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PDF file - 87K, Broad panel kinase selectivity of compound 69407.

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PDF file - 94K, Effect of compound 69407 on Aurora B kinase activity.

Acetylcholinesterase (AChE) is a pivotal enzyme that is closely related with multiple neurological diseases, such as brain disorders or alterations in the neurotransmission and cancer. The development of convenient methods for imaging AChE activity in biological samples is very important to understand its mechanisms and functions in a living system. Herein, a fluorescent probe exhibiting emission in the near-infrared (NIR) region is developed to detect AChE and visualize biological AChE activities. This probe exhibits a quick response time, reasonable detection limit, and a large Stokes shift accompanied by the NIR emission. The probe has much better reactivity toward AChE than butyrylcholinesterase, which is one of the significant interfering substances. The outstanding specificity of the probe is proved by cellular imaging AChE activity and successful mapping in different regions of zebrafish. Such an effective probe can greatly contribute to ongoing efforts to design emission probes that have distinct properties to assay AChE in biological systems.

Two new polyketide glycosides jejuketomycins A (1) and B (2), were isolated from a culture of Streptomyces sp. KCB15JA151.

A new homocysteine thiolactone derivative, thiolactomide (1), was isolated along with a known compound, N-acetyl homocysteine thiolactone (2), from a culture extract of soil-derived Streptomyces sp. RK88-1441. The structures of these compounds were elucidated by detailed NMR and MS spectroscopic analyses with literature study. Biological evaluation studies revealed that both 1 and 2 exhibit neuroprotective activity against 6-hydroxydopamine (6-OHDA) mediated neurotoxicity by blocking generation of hydrogen peroxide in neuroblastoma SH-SY5Y cells.

Three new trichostatin analogues, ulleunganilines A-C (1-3), and seven known trichostatins (4-10) were isolated from cultures of Streptomyces sp. 13F051. NMR, UV, and MS data indicated that the planar structures of 1-3 consisted of modified side chains in the trichostatic acid moiety. The absolute configuration of the 2,4-dimethyl-branched carbon chains in 1 and 2 was determined by the PGME method, while the amino acid group in 3 was identified by advanced Marfey's method. Based on the structure of the modified side chains, the origin of 1-3 is proposed. Further experiments indicated that 1 and 3 displayed moderate histone deacetylase inhibitory activity, suggesting that not only the hydroxamate group but also the N,N-dimethyl group were essential for the inhibitory activity.

A bioassay-guided investigation led to the isolation of three new carbazole glycosides, jejucarbazoles A–C (1–3), from Streptomyces sp. KCB15JA151. Their planar structures were elucidated by detailed NMR and MS spectroscopic analysis with a literature study. Their relative and absolute configurations were established by ROESY correlations, coupling constants, LC-MS analysis of thiocarbamoyl-thiazolidine carboxylate derivatives, and ECD calculation. Compounds 1–3 showed indoleamine 2,3-dioxygenase 1 (IDO1) inhibitory activity with IC50 values of 18.38, 9.17, and 8.81 μM. The molecular docking analysis suggested that all compounds act as heme-displacing inhibitors against IDO1 enzyme.

In this study, screening by LC-MS and cytotoxicity-guided isolation led to the identification of ulleungamide C (1), a previously unknown pipecolic acid-rich branched cyclic depsipeptide, from a soil actinobacterium Streptomyces sp. KCB13F003. The structure of 1 was determined by interpretation of spectroscopic and spectrometric data from 1D and 2D NMR and HRESIMS experiments. Antiproliferative assays using mammalian cancerous cells revealed that 1 inhibits the proliferation of HL-60 human promyelocytic leukemia cells. Cell cycle analysis showed an increased accumulation of cells in the G0/G1 phase after treatment with 1. Results of immunoblotting assays revealed that 1 reduced the expression levels of cyclin-dependent kinase 4 (CDK4), CDK6, retinoblastoma protein (Rb), and phosphorylated Rb, whereas it induced cyclin-dependent kinase inhibitor 1B (p27/Kip1) expression.

LC/MS-based chemical screening of culture extract led to a new highly oxygenated angucycline derivative, grecocycline D (1), from Streptomyces sp. KCB15JA014, isolated from a soil sample of Oedolgae in Jeju Island, Korea. The planar structure was determined on the basis of spectroscopic analysis, including 1D and 2D NMR techniques as well as HRESIMS and comparison with data from the literature. A relative and absolute configuration of 1 was assigned by ROESY experiment and electronic circular dichroism calculation. Compound 1 showed weak inhibitory activity against indoleamine 2,3-dioxygenase.

Xylaria species are prolific natural product producers. Here, we report the characterization of a new glycosylated incisterol derivative, called xyloneside A (1) and two known lignans (2 and 3) from the ascomycetous Xylaria sp. FB. The structure of xyloneside A (1) was determined by 1D and 2D NMR spectroscopy, high-resolution electrospray ionization mass spectrometry and electronic circular dichroism measurements. Xyloneside A is composed of a 1,2,3,4,5,10,19-heptanorergosterane skeleton and a β-D-mannopyranose moiety. This is the first report of an incisterol derivative from an Ascomycete. The biological effects of the isolated metabolites on cytotoxicity, autophagy, cell-migration, and angiogenesis were evaluated.

We previously identified a new heparinase inhibitor fungal metabolite, named CRM646-A, which showed inhibition of heparinase and telomerase activities in an in vitro enzyme assay and antimetastatic activity in a cell-based assay. In this study, we elucidated the mechanism by which CRM646-A rapidly induced nucleus condensation, plasma membrane disruption and morphological changes by increasing intracellular Ca2+ levels. Furthermore, PD98059, a mitogen-activated protein kinase (MEK) inhibitor, inhibited CRM646-A-induced nucleus condensation through ERK1/2 activation in rat 3Y1 fibroblast cells. We identified CRM646-A as a Ca2+ ionophore-like agent with a distinctly different chemical structure from that of previously reported Ca2+ ionophores. These results indicate that CRM646-A has the potential to be used as a new and effective antimetastatic drug.

Kurarinone (KR), a naturally occurring flavonoid in Sophora flavescens Aiton and a traditional herbal medicine, reportedly has anti-cancer activity against various cancer types both in vitro and in vivo. However, the cellular mechanism of KR remains unknown. Therefore, we aimed to elucidate the mechanism of cell cycle arrest induced by KR in human colorectal cancer cells. KR not only reduced cell proliferation but also induced G0/G1 arrest of colorectal cancer cell lines. The results of western blotting analysis showed that KR reduced the protein levels of cyclin D1/D3 and CDK4/6 by downregulating signaling proteins such as K-RAS, c-MYC, and p-extracellular signal-regulated kinase. Additionally, KR arrested the cell cycle in the G0/G1 phase in a p53-independent manner, and decreased the protein level of K-RAS by proteasomal degradation dependent on WDR76, an E3 ubiquitin ligase. From these results, we propose that KR could be a potent anti-cancer agent, acting through the degradation of K-RAS dependent on WDR76, regardless of the p53 status.

A LC-MS-guided screening led to the isolation of two new streptimidone derivatives (2 and 3) containing a glutarimide ring and two glutarimide ring-opened compounds (4 and 5) along with a known glutarimide-containing polyketide, streptimidone (1) from Streptomyces sp. W3002 strain. Their structures were elucidated by MS and NMR spectroscopic analyses and by comparison with data from the literature. Compound 2 is a non-hydroxylated analog at the C-5 position of streptimidone. The structure of 3 was determined as a streptimidone derivative possessing the α, β-unsaturated ketone moiety at positions C-5 and C-6. Compound 4 had similar chemical shifts and splitting patterns with 3, but the glutarimide ring is opened. Compound 5 closely resembles that of 4 with the only difference being the existence of an additional methoxy group instead of an amide group. Streptimidone (1) and 3 showed weak cytotoxic activity against three human cancer cell lines, respectively.

Phenalenone derivatives sourced from fungi are polyketides that have attracted significant interest because of their diverse chemical structures and potential bioactivities. As part of our ongoing quest to discover novel natural products with biological properties from diverse natural resources, three unreported phenalenone derivatives (1-3), named ent-12-methoxyisoherqueinone (1), (-)-scleroamide (2), and (+)-scleroamide (3), together with four known phenalenone derivatives, ent-atrovenetinone (4), isoherqueinone (5), herqueinone (6), and ent-peniciherquinone (7) were isolated from the Hawaiian soil fungus Penicillium herquei FT729, collected on the Big Island, Hawaii. Compounds 2 and 3 were enantiomers, which were separated using a chiral-phase HPLC column, which provided optically pure compounds 2 and 3. The structures of the novel compounds were established by extensive spectroscopic analyses, including 1D and 2D NMR and high-resolution ESIMS. Their absolute configurations were determined using quantum chemical electronic circular dichroism (ECD) calculations. The inhibitory activity of the isolated compounds (1-7) against indoleamine 2,3-dioxygenase 1 (IDO1) was assessed. Compounds 1, 5-7 inhibited IDO1, with IC

A chemical investigation of a culture extract from

Two new fusicoccane-type diterpenoids, streptooctatins A (1) and B (2), together with a known compound cyclooctatin (3) were isolated from Streptomyces sp. KCB17JA11. The structures of 1 and 2 were determined by analyzing spectroscopic and spectrometric data from 1D and 2D NMR and HRESIMS experiments. Compounds 1 and 2 induced EGFP-LC3 puncta indicating autophagic activities against HeLa cells without cytotoxicity.

Spinal muscular atrophy (SMA) is caused by homozygous survival of motor neurons 1 (SMN1) gene deletion, leaving a duplicate gene, SMN2, as the sole source of SMN protein. However, a defect in SMN2 splicing, involving exon 7 skipping, results in a low level of functional SMN protein. Therefore, the upregulation of SMN protein expression from the SMN2 gene is generally considered to be one of the best therapeutic strategies to treat SMA. Most of the SMA drug discovery is based on synthetic compounds, and very few natural compounds have been explored thus far. Here, we performed an unbiased mechanism-independent and image-based screen of a library of microbial metabolites in SMA fibroblasts using an SMN-specific immunoassay. In doing so, we identified brefeldin A (BFA), a well-known inhibitor of ER-Golgi protein trafficking, as a strong inducer of SMN protein. The profound increase in SMN protein was attributed to, in part, the rescue of the SMN2 pre-mRNA splicing defect. Intriguingly, BFA increased the intracellular calcium concentration, and the BFA-induced exon 7 inclusion of SMN2 splicing, was abrogated by the depletion of intracellular calcium and by the pharmacological inhibition of calcium/calmodulin-dependent kinases (CaMKs). Moreover, BFA considerably reduced the expression of Tra2-β and SRSF9 proteins in SMA fibroblasts and enhanced the binding of PSF and hnRNP M to an exonic splicing enhancer (ESE) of exon 7. Together, our results demonstrate a significant role for calcium and its signaling on the regulation of SMN splicing, probably through modulating the expression/activity of splicing factors.

Three new trichostatin analogues, ulleunganilines A-C (

A new homocysteine thiolactone derivative, thiolactomide (1), was isolated along with a known compound

The initiation of centrosome duplication is regulated by the Plk4/STIL/hsSAS-6 axis; however, the involvement of other centrosomal proteins in this process remains unclear. In this study, we demonstrate that Cep131 physically interacts with Plk4 following phosphorylation of residues S21 and T205. Localizing at the centriole, phosphorylated Cep131 has an increased capability to interact with STIL, leading to further activation and stabilization of Plk4 for initiating centrosome duplication. Moreover, we found that Cep131 overexpression resulted in centrosome amplification by excessive recruitment of STIL to the centriole and subsequent stabilization of Plk4, contributing to centrosome amplification. The xenograft mouse model also showed that both centrosome amplification and colon cancer growth were significantly increased by Cep131 overexpression. These findings demonstrate that Cep131 is a novel substrate of Plk4, and that phosphorylation or dysregulated Cep131 overexpression promotes Plk4 stabilization and therefore centrosome amplification, establishing a perspective in understanding a relationship between centrosome amplification and cancer development.

A bioassay-guided investigation led to the isolation of three new carbazole glycosides, jejucarbazoles A-C (1-3), from

Autophagy plays an important role in maintaining tumor cell progression and survival in response to metabolic stress. Thus, the regulation of autophagy can be used as a strategy for anticancer therapy. Here, we report dutomycin (DTM) as a novel autophagy enhancer that eventually induces apoptosis due to excessive autophagy. Also, human serine protease inhibitor B6 (SERPINB6) was identified as a target protein of DTM, and its novel function which is involved in autophagy was studied for the first time. We show that DTM directly binds SERPINB6 and then activates intracellular serine proteases, resulting in autophagy induction. Inhibitory effects of DTM on the function of SERPINB6 were confirmed through enzyme- and cell-based approaches, and SERPINB6 was validated as a target protein using siRNA-mediated knockdown and an overexpression test. In a zebrafish xenograft model, DTM showed a significant decrease in tumor area. Furthermore, the present findings will be expected to contribute to the expansion of novel basic knowledge about the correlation of cancer and autophagy by promoting active further research on SERPINB6, which was not previously considered the subject of cancer biology.

Studies on ethanol-induced stress and acetaldehyde toxicity are actively being conducted, owing to an increase in alcohol consumption in modern society. In this study, ent-peniciherqueinone (EPQ) isolated from a Hawaiian volcanic soil-associated fungus Penicillium herquei FT729 was found to reduce the acetaldehyde-induced cytotoxicity and oxidative stress in PC12 cells. EPQ increased cell viability in the presence of acetaldehyde-induced cytotoxicity in PC12 cells. In addition, EPQ reduced cellular reactive oxygen species (ROS) levels and restored acetaldehyde-mediated disruption of mitochondrial membrane potential. Western blot analyses revealed that EPQ treatment increased protein levels of ROS-scavenging heme oxygenase-1 and superoxide dismutase, as well as the levels of aldehyde dehydrogenase (ALDH) 1, ALDH2, and ALDH3, under acetaldehyde-induced cellular stress. Finally, EPQ reduced acetaldehyde-induced phosphorylation of p38 and c-Jun N-terminal kinase, which are associated with ROS-induced oxidative stress. Therefore, our results demonstrated that EPQ prevents cellular oxidative stress caused by acetaldehyde and functions as a potent agent to suppress hangover symptoms and alcohol-related stress.

In this study, screening by LC-MS and cytotoxicity-guided isolation led to the identification of ulleungamide C (1), a previously unknown pipecolic acid-rich branched cyclic depsipeptide, from a soil actinobacterium Streptomyces sp. KCB13F003. The structure of 1 was determined by interpretation of spectroscopic and spectrometric data from 1D and 2D NMR and HRESIMS experiments. Antiproliferative assays using mammalian cancerous cells revealed that 1 inhibits the proliferation of HL-60 human promyelocytic leukemia cells. Cell cycle analysis showed an increased accumulation of cells in the G0/G1 phase after treatment with 1. Results of immunoblotting assays revealed that 1 reduced the expression levels of cyclin-dependent kinase 4 (CDK4), CDK6, retinoblastoma protein (Rb), and phosphorylated Rb, whereas it induced cyclin-dependent kinase inhibitor 1B (p27/Kip1) expression.

LC/MS-based chemical screening of culture extract led to a new highly oxygenated angucycline derivative, grecocycline D (1), from Streptomyces sp. KCB15JA014, isolated from a soil sample of Oedolgae in Jeju Island, Korea. The planar structure was determined on the basis of spectroscopic analysis, including 1D and 2D NMR techniques as well as HRESIMS and comparison with data from the literature. A relative and absolute configuration of 1 was assigned by ROESY experiment and electronic circular dichroism calculation. Compound 1 showed weak inhibitory activity against indoleamine 2,3-dioxygenase.

Melanoma is the most serious type of skin cancer and remains highly drug-resistant. Therefore, the discovery of novel effective agents against melanoma is in high demand. Herein, we investigated the cytotoxic activities in melanoma cells and underlying molecular mechanisms of beauvericin (BEA) and its analogue beauvericin G1 (BEA G1), which are cyclohexadepsipeptides isolated from fungi. BEA and BEA G1 significantly suppressed the growth, clonogenicity, migration, and invasion of A375SM human melanoma cells and promoted caspase-dependent apoptosis through upregulation of death receptors, as well as modulation of pro- and anti-apoptotic Bcl-2 family members. Furthermore, the effects of BEA and BEA G1 were associated with the suppression of multiple molecular targets that play crucial roles in melanoma oncogenesis, including ERK, JNK, p38, NF-&kappa, B, STAT3, and MITF. Notably, the cytotoxic efficacy of BEA G1 against A375SM cells was stronger than that of BEA. These findings suggest that BEA and BEA G1 can be further investigated as potent cytotoxic natural compounds for the suppression of melanoma progression.

New glycosylated 26-membered triene macrolides catenulisporolides, the first polyketide metabolites from Catenulispora species, were obtained by targeting slow-forming colonies on selection agar plates and applying long-term cultivation. Their structures, including the full stereochemistry, were defined by comprehensive spectroscopic and chemical methods and confirmed by bioinformatics analysis. Analysis of the genome sequence revealed the responsible biosynthetic gene cluster spanning ∼160 kbp, and feeding experiments with isotope-labeled precursors showed that isovaleric acid acts as a rare starter unit. Catenulisporolides exhibited antimalarial activities against resistant strains of Plasmodium falciparum, and enhanced activity was observed in semisynthetic derivatives.

A chemical investigation of a culture extract from a soil-derived Streptomyces sp. RK88-1441 led to the isolation and characterization of two new glycosylated anthraquinones, aturanosides A (1) and B (2), and a new anthraquinone derivative, aturanocin (3). The structures of these compounds were elucidated by detailed NMR and MS spectroscopic analyses. The absolute configurations of the sugar units, based on the magnitudes of the coupling constants, ROESY correlations, and chemical derivatization, from 1 and 2 are 6- O-[ N-acetyl-α-d-glucosamino-(1→2)-α-l-rhamnoside] and 6- O-α-l-rhamnoside, respectively. Compounds 1 and 2 showed no cytotoxicity against human umbilical vein endothelial cells (HUVECs), but significantly suppressed vascular endothelial growth factor (VEGF)-induced tube formation and invasion of HUVECs. The down-regulation of both the phosphorylation of VEGF receptor 2 and the expression of vascular endothelial cadherin at the protein level were also observed.

While exploring new angiogenesis inhibitors from microbial metabolites, we recently isolated ahpatinins C, E, and G from a soil‑derived Streptomyces sp. 15JA150. Ahpatinins C, E and G are known to have pepsin and renin inhibitory activities; however, their antiangiogenic activities and underlying molecular mechanisms have not been fully elucidated. In the present study, the antiangiogenic properties of ahpatinins C, E and G were investigated. The results revealed that the natural compounds significantly inhibited the vascular endothelial growth factor (VEGF)‑induced proliferation, invasion, adhesion, and tube formation of human umbilical vein endothelial cells (HUVECs) without exhibiting any cytotoxicity. It was also revealed that ahpatinin E effectively suppressed the neovascularization of the chorioallantoic membranes in growing chick embryos. Notably, ahpatinins C, E, and G led to the downregulation of VEGF‑induced activation of VEGF receptor 2 (VEGFR2) and its downstream signaling mediators, including AKT, ERK1/2, JNK, p38, and NF‑κB, in HUVECs. Moreover, they reduced the expression of matrix metalloproteinase (MMP)‑2 and MMP‑9 in the HUVECs following stimulation with VEGF. Furthermore, ahpatinins C, E, and G reduced the tumor cell‑induced invasion and tube forming abilities of HUVECs, as well as the expression of VEGF, by suppressing hypoxia‑inducible factor‑1α (HIF‑1α) activity in U87MG glioblastoma cells. Collectively, the present findings indicated that ahpatinins C, E, and G may be used in anticancer therapy by targeting tumor angiogenesis through the inhibition of both VEGFR2 and HIF‑1α pathways.