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.

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.

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.

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.

IMB5476, a novel microtubule inhibitor, induces mitotic catastrophe and overcomes multidrug resistance in tumors.

IMB5046 is a nitrobenzoate microtubule inhibitor we reported previously. During screening of its structural analogues, we identified a novel compound IMB5476 with increased aqueous solubility. Here, its antitumor activity and the underlying mechanism were investigated. IMB5476 disrupted microtubule networks in cells and arrested cell cycle at G2/M phase. It inhibited purified tubulin polymerization in vitro. Competition assay indicated that it bound to tubulin at the colchicine pocket. Further experiments proved that it induced cell death by mitotic catastrophe and apoptosis. Notably, it was a poor substrate of P-glycoprotein and exhibited potent cytotoxicity against drug-resistant tumor cells. In addition, IMB5476 could inhibit angiogenesis in vitro. IMB5476 also inhibited the growth of drug-resistant KBV200 xenografts in mice. Conclusively, our data reveal a novel nitrobenzoate microtubule inhibitor with improved aqueous solubility and can overcome multidrug resistance.

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].

Identification of Novel Compounds Enhancing SR-BI mRNA Stability through High-Throughput Screening.

Atherosclerosis is the pathological basis of most cardiovascular diseases. Reverse cholesterol transport (RCT) is a main mechanism of cholesterol homeostasis and involves the direct transport of high-density lipoprotein (HDL) cholesteryl ester by selective cholesterol uptake. Hepatic scavenger receptor class B member 1 (SR-BI) overexpression can effectively promote RCT and reduce atherosclerosis. SR-BI may be an important target for prevention or treatment of atherosclerotic disease. In our study, we inserted human SR-BI mRNA 3' untranslated region (3'UTR) downstream of the luciferase reporter gene, to establish a high-throughput screening model based on stably transfected HepG2 cells and to screen small-molecule compounds that can significantly enhance the mRNA stability of the SR-BI gene. Through multiple screenings of 25 755 compounds, the top five active compounds that have similar structures were obtained, with a positive rate of 0.19%. The five positive compounds could enhance the SR-BI expression and uptake of DiI-HDL in the hepatocyte HepG2. E238B-63 could also effectively extend the half-life of SR-BI mRNA and enhance the SR-BI mRNA and protein level and the uptake of DiI-HDL in hepatocytes in a time-dependent and dose-dependent manner. The structure-activity relationship analysis showed that the structure N-(3-hydroxy-2-pyridyl) carboxamide is possibly the key pharmacophore of the active compound, providing reference for acquiring candidate compounds with better activity. The positive small molecular compounds obtained in this study might become new drug candidates or lead compounds for the treatment of cardiovascular diseases and contribute to the further study of the posttranscriptional regulation mechanism of the SR-BI gene.

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.

Novel cathepsin K inhibitors block osteoclasts in vitro and increase spinal bone density in zebrafish.

Cathepsin K (Cat K) is a predominant cysteine protease and highly potent collagenase expressed in osteoclasts. Cat K inhibitors are anti-resorptive agents to treat osteoporosis. A novel scaffold of cathepsin K inhibitors, exemplified by lead compound 1x, was used as the template for designing and synthesizing a total of 61 derivatives that have not been reported before. An exploratory structure-activity relationship analysis identified the potent Cat K inhibitor A22, which displayed an IC50 value of 0.44 µM against Cat K. A22 was very specific for Cat K and caused a significantly higher in vitro inhibition of the enzyme as compared to that of lead compound 1x. A surface plasmon resonance analysis confirmed in vitro binding of A22 to Cat K. Molecular docking studies indicated several favourable interaction sites for A22 within the active pocket of Cat K. Furthermore, A22 also blocked active osteoclasts in vitro and increased spinal bone density in zebrafish, in which it showed an activity that was higher than that of the marketed therapeutic bone metabolizer etidronate disodium. A22 represents a very promising lead compound for the development of novel antiresorptive agents functioning as orthosteric inhibitors of Cat K.

T63 inhibits osteoclast differentiation through regulating MAPKs and Akt signaling pathways.

Inhibition of excessive osteoclast differentiation and activity is a valid approach for the treatment of osteoporosis. T63 is a small-molecule compound identified from a high throughput screening based on RUNX2 transcriptional activity, and has been reported to stimulate osteoblast formation. However, whether the compound has any effect on osteoclast differentiation remains unknown. Here, we examined the in vitro effect of T63 on osteoclastogenesis. T63 was found to inhibit the number of TRAP-positive cells in an osteoblast-osteoclast co-culture system, and inhibited Rankl expression in the preosteoblast MC3T3-E1 cells. The compound also directly suppressed RANKL-induced osteoclast differentiation in both dose- and time-dependent manner, as evidenced by the decrease of TRAP activity, F-actin formation and osteoclastogenesis-related genes expression in RAW264.7 cells. Moreover, pretreatment with T63 markedly decreased the activation of mitogen-activated protein kinases and Akt, both of which are positively involved in the regulation of osteoclastogenesis. Collectively, our findings suggest T63 has a protective effect against bone loss by inhibiting bone resorption. Its regulatory effect on bone metabolism makes the compound a more promising candidate for the potential application in the treatment of osteoporosis.

Ahmpatinin iBu, a new HIV-1 protease inhibitor, from Streptomyces sp. CPCC 202950.

Ahmpatinin iBu (1) and statinin iBu (2), two new linear peptides, a novel pyrrolidine derivative, (-)-(S)-2-[3-(6-methylheptanamido)-2-oxopyrrolidin-1-yl] acetic acid (3), and three known pepstatin derivatives (4-6) along with their corresponding methanolysis artifacts (7-9) were isolated from Streptomyces sp. CPCC 202950. Their structures were elucidated on the basis of extensive spectroscopic data using Marfey's analysis, chiral-phase HPLC, and ECD and OR calculation to determine the absolute configurations. Compound 1 contains an unusual amino acid, 4-amino-3-hydroxy-5-(4-methoxyphenyl)pentanoic acid (Ahmppa), and 3 is the first natural product with a 2-(3-amino-2-oxopyrrolidin-1-yl)acetic acid system. Compounds 1, 2, and 4-9 are HIV-1 protease inhibitors. In particular, ahmpatinin iBu (1) exhibits significant inhibitory activity against HIV-1 protease with an IC50 value of 1.79 nM. A preliminary structure-activity relationship is discussed.

Small molecule T63 suppresses osteoporosis by modulating osteoblast differentiation via BMP and WNT signaling pathways.

Osteoporosis results from the imbalance between bone resorption and bone formation, and restoring the normal balance of bone remodeling is highly desirable for identification of better treatment. In this study, using a cell-based high-throughput screening model representing Runt-related transcription factor 2 (RUNX2) transcriptional activity, we identified a novel small-molecular-weight compound, T63, as an efficient up-regulator of osteogenesis. T63 increased the alkaline phosphatase (ALPL) activity and mineralization as well as gene expression of Alpl and other osteogenic marker genes in mouse osteoblasts and mesenchymal stem cell-like cells. Upon induction of osteoblast differentiation, T63 inhibited adipogenic differentiation in the pluripotent mesenchymal cells. Consistently, T63 up-regulated RUNX2 mRNA and protein levels, and knockdown of RUNX2 reduced the osteogenic role of T63. Mechanistically, T63 activated both BMPs and WNT/ß-catenin signaling pathways. Inhibition of either signaling pathway with specific inhibitor suppressed T63-induced RUNX2 expression and the osteogenic phenotypes. Moreover, T63 markedly protected against bone mass loss in the ovariectomized and dexamethasone treated rat osteoporosis model. Collectively, our data demonstrate that T63 could be a promising drug candidate and deserves further development for potential therapeutics in osteoporosis.

[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).

Berberine-induced bioactive metabolites of the gut microbiota improve energy metabolism.

OBJECTIVE: Berberine (BBR) clinically lowers blood lipid and glucose levels via multi-target mechanisms. One of the possible mechanisms is related to its effect on the short chain fatty acids (SCFAs) of the gut microbiota. The goal of this study is to investigate the therapeutic effect and mode of action of BBR working through SCFAs of the gut microbiota (especially, butyrate). METHODS: Gas chromatography (GC) was used to detect butyrate and other SCFAs chemically. The effect of BBR on butyrate production was investigated in vitro as well as in several animal systems. Microarrays were used to analyze the composition change in the intestinal bacteria community after treatment with BBR. BBR-induced change in the energy production and gene regulation of intestinal bacteria was examined in order to elucidate the underlying molecular mechanisms. RESULTS: We show that oral administration of BBR in animals promoted the gut microbiota to produce butyrate, which then enters the blood and reduces blood lipid and glucose levels. Incubating gut bacterial strains in vitro with BBR increased butyrate production. Orally treating animals directly with butyrate reduced blood lipid and glucose levels through a mechanism different from that of BBR. Intraperitoneal BBR administration did not increase butyrate but reduced blood lipid and glucose levels, suggesting that BBR has two modes of action: the direct effect of the circulated BBR and the indirect effect working through butyrate of the gut microbiota. Pre-treating animals orally with antibiotics abolished the effect of BBR on butyrate. A mechanism study showed that BBR (given orally) modified mice intestinal bacterial composition by increasing the abundance of butyrate-producing bacteria. Furthermore, BBR suppressed bacterial ATP production and NADH levels, resulting in increased butyryl-CoA and, eventually, butyrate production via upregulating phosphotransbutyrylase/butyrate kinase and butyryl-CoA:acetate-CoA transferase in bacteria. CONCLUSION: Promotion of butyrate (etc) production in gut microbiota might be one of the important mechanisms of BBR in regulating energy metabolism.

[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 Novel Nitrobenzoate Microtubule Inhibitor that Overcomes Multidrug Resistance Exhibits Antitumor Activity.

Multidrug resistance is a major limitation for microtubule-binding agents in cancer treatment. Here we report a novel microtubule inhibitor (2-morpholin-4-yl-5-nitro-benzoic acid 4-methylsulfanyl-benzyl ester, IMB5046), its cytotoxicity against multidrug-resistant cell lines and its antitumor efficacy in animal models. IMB5046 disrupted microtubule structures in cells and inhibited purified tubulin polymerization in vitro. It bound to the colchicine pocket of tubulin. IMB5046 displayed potent cytotoxicity against multiple tumor cell lines with an IC50 range of 0.037-0.426 µM. Notably, several multidrug-resistant cell lines which were resistant to colchicine, vincristine and paclitaxel remained sensitive to IMB5046. IMB5046 was not a P-glycoprotein substrate. IMB5046 blocked cell cycle at G2/M phase and induced cell apoptosis. Microarray assay indicated that the differentially expressed genes after IMB5046 treatment were highly related to immune system, cell death and cancer. In a mouse xenograft model IMB5046 inhibited the growth of human lung tumor xenograft by 83% at a well-tolerated dose. It is concluded that IMB5046 is a tubulin polymerization inhibitor with novel chemical structure and can overcome multidrug resistance. It is a promising lead compound for cancer chemotherapy, especially for treatment of multidrug-resistant tumors.

[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 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).