Cha-Gyun Shin

HIV-1 integrase inhibitory phenylpropanoid glycosides from Clerodendron trichotomum.

Seven phenylpropanoid glycosides named acteoside (1), acteoside isomer (2), leucosceptoside A (3), plantainoside C (4), jionoside D (5), martynoside (6), and isomartynoside (7) were isolated from Clerodendron trichotomum. Compounds 1 and 2 showed potent inhibitory activities against HIV-1 integrase with IC50 values of 7.8 +/- 3.6 and 13.7 +/- 6.0 microM, respectively.

Cytotoxicities of enniatins H, I, and MK1688 from Fusarium oxysporum KFCC 11363P.

Enniatins (ENs) H, I, and MK1688 and beauvericin (BEA) were purified from concentrated chloroform extracts of Fusarium oxysporum KFCC 11363P submerged cultures using HPLC, and their in vitro cytotoxicities were evaluated against four human carcinoma cell lines (lung, A549; ovarian, SK-OV-3; skin melanoma, SK-MEL-2; and colon, HCT15) using the sulforhodamine B (SRB) method. ENs I and MK1688 inhibited the growth of cancer cell lines most strongly and had similar cytotoxic effects on the tested human cancer cell cultures. The cytotoxicity of ENs I and MK1688 was three- to fourfold higher than that of BEA and EN H. When cultivated in Fusarium-defined medium (FDM), the concentrations of ENs and BEA produced in F. oxysporum KFCC 11363P decreased in the following order: EN MK1688 (0.81 g/L) >EN I (0.55 g/L) >BEA (0.17 g/L) > EN H (0.16 g/L). This study has shown that ENs H, I, and MK1688 exhibit cytotoxicity against certain adenocarcinoma cell lines. The results indicate the need for more investigations into the significance of the biological properties of these new ENs.

Inhibition of HIV-1 reverse transcriptase and HIV-1 integrase and antiviral activity of Korean seaweed extracts

Forty-seven species of marine macroalgae from the coast of Korea havebeen screened for the presence of inhibitory compounds against humanimmunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and HIV-1integrase (IN). One of 4 Chlorophyta, 8 of 17 Phaeophyta and 6 of 26 Rhodophytashowed inhibitory activity against HIV-1 reverse transcriptase. Five species(Ecklonia cava, Ishige okamurae,Sargassum confusum, Sargassumhemiphyllum, Sargassum ringgoldianum) belongingto Phaeophyta showed to inhibit the 3′-processing activity of HIV-1integrase. In cell-based assays, the methanol extracts ofBossiella sp. and Chondriacrassicaulis inhibited cytopathogenecity of HIV-1 at a concentrationbelow that cytotoxic for MT4 cells.

Apoptosis induced by enniatins H and MK1688 isolated from Fusarium oxysporum FB1501.

Enniatins are cyclic peptides isolated from bacteria, fungi, and plants, with numerous biological effects on animal systems. Recently, we have reported that certain enniatins (ENs), such as EN H and EN MK1688, have cytotoxic effects on several adenocarcinoma cell lines. In an effort to understand the mechanism behind their cytotoxicity, we investigated whether ENs can induce apoptosis in human colorectal carcinoma cells (HCT-15 cells). Treatment with the ENs H and MK1688 resulted in an alteration of cellular and nuclear morphology, leading to an increase in the number of the cells with apoptotic nuclei (seen as condensed or fragmented nuclei). Furthermore, it was observed that cellular DNA fragmentation increased in a dose-dependent manner in EN treated cells. These cells have elevated activity levels for caspase-3, the enzyme responsible for initiating cell death, compared with the untreated cells. Normal caspase-3 activity levels were observed when Z-VAD-FMK, a caspase inhibitor, was added simultaneously with the ENs. Based on our results, we propose that the new ENs H and MK1688 induce cytotoxicity via an apoptotic pathway.

HIV integrase inhibitory activity ofAgastache rugosa

We have been screening anti-HIV integrase compounds from Korean medicinal plants by using anin vitro assay system which is mainly composed of recombinant human immunodeficency virus type 1 integrase and radiolabeled oligonucleotides. From the above screening, the aqueous methanolic extract of the roots ofAgastache rugosa exhibited a significant activity. Bioactivity-guided chromatographic fractionation of the methanolic extract resulted in the isolation of rosmarinic acid. The structure of the compound was determined by spectroscopic data and by the comparison with the reported values. The IC50 of the rosmarinic acid was approximately 10 μ/ml against HIV integrase.

Beauvericin and enniatins H, I and MK1688 are new potent inhibitors of human immunodeficiency virus type-1 integrase

Some enniatins (ENs) reportedly exhibit antiretroviral activities in vivo. The potential inhibitory activities of cyclic hexadepsipeptides such as beauvericin (BEA) and ENs H, I and MK1688 were investigated in vitro against human immunodeficiency virus type-1 (HIV-1) integrase and Moloney murine leukemia virus reverse transcriptase. BEA, EN I and EN MK1688 exhibited strong inhibitory activities against HIV-1 integrase, whereas EN H showed relatively weak activity. None of the examined compounds showed anti-reverse transcriptase activity. BEA was the most effective inhibitor of the tested cyclic hexadepsipeptides in inhibiting HIV-1 integrase. These results indicate the potential of cyclic hexadepsipeptides as a new class of potent inhibitors of HIV-1 integrase.

Hormone-independent embryogenic callus production from ginseng cotyledons using high concentrations of NH4NO3 and progress towards bioreactor production

Cotyledon explants of Panax ginseng produced somatic embryos directly on solid hormone-free MS medium containing 3% (w/v) sucrose while high concentration of NH4NO3 (60 mM) induced embryogenic callus. Ten subcultures of the embryogenic callus on hormone-free MS medium with 40 mM NH4NO3 gave hormone-independent proliferation of callus, which exhibited proliferation potential even on MS medium with a standard level of NH4NO3 (20 mM). Pulse treatment of callus with exogenous auxin or cytokinin (1.0 mg 1−1 2,4-D, 1.0 mg 1−1 kinetin) resulted in the loss of the hormone-independent characteristic and caused the callus to brown. For the suspension culture, embryogenic callus was transferred to MS liquid medium containing 3% (w/v) sucrose in an 500 ml Erlenmyer flask. Embryogenic cell clumps in full-strength MS liquid medium discharged toxic substances, resulting in strong suppression of cell growth. In 1/3-strength MS medium, exudation of toxic material did not occur. Embryogenic cell clumps were mass-grown on a large-scale in a bioreactor (20-1), showing a 7.1 increase of fresh weight in 1/3-strength MS medium with 3% (w/ v) sucrose after 5 weeks of culture. Total ginsenoside content of cultured embryogenic cell clumps was low and 6 times below naturally-cultivated ginseng roots.

Synthesis and HIV-1 integrase inhibitory activities of caffeoylglucosides.

Caffeoylglucosides, which have a glucose ring as a central linker, were synthesized from methyl D-glucosides, and their anti-HIV-1 activities were tested. Among them, four dicaffeoylglucosides (IC50 = 29.1+/-35.1 microM), 6a, 6b, 9b and 10b, showed HIV-1 integrase inhibitory activity as potent as L-chicoric acid.

Cellular and viral determinants of retroviral nuclear entry

Retroviruses must integrate their cDNA into the host genome to generate proviruses. Viral DNA-protein complexes interact with cellular proteins and produce pre-integration complexes, which carry the viral genome and cross the nuclear pore channel to enter the nucleus and integrate viral DNA into host chromosomal DNA. If the reverse transcripts fail to integrate, linear or circular DNA species such as 1- and 2-long terminal repeats are generated. Such complexes encounter numerous cellular proteins in the cytoplasm, which restrict viral infection and protect the nucleus. To overcome host cell defenses, the pathogens have evolved several evasion strategies. Viral proteins often contain nuclear localization signals, allowing entry into the nucleus. Among more than 1000 proteins identified as required for HIV infection by RNA interference screening, karyopherins, cleavage and polyadenylation specific factor 6, and nucleoporins have been predominantly studied. This review discusses current opinions about the synergistic relationship between the viral and cellular factors involved in nuclear import, with focus on the unveiled mysteries of the host-pathogen interaction, and highlights novel approaches to pinpoint therapeutic targets.

Characterization of nuclear localization signals of the prototype foamy virus integrase.

To analyse the potential karyophilic activity of prototype foamy viruses (PFVs), we expressed the PFV integrase (IN) and its mutants as fusion proteins with enhanced green fluorescence protein. The subcellular localization of the fusion proteins was investigated by fluorescence microscopy. The PFV IN was found to be karyophilic and targeted the fusion protein to the nucleus. Mutational analyses demonstrated that the PFV IN contains a potent but non-transferable nuclear localization signal (NLS) in its C-terminal domain and contains five arginine and lysine residues between amino acids 308 and 329 that are critical for its NLS function.