Diverse Effects of Small Molecule Inhibitors on Actin Cytoskeleton Dynamics in HIV-1 Infection

The dynamics of the actin cytoskeleton plays a pivotal role in the process of cell division, the transportation of organelles, vesicle trafficking and cell movement. Human immunodeficiency virus type 1 (HIV-1) hijacks the actin dynamics network during the viral entry and migration of the pre-integration complex (PIC) into the nucleus. Actin dynamics linked to HIV-1 has emerged as a potent therapeutic target against HIV infection. Although some inhibitors have been intensely analyzed with regard to HIV-1 infection, their effects are sometimes disputed and the exact mechanisms for actin dynamics in HIV infection have not been well elucidated. In this study, the small molecules regulating HIV-1 infection from diverse inhibitors of the actin dynamic network were screened. Two compounds, including Chaetoglobosin A and CK-548, were observed to specifically bar the viral infection, while the cytochalasin family, 187-1, N-WASP inhibitor, Rho GTPase family inhibitors (EHop-016, CID44216842, and ML-141) and LIMK inhibitor (LIM domain kinase inhibitor) increased the viral infection without cytotoxicity within a range of ~ µM. However, previously known inhibitory compounds of HIV-1 infection, such as Latrunculin A, Jasplakinolide, Wiskostatin and Swinholide A, exhibited either an inhibitory effect on HIV-1 infection combined with severe cytotoxicity or showed no effects. Our data indicate that Chaetoglobosin A and CK-548 have considerable potential for development as new therapeutic drugs for the treatment of HIV infection. In addition, the newly identified roles of Cytochalasins and some inhibitors of Rho GTPase and LIMK may provide fundamental knowledge for understanding the complicated actin dynamic pathway when infected by HIV-1. Remarkably, the newly defined action modes of the inhibitors may be helpful in developing potent anti-HIV drugs that target the actin network, which are required for HIV infection.

Letalidad de citocalasina B y otros compuestos aislados del hongo Aspergillus spp. (Trichocomaceae) endófito de Bauhinia guianensis (Fabaceae) / Lethality of cytochalasin B and other compounds isolated from fungus Aspergillus sp. (Trichocomaceae) endophyte of Bauhinia guianensis (Fabaceae)

Los hongos endofíticos son hongos que colonizan los tejidos internos de las plantas; varios compuestos biológicamente activos se han aislado a partir de estos hongos. Existen pocos estudios de compuestos aislados de hongos endófitos de plantas amazónicas. Por lo tanto, este estudio tuvo como objetivo el aislamiento y la identificación estructural de ergosterol (1), peróxido de ergosterol (2), mevalonolactona (3), citocalasina B (4) y citocalasina H (5) a partir de Aspergillus spp. EJC 04, un hongo endofítico de Bauhinia guianensis. La citocalasina B (4) y el derivado diacetato de citocalasina B (4a) mostraron una alta letalidad en el ensayo de Artemia salina. Esta es la primera aparición de citocalasinas en hongos endófitos amazónica de B. guianensis

Endophytic fungi are fungi that colonize internal tissues of plants; several biologically active compounds have been isolated from these fungi. There are few studies of compounds isolated from endophytic fungi of Amazon plants. Thus, this study aimed the isolation and structural identification of ergosterol (1), ergosterol peroxide (2), mevalonolactone (3), cytochalasin B (4) and cytochalasin H (5) from Aspergillus sp. EJC 04, an endophytic fungus from Bauhinia guianensis. The cytochalasin B (4) and the diacetate derivative of cytochalasin B (4a) showed high lethality in the brine shrimp assay. This is the first occurrence of cytochalasins in Amazonian endophytic fungi from B. guianensis

Antifungal activity of extracts from Atacama Desert fungi againstParacoccidioides brasiliensis and identification ofAspergillus felis as a promising source of natural bioactive compounds

Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity.

A new cytochalasin from endophytic Phomopsis sp. IFB-E060 / 中国天然药物

AIM@#To study the chemical constituents of the solid culture of the endophyte Phomopsis sp. IFB-E060 in Vatica mangachapoi.@*METHOD@#Isolation and purification were performed through silica gel column chromatography, gel filtration over Sephadex LH-20, ODS column chromatography, and HPLC. Structures of the isolated compounds were elucidated by a combination of spectroscopic analyses (UV, CD, IR, MS, 1D, and 2D NMR). The cytotoxicity of the isolates was evaluated in vitro by the MTT method against the human hepatocarcinoma cell line SMMC-7721.@*RESULTS@#Five compounds were isolated from the solid culture of the endophyte Phomopsis sp. IFB-E060 and their structures were identified as 18-methoxy cytochalasin J (1), cytochalasin H (2), (22E, 24S)-cerevisterol (3), ergosterol (4), and nicotinic acid (5). Compound 1 had an inhibition rate of 24.4% at 10 μg·mL(-1) and 2 had an IC50 value of 15.0 μg·mL(-1), while a positive control 5-fluorouracil had an inhibition rate of 28.7% at 10 μg·mL(-1).@*CONCLUSION@#18-Methoxy cytochalasin J (1), produced by endophytic Phomopsis sp. IFB-E060, is a new cytochalasin with weak cytotoxicity to the human hepatocarcinoma cell line SMMC-7721.

Production of cytochalasin B by Helminthosporium solani under different culture conditions and its effect on the mitosis of onion root cells

The optimum temperature for maximum production of cytochalasin B [CB] by Helminthosporium solani was 30°C. The optimum pH value was 5.5 - 6.0, and the maximum CB production was attained after nine days of incubation. Glucose and sodium nitrate were the best carbon and nitrogen sources for CB production. CB at the concentration of 30 microg/ml decreased the mitotic index [MI%] of Allium cepa L. [onion, Giza, 20] roots from 8.42 to 4.83%. The spindle constituents [microtubules] were affected in a way that gave rise to a number of chromosomal abnormalities, namely; stickiness, un-oriented, bridges, free and distributed spindles without multinucleated cells production. CB at this concentration decreased onion seed production by 5.7% compared with the control. CB also induced morphological changes to roots and decreased the root length

Ultrastructural cell surface alterations in developing embryos of frog (Microhyla ornata) treated with cytochalasins.

Scanning electron microscopic examination of M. ornata embryos treated with cytochalasins A, B and H (CA, CB and CH) showed extensive cell disaggregation resulting in large intercellular spaces and apparent loss of intercellular communication. All the three cytochalasins significantly reduced surface features, such as, filopodia and membrane ruffling which are considered essential for normal morphogenetic movements. Appreciable qualitative differences could not be detected in effects exerted by CA, CB and CH although potency of the three drugs clearly differed. The results demonstrate that in spite of the differences in their primary mechanisms of action, treatment with all the three cytochalasins culminates in comparable effects on the cell surface architecture resulting into abnormal morphogenesis.