Jang Won Choi

Novel tripeptides with α-glucosidase inhibitory activity isolated from silk cocoon hydrolysate.

Active compounds with antidiabetic potential were isolated from silk peptide E5K6 by consecutive ultrafiltration and gel filtration using Biogel P-2 and RS-HPLC using a YMC-Pack Pro C18 column. The highest α-glucosidase inhibitory activity of silk peptide E5K6 resulted from fractions with MW <1 kDa. The activities of gel-filtered fractions from silk peptide E5K6 of <1 kDa were assayed in vitro, demonstrating that the fourth peak (F4) had the highest α-glucosidase inhibitory activity (IC(50) = 37.1 mg/mL). F4 of silk peptide E5K6 was separated by HPLC into two peaks. Moreover, the purified compounds were identified as Gly-Glu-Tyr (GEY, MW = 367 Da) and Gly-Tyr-Gly (GYG, MW = 295 Da) according to amino acid sequences, and their α-glucosidase inhibitory activities (IC(50)) were 2.7 and 1.5 mg/mL, respectively.

Enhancement of anti-complementary and radical scavenging activities in the submerged culture of Cordyceps sinensis by addition of citrus peel

To investigate the optimal conditions for the production of Cordyceps sinensis by the submerged culture method, glucosamine and exopolysaccharide (EPS) productivities were determined in culture broth containing different carbon sources, principally rice bran and citrus peel. An optimal medium composition (1.5% rice bran, 0.5% molasses, 3% CSL, 0.1% KH(2)PO(4), and 0.05% MgSO(4)) and the optimal condition (25 degrees C and 5-6 d culture time) for high EPS productivity with potent immune-stimulating activities were obtained. The addition of citrus peel to the culture of C. sinensis under the optimized conditions improved EPS productivity and glucosamine content. Furthermore, anti-complementary activity was higher (58.0-80.8%) using citrus peel as compared to no addition of citrus peel (48.2-68.7%). Antioxidant activity (AEAC value) of the citrus peel culture was high (284.3-384.6 mg/100g) compared to that of the culture without citrus peel (142.8-219.5mg/100g), indicating that the citrus peel helped enhance the anti-complementary and antioxidant activities of C. sinensis.

Anti-complementary activity of enzyme-treated traditional Korean rice wine (Makgeolli) hydrolysates

BACKGROUND Makgeolli brewed from rice contains about 150 g kg(-1) alcohol and has a fragrance as well as an acidic and sweet taste. During the brewing process, by-products such as rice bran and brewery cake are produced. At the end of fermentation the matured mash is transferred to a filter cloth and the Makgeolli is squeezed out from the cake, leaving the lees of the mash. These by-products have continued to increase every year, resulting in an ecological problem. It is therefore important to develop new uses for them. The objective of this study was to use the by-products from the brewing of Makgeolli as a valuable functional food or nutraceutical. RESULTS The anti-complementary activities of crude polysaccharides isolated from Cytolase hydrolysates of Makgeolli lees at concentrations of 1000 and 500 µg mL(-1) were 84.15 and 78.70% respectively. The activity of polysaccharide krestin (PSK) was 60.00% at 1000 µg mL(-1). The active polysaccharide obtained with Cytolase comprised mainly glucose and mannose (molar ratio 1.00:0.62). CONCLUSION Glucose- and mannose-rich crude polysaccharides were isolated from the Cytolase hydrolysate of Makgeolli lees. The polysaccharides retain anti-complementary activity to enhance the immune system as a functional food or nutraceutical.

Optimization for rice koji preparation using aspergillus oryzae CJCM-4 isolated from a korean traditional meju

To obtain a useful mold strain in rice-doenjang production, enzyme activities were investigated in rice and wheat koji prepared with 13 different strains isolated from traditional Korean meju. The CJCM-4 strain, which had been selected as a superior strain for the production of protease, was identified as Aspergillus oryzae by the gene sequence of the ITS-5.8S rDNA region as well as aflatoxin production capacity. The enzyme activities of koji prepared with CJCM-4 according to the polishing degree of rice bran were examined. The enzyme activities of koji prepared with 70% milling degree of rice bran were higher than those of other kojis. Protease activity showed its highest level on day 3 at 30°C. Glucoamylase activity showed its highest level on day 2 at 30°C. The optimum enzyme production of koji was determined at different conditions such as incubation time, temperature, moisture, and inorganic salt content. The optimum ratio of water added to the rice for the production of enzymes was 35% on the dry basis of the rice, and the optimum temperature was 25°C. When inorganic salts were added to increase enzyme activity, the combined addition of 0.15% CaCO3 and 0.05% NaH2PO4 resulted in the highest enzyme activities.

Hypoglycemic effects of Cyclo (His-Pro) in streptozotocin-induced diabetic rats

The effects of Cyclo (His-Pro) (CHP), a cyclic dipeptide structurally related to thyrotropin-releasing hormone (TRH), on glucose metabolism, blood insulin level, lipid profile, and the viability of pancreatic cells were investigated in streptozotocin (STZ)-induced diabetic rats. The rats (Sprague-Dawley) with a blood glucose level above 300 mg/dL after induction with STZ (50 mg/kg of body weight) were considered to be diabetic and used for the treatment with CHP (4 mg/day/kg of body weight). The blood glucose level in the CHP-fed rats was reduced remarkably by approximately 56% as compared to the untreated diabetic group at 21 days of feeding. In an oral glucose tolerance test, blood glucose levels were restored to baseline at 120 min after CHP treatment, although the levels increased significantly after 30 min. Plasma insulin levels in the CHP-treated group were also enhanced by 2-fold compared to the untreated group. Triglyceride and total cholesterol levels in CHP-treated rats almost returned to normal levels. Moreover, histological examination showed that CHP treatment restored impaired β-cells in the pancreas up to two-thirds of the normal level. The transcriptional level of C-reactive protein (CRP), used mainly as a marker of inflammation, was also restored mimicking normal level in the CHP-treated-group, suggesting that the β-cells destroyed by STZ were, at least in part, recovered. Accordingly, CHP was concluded to have an excellent hypoglycemic effect by lowering average plasma glucose levels, increasing insulin secretion, and restoring the viability of pancreatic β-cells in diabetic rats. We suggest that CHP might be a potential candidate to control Type I diabetes mellitus.

Prohibitin deficiency causes opposing lipid metabolism between 3T3-L1 adipocytes and Clone 9 hepatocytes

Prohibitin (PHB) is a highly conserved protein in eukaryotic cells that are present in multiple cellular compartments and has potential roles as a tumor suppressor, an anti-proliferative protein, a regulator of cell-cycle progression and in apoptosis. In the present study, we generated PHB-deficient 3T3-L1 adipocytes and Clone 9 (C9) hepatocytes by oligonucleotide siRNA and investigated whether PHB affect lipid metabolism. It was revealed that PHB deficiency caused opposing lipid metabolism between the two cell models. PHB deficiency increased expression of adipogenic, lipogenic, and other lipid metabolic proteins in 3T3-L1 adipocytes, whereas significantly decreased the levels of those proteins in C9 cells. Collectively, PHB deficiency promoted lipid metabolism in 3T3-L1 adipocytes while it aggravated lipid metabolism in C9 hepatocytes.

Functional expression of bovine growth hormone gene in Pleurotus eryngii

The expression of the bovine growth hormone (bGH) gene was examined in Pleurotus eryngii, which belongs to the family of oyster mushrooms. The region encoding mature bGH, which has a variety of regulatory effects on growth and metabolic processes, was amplified using designed primers containing initiation and termination codons and then subcloned into pPEV binary expression vector. The recombinant vector (pPEVbGH) was introduced in P. eryngii via Agrobacterium tumefaciens-mediated transformation. Recombinant bGH was expressed in P. eryngii harboring pPEVbGH vector under control of the cauliflower mosaic virus (CaMV) 35S promoter up to a level of approximately 26% of total cell proteins after 6 days of cultivation, after which the recombinant protein was analyzed by SDS-PAGE and Western blotting. Interestingly, the growth rate of P. eryngii mycelia harboring pPEVbGH vector was approximately three times faster than that of control P. eryngii, suggesting that bGH affected the growth of P. eryngii. Biological activities were examined in Sprague-Dawley rats, which were administered regular feed mixed with mycelial extracts containing bGH (0.1 or 0.2 μg of bGH per g of animal feed). Mycelial extracts containing bGH significantly affected growth rates and lipid profiles; total cholesterol, triglyceride, HDL, and LDL levels were improved in rats fed mycelial extracts compared with those administered regular feed containing nontransgenic P. eryngii. This result indicates that P. eryngii harboring pPEVbGH vector could produce biologically active bGH. Further, levels of all growth-related factors increased, resulting in faster growth rates in bGH-treated groups. Accordingly, these data suggest that P. eryngii can be applied to the production of industrially useful proteins using a plant expression vector as an efficient mushroom host system.

Molecular cloning and functional expression of a fibrinolytic protease gene from the polychaeta, Periserrula leucophryna

Full-length cDNA encoding a fibrinolytic protease (PLFP) from the cDNA library of the polychaete, Periserrula leucophryna was cloned, sequenced and expressed in Escherichia coli. The entire cDNA of the PLFP clone was 921 bp (CDS: 41-837), including a coding nucleotide sequence of 798 bp, a 5′-untranslaed region of 40 bp, and a 3′-noncoding region of 83 bp. The ORF encoded a 265-amino acid polypeptide precursor consisting of a 36-residue signal sequence and a 229-residue mature polypeptide. The sequence alignment results of PLFP revealed sequence similarity with several fibrinolytic enzymes. Sequence analysis revealed a conserved catalytic triad of His78, Asp126 and Ser219 residues, suggesting that PLFP is a serine protease. Mature PLFP had an apparent molecular weight of approximately 25 kDa and was produced in inclusion bodies when expressed in E. coli. Substrate specificity results that recombinant PLFP was active towards Arg-X or Lys-X and did not hydrolyze substrates with nonpolar amino acids at the P1 site. Recombinant PLFP was strongly inhibited by typical serine protease inhibitors, further indicating that PLFP is a member of the serine protease family. PLFP was able to dissolve artificial plasminogenfree fibrin, and its fibrinolytic behavior was similar to that of plasmin. Taken these results together, PLFP is a new member of the fibrinolytic enzyme family with selective specificity on fibrin, and the availability of PLFP offers an attractive alternative approach for thrombolysis therapy because rPLFP is believed to have advantages over currently used plasminogen activators, that is, lower price and lower side effect.

Water-Soluble Red Pigment Production by Paecilomyces sinclairii and Biological Characterization

Natural pigments have several advantages over synthetic colorants. In this study, the production of red pigment produced by Paecilomyces sinclairii in microbial fermentation was demonstrated and the pigment was purified and characterized. The red pigment was produced from submerged fungal fermentation and fractionated by medium pressure flash chromatography. After fractionation, the spectrophotometric characterization of the red pigment revealed an λmax at 520 nm. Antimicrobial activity of the red pigment fraction was also studied against Escherichia coli O157 and Pseudomonas aeruginosa PAO1. The fraction (F2-F6) of the red pigment exhibited broad-spectrum antimicrobial activity in both bacteria. These results demonstrate the potential of this pigment in inhibiting bacterial growth and in food processing and other foodrelated applications.

Anti-diabetic effect of Cyclo-His-Pro (CHP)-enriched yeast hydrolysate in streptozotocin-induced diabetic mice

The present study was designed to investigate the hypoglycemic effects of the daily oral dose of 0.50 to 0.75 g/kg of yeast hydrolysate (YH) containing high Cyclo-His-Pro (51.0 mg CHP/g YH) on normal and streptozotocin (STZ)-induced diabetic rats for 14 days. In STZ-induced diabetic rats, after administrations of the YH for 14 days, the body weight gain was significantly increased in dose dependent manner, and the plasma glucose levels were decreased approximately (60%) as compared to the STZ induced diabetic control group. Glucose level showed significant differences between the diabetic control (DC) and the YH administered groups in oral glucose tolerance test (OGTT) ( P <0.05). Results of the OGTT showed a significant decrease in the area under curve (AUC) value of YH supplemented groups as compared to the DC group. The present data suggests that the CHP-enriched YH has potential anti-diabetic effect, which can help in the cure and management of diabetes. Keywords: Yeast hydrolysate, Cyclo-His-Pro (CHP), diabetes, streptozotocin. African Journal of Biotechnology Vol. 12(35), pp. 5473-5479