• Natural Product Sciences
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• v.11 no.2
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• pp.89-91
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• 2005

Effect of the neolignans, honokiol (1) and magnolol (2), isolated from Magnoliae Cortex on mushroom tyrosinase activity was investigated in vitro using L-tyrosine as a substrate. Honokiol (1) inhibited tyrosinase activity significantly in a concentration-dependent manner, on the other hand, magnolol (2) did not show tyrosinase inhibitory effect. Honokiol exhibited tyrosinase inhibitory effect with $IC_{50}$ value of $67.9\;{\mu}M$, and proved to act as a non-competitive inhibitor by the analysis of Lineweaver-Burk plot.

• Korean Journal of Pharmacognosy
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• v.23 no.3
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• pp.142-145
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• 1992

MeOH extract of twenty medicinal herbs were screened for their effects against protein kinase C (PKC) using bleb-forming assay and PKC enzyme assay. Smilax china and Sanguisorba officinalis showed potent anti-PKC activity. Campsis grandiflora and Galla Halepensis showed moderate inhibitory effect on PKC.

• Korean Journal of Pharmacognosy
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• v.14 no.4
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• pp.175-177
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• 1983

The BuOH fraction prepared from the methanol extract of Acanthopanacis Cortex showed inhibitory activity against ADP-induced platelet aggregation. The inhibitory activity remained in ether layer when the BuOH fraction was refluxed with 5% aq. HCl-EtOH (1 : 1 mixture) and extracted with ether. From the ether layer, ethoxy-hydroxy-benzoic acid $(m.p.\;128{\sim}130^{\circ}C)$, a platelet antiaggregating substance, was isolated.

• Korean Journal of Pharmacognosy
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• v.18 no.4
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• pp.249-253
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• 1987

Antimicrobial activities of three different extracts from experimentally prepared scute decoction, commercial scute decoction and an extract from Scutellaria baicalensis were evaluated and their inhibitory potencies were compared. Both the extracts from scute decoction and Scutellaria showed rather strong antimicrobial activities against E. coli and St. aureus at the low concentration of 2.5 mg/ml. On the other hand, the extract of commercial scute decoction was found to show an inhibitory effect at higher concentration (75 mg/ml). All preparations did not inhibit the fungal growth of Aspergillus niger. Both Sh. dysenteriae (Subgroup A) and Sh. boydii (Subgroup C) which were used for determination of the strain differences in Shigelia spp. had almost the same susceptibility to the extract from sucute decoction.

• Biomolecules & Therapeutics
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• v.16 no.4
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• pp.416-424
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• 2008

A series of N,N'-substituted iminodiacetamide derivatives was synthesized and evaluated their inhibitory effects on the histamine-induced smooth muscle contraction in guinea-pig ileum and on the histamine release from IgE-sensitized RBL-2H3 cells (rat basophilic leukemia cell line). Compounds A3, A4 and A5 which have 1-(4-chlorobenzhydryl) piperazine moiety, showed both moderate antihistamine activity and histamine release inhibitory activity.

• YAKHAK HOEJI
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• v.33 no.3
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• pp.175-182
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• 1989

To find ${\alpha}-amylase$ inhibitors produced by microorganisms from soil, a strain which had a strong inhibitory activity against bacterial ${\alpha}-amylase$ was isolated from the soil sample collected in Korea. The morphological and physiological characteristics of this strain on several media and its utilization of carbon sources showed that it was one of Streptomyces species according to the International Streptomyces Project method. The amylase inhibitor of this strain was purified by active carbon adsorption, silicagel column chromatography, SP-Sephadex C-25 column chromatography, adsorption on Amberlite XAD-2. The inhibitor was oligosaccharide which was composed of glucose. The inhibitor had inhibitory activity against other amylase such as salivary ${\alpha}-amylase$, pancreatic ${\alpha}-amylase$, fungal ${\alpha}-amylase$ and gluco-amylase.

• YAKHAK HOEJI
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• v.45 no.6
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• pp.701-707
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• 2001

Melanogenesis is a physiological process resulting in the synthesis of melanin pigment. We investigated the inhibitory effect of crude polysaccharide of water extract of Artemisia iwayomgi Kitamura (AI) on melanin biosystheies in B16/F10 melanoma cells. Crude polysaccharide of water extract of Artemisia iwayomgi Kitamura significantly inhibited tyrosinase activity and melanin contents with or without $\alpha$-MSH in vivo. Melanin contents and tyrosinase activity were decreased in a dose-dependent manner,These results show that crude polysaccharide of water extract of Artemisia iwayomgi Kitamura could be developed as skin whitening components of cosmetics.

• YAKHAK HOEJI
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• v.45 no.3
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• pp.245-250
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• 2001

Aminoacyl tRNA synthetases of bacteria are known as potential targets for new anti-microbial agents. To isolate new inhibitors of bacterial methionyl-tRNA synthetases from natural sources, a new target-oriented screening system using whole cells which are over-expressing a target enzyme was developed. Approximately 8,000 culture broths of microorganisms from soils were tested by this screening system. Among them, ten culture broths was found to contain inhibitory activity against methionyl -tRNA synthetases of Escherichia coli. For the validation of the screening system, this new method was compared with in vitro enzymatic method. Seven out of 10 culture broths showed inhibitory activity against methionyl-tRNA synthetases of E. coli. This result showed that the new screening system was comparable to the enzyme assay. Thus we believe that our screening system as a new method can be applied for the screening of new antibiotics inhibiting bacterial methionyl-tRNA synthetases from natural products.

• YAKHAK HOEJI
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• v.43 no.4
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• pp.509-515
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• 1999

To search for new chitin biosynthesis inhibitors from natural sources, several higher plants were examined the inhibitory activity against chitin synthase IIby enzymatic assay. Among them, the extract of Schizandra chinensis strongly showed the inhibitory activity against chitin synthase II. Gomisin N and wuweizisu C were isolated from Schizandra chinensis and showed $IC_50$ value of $62.4{\;}\mu\textrm{g}/ml$ and $19.2{\;}\mu\textrm{g}/ml$, respectively. Activities of these compounds were more stronger than that of polyxin D. However, gomisin N and wuweizisu C showed weakly antifungal activities against various human pathogens.

• YAKHAK HOEJI
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• v.52 no.2
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• pp.131-136
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• 2008

Sesamol, one of constituents isolated from sesame seed (Sesamum indicum L.) has been known to have natural antioxidant property. Nicotinic acid and clofibric acid have been used for treatment of hyperlipidemia. Sesamol derivatives prepared by conjugation with nicotinic acid (SJ-301) and clofibric acid (SJ-302) were expected to have various biological activity caused by synergistic effect of sesamol. Thus, this study were carried out to investigate the synthesis of sesamol derivatives from seasamol and antihyperlipidemia drugs and their biological activities. As a result, SJ-301 showed a stronger antihyperlipidemia activity in vivo and inhibitory effect on $TNF-{\alpha}$ release in vitro compared to the original agents such as sesamol, nicotinic acid and clofibric acid.