after inoculation of 77.8 and 55.6%, respectively. C. gloeosporioides, C. aenigma, and C. nymphaeae showed strong pathogenicity to leaves but weak pathogenicity to petioles, with plant mortality 30 days after inoculation of 5.6, 16.7, and 11.1%, respectively. The five species were divided into four classes based on their maximum growth temperatures. Isolates of C. murrayae and C. gloeosporioides were more tolerant to high temperature (>34°C) than isolates of other species, followed by C. fructicola and C. aenigma. Isolates of C. nymphaeae, which are only distributed in areas of higher altitude (1,100 m), were highly sensitive to higher temperature. These results indicate that pathogenicity and adaptation to temperature are important factors in the distribution of Colletotrichum spp. on strawberry plants. This research may increase our understanding of how Colletotrichum spp. emerge and spread to geographical regions with different latitudes or elevations.

Synthesis and herbicidal activity evaluation of novel α-amino phosphonate derivatives containing a uracil moiety

A series of novel α-amino phosphonate derivatives containing a uracil moiety 3a-3l were designed and synthesized by a Lewis acid (magnesium perchlorate) catalyzed the Kabachnik-Fields reaction. The bioassays {in vitro, in vivo [Glass House 1 (GH1) and Glass House 2 (GH2)]} showed that most of compounds 3 exhibited excellent and selective herbicidal activities; for example, in GH1 test, compounds 3b, 3d, 3f, 3h and 3j showed excellent and wide spectrum herbicidal activities at the dose of 1000 g/ha, and compounds 3b and 3j exhibited 100% inhibition activities against the four plants in both post- and pre-emergence treatments. Moreover, most of compounds 3 showed higher inhibition against Amaranthus retroflexus and Digitaria sanguinalis than Glyphosate did in pre-emergence treatment. In GH2 test, the four compounds (3b, 3d, 3h and 3j) exhibited 100% inhibition against Solanum nigrum, Amaranthus retroflexus and Ipomoea hederacea in post-emergence treatment and displayed 100% inhibition against Solanum nigrum, Amaranthus retroflexus in pre-emergence treatment at the rate of 250 g/ha, and compound 3b showed the best and broad spectrum herbicidal activities against the six test plants. However, the four compounds displayed weaker herbicidal activities against Lolium perenne and Echinochloa crus-galli than the other four plants at the rate of 250 g/ha in both pre- and post-emergence treatments. So, compounds 3 can be used as a lead compound for further structure optimization for developing potential selective herbicidal agent. Their preliminary structure-activity relationships were also investigated.