• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.858-863
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• 2002

An antimicrobial compound was isolated from the MeOH extract of Catalpa ovata G.$D_{ON}$ fruits, and its structure was Identified as 4,9-dihydroxy-2,2-dimethyl-3,4-Uihydronaphtho[2,3-b]pyran-5,10-dione (HMNP). The antimicrobial activity of the Un was determined by measuring the dose-response inhibiton of microbial growth in liquid cultures and then compared with that of lapachol, a well known antimicrobial 1,4-naphthoquinone. The antimicrobial activity of the HMNP was more effective than that of lapachol over a wide range of test organisms. Gram-positive bacteria, yeast, and fungi ($IC_{50}$ $20-75\muM$) were found to be more sensitive to the HMNP than Cram-negative bacteria ($IC_{50}$ > $100\muM$). The HMNP also inhibited germination of spores of many fungi. The morphological defurmation of the fungal spores was induced by the treatment of HMNP, as illustrated by Scanning Electron Microscopy (SEM).

• Animal cells and systems
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• v.11 no.1
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• pp.9-15
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• 2007

The naphthoquinone analog (2,3-dichloro-6,9-dihydroxy-1,4-naphtoquinone, NA) has an inhibitory effect on cdc25A protein phosphatase in vitro, which is responsible for G1/S transition during cell cycle. However, the exact mechanism inducing the growth inhibition is not understood. In this study, we investigated the regulatory mechanisms of growth arrest induced by NA, as a new potent inhibitor of cdc25A phosphatase, in human hepatocarcinoma SK-hep-1 cells. We found that NA induced the G1 arrest by perturbation of protein tyrosine dephosphorylation of Cdk2, which may be resulting from inhibition of cdc25A phosphatase. In addition, p21 was expressed in a p53-independent manner and participated in the NA-induced G1 arrest by inhibiting Cdk2 activity. Although the exact mechanism is not known, the p21 expression might be related to MAPK activation. From these results, we suggest that NA induces G1 arrest via inhibition of cdc25A and induction of p53-independent p21 expression in SK-Hep-1 cells.

• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.269-279
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• 1975

Photosensitive properties of naphthoquinone-1,2-diazide-5-sulfonyl esters (PGND, BEND and PVAND) of polyglyceryl phthalate(PG), bisphenol A-epichlorohydrin condensate(BE) and polyvinyl alcohol(PVA) were investigated by the change of solubility before and after exposing to light. Various samples coated on glass or quartz plates were exposed to light under various conditions and steeped in aqueous alkali solution, and then the yield of residual film(W/W0) was determined. The yield of residual film, which was closely related to the sensitivity of the film, was affected by the degree of polymerization of the backbone resin, sensitizers and their concentration. In polymer homologs, the sensitivity was dependent on the degree of polymerization(the higher, the better). And also, it was most effective when 5 % of sensitizers to esters was used. The minimum exposed time was 0.6 min. for PGND-1, 1.0 min. for BEND-1, and 3.0 min. for PVAND-1. Most effective sensitizers for PGND, BEND and PVAND among those used here were benzanthrone, 5-nitroacenaphthene and picramide, respectively. The spectral sensitivities of PGND, BEND and PVAND were examined by comparing their spectrograms with UV-spectra in a solid state. Also, the sensitization and spectral sensitivity of the above polymers were studied. All the polymers containing the sensitizers showed optical sensitization. From the fact that in either case of sensitized or unsensitized sample, the ranges of absorption-maximum wave length were almost consistent with sensitivity maximum wave length, it was proved that the light absorbed by a sample served efficiently for photochemical reactions. Benzanthrone was found to be an excellent sensitizer for PGND.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.152-156
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• 1994

The purplish red pigment from the roots of Lithospermum erythrorhizon, a Korean edible wild plant, has been investigated concerning it's value as a natural colorant for Korean traditional foods. An attempt was made to isolate pigments and define their characteristics. Two compounds of isobutylshikonin and acetylshikonin were identified by melting point determination and spectra of UV, IR, and $^{1}H-NMR$. To examine the utility of these naphthoquinone pigments for foods, the effect of various pH values on stability were determined over a period of storage. Buffered solutions of acetylshikonin and isobutylshikonin at pH 3 and 5 showed stable purplish red. The absorption maxima if acetylshikonin and isobutylshikonin over the range of pH 3 to 7 were 518 nm and 520 nm, respectively. A bathochromic shift to 588 nm at pH 10 was observed on these two naphthoquinone pigments. Sensory evaluation was performed with acetylshikonin and isobutylshikonin of identical absorbance. These two pigments revealed purplish red color in Munsell system.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1619-1620
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• 2013

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.118-118
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• 2002

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1408-1410
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• 2004

• Archives of Pharmacal Research
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• v.22 no.4
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• pp.384-390
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• 1999

Thirty-four glutathione conjugates of 5,8-dimethoxy-1,4-naphthoquinones (DMNQ) were synthesized and their structure was determined. The yield of GSH conjugate was dependent on size of alkyl group; the longer the size of alkyl group was, the lower was the yield. It was also found that the length of alkyl side chain influenced the chemical shift of quinonoid protons; the quinonoid protons of 2-glutathionyl DMNQ derivatives with R=H to propyl, 6.51-6.59 ppm vs. other ones with R=butyl to heptyl, 6.64-6.68 ppm. this was explained to be due to a folding effect of longer alkyl group. Glutathione (GSH) reacted with DMNQ derivative first to form a 1,4-adduct (2- or 3-glutathionyl-1,4-dihydroxy-5,8-dimethoxynaphthalenes) and then the adduct was autooxidized to 2- or 3-glutathionyl-DMNQ derivatives. Moreover, GSH reduced DMNQ derivatives to their hydrogenated products. It was suggested that such an organic reaction might play an important role for a study of metabolism or toxicity of DMNQ derivative sin the living cells.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.250-259
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• 2011

This study was conducted to assess the possibility of 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) as a environmental friendly herbicide candidate. Foliar application of DHNQ showed excellent herbicidal effect to the 3 grasses and 5 broad-leaved weeds. Among them, Digitaria sanguinalis and Solanum nigrum were completely controlled by $250{\mu}g\;mL^{-1}$ of DHNQ with main symptoms of desiccation or burndown within 24 hours. Aeschynomene indica was also sensitive to DHNQ treatment. All of the eight weed species were controlled by 90~100% at a concentration of $1000{\mu}g\;mL^{-1}$. However, soil application of DHNQ to Digitaria sanguinalis did not show any herbicidal symptoms. DHNQ strongly inhibited KAPAS activities in vitro and the $IC_{50}$ was $4.4{\mu}M$. Cellular leakage from cucumber leaf squares treated with DHNQ increased depending on the concentrations increased from 6.25 to $100{\mu}M$ after 24 hours incubation with or without light. However, chlorophyll loss in cucumber leaf squares was negligible. Biotin supplements significantly rescued the inhibition of germination rate of Arabidopsis thaliana seeds previously inhibited by the DHNQ. According to above results, DHNQ is a good natural herbicide candidate having a new target KAPAS, which is involved in biotin biosynthesis pathway, with environmental friendly.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.2
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• pp.245-251
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• 2019

This study examined the effects of 2-methoxy-1,4-naphthoquinone (MQ) on the monocyte chemoattractant protein-1 (MCP-1)-induced migration of monocytes, which is an important phenomenon for the body defense and immune response. MQ is a major component extracted from Impatiens balsamina leaves, which have been used for many years in Asian medicine for the treatment of a range of diseases and pain. The cytotoxicity of MQ began to appear at a concentration of $10{\mu}M$, and approximately 50% cytotoxicity was confirmed at $100{\mu}M$. The MCP-1 induced migration of the THP-1 monocyte cell line increased after MQ treatment in a dose dependent manner and the largest increase was observed at $0.1{\mu}M$. The level of cAMP expression decreased after a treatment with $0.1{\mu}M$ MQ. The phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2), a key signaling protein involved in the signaling pathway of C-C motif chemokine receptor 2 (CCR2), a receptor for MCP-1, was increased by the simultaneous treatment of $0.1{\mu}M$ MQ. These results show that MQ increases the MCP-1-induced migration of THP-1, decreases the level of cAMP expression, and increases the level of Erk1/2 phosphorylation.