A novel small-molecule PCSK9 inhibitor E28362 ameliorates hyperlipidemia and atherosclerosis.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the epidermal growth factor precursor homologous domain A (EGF-A) of low-density lipoprotein receptor (LDLR) in the liver and triggers the degradation of LDLR via the lysosomal pathway, consequently leading to an elevation in plasma LDL-C levels. Inhibiting PCSK9 prolongs the lifespan of LDLR and maintains cholesterol homeostasis in the body. Thus, PCSK9 is an innovative pharmacological target for treating hypercholesterolemia and atherosclerosis. In this study, we discovered that E28362 was a novel small-molecule PCSK9 inhibitor by conducting a virtual screening of a library containing 40,000 compounds. E28362 (5, 10, 20 µM) dose-dependently increased the protein levels of LDLR in both total protein and the membrane fraction in both HepG2 and AML12 cells, and enhanced the uptake of DiI-LDL in AML12 cells. MTT assay showed that E28362 up to 80 µM had no obvious toxicity in HepG2, AML12, and HEK293a cells. The effects of E28362 on hyperlipidemia and atherosclerosis were evaluated in three different animal models. In high-fat diet-fed golden hamsters, administration of E28362 (6.7, 20, 60 mg·kg-1·d-1, i.g.) for 4 weeks significantly reduced plasma total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C) and PCSK9 levels, and reduced liver TC and TG contents. In Western diet-fed ApoE-/- mice (20, 60 mg·kg-1·d-1, i.g.) and human PCSK9 D374Y overexpression mice (60 mg·kg-1·d-1, i.g.), administration of E28362 for 12 weeks significantly decreased plasma LDL-C levels and the area of atherosclerotic lesions in en face aortas and aortic roots. Moreover, E28362 significantly increased the protein expression level of LDLR in the liver. We revealed that E28362 selectively bound to PCSK9 in HepG2 and AML12 cells, blocked the interaction between LDLR and PCSK9, and induced the degradation of PCSK9 through the ubiquitin-proteasome pathway, which finally resulted in increased LDLR protein levels. In conclusion, E28362 can block the interaction between PCSK9 and LDLR, induce the degradation of PCSK9, increase LDLR protein levels, and alleviate hyperlipidemia and atherosclerosis in three distinct animal models, suggesting that E28362 is a promising lead compound for the treatment of hyperlipidemia and atherosclerosis.

Chromomycins from soil-derived Streptomyces sp. inhibit the growth of human non-small cell lung cancer cells by targeting c-FLIP.

Three chromomycin derivatives, chromomycins A3 (1, CA3), A5 (2, CA5), and monodeacetylchromomycin A3 (3, MDA-CA3), were identified from the soil-derived Streptomyces sp. CGMCC 26516. A reinvestigation of the structure of CA5 is reported, of which the absolute configuration was unambiguously determined for the first time to be identical with that of CA3 based on nuclear magnetic resonance (NMR) data analysis as well as NMR and electronic circular dichroism calculations. Compounds 1-3 showed potent cytotoxicity against the non-small-cell lung cancer (NSCLC) cells (A549, H460, H157-c-FLIP, and H157-LacZ) and down-regulated the protein expression of c-FLIP in A549 cells. The IC50 values of chromomycins in H157-c-FLIP were higher than that in H157-LacZ. Furthermore, si-c-FLIP promoted anti-proliferation effect of chromomycins in NSCLC cells. In nude mice xenograft model, 1 and 2 both showed more potent inhibition on the growth of H157-lacZ xenografts than that of H157-c-FLIP xenografts. These results verify that c-FLIP mediates the anticancer effects of chromomycins in NSCLC.

Moldavica acid A, a new salicylic acid derivative from Dracocephalum moldavica.

In this paper, we present the discovery of a novel salicylic acid derivative, moldavica acid A (1), and a new natural dibenzo[b,f]oxepin, moldavica acid B (2), together with four known phenylpropionic acids (3-6) and protocatechuic acid (7) that were isolated from Dracocephalum moldavica L. Their structures were elucidated by comprehensive spectroscopic methods, including infrared and nuclear magnetic resonance. Compound 1 is the first example of salicylic acid linking a carboxylated α-pyrone via an ethyl bridge. Beyond expanding the knowledge of the chemical diversity of D. moldavica, both compounds 1 and 2 were shown to upregulate the expression of Kruppel-like factor 2, which could serve as a prospective therapeutic target for the treatment of atherosclerosis.

Cytochalasin Derivatives from the Endozoic Curvularia verruculosa CS-129, a Fungus Isolated from the Deep-Sea Squat Lobster Shinkaia crosnieri Living in the Cold Seep Environment.

A new cytochalasin dimer, verruculoid A (1), three new cytochalasin derivatives, including 12-nor-cytochalasin F (2), 22-methoxycytochalasin B6 (3), and 19-hydroxycytochalasin B (4), and 20-deoxycytochalasin B (5), a synthetic product obtained as a natural product for the first time, together with four known analogues (6-9), were isolated and identified from the culture extract of Curvularia verruculosa CS-129, an endozoic fungus obtained from the inner fresh tissue of the deep-sea squat lobster Shinkaia crosnieri, which was collected from the cold seep area of the South China Sea. Structurally, verruculoid A (1) represents the first cytochalasin homodimer containing a thioether bridge, while 12-nor-cytochalasin F (2) is the first 12-nor-cytochalasin derivative. Their structures were elucidated by detailed interpretation of the NMR spectroscopic and mass spectrometric data. X-ray crystallographic analysis and ECD calculations confirmed their structures and absolute configurations. Compound 1 displayed activity against the human pathogenic bacterium Escherichia coli (MIC = 2 µg/mL), while compounds 4, 8, and 9 showed cytotoxicity against three tumor cell lines (HCT-116, HepG-2, and MCF-7) with IC50 values from 5.2 to 12 µM. The structure-activity relationship was briefly discussed.

Fusapyrone A, a γ-pyrone derived from a desert Fusarium sp.

In this work, we isolated and characterized fusapyrone A (1), a new γ-pyrone derivative, along with six previously described compounds from the rice fermentation of Fusarium sp. CPCC 401218, a fungus collected from the desert. The structure of 1 was characterized using various spectroscopic analyses, such as MS, IR, 1D, and 2D NMR. The absolute configuration of 1 was determined through the use of 13C NMR chemical shifts, electronic circular dichroism (ECD) and optical rotation (OR) calculations. Compound 1 was found to have weak antiproliferative activity for Hela cells, with an IC50 of 50.6 µM.[Formula: see text].

Synthesis and Biological Evaluation of Quinoline Derivatives as a Novel Class of Broad-Spectrum Antibacterial Agents.

Nineteen new quinoline derivatives were prepared via the Mannich reaction and evaluated for their antibacterial activities against both Gram-positive (G⁺) and Gram-negative (G-) bacteria, taking compound 1 as the lead. Among the target compounds, quinolone coupled hybrid 5d exerted the potential effect against most of the tested G⁺ and G- strains with MIC values of 0.125⁻8 µg/mL, much better than those of 1. Molecular-docking assay showed that compound 5d might target both bacterial LptA and Top IV proteins, thereby displaying a broad-spectrum antibacterial effect. This hybridization strategy was an efficient way to promote the antibacterial activity of this kind, and compound 5d was selected for the further investigation, with an advantage of a dual-target mechanism of action.

[Screening of small molecule inhibitors for PLK1 PBD and evaluation of antitumor activities].

With the method of fluorescence polarization (FP), we screened small molecule inhibitors for PLK1 PBD to identify the lead compounds for antitumor drugs. FP led to the identification of a potent hit, F083-0063, whose inhibition rate was (99.7 ± 0.4) % at 10 µg·mL−1. The IC50 was calculated to be 1.9 ± 0.1 µmol·L−1 using Graphpad Prism 5. The effect of the compound on cells' multiplication was measured by MTT assay which showed that F083-0063 inhibited the proliferation of many tumor cell lines. Flow cytometry analysis indicated that the F083-0063 promoted cell apoptosis and induced cell G2/M arrest. Migration abilities of cells, evaluated using scratch test, increased significantly in the presence of F083-0063 with the migration rate as low as (37.6 ± 0.7) % at 20 µmol·L−1. Molecular linkage technique found F083-0063 had good affinity with PLK1 PBD. The results of Western blotting showed that the expression of cyclin-dependent proteins was increased after treatment with F083-0063. In summary, F083-0063 has an antitumor activity and is expected to be an antitumor lead compound targeting PLK1 PBD.

[A new benzamide derivative from rice fermentation of Streptomyces sp. CPCC 202950].

Eight compounds were isolated from the rice fermentation of Streptomyces sp. CPCC 202950 by a combination of various chromatographic techniques including column chromatography over silica, Sephadex LH-20, flash C18, and reversed-phase HPLC. Their structures were identified as 3-[(3'-amino-3'-oxoprop-1'-en-2'-yl)oxy]benzamide (1), m-hydroxybenzamide (2), leptosphaepin (3), 5-methyluracil (4), feruloylamide (5), p-hydroxyphenylacetoamide (6), vanillamide (7), cyclo (L-val-L-ala) (8). Among them, 1 was a new benzamide analogue, and 2 was a new natural product. In the preliminary assays, none of the compounds 1-8 exhibited obvious inhibition of HIV-1 protease activity, and toxic with the Hela, HepG2, and U2OS cells. (IC50 > 10 µmol•L⁻¹).

[Evaluation of osteogenic effects of BMP2 up-regulator E40071 in vitro].

Bone morphogenetic protein 2(BMP2) plays a key role in bone development and reestablishment. In the study, we screened up-regulators of BMP2 among 20 000 compounds through a cell-based high throughput screening model and a positive compound E40071 [2-(4-(5-methyl-3-phenylpyrazolo[1,5-a]pyrimidin-7-yl) piperazin-1-yl)ethan-1-ol] was found as the positive hit. The EC(50) value of E40071 was 2.73 µmol·L(-1). In vitro, E40071 upregulated the m RNA levels of BMP2 and the downstream transcription factors, Runx2 and Osx in MC3T3-E1(subclone 14). Protein expression of Runx2 was up-regulated by E40071 through induction of Smad1/5/8 phosphorylation. The alkaline phosphatase(ALP) activity was increased by E40071. Moreover, E40071 promoted the mineralization of MC3T3-E1(subclone 14) by Alizarin red S staining. In addition, E40071 markedly inhibited osteoclast differentiation of mice macrophage Raw264.7 induced by RANKL and reduced the expression of osteoclast differentiation markers, including MMP9 and NFATc1. The results suggest that E40071 is able to promote bone formation activity of osteoblasts and inhibit differentiation of osteoclasts.

[In vitro effect and mechanistic study of compound E23869 on lipid metabolism].

This study was designed to identify inducers of ATP-binding cassette transporter A1(ABCA1) and CD36 and lysosomal integral membrane protein-II analogous-1(CLA-1) and to evaluate the in vitro effect of the active compound on lipid metabolism. Among 20 000 compounds screened, E23869 was found as a positive hit using cell-based high throughput screening models. The up-regulating activities of E23869 in ABCA1p-LUC and CLA-1p-LUC Hep G2 cells were 196% and 198%, respectively. The EC(50) values of E23869 in ABCA1p- LUC and CLA-1p-LUC Hep G2 cells were 0.25 µmol·L(-1) and 0.66 µmol·L(-1), respectively. E23869 significantly upregulated the protein levels of ABCA1, scavenger receptor class B type I(SR-BI)/CLA-1 and ATP-binding cassette transporter G1(ABCG1) in both macrophages RAW264.7 and L02 cells by Western blotting analysis. Foam cell assay showed that E23869 inhibited lipids accumulations in macrophages RAW264.7. Cholesterol efflux assay showed that E23869 induced HDL-mediated cholesterol efflux in macrophages RAW264.7. Moreover, E23869 up-regulated ABCA1, SR-BI/CLA-1 and ABCG1 expressions through activation of PPARα and PPARγ. In addition, E23869 weakly promoted in vitro differentiation of mouse preadipocytes 3T3-L1. In conclusion, E23869 up-regulated ABCA1, SR-BI/CLA-1 and ABCG1 expressions to promote cholesterol efflux, which is a good leading compound for regulation of lipid metabolism.

A new trichostatin analog from Streptomyces sp. CPCC 203909.

A new trichostatin analog (1) and two known analogs (2, 3) have been isolated from the rice fermentation of the Streptomyces sp. CPCC 203909. Their structures were determined by spectroscopic and chemical methods. The absolute configurations of 1 were assigned by Marfey's method, combined with comparing the NMR and circular dichroism spectroscopic data of 2 and 3. Compound 1 showed cytotoxicity against human embryonic kidney 293 cell line with IC50 value of 39.2 µM.

[The in vitro anti-atherosclerotic activity of compound E0869].

ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI/CLA-1) are the key proteins in reverse cholesterol transport (RCT). The high expression of ABCA1 and SR-BI/CLA-1 can decrease the danger of atherosclerosis. The purpose of the study is to find ABCA1 and CLA-1up-regulators for treating atherosclerosis by using cell-based high throughput screening models. Among 20 000 compounds screened, E0869 [1-(3, 4-dimethylphenyl)-1-oxopropan-2-yll4-((methylsulfonyl)methyl)benzoate] was found as the positive hit. The up-regulated activities of E0869 in ABCAl1-LUC and bCA-l1-LUC HepG2 cell were 160% and 175%, respectively. The EC50 values of E0869 in ABCAl1-LUC and CLA-l1-LUC HepG2 cell were 3.79 and 1.42 pµol- x ,(-1) respectively. E0869 could upregulate the mRNA and protein levels of ABCA1, SR-BI/CLA-1 and ABCGJ1genes in HepG2 and RAW264.7 cells by Real-Time Quantitative PCR and Western blotting analysis, but could not influence the expression of FAS, SREBP-l1 and CD36. Foam cell assay showed that E0869 could inhibit lipids accumulation in mouse peritoneal macrophages RAW264.7. Cholesterol efflux assay showed that E0869 could induce HDL-mediated cholesterol efflux in mouse peritoneal macrophages RAW264.7. In conclusion, E0869 could up-regulate ABCA1 and CLA-1 activity, and had good anti-atherosclerotic activity in vitro.

[A novel trichostatin analogue culture of Streptomyces sp. CPCC 203909].

By using a cell-based high throughput screening model for the CLA-1 up-regulator, Streptomyces 203909 was found to produce up-regulator of CLA-1. A novel trichostatin analogue was isolated from the rice fermentation of Streptomyces sp. CPCC 203909by a combination of various chromatographic techniques including column chromatography (CC) over silica gel, flash C18 CC, and reversed-phase HPLC. Its structure was identified as (-)-(R,2E,4Z)-7-[(4'-dimethylamino) phenyl]-4,6-dimethyl-7-oxohepta-2,4-dienoyl-L-glutamine (1) by the spectroscopic and chemical methods, and combination with the CD spectroscopy and Marfey's method. In the prelimi- nary assays, Compound 1 showed cytotoxicity against human embryonic kidney 293 cell line with IC50 value 35.3 [µmol · L(-1).

[Chemical constituents from culture of Streptomyces sp. CPCC 202950].

Eleven compounds were isolated from the culture of Streptomyces sp. CPCC 202950 by a combination of various chromatographic techniques including column chromatography over macroporous resin HP-20, MCI, and reversed-phase HPLC. Their structures were identified as 1H-pyrrole-2-carboxamide(1),5'-deoxy-5'-methylthioinosine(2), vanillamide(3), trans-3-methylthioacrylamide(4), 1,2,3,4-Tetraydro-1H-pyrido[3,4-b]indole-3-carboxylic acid(5), cyclo(L-pro-L-tyr) (6), N-[2-(4-hydroxyphenyl)]ethylacetamide(7), benzamide (8), cyclo ('L-leucyl-trans-4-hydroxy-L-proline)(9), cyclo-(Phe-Gly) (10), and tryptophan (11). Among them, compounds 1 and 2 were new natural products. In the preliminary assays, none of the compounds exhibited obvious inhibition of HIV-1 protease activity (IC50 > 10 micromol x L(-1)).

Crystal structure of tRNA m(1)A58 methyltransferase TrmI from Aquifex aeolicus in complex with S-adenosyl-L-methionine.

The N (1)-methyladenosine residue at position 58 of tRNA is found in the three domains of life, and contributes to the stability of the three-dimensional L-shaped tRNA structure. In thermophilic bacteria, this modification is important for thermal adaptation, and is catalyzed by the tRNA m(1)A58 methyltransferase TrmI, using S-adenosyl-L-methionine (AdoMet) as the methyl donor. We present the 2.2 Å crystal structure of TrmI from the extremely thermophilic bacterium Aquifex aeolicus, in complex with AdoMet. There are four molecules per asymmetric unit, and they form a tetramer. Based on a comparison of the AdoMet binding mode of A. aeolicus TrmI to those of the Thermus thermophilus and Pyrococcus abyssi TrmIs, we discuss their similarities and differences. Although the binding modes to the N6 amino group of the adenine moiety of AdoMet are similar, using the side chains of acidic residues as well as hydrogen bonds, the positions of the amino acid residues involved in binding are diverse among the TrmIs from A. aeolicus, T. thermophilus, and P. abyssi.

[Application of temperature sensitive yeast models with definite target in the screening of potential human Pin1 inhibitors].

This study is to explore new lead compounds by inhibition of Pin1 for anticancer therapy using temperature sensitive mutants. As Pin1 is conserved from yeast to human, we established a high-throughput screening method for Pin1 inhibitors, which employed yeast assay. This method led to the identification of one potent hits, 8-11. In vitro, 8-11 inhibited purified Pin1 enzyme activity with IC50 of (10.40 +/- 1.68) micromol x L(-1), induced G1 phase arrest and apoptosis, showed inhibitory effects on a series of cancer cell proliferation, reduced Cyclin D1 expression, was defined as reciprocally matched for protein-ligand complex in virtual docking analysis and reduced cell migration ability. In vivo, we could observe reduction of tumor volume after treatment with 8-11 in xenograft mice compared with vehicle DMSO treatment. Altogether, these results provide for the first time the involvement of 8-11 in the anticancer activity against Pin1.

[The in vitro anti-atherosclerotic activity of compound IMB-1680].

In the previous study, a high-throughput screening method was established to find the antagonists of CD36. In the present study, a new compound named IMB-1680 was found using this method. The anti-atherosclerotic activities of IMB-1680 were then evaluated. Dose-dependent activities of IMB-1680 were detected by using Sf9 [hCD36] and CHO [hCD36] models. Fluorescence microscopic photography and flow cytometry were used to analyze uptake of mLDL. Foam cell test with RAW264.7 macrophages was used to examine lipid accumulation. The results showed that IMB-1680 inhibited CD36 activity with IC50 of 2.80 and 8.79 micromol x L(-1) in Sf9[hCD36] and CHO [hCD36] cells, respectively. Fluorescence microscopic photography and flow cytometry revealed that IMB-1680 could significantly reduce DiI-AcLDL uptake. Meanwhile, IMB-1680 also could reduce lipids accumulation in RAW264.7 macrophages. In all, the data indicated that IMB-1680 might be a potent effective anti-atherosclerotic leading compound.

Three new isocoumarin analogues from an endolichenic fungus Aspergillus flavus CPCC 400810.

Five isocoumarin derivatives including three new compounds, aspermarolides A-C (1-3), and two known analogues, 8-methoxyldiaporthin (4) and diaporthin (5) were obtained from the culture extract of Aspergillus flavus CPCC 400810. The structures of these compounds were elucidated by spectroscopic methods. The double bond geometry of 1 and 2 were assigned by the coupling constants. The absolute configuration of 3 was determined by electronic circular dichroism experiment. All compounds showed no cytotoxic activities against the two human cancer cells HepG2 and Hela.

Substituted benzamides containing azaspiro rings as upregulators of apolipoprotein A-I transcription.

Apolipoprotein A-I (Apo A-I) is the principal protein component of high density lipoprotein (HDL), which is generally considered as a potential therapeutic target against atherosclerosis. The understanding of the Apo A-I regulation mechanism has fuelled the development of novel HDL targeted therapeutic approaches. To identify novel agents that can upregulate Apo A-I expression, we performed a cell-based reporter assay to screen 25,600 small molecules. Based on the dataset obtained from screening, a series of novel analogs of substituted benzamides containing azaspiro rings were assessed for their ability to induce the transcription of the Apo A-I gene, and the structure-activity relationship (SAR) around these analogs was also proposed. The results indicated that the trifluoromethyl substituted benzamide containing an azaspiro ring is a promising backbone for designing Apo A-I transcriptional upregulator and could be viable leads for development of new drugs to prevent and treat atherosclerosis in the future.

[Screening and identification of the upregulators of ATP-binding cassette transporter A1].

ATP-binding cassette transporter A1 (ABCA1) promotes cholesterol and phospholipid efflux from cells to lipid-poor apolipoprotein A-I (apoA-I), and plays a key role in the initial steps of the whole process of reverse cholesterol transport (RCT). Upregulation of ABCA1 is beneficial for atherosclerosis (AS) prevention and/or therapy, which indicated that ABCA1 was a target for anti-AS drug development. In the previous study, a high-throughput screening method was established using ABCA1p-LUC HepG2 cell line to find the upregulators of ABCA1. In the present study, compound 2030421B was found using this method, with EC50 of 0.50 microg x mL(-1). The compound was further identified as an upregulator of ABCA1 expression by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting analysis. Studies also showed that the 2030421B could induce apoA-I-mediated cholesterol efflux and inhibit lipids uptake into mouse peritoneal macrophages RAW264.7.