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Biomedical subjects

Jung Sook Kang

Publications and source records attributed to Jung Sook Kang.

16 recordsLinked to original sources
PubMed2006

A new antibacterial dioxopiperazine alkaloid related to gliotoxin from a marine isolate of the fungus Pseudallescheria.

A new antibacterial dioxopiperazine, dehydroxybisdethiobis(methylthio)gliotoxin (1), and the previously described bisdethiobis(methylthio)gliotoxin (2) and gliotoxin (3), have been isolated from the broth of a marine-derived fungus of the genus Pseudallescheria. The structure and absolute stereochemistry of the new compound was assigned on the basis of NMR and CD experiments. Compounds 1 to approximately 3 exhibit potent antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus with MIC values of 31.2, 31.2, and 1.0 microg/ml, respectively. Compound 3 also exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 value of 5.2 microM.

Anti-Bacterial Agents↗
PubMed2006

A new radical scavenging anthracene glycoside, asperflavin ribofuranoside, and polyketides from a marine isolate of the fungus microsporum.

A new anthracene glycoside, asperflavin ribofuranoside (1), and the previously described polyketides, flavoglaucin (2), isodihydroauroglaucin (3), and citrinin (4) have been isolated from the marine-derived fungus Microsporum sp. The structure and absolute stereochemistry of a new compound (1) was assigned on the basis of physicochemical data. Compounds 1-3 exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC(50) values of 14.2, 11.3, and 11.5 microM, respectively, which are more potent than the positive control, ascorbic acid (IC(50), 20 microM). Compound 1 also showed a moderate antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus (MRSA and MDRSA) with MIC value of 50 microg/ml.

Anthracenes↗
PubMed2005

Dynamics of supercoiled and linear pBluescript II SK(+) Phagemids probed with a long-lifetime metal-ligand complex.

We extended the measurable time scale of DNA dynamics to microsecond using [Ru(phen)(2)(dppz)](2+)(phen = 1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine)(RuPD) , which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids ( = 489.7 ns) was somewhat shorter than that for the linear phagemids ( = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.

DNA, Superhelical↗
PubMed2005

Myrothenones A and B, cyclopentenone derivatives with tyrosinase inhibitory activity from the marine-derived fungus Myrothecium sp.

New 3-amino-5-ethenylcyclopentenones, myrothenones A (4) and B (5), were isolated together with known 6-n-pentyl-alpha-pyrone (1), trichodenone A (2), and cyclonerodiol (3) from the marine algicolous fungus of genus of Myrothecium. The structure and absolute stereochemistry of the new compounds were established by spectral interpretation and X-ray analysis. Compounds 1 and 4 exhibited a tyrosinase inhibitory activity with IC(50) value of 0.8 and 6.6 muM, respectively, which are more active than kojic acid (IC(50), 7.7 muM) currently being used as a functional personal-care compound.

Ascomycota↗
PubMed2004

Golmaenone, a new diketopiperazine alkaloid from the marine-derived fungus Aspergillus sp.

A new diketopiperazine alkaloid, golmaenone (1). and related alkaloids, neoechinulin A (2). and L-alanyl-L-tryptophan anhydride (3). have been isolated from the culture broth of the marine-derived fungus Aspergillus sp. The structure and absolute stereochemistry of the new compound (1). was assigned by spectroscopic methods and the advanced Marfey's method. Compounds 1 and 2 exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC(50) values of 20 and 24 microM, respectively, which are similar to the positive control, ascorbic acid (IC(50), 20 microM). Compounds 1 and 2 also showed an ultraviolet-A (UV-A) (320--390 nm) protecting activity with ED(50) values of 90 and 170 microM, respectively, which are more active than oxybenzone (ED(50), 350 microM) currently being used as sunscreen.

Ascorbic Acid↗
PubMed2003

Gamma-pyrone derivatives, kojic acid methyl ethers from a marine-derived fungus Alternaria [correction of Altenaria] sp.

Kojic acid dimethyl ether (1), and the known kojic acid monomethyl ether (2), kojic acid (3) and phomaligol A (4) have been isolated from the organic extract of the broth of the marine-derived fungus Alternaria sp. collected from the surface of the marine green alga Ulva pertusa. The structures were assigned on the basis of comprehensive spectroscopic analyses. Each isolate was tested for its tyrosinase inhibitory activity. Kojic acid (3) was found to have significant tyrosinase inhibitory activity, but compounds 1, 2, and 4 were found to be inactive.

Alternaria↗
PubMed2003

New polyoxygenated farnesylcyclohexenones, deacetoxyyanuthone A and its hydro derivative from the marine-derived fungus Penicillium sp.

New polyoxygenated farnesylcyclohexenones, 7-deacetoxyyanuthone A (1) and its 2,3-hydro derivative (2), were isolated together with the known farnesylquinones (3, 4) from a marine isolate of the genus Penicillium. The structures of the new deacetoxyyanuthone A (1) and its 2,3-hydro derivative (2) were assigned by spectroscopic methods, including 2D NMR and CD for the Cotton effect of alpha-epoxyketone experiments. Compounds 1 and 3 showed moderate in vitro cytotoxicity in a panel of five human tumor cell lines, and 1 also exhibited mild in vitro antibacterial activity against methicillin-resistant and multidrug-resistant Staphylococcus aureus (MIC, 50 microg/mL).

Anti-Bacterial Agents↗
PubMed2003

Microbial transformation of terreusinone, an ultraviolet-A (UV-A) protecting dipyrroloquinone, by Streptomyces sp.

Biotransformation study was conducted on the marine dipyrroloquinone, terreusinone (1) isolated from the marine-derived fungus Aspergillus terreus. Preparative-scale fermentation of terreusinone with Streptomyces sp. has resulted in the isolation of a new oxidized metabolite, terreusinol (2). The structure was elucidated as 2-[(1R)-1-hydroxyisobutyl]-6-[(1R)-1,2-dihydroxyisobutyl]-1H,5H-pyrrolo[2,3-b]indole-4,8-dione (2) on the basis of physicochemical evidence. Terreusinol (2) showed an ultraviolet-A (UV-A) (320-390 nm) protecting activity with ED(50) values of 150 microM, which is more active than oxybenzone (ED(50), 350 microM) currently being used as sunscreen.

Aspergillus↗
PubMed2002

Ratiometric pH measurements using LysoSensor DND-192.

A method for the ratiometric pH sensing using LysoSensor DND-192 is presented in this paper. It works in the physiological pH range. It is based on the use of two fluorophores which differ significantly in their lifetimes. As the discrimination of their emissions is performed through two different frequencies, this method can allow significant overlap of the emission spectra. A simple long-pass filter, or a combination of long- and short-pass filters, was used instead of narrow-bandpass devices. Importantly, the measurements were carried out under strong ambient light. The method could be used in a wide variety of applications, such as intracellular measurements, microscopy, bioprocess monitoring, etc.

Fluorescent Dyes↗
PubMed2002

Dynamics of supercoiled and relaxed pTZ18U plasmids probed with a long-lifetime metal-ligand complex.

[Ru(bpy)2(dppz)](2+) (bpy = 2,2'-bipyridine, dppz = dipyrido- [3,2-a:2',3'-c]phenazine) (RuBD), a long-lifetime metalligand complex, displays favorable photophysical properties. These include long lifetime, polarized emission, but no significant fluorescence from the complex that is not bound to DNA. To show the usefulness of this luminophore (RuBD) for probing the bending and torsional dynamics of nucleic acids, its intensity and anisotropy decays when intercalated into supercoiled and relaxed pTZ18U plasmids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetimes for the supercoiled plasmids (< tau > = 148 ns) were somewhat shorter than those for the relaxed plasmids (< tau > = 160 ns). This suggests that the relaxed plasmids were shielded more efficiently from water. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled plasmids (288 ns) than for the relaxed plasmids (355 ns). The presence of two rotational correlation times suggests that RuBD reveals both the bending and torsional motions of the plasmids. These results indicate that RuBD can be useful for studying both the bending and torsional dynamics of nucleic acids.

DNA, Superhelical↗
PubMed2002

High-molecular-weight protein hydrodynamics studied with a long-lifetime metal-ligand complex.

[Ru(2,2'-bipyridine)(2)(4,4'-dicarboxy-2,2'-bipyridine)](2+) (RuBDc) is a very photostable probe that possesses favorable photophysical properties including long lifetime, high quantum yield, large Stokes' shift, and highly polarized emission. In the present study, we demonstrated the usefulness of this probe for monitoring the rotational diffusion of high-molecular-weight (MW) proteins. Using frequency-domain fluorometry with a high-intensity, blue light-emitting diode (LED) as the modulated light source, we compared the intensity and anisotropy decays of RuBDc conjugated to immunoglobulin G (IgG) and immunoglobulin M (IgM), which show a six-fold difference in MW We obtained slightly longer lifetimes for IgM ( =428 ns in buffer) than IgG ( =422 ns in buffer) in the absence and presence of glycerol, suggesting somewhat more efficient shielding of RuBDc from water in IgM than in IgG. The anisotropy decay data showed longer rotational correlation times for IgM (1623 and 65.7 ns in buffer) as compared to IgG (264 and 42.5 ns in buffer). Importantly, the ratio of the long rotational correlation times of IgM to IgG in buffer was 6.2, which is very close to that of MW of IgM to IgG (6.0). The shorter correlation times are most likely to be associated with domain motions within the proteins. The anisotropy decays reflect both the molecular size and shape of the immunoglobulins, as well as the viscosity. These results show that RuBDc can have numerous applications in studies of high-MW protein hydrodynamics and in fluorescence polarization immunoassays (FPI) of high-MW analytes.

2,2'-Dipyridyl↗
PubMed2002

Dynamics of supercoiled and linear pTZ18U plasmids observed with a long-lifetime metal-ligand complex.

The metal-ligand complex, [Ru(bpy)2(dppz)]2+ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (Ru-BD), was used as a spectroscopic probe for studying nucleic acid dynamics. The Ru-BD complex displays a long lifetime of over 100 ns and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To further show the usefulness of this luminophore (Ru-BD) for probing DNA dynamics, we examined its intensity and anisotropy decays when intercalated into supercoiled and linear pTZ18U plasmids using frequency-domain fluorometry with a light-emitting diode (LED) as the modulated light source. Compared to the supercoiled plasmids with an average intensity decay time of 120.8 ns at 25 degrees C, we obtained somewhat longer lifetimes for the linear plasmids ((tau) = 141.4 ns at 25 degrees C), suggesting a more efficient shielding from water by the linear plasmids. The anisotropy decay data also showed longer rotational correlation times for the linear plasmids (495 and 35 ns at 25 degrees C) as compared to the supercoiled plasmids (412 and 27 ns at 25 degrees C). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the plasmids, respectively. The anisotropy values were quite similar, although the values of the supercoiled plasmids were slightly higher in both the steady-state and anisotropy decay measurements. These results indicate that Ru-BD can be applied in the study of both bending and torsional dynamics of nucleic acids.

DNA, Superhelical↗
PubMed2002

DNA dynamics: a fluorescence resonance energy transfer study using a long-lifetime metal-ligand complex.

Fluorescent probes bound to DNA typically display nanosecond decay times and reveal only nanosecond motions. We extend the time range of measurable DNA dynamics using [Ru(bpy)2(dppz)]2+ (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c]phenazine) (RuBD) which displays a mean lifetime near 90 ns. To test the usefulness of RuBD as a probe for diffusive processes in calf thymus DNA, we compared the efficiencies of fluorescence resonance energy transfer (FRET) using three donors which display lifetimes near 5 ns for acridine orange (AO), 22 ns for ethidium bromide (EB) and 92 ns for RuBD, with nile blue (NB) as the acceptor. The Forster distances for AO-NB, EB-NB and RuBD-NB donor-acceptor pairs were 42.3, 52.3, and 30.6 A, respectively. All three donors showed dramatic decreases in fluorescence intensities and more rapid intensity decays with increasing NB concentrations. The intensity decays of AO and EB in the presence of varying concentrations of NB were satisfactorily described by the one-dimensional FRET model without diffusion (Blumen and Manz, 1979). In the case of the long-lifetime donor RuBD, the experimental phase and modulation somewhat deviated from the recovered values computed from this model. The recovered NB concentrations and FRET efficiencies from the model were slightly larger than the expected values, however, the recovered and expected values did not show a significant difference. Thus, it is suggested that the lifetime of RuBD is too short to measure diffusive processes in calf thymus DNA.

DNA↗
PubMed2002

Parasitenone, a new epoxycyclohexenone related to gabosine from the marine-derived fungus Aspergillus parasiticus.

Bioassay-guided fractionation of an organic extract of the broth from the marine-derived fungus culture of Aspergillus parasiticus led to the isolation and subsequent structural elucidation of a new gabosine derivative, parasitenone (1), and two known benzyl alcohols, 3-chloro-4,5-dihydroxybenzyl alcohol (2) and gentisyl alcohol (3). The benzyl alcohols (2, 3) were identified as the principal free radical scavenging components. Parasitenone (1) also showed moderate activity in the free radical scavenging assay.

Acetylation↗