• 약학회지
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• 제34권4호
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• pp.262-266
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• 1990

Acetylshikonine, isolated from the root of Lithospermum erythrorhizon showed a strong cytotoxic activity ($ED_{50}=0.10\;ug/ml$) against L1210 cell and T/C = 182% in ICR mice bearing S-180 at a dose of 5 mg/kg. Administrations of 10 mg/kg and 15 mg/kg reduced the T/C values to 60 and 77% respectively. Higher doses reveal toxicity. Seven naphthazarin derivatives synthesized showed good cytotoxic activities against L1210 cell. Especially, naphthazarin and hydronaphthazarin have strong activities ($ED_{50}=0.05\;ug/ml$ for both). Naphthazarin showed a severe toxic effect on ICR mice bearing S-180; no significant toxic effect was observed at a dose of 1 mg/kg or 2 mg/kg, but a severe toxicity (T/C = 23%) by administration of 5 mg/kg. Alkylation of C-2 of naphthazarin is necessary for reducing the toxic effect on ICR mice bearing S-180.

• Archives of Pharmacal Research
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• 제23권1호
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• pp.22-25
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• 2000

Formation of glutathione (GSH) conjugates with 2- or 6-(1-hydroxymethyl)- and 2-(1-hydroxyethyl)-DMNQ derivatives (DMNQ, 5,8-dimethoxy-1,4-naphthoquone was carried out in phosphate buffer (pH 7.4), in the presence of glutathione-S-transferase (GST), in rat liver S-9 fraction and by perfusion, and the rates of conjugates formation were compared and correlated to cytotoxicity. The GSH conjugates of 6-(1-hydroxyalkyl)-DMNQ derivatives were formed faster than 2-(1-hydroxyalkyl)-DMNQ derivatives under all of the media, implying that steric hindrance was the cause of lowering the rate of conjugate formation of 2-substituted derivatives. For both isomers, addition of GST did not improve the reaction rate, compared with that in buffer, while the reaction in the S-9 fraction and the perfusate was accelerated to a great extent. The catalytic effect of the S-9 fraction and the perfusate contain an effective system relaxing the steric hindrance of 2-(1-hydroxyalkyl)-DMNQ derivatives. Furthermore, a good correlation between the formation of the GSH conjugates and the cytotoxic activity of both naphthazarin isomers suggests that the steric hindrance is a cause of lowering the cytotoxicity of 2-isomers.

• Journal of Microbiology and Biotechnology
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• 제18권2호
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• pp.314-321
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• 2008

Acaricidal effects of materials derived from Diospyros kaki roots against Dermatophagoides farinae and D. pteronyssinus were assessed using impregnated fabric disk bioassay and compared with that of the commercial benzyl benzoate. The observed responses varied according to dosage and mite species. The $LD_{50}$ values of the chloroform extract of Diospyros kaki roots were 1.66 and $0.96{\mu}g/cm^2$ against D. farinae and D. pteronyssinus. The chloroform extract of Diospyros kaki roots was approximately 15.2 more toxic than benzyl benzoate against D. farinae, and 7.6 times more toxic against D. pteronyssinus. Purification of the biologically active constituent from D. kaki roots was done by using silica gel chromatography and high-performance liquid chromatography. The structure of the acaricidal component was analyzed by GC-MS, $^1H-NMR,\;^{13}C-NMR,\;^1H-^{13}C$ COSY-NMR, and DEPT-NMR spectra, and identified as plumbagin. The acaricidal activity of plumbagin and its derivatives (naphthazarin, dichlon, 2,3-dibromo-1,4-naphthoquinone, and 2-bromo-1,4-naphthoquinone) was examined. On the basis of $LD_{50}$ values, the most toxic compound against D. farinae was naphthazarin $(0.011{\mu}g/cm^2)$ followed by plumbagin $(0.019{\mu}g/cm^2),$ 2-bromo-1,4-naphthoquinone $(0.079{\mu}g/cm^2)$, dichlon $(0.422{\mu}g/cm^2)$, and benzyl benzoate $(9.14{\mu}g/cm^2)$. Additionally, the skin color of the dust mites was changed from colorless-transparent to dark brown-black by the treatment of plumbagin. Similar results have been exhibited in its derivatives (naphthazarin, dichlon, and 2-bromo-1,4-naphthoquinone). In contrast, little or no discoloration was observed for benzyl benzoate. From this point of view, plumbagin and its derivatives can be very useful for the potential control agents, lead compounds, and indicator of house dust mites.

• Archives of Pharmacal Research
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• 제24권1호
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• pp.35-38
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• 2001

Various analogues of 5,8-dimethoxy-1,4-naphthoquinone (DMNQ) such as 2- or 6-(1-hydro-xyiminoalkyl)-DMNQs were prepared and evaluated for the antitumor action. (1-Hydroxyiminoalkyl)-DMNQ derivatives expressed greater antitumor action than (1 -hydroxyalkyl)- or acyl-DMNQ derivatives. Moreover, 6-(1-hydroxyiminoalkyl)-DMNQ derivatives expressed higher anti-tumor action than 2-sudstituted ones, suggestive of a steric effect. Some of 6-(1-propyloxyalkyl)-DMNQ derivatives with an alkyl group of butyl to octyl moiety showed T/C values of > 400 %.

• Archives of Pharmacal Research
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• 제24권3호
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• pp.190-193
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• 2001

Various analogues of 5,8-dimethoxy-1,4-naphthoquinone (DMNQ) such as 2- or 6-(1-hydroxyiminoalkyl)-DMNQs were prepared and evaluated for the antitumor action. (1 -Hydroxyiminoalkyl)-DMNQs derivatives expressed greater antitumor action than (1-hydroxyalkyl) - or acyl-DMNQ derivatives. Moreover, 6-(1-hydroxyiminoalkyl)-DMNQ derivatives expressed higher antitumor action than 2-substituted ones, suggestive of a steric effect. Some of 6-(1-propyloxyalkyl)-DMNQ derivatives with an alkyl group of butyl to octyl moiety showed T/C values of >400%

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.208.1-208.1
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• 2003

We synthesized naphthazarin derivatives from shikonin, a major compound from Lithospermum erythrorhion Sieb et ZUCC. Of derivatives, DMNQ S64, 2-or 6-(l-hydroxyiminoalkyl) effectively showed antitumor activity on A549, human lung cancer cells (IC$\sub$50/= 30 ${\mu}$M). It significantly inhibited prostaglandin E$_2$(IC$\sub$50/= 10 ${\mu}$M). We also confirmed it selectively downregulated the expression of cyclooxygenase 2(COX-2), while it didn't affect COX-1. The induction of apoptosis by DMNQ S64 is underway.

• Archives of Pharmacal Research
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• 제21권5호
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• pp.595-598
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• 1998

The rate of the GSH conjugate formation, the inhibition of DNA topoisomerase-I and the cytotoxic activity against L1210 cells of the naphthoquinones showed the same order; 5,8-dimethoxy-1,4-naphthoquinone (DMNQ)>6-(1-hydroxyethyl)-DMNQ>2-(1-hydroxyethyl)-DMNQ; the steric hindrance of the substituents, particularly 2-substutuent, in reacting with cellular nucleophiles must be the main cause for lowering the bioactivities. Acetylation of 2-(1-hydroxyethyl)-DMNQ producing 2-(acetyloxyethyl)-DMNQ potentiated the bioactivities; 2-(-hydroxyethyl)-DMNQ did not react with GSH and the enzyme, and showed $ED_{50}$ of 0.146 mg/ml for the cytotoxcity. Furthermore, the acetylation 2-(1-hydroxyethyl)-DMNQ(T/C, 119%) enhanced the T/C values for the mice bearing S-180 tumor {T/C of 2-(1-acetyloxyethyl)-DMNQ, 276%]. It was assumed that the difference in bioactivities ensued by acetylation was based on the mechanism of the so-called bioreductive alkylation.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.109-109
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• 1997

Inhibitory effect on DNA topoisomerase-I, rate of glutathione conjugation and cytotoxicity of naphthoquinone derivatives were correlated. During 5 min exposure of the derivatives to glutathione (GSH), it was found that 14% of 5,8-dimethoxy-1,4-naphthoquinone(DMNQ) was converted into a GSH-conjugate, whereas 5,8-dihydroxy-1,4-naphthoquinone(DHNQ) did not interact with GSH, implying that DMNQ exerted higher electrophilicity than DHNQ. However, DHNQ (IC$\_$50/, 0.15 ${\mu}$M) showed stronger cytotoxicity in L1210 cells than DMNQ(IC$\_$50/, 0.45 ${\mu}$M). The stronger cytotoxicity of DHNQ, compared to DMNQ, could be ascribed to more rapid redox cycling. Both naphthoquinones (IC$\_$50/, 60-65 ${\mu}$M) exhibiting about the same inhibitory effect on DNA topoisomerase-I were more potent than 1,4-naphthoquinone(1,4-NQ, IC$\_$50/, 134 ${\mu}$M). Thus, 5,8-oxy groups in the structure seem to be important for the inhibition of the enzyme. DMNQ showed a broader dose range while maintaining a good antitumor activity against S-180 fluid tumor. For these reasons, DMNQ was taken as useful pharmacophore for structural modification. Introduction of 1-hydroxyalkyl groups at C-2 of DMNQ lowered all of the activities mentioned above, while acetylation of 1-hydroxyalkyl moiety enhanced the activities by 4-5 times. Introduction of the same side chains at C-6 exhibited stronger activities than 2-substituted ones. Based on these results it was suggested that the quinonoid moiety in 6-substituted DMNQ was more exposed to cellular nucleophiles such as DNA, thiols of enzymes and so on. The synthesis of DHNQ or DMNQ derivatives are going on, and the corelationship between structure-activity will be discussed.