Soo Jeong Cho

Towards Structural Determination of the ComX Pheromone: Synthetic Studies on Peptides Containing Geranyltryptophan

Bacteria produce and respond to signal molecules depending on their cell density. This process is called “quorum sensing”. The ComX pheromone, controlled by quorum sensing, activates natural genetic competence in Bacillus subtilis. ComX is an oligopeptide with a posttranslational modification. It has been suggested that ComX pheromone is modified with an isoprenoid at its tryptophan residue, but the complete chemical structure is unknown. We first determined the molecular formula of ComXRO-E-2, a competence factor for B. subtilis strain RO-E-2. Then we synthesized putative pheromones with 1-, 2-, 4-, 5-, 6-, or 7-geranyl substituted tryptophan residues. The regio- and stereo-selective synthesis of the geranyl tryptophans was successful, and we prepared the six peptides with modified tryptophan residues. These peptides had the same molecular formula and showed similar hydrophobicity to the natural ComXRO-E-2 in LC–MS analysis. But, none of them showed the same retention time as the natural pheromone and none exhibited its biological activity. These results suggest that the isoprenoid modification pattern of the tryptophan residue is more complex than postulated.

nhibition of Melanin Synthesis by Mycelial Culture Broth of Paecilomyces japonica in the Mulberry

This study was carried out to investigate the whitening effect of mycelial culture broth of P. japonica in the mulberry leaf extract. The culture broth inhibited melanin synthesis in vitro in the concentration dependent manner of 10 to 50%. The mulberry leaf extract itself has a cytotoxicity to the mouse melanoma cell, B16BL6 with the value of IC of 7% concentration. But the culture broth of P. japonica in the mulberry leaf extract did not show any cytotoxicity up to 50%. Therefore, we concluded the mycelial culture broth of P. japonica in the extract of mulberry leaf can be used as a whitening cosmetic resource.

Cloning and Identification of Essential Residues for Thermostable β-glucosidase (BgIB) from Thermotoga maritima

A hyperthermophilic bacterium Thermotoga maritima produced thermostable β-glucosidase. The gene encoding β-glucosidase from T. maritima MSB8 was cloned and expressed in Escherichia coli. The enzyme (BglB) hydrolyzed β-glucosidic linkages between glucose and alkyl, aryl of saccharide groups such as salicin, arbutin, and ρNPG. The insert DNA contained ORF with 2,166 bp encodes a 721 amino acids (calculated molecular mass of 80,964 and pI of 4.93). The amino acid sequence of BglB showed the similarity to family 3 glycosyl hydrolases. The molecular weight of the enzyme was estimated to be approximately 81 kDa by MUG-nondenaturing PAGE (4-methylumbelliferyl β-D-glucoside-nondenaturing polyacrylamide gel electophoresis) and SDS-PAGE. The β-glucosidase exhibited maximal activity at pH 7.0 and 80°C. By exchanging two possible residues (Glu-232 and Asp-242) to Ala by site-directed mutagenesis method, it was found that these were essential for enzymatic activity.

Interaction with Polyphenols and Antibiotics

항산화, 항알러지, 항염증, 항암, 항고혈압, 항균 활성을 나타내는 폴리페놀 화합물은 고등식물에 의해 생산되는 2차 대사산물이다. 일반적으로 폴리페놀 화합물은 플라보노이드와 비 플라보노이드 화합물로 나뉘며 병원균에 대한 항균활성은 비 플라보노이드 화합물에 비해 플라보노이드 화합물이 우수하다. 항균활성을 나...

Comparison of Antioxidant Activities of Pileus and Stipe from White Beech Mushrooms (Hypsizygus marmoreus)

Su Cheol Kim 1,2† , Hyun Sook Kwon 3† , Chul Hwan Kim 1 , Hye Soo Kim 1 , Chang Yun Lee 4 and Soo Jeong Cho* Department of Pharmaceutical Engineering, Gyeongnam National University of Science and Technology, 33 Dongjin-ro, Jinju 52725, Korea 2 Amicogen Inc., Jinju 52621, Korea National Development Institute of Korean Medicine, Gyeongsan 38540, Korea SBbio, 19 Donghwa-Road, Maejun-Myun, Cheongdo-Gun 38359, Korea

Tyrosinase Inhibitory Activities of Meso-dihydroguaiaretic Acid from Machilus thunbergii

Machilus thunbergii (Lauraceae) is an evergreen tree cultivated in Korea and Japan. M. thunbergii has long been used as a traditional medicine in Korea, China, and Japan to treat various diseases, including edema, abdominal pain, and abdominal distension. In this study, dried stem bark of M. thunbergii extracted in methanol and extract was partitioned into n-hexane, CHCl₃, and BuOH. The CHCl₃-soluble extracts chromatographed on silica gel column using a CHCl₃/acetone and n-hexane/EtOAc mixture to afford Compound 1 and 2. Two dibenzylbutane lignans, macelignan (1) and meso-dihydroguaiaretic acid (2), were isolated from the CHCl₃-soluble extract of M. thunbergii stem bark. The structures of 1 and 2 were determined by 1 H- and 13 C-NMR spectroscopic data analyses and a comparison with literature data. The tyrosinase inhibitory activity of the isolated compounds was evaluated. Among these compounds, Compound 2 strongly inhibited the monophenolase (IC 50 =10.2 μM) activity of tyrosinase. A kinetic analysis showed that Compound 2 was a competitive inhibitor. The apparent inhibition constant (K i ) for Compound 2 binding to free enzyme was 4.8 μM. Based on these results, it can be concluded that meso-dihydroguaiaretic acid (2) is a potential candidate for the treatment of melanin biosynthesis-related skin diseases.