Nam Keun Lee

Platycosides from the Roots of Platycodon grandiflorum and Their Health Benefits

The extracts and pure saponins from the roots of Platycodon grandiflorum (PG) are reported to have a wide range of health benefits. Platycosides (saponins) from the roots of PG are characterized by a structure containing a triterpenoid aglycone and two sugar chains. Saponins are of commercial significance, and their applications are increasing with increasing evidence of their health benefits. The biological effects of saponins include cytotoxic effects against cancer cells, neuroprotective activity, antiviral activity, and cholesterol lowering effects. Saponins with commercial value range from crude plant extracts, which can be used for their foaming properties, to high purity saponins such as platycodin D, which can be used for its health applications (e.g., as a vaccine adjuvant). This review reveals that platycosides have many health benefits and have the potential to be used as a remedy against many of the major health hazards (e.g., cancer, obesity, alzheimer’s) faced by populations around the world. Methods of platycoside purification and analysis are also covered in this review.

Inhibitory Effect of Cinnamon Essential Oils on Selected Cheese-contaminating Fungi (Penicillium spp.) during the Cheese-ripening Process

The antifungal effects of essential oils (EOs) on cultures of the known cheese fungal contaminants Penicillium spp. were evaluated. Cinnamon leaf and bark EOs were the most effective among 8 EOs tested. The main components of both cinnamon EOs were eugenol, cinnamaldehyde, and linalool. Both inhibited growth of Penicillium spp. at a concentration of 10% v/v (2,000 ppm/mm2) on a lawn cell plate. When tested using 3 commercially available cheese starters, cinnamon EOs showed no effect against the FD-DVS ABT-5 cheese starter. However, growth of lactobacilli was inhibited in the presence of ≥10% (v/v) of leaf and bark EOs for the KAZU 1 starter, and ≥5% (v/v) for the FD-DVS FLORA-DANICA starter. A concentration of 4,000 ppm/mm2 of cinnamon EOs completely inhibited growth of the Penicillium spp. that naturally contaminates the surface of Appenzeller cheese.

Optimization of ergosterol to vitamin D2 synthesis in Agaricus bisporus powder using ultraviolet-B radiation

Response surface methodology (RSM) was applied to determine the optimum circumstances for conversion of ergosterol to vitamin D2 via ultraviolet-B (UV-B) in white button mushroom (Agaricus bisporus) powder. Three independent variables, namely, exposure time, ambient temperature, and irradiation intensity were investigated using a central composite rotatable design. The RSM ridge analysis determined the following ideal states: exposure time of 10.4 min, ambient temperature of 26.33°C, and UV-B irradiation intensity of 1.36 W/m2. A vitamin D2 content of 741.50±23.75 μg/g (the predicted value was 780.4 μg/g) was obtained under these ideal conditions.

Lactic acid bacteria-mediated fermentation of Cudrania tricuspidata leaf extract improves its antioxidative activity, osteogenic effects, and anti-adipogenic effects

The goal of this study was to assess the potential of fermented Cudrania tricuspidata leaf (CTL) aqueous extract as a functional food material. The CTL aqueous extract was fermented using lactic acid bacteria (LAB) isolated from soybean-fermented foods and the biological effects of the resultant fermented extracts on MG-63 human osteoblastic cells and 3T3-L1 mouse pre adipocytes were examined in vitro. We found that (1) the radical scavenging activities of CTL extracts fermented by various LAB strains (fermented CTL, F-CTL) were ~2- fold higher than that of non-fermented CTL extract (NFCTL), (2) F-CTL extract enhanced MG-63 cell proliferation compared to NF-CTL-treated cells, (3) the level of alkaline phosphatase activity in F-CTL-treated MG-63 cells was significantly higher than that in NF-CTL-treated cells, and (4) 3T3-L1 cell differentiation was dramatically decreased by F-CTL treatment, but not by NF-CTL. These findings suggest that CTL that has undergone LAB-mediated fermentation may be beneficial for promoting osteogenic differentiation of osteoblastic cells and inhibiting fat accumulation in adipocytes.

Enhancement of 1-deoxynojirimycin content and α-glucosidase inhibitory activity in mulberry leaf using various fermenting microorganisms isolated from Korean traditional fermented food

Mulberry leaf is known to be effective in inhibiting increases in blood glucose levels in diabetic patients. 1-Deoxynojirimycin (DNJ), a α-glucosidase inhibitor, is the major effective component in mulberry leaf. The aim of this study was to evaluate the level of DNJ in mulberry leaves fermented by various microorganisms, including lactic acid bacteria, yeast, and the bacillus isolated from Korean traditional fermented soybean food, and to assess the inhibitory effect of fermented mulberry leaf powder extract (FMLE) on α-glucosidase activity. The DNJ content in unfermented mulberry leaf powder extract (UFMLE), the control, was determined to be 53.2 ± 1.5 mg/100 g (dry weight eq.). Lactobacillus plantarum, Zygosaccharomyces rouxii, Wickerhamomyces anomalus, and Bacillus subtilis remarkably increased the DNJ levels in mulberry leaves by 1.2, 1.5, 2.0, and 1.8-fold, respectively, compared to the control. The inhibitory effects of the FMLEs on α-glucosidase were also examined at various concentrations, and their α-glucosidase inhibitory effects tended to be higher than that in UFMLE. These findings suggest that Korean traditional fermenting microorganisms can be used as starter strains for the development of DNJ-enhanced food products, and that FMLEs have the potential to be used in various functional foods for the prevention of diabetes.

Statistical Optimization of Medium and Fermentation Conditions of Recombinant Pichia pastoris for the Production of Xylanase

Recombinant xylanase (rPcXynC) from Pichia pastoris was produced on large-scale by optimizing production-medium composition using statistical experimental methods. Production medium was optimized through the use of statistical methods such as one factor at a time (OFAT), Plackett-Burman design, fractional factorial design (FFD), steepest ascent method (SAM), and response surface methodology (RSM). The optimum medium composition was established to be (g/L); wheat bran 11.62, yeast extract 30, Tween 60.5, DL-β-Phenylalanine 0.5, Thiamine 0.5, FeSO4 0.01, KH2PO4 0.66, and KHSO4 0.09. The optimum medium composition yielded 3,051 mU/mL of xylanase activity which was three times higher than that obtained from the initial medium composition. Finally, fermentation conditions were examined using the optimized production medium in a laboratory bioreactor. The optimal fermentation conditions were found to be 25ºC, pH 6, 170 rpm and 1 vvm with intermittent feeding of methanol (67.5 mL) and the xylanase activity was 3,683 mU/mL. In repeated-batch fermentation using optimized production medium and fermentation condition, the xylanase activity was 3,680 mU/mL at the first cycle of 96 h harvesting time using 90% of the culture solution. The activity was similarly maintained until the last cycle of 264 h.

RNA-seq Analysis of Antibiotic-Producing Bacillus subtilis SC-8 in Response to Signal Peptide PapR of Bacillus cereus

Bacillus subtilis SC-8 produces an antibiotic that has narrow antagonistic activity against bacteria in the Bacillus cereus group. In B. cereus group bacteria, peptide-activating PlcR (PapR) plays a significant role in regulating the transcription of virulence factors. When B. subtilis SC-8 and B. cereus are co-cultured, PapR is assumed to stimulate antibiotic production by B. subtilis SC-8. To better understand the effect of PapR on this interspecies interaction, the global transcriptome profile of B. subtilis SC-8 was analyzed in the presence of PapR. Significant changes were detected in 12.8xa0% of the total transcripts. Genes related to amino acid transport and metabolism (16.5xa0%) and transcription (15xa0%) were mainly upregulated, whereas genes involved in carbohydrate transport and metabolism (12.7xa0%) were markedly downregulated. The expression of genes related to transcription, including several transcriptional regulators and proteins involved in tRNA biosynthesis, was increased. The expression levels of genes associated with several transport systems, such as antibiotic, cobalt, and iron complex transporters, was also significantly altered. Among the downregulated genes were transcripts associated with spore formation, the subtilosin A gene cluster, and nitrogen metabolism.

Schizandrin reduces cytoplasmic TDP-43 accumulation in hippocampal neuronal cells

Transactive response DNA binding protein 43 kDa (TDP-43, encoded by the TARDBP gene) is involved in transcriptional regulation and alternative splicing process. TDP-43 proteins are located in the nucleus and shuttles transcripts to the cytoplasm in normal neurons; however, they are observed in the forms of cytoplasmic inclusions in the degenerating cells. The abnormal accumulation of TDP-43 proteins is a pathologic feature of neurodegenerative diseases, such as Lou Gehrig’s disease and dementia including frontotemporal lobar degeneration and Alzheimer’s disease. In this study, we examined whether schizandrin, a main effective compound of Schisandra chinensis (Turcz.), so called omija in Korean, reduces TDP-43 accumulation in the hippocampal neurons in vitro. An immortalized mouse hippocampal neuronal cell line, HT22 cells, were treated with a proteasome inhibitor, MG132, in the absence or presence of schizandrin. We found that schizandrin treatment increased HT22 cell viability and reduced MG132-induced cytoplasmic accumulation of TDP-43. Our results suggest that schizandrin may be a promising compound for development of functional food materials beneficial to the neuronal protection against TDP-43 proteinopathies.