• 생약학회지
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• 제39권2호
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• pp.155-163
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• 2008

This study was carried out to search the natural antioxidants from the 36 medicinal plants. $IC_{50}$ values of linoleic acid peroxidation inhibition to the BHA, BHT and ${\alpha}-tocopherol$ showed $7.2{\mu}g/ml$, $7.3{\mu}g/ml$, and $26.6{\mu}g/ml$, but hexane extract of Zingiber officinale showed $13.2{\mu}g/ml$, EtOAc extracts of Phellinus linteus, Morus alba, Zingiber officinale and butanol extract of Diospyros kaki showed $15.9{\mu}g/ml$, $16.9{\mu}g/ml$, $20.1{\mu}g/ml$, and $21.5{\mu}g/ml$ respectively. $IC_{50}$ values of DPPH radical scavenging activity of BHA, BHT and $\alpha$-tocopherol showed $14.9{\sim}27.7{\mu}g/ml$, but EtOAc extract of Paeonia suffruticosa showed the lowest $6.5{\mu}g/ml$ than those of other extracts, EtOAc extracts of Camellia sinensis, Salvia miltiorrhiz, and Phellinus linteus showed $8.0{\mu}g/ml$, $11.5{\mu}g/ml$, and $13.0{\mu}g/ml$ respectively.

• Parasites, Hosts and Diseases
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• 제47권2호
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• pp.139-144
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• 2009

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ+sulphadoxine (S)+pyrimethamine (P), MQ alone and MQ+ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of $[^3H]$ hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the $IC_{50}$ values of CQ and QN, as well as between the $IC_{50}$, values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.

• Archives of Pharmacal Research
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• 제27권12호
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• pp.1226-1232
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• 2004

Extracts from seventeen seaweeds were determined for tyrosinase inhibitory activity using mushroom tyrosinase with L-tyrosine as a substrate. Only one of them, Ecklonia stolonifera OKAMURA (Laminariaceae) belonging to brown algae, showed high tyrosinase inhibitory activity. Bioassay-guided fractionation of the active ethyl acetate (EtOAc) soluble fraction from the methanolic extract of E. stolonifera, led us to the isolation of phloroglucinol derivatives [phloroglucinol (1), eckstolonol (2), eckol (3), phlorofucofuroeckol A (4), and dieckol (5)]. Compounds 1~5 were found to inhibit the oxidation of L-tyrosine catalyzed by mushroom tyrosinase with $IC_{50}$ values of 92.8, 126, 33.2, 177, and 2.16 ${\mu}g$ /mL, respectively. It was compared with those of kojic acid and arbutin, well-known tyrosinase inhibitors, with $IC_{50}$ values of 6.32 and 112 ${\mu}g$ / mL, respectively. The inhibitory kinetics analyzed from Lineweaver-Burk plots, showed compounds 1 and 2 to be competitive inhibitors with $K_i$ of $2.3{\times}10^{-4}\;and\;3.1{times}10^{-4}$ M, and compounds 3~5 to be noncompetitive inhibitors with $K_i$ of $1.9{\times}10^{-5},\;1.4{\times}10^{-3}\;and\;1.5{\times}10^{-5}$ M, respectively. This work showed that phloroglucinol derivatives, natural compounds found in brown algae, could be involved in the control of pigmentation in plants and other organisms through inhibition of tyrosinase activity using L-tyrosine as a substrate.

• Archives of Pharmacal Research
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• 제28권10호
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• pp.1170-1176
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• 2005

2-Methyl-2-(2-methylpropenyl)-2,3-dihydronaphthoquinone[2,3-b]furan-4,9-dione (N FD-37) is a synthetic furonaphthoquinone compound. In this study, we determined that NFD-37 could inhibit the lipopolysaccharide (LPS)-induced production of inflammatory mediators in macrophages RAW 264.7. This compound inhibited LPS-induced nitric oxide (NO) or prostaglandin (PG) $E_{2}$ production in dose-dependent manners, with $IC_{50}$ values of 7.2 ${\mu}M$ and 5.3 ${\mu}m$, respectively. As the positive controls, pyrrolidine dithiocarbamate (30 ${\mu}M$) exhibited a $57{\%}$ inhibition of NO production, and NS-398 ($1{\mu}M$) manifested a $48{\%}$ inhibition of $PGE_2$ production. The inhibitory effects of NFD-37 on NO and $PGE_2$ production were determined to occur in conjunction with the suppression of inducible NO synthase or cyclooxygenase-2 expression. NFD-37 also inhibited the production of LPS-inducible tumor necrosis factor-${\alpha}$, interleukin (IL)-$1{\beta}$ and IL-6, at $IC_{50}$ values of 4.8-8.9 ${\mu}M$. We also determined the anti-inflammatory efficacy of NFD-37 using carrageenin-induced paw edema in experimental mice.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 춘계학술발표회
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• pp.62-62
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• 2018

Inhibition of aldose reductase (AR) has been shown to prevent the onset and progression of many diabetic complications wherein several AR inhibitors were isolated from plants abundant in polyphenolic compounds. Lespedeza cuneata (Fabaceae), a perennial plant indigenous in East Asian countries, is shown to be abundant in these polyphenolic substances such as flavonoids and tannins. However, there are no studies to date regarding its effects on AR. In this study, the inhibitory activity of the methanol extract and stepwise polarity fractions of Lespedeza cuneata on AR was investigated. The bioactive compounds purified from L. cuneata by repeated column chromatography were also tested for AR inhibition. Results show that the ethyl acetate and n-butanol fractions of L. cuneata exhibited potent inhibition against AR with $IC_{50}$ values of 0.57 and $0.49{\mu}g/mL$, respectively. Further analysis led to the isolation of acacetin (1), afzelin (2), astragalin (3), kaempferol (4), and scutellarein 7-O-glucoside (5). The AR inhibitory effects these five compounds were also determined in which compounds 2, 3, and 5 showed potent AR inhibitory effects with $IC_{50}$ values of 2.20, 1.91, and $12.87{\mu}M$, respectively. Quantitative analysis of astragalin (3) by HPLC-UV was also performed in the leaves and roots of L. cuneata (0.626 and 0.671 mg/g, respectively). This study reports that the flavonoids isolated from L. cuneata show promising AR inhibitory activities which can be further developed as natural therapies for treating and managing diabetic complications.

• Preventive Nutrition and Food Science
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• 제10권4호
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• pp.316-325
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• 2005

The antioxidant potential of a $75\%$ methanolic extract of highbush blueberry (Vaccinium corymbosum L.) and its different fractions was investigated using different reactive oxygen species (ROS), nitric oxide (NO.), metal chelating and lipid peroxidation assays. Methylene chloride and $75\%$ methanol fractions showed equally high activities $(IC_{50} 0.010 mg/mL)$ for hydroxyl radical (HO) scavenging. Higher hydrogen peroxide $(H_2O_2)$ scavenging values were reported for the ethyl acetate and methylene chloride fractions and their $IC_{50}$ values were 0.20 and 0.15 mg/mL, respectively. Nitric oxide (NO.) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activities were higher in ethyl acetate and methylene chloride fractions. Chloroform and water fractions showed higher activities in superoxide $(O_2.)$ scavenging. All fractions showed strong metal chelating capacities compared with the commercial antioxidants tested. The $0.1\%$ ethyl acetate fraction showed notable capacity to suppress lipid peroxidation in both fish oil and linoleic acid. Phenolic content was measured in all the fractions and methanolic extract. Among the fractions, ethyl acetate fraction showed the highest phenolic content.

• Natural Product Sciences
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• 제13권4호
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• pp.311-316
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• 2007

In this study, the twenty-four ethyl acetate extracts of twenty-two medicinal plants, traditionally used in Vietnam as anti-diabetes agents, were investigated for ${\alpha}$-amylase and protein tyrosine phosphatase 1B (PTP1B) enzymes inhibitory activity in vitro. The results indicated that, twelve materials (50.0%) showed moderate to strong inhibitory activity in ${\alpha}$-amylase inhibitory activity with $IC_{50}$ values ranging from 2.5 to $48.8{\mu}g/mL$; meanwhile, ten extracts (41.6%) could demonstrate PTP1B activity with $IC_{50}$ values less than $30.5{\mu}g/mL$. Some plants presented interesting activities against both of ${\alpha}$-amylase and PTP1B enzymes such as Catharanthus roseus, Carthamus tinctorius, Momordica charantia, Gynostemma pentaphyllum, Glycyrrhiza glabra, Smilax glabra, Psidium guajava (leave), and Rehmannia glutinosa. The study may provide a proof, at least in a part, for the ethno-medical use in diabetes disease of these plants.

• 생약학회지
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• 제24권3호
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• pp.223-230
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• 1993

Antineoplastic activity against human gastric, colon and hepatocellular carcinoma cell lines were measured in 100 extracts from 80 medicinal plants using MTT (3-[4, 5-dimethyl thiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) method. Seventeen extracts from fourteen plants, all of which have previously been reported to have antineoplastic effect, had $IC_{50}$(50% inhibitory concentration) values of less than $230{\;}{\mu}g/ml$ in at least one of the three cell lines. Extracts from remaining sixty-six medicinal plants failed to show significant cytotoxic effect at the concentration of less than $230{\;}{\mu}g/ml$.

• Mass Spectrometry Letters
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• 제5권3호
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• pp.84-88
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• 2014

Licoricidin isolated from Glycyrrhiza uralensis is known to have anticancer, anti-nephritic, anti-Helicobacter pylori, and antibacterial effects. In this study, a cocktail probe assay and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to investigate the modulating effect of licoricidin on cytochrome P450 (CYP) enzymes in human liver microsomes. When licoricidin was incubated at $0-25{\mu}m$ with CYP probes for 60 min at $37^{\circ}C$, it showed potent inhibitory effects on CYP2B6-catalyzed bupropion hydroxylation and CYP2C9-catalyzed diclofenac 4'-hydroxylation with half maximal inhibitory concentration ($IC_{50}$) values of 3.4 and $4.0{\mu}m$, respectively. The inhibition mode of licoricidin was revealed as competitive, dose-dependent, and non-time-dependent, and following the pattern of Lineweaver-Burk plots. The inhibitory effect of licoricidin has been confirmed in human recombinant cDNA-expressed CYP2B6 and 2C9 with $IC_{50}$ values of 4.5 and $0.73{\mu}m$, respectively. In conclusion, this study has shown the potent inhibitory effect of licoricidin on CYP2B6 and CYP2C9 activity could be important for predicting potential herb-drug interactions with substrates that mainly undergo CYP2B- and CYP2C9-mediated metabolism.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.587-596
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• 2019

This study aimed to determine the antimalarial effect of the Strychnos ligustrina (SLW) wood extracts and to analyze its phytochemicals. The SLW powder samples were macerated with 100% ethanol (E100), 75% ethanol (E75), 50% ethanol (E50), 25% ethanol (E25), and aqueous (A100). The extracts were analyzed by LCMS/MS, and its in-vitro antimalarial activity was tested with Plasmodium falciparum. The results showed that the extract yields of E100, E75, E50, E25, and A100 were 4.3, 5.2, 5.3, 4.7, and 3.6%, respectively. The antimalarial activities of the A100, E25, E50, and E75 extracts were classified as active with $IC_{50}$ values of 38.6, 42.6, 42.9, and $43.7{\mu}g/mL$, respectively. But, the antimalarial activity of the E100 extract was classified as slightly active with $IC_{50}$ values of $87.4{\mu}g/mL$. The dominant compounds contained in the extracts of A100, E25, E50, E75, and E100 was the alkaloid compound, namely brucine with relative concentrations of 24.96, 24.55, 21.33, 11.79, and 11.62%, respectively.