• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.135-139
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• 2003

During the screening for inhibitors of melanin biosynthesis from plant extract, Angelica polymorpha MAXIM which showed a high level of inhibition was selected. The inhibiting substances were purified form methanol extract of Angelica polymorpha MAXIM followed by silica gel column chromatography and HPLC. The inhibitors were identified as heraclenin, isosaxalin and heraclenol 3'-Me ether, by spectrescopic methods of ESI-MS, H-NMR, C-NMR, DEPT, HMQC and HMBC. These compounds did not have mushroom tyrosinase inhibitory activity, but showed a highly potent melanin biosynthesis inhibition zone in the plate culture of Streptomyces bikiniensis, a bacterium used as an indicator organism in this work. These compounds did not show any growth inhibition against S. bikiniensis at the same concentration of melanin biosynthesis test.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.97-99
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• 2001

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.139-143
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• 1993

Three isoflavonoids having tyrosinase-inhibiting activity were isolated from the culture filtrate of Streptomyces sp. 20747. Their structures were determined by UV, EI-MS, 1H-NMR, 13C-NMR to be daidzein, daidzein 7-rhamnoside, and genistein 7-rhamnoside, which were competitive with substrate and had IC50 value of 14, 19, and 16 ng/ml, respectively to mushroom tyrosinase and did not inhibit melanin production of Streptomyces bikiniensis. Soybean meal as well as peptone were found to be a good nitrogen source for tyrosinase-inhibiting isoflavonoids production, susgesting that soybean meal is not the origin of tyrosinase inhibiting isoflavonoids formation in Streptomyces sp. 20747 strain.

• The Korean Journal of Mycology
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• v.20 no.1
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• pp.65-71
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• 1992

The two isolates of Streptomyces antagonistic to Phytophthora nicotianae var. parasitica and Fusarium oxysporum f. sp. vasinfectum were identified as based on the morphological, cultural and physiological characteristics on various culture media. Spore chains of St-11 isolate was rectus-flexibilis(RF), whereas the other isolate, St-20, was shown rectinaculum-apertum(RA). Spore surface of St-11 isolate was smooth, while St-20 was spiny. Aerial mycelia of the two isolates were all gray color and growing conditions on media were good as a whole. Any soluble pigment was not shown in cultivation of the two isolates. Stoll isolate showed negative response on starch hydrolysis and gelation liquefaction, whereas St-20 isolate was positive on starch hydrolysis and a negative on gelatin reaction. Stoll isolate was identified as Streptomyces bikiniensis and St-20 Streptomyces echinoruber, respectively.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1977-1983
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• 2006

Kaempferol was isolated and identified from the methanol extract of the flowers of Impatiens balsamina. Kaempferol showed inhibitory activity against mushroom tyrosinase with an $ID_{50}$ of 0.042 mM. Inhibition kinetics, as determined using a Lineweaver-Burk plot, showed kaempferol to be a competitive inhibitor of mushroom tyrosinase with a $K_i$ value of 0.011 mM. The lag phase of tyrosine hydroxylation catalyzed by mushroom tyrosinase clearly increased on increasing the concentration of kaempferol. In addition to its tyrosinase inhibiting activity, kaempferol strongly inhibited melanin production by Streptomyces bikiniensis, in a dose-dependent manner, without inhibiting cell growth. For comparative purposes, the tyrosinase inhibitory activity of kaempferol was also assayed versus quercetin, a positive standard.

• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.209-213
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• 1995

During the screening of inhibitors of melanin biosynthesis from microbial secondary metabolites, a fungal strain MR-93 which was capable of producing high level of an inhibitor was selected from plant leaf. Based on taxonomic studies, the fungus could be classified as a strain of Trichoderma sp.. The active compound (MR-93D) was purified from the culture broth by Diaion HP-20 column chromatography, ethylacetate extraction, Sephadex LH-20 column chromatography and HPLC. The inhibitor was identified as 4-hydroxy-8-isocyano-l-oxaspiro[4-4]cyclonon-8-en-2- one by spectroscopic methods of UV, $^{1}$H-NMR, ESIMS and IR. MR-93D showed a strong tyrosinase inhibitory activity with 0.03 $\mu$g/m of IC$_{50}$ value. It also inhibited melanin biosynthesis with 35 mm inhibition zone at 30 $\mu$g/paper disc in Streptomyces bikiniensis, a bacterium used as an indicator organism in this work.

• Applied Biological Chemistry
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• v.51 no.3
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• pp.153-158
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• 2008

An actinomycetes F-97 producing tyrosinase inhibitor was isolated from soil samples. Isolation and purification of tyrosinase inhibitor produced by F-97 was performed as follows: IRC-120 ($NH_4^+$ type) column chromatography, silica gel column chromatography, $C_{18}$ column chromatography and Sephadex LH-20 column chromatography were used successively after the centrifuged supernatant was adjusted to pH 4.0. To identify the purity of the inhibitor, octadecylsilyl(ODS) HPLC was carried out with 5% methanol as a mobile phase. Finally, the purification yield of a tyrosinase inhibitor was 5.24%. The inhibitor was very soluble in water, methanol and ethanol but insoluble in acetone, butanol, ethylacetate and chloroform. The ${\lambda}_{max}$ value of this inhibitor in water was 194nm under UV light. The biochemical test of the inhibitor was positive in Molish, Benedict, cone. $H_2SO_4$, and $KMnO_4$ tests but negative in iodine, ninhydrin, Million, Sakaguchi, xanthoproteic and Emerson tests. The tyrosinase inhibitor was stable against heat treatment of $100^{\circ}C$ for 50 minutes and pH $4{\sim}9$. The $IC_{50}$ value of this inhibitor was $19.2{\mu}g/ml$ for mushroom tyrosinase. In $1,000{\mu}g/ml$ inhibitor concentration, inhibition zone was 27 mm for Streptomyces bikiniensis NRRL B-1049. The inhibition of F-97 against mushroom tyrosinase was competitive with tyrosine.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.641-646
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• 1995

During the screening of inhibitors of melanin biosynthesis from microbial secondary metabolites, a fungal strain MR304 which was capable of producing high level of an inhibitor was selected. Based on taxonomic studies, this fungus could be classified as Trichoderma harzianum. The active compound (MR304-1) was purified from culture broth by Diaion HP-20 column chromatography, ethylacetate extraction, Sephadex LH-20 column chromatographv and HPLC. The inhibitor was identified as 3-(1,5-dihvdroxy-3-isocyanocyclopent-(E)-3-envl)prop-2-enoate by spectroscopic methods of UV, ESIMS, $^{1}$H-NMR, $^{13}$C-NMR, NOE, HMQC and HMBC. MR304-1 showed strong mushroom tyrosinase inhibitory activity with IC$_{50}$ value of 0.25 $\mu $g/ml. It inhibited melanin biosynthesis with 15 mm inhibition zone at 30 $\mu $g/paper disc in Streptomyces bikiniensis, a bacterium used as an indicator organism in this work. It also inhibited melanin biosynthesis in B16 melanoma cells with a niinimum inhibitory concentration of 0.05 $\mu $g/ml.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.874-879
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• 2008

Tyrosinase is a key enzyme for melanin biosynthesis, and hyperpigmentation disorders are associated with abnormal accumulation of melanin pigments, which can be reduced by treatment with depigmenting agents. The methanol extract of Lespedeza cyrtobotrya $M_{IQ}$ showed inhibitory activity against mushroom tyrosinase. The active compound was purified from the methanol extract of L. cyrtobotrya, followed by several chromatographic methods, and identified as dalbergioidin (DBG) by spectroscopic methods. The results showed that DBG exhibited tyrosinase inhibitory activity with an $IC_{50}$ of $20\;{\mu}M$. The kinetic analysis of tyrosinase inhibition revealed that DBG acted as a noncompetitive inhibitor. In addition, DBG showed a melanin biosynthesis inhibition zone in the culture plate of Streptomyces bikiniensis that has commonly been used as an indicator organism. Furthermore, $27\;{\mu}M$ DBG decreased more than 50% of melanin contents on the pigmentation using the immortalized mouse melanocyte, melan-a cell.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.49-54
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• 2009

Rhapontin is the glycosylated stilbene compound, and comprising major component of rhubarb root extract. Rhapontin has been used as a raw material of skin-whitening cosmetics in Korea. Rhapontigenin, the aglycone of rhapontin, has been suggested to be more active than its glycosylated form. Therefore, the rhubarb root extract was treated with commercial enzyme, Pectinex to remove glycosylated moiety of rhapontin and rhapontigenin was prepared. The resulting material was analysed and identified as rhapontigenin by proton NMR and MALDI-Mass. Rhapontigenin exhibited tyrosinase inhibitory activity with an $IC_{50}$ of $126.72{\mu}g/mL$. The tyrosinase inhibitory activity of rhapontigenin was six times higher than that of rhapontin. In melanin biosynthesis inhibition assay using Streptomyces bikiniensis, rhapontigenin showed wider inhibition zone than that of rhapontin. From these results, we expect that rhapontigenin has stronger skin whitening effect than rhapontin and has advantages in cosmetic industry.