Jong-Hyun Lee

Biosynthesis of the Allylmalonyl-CoA Extender Unit for the FK506 Polyketide Synthase Proceeds through a Dedicated Polyketide Synthase and Facilitates the Mutasynthesis of Analogues

The allyl moiety of the immunosuppressive agent FK506 is structurally unique among polyketides and critical for its potent biological activity. Here, we detail the biosynthetic pathway to allylmalonyl-coenzyme A (CoA), from which the FK506 allyl group is derived, based on a comprehensive chemical, biochemical, and genetic interrogation of three FK506 gene clusters. A discrete polyketide synthase (PKS) with noncanonical domain architecture presumably in coordination with the fatty acid synthase pathway of the host catalyzes a multistep enzymatic reaction to allylmalonyl-CoA via trans-2-pentenyl-acyl carrier protein. Characterization of this discrete pathway facilitated the engineered biosynthesis of novel allyl group-modified FK506 analogues, 36-fluoro-FK520 and 36-methyl-FK506, the latter of which exhibits improved neurite outgrowth activity. This unique feature of FK506 biosynthesis, in which a dedicated PKS provides an atypical extender unit for the main modular PKS, illuminates a new strategy for the combinatorial biosynthesis of designer macrolide scaffolds as well as FK506 analogues.

Heterologous production of 4-O-demethylbarbamide, a marine cyanobacterial natural product.

Heterologous expression of the barbamide biosynthetic gene cluster, obtained from the marine cyanobacterium Moorea producens, in the terrestrial actinobacterium Streptomyces venezuelae, resulted in the production of a new barbamide congener 4-O-demethylbarbamide, demonstrating the potential of this approach for investigating the assembly and tailoring of complex marine natural products.

Arctigenin Inhibits Adipogenesis by Inducing AMPK Activation and Reduces Weight Gain in High-Fat Diet-Induced Obese Mice.

Although arctigenin (ARC) has been reported to have some pharmacological effects such as anti‐inflammation, anti‐cancer, and antioxidant, there have been no reports on the anti‐obesity effect of ARC. The aim of this study is to investigate whether ARC has an anti‐obesity effect and mediates the AMP‐activated protein kinase (AMPK) pathway. We investigated the anti‐adipogenic effect of ARC using 3T3‐L1 pre‐adipocytes and human adipose tissue‐derived mesenchymal stem cells (hAMSCs). In high‐fat diet (HFD)‐induced obese mice, whether ARC can inhibit weight gain was investigated. We found that ARC reduced weight gain, fat pad weight, and triglycerides in HFD‐induced obese mice. ARC also inhibited the expression of peroxisome proliferator‐activated receptor gamma (PPARγ) and CCAAT/enhancer‐binding protein alpha (C/EBPα) in in vitro and in vivo. Furthermore, ARC induced the AMPK activation resulting in down‐modulation of adipogenesis‐related factors including PPARγ, C/EBPα, fatty acid synthase, adipocyte fatty acid‐binding protein, and lipoprotein lipase. This study demonstrates that ARC can reduce key adipogenic factors by activating the AMPK in vitro and in vivo and suggests a therapeutic implication of ARC for obesity treatment. J. Cell. Biochem. 117: 2067–2077, 2016.

Effects of Taraxacum officinale on Fatigue and Immunological Parameters in Mice

In Korean herbal medicine dandelion (Taraxacum officinale, TO) has been used to improve energy levels and health. However, the effects of TO in experimental models remain unclear. We examined the anti-fatigue and immune-enhancing effects of TO in mice by performing a forced swimming test (FST) and in vitro by using peritoneal macrophages, respectively. After daily oral administration of TO, blood biochemical parameters related to fatigue were measured after the FST. FST immobility time was significantly decreased in the TO-treated group (100 mg/kg) on the tenth day. TO (10 and 100 mg/kg) treatment significantly increased glucose levels, acting as an energy source. The level of lactic dehydrogenase, which is an accurate indicator of muscle damage, tended to decline after TO administration (10 and 100 mg/kg). When TO (100 mg/kg) was orally administered to mice, blood urea nitrogen levels decreased significantly. We also examined the effect of TO on the production of cytokines and nitric oxide (NO) in mouse peritoneal macrophages. When TO was used in combination with recombinant interferon-gamma (rIFN-γ), a noticeable cooperative induction of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-12p70, and IL-10 production was observed. Furthermore, in peritoneal macrophages, rIFN-γ plus TO treatment significantly increased the production of NO through inducible nitric oxide synthase (iNOS) induction. Taken together, these results suggest that TO improves fatigue-related indicators and immunological parameters in mice.

Phytochemical and pharmacological aspects of Siraitia grosvenorii, luo han kuo

Siraitia grosvenorii, an herbaceous perennial vine, is native to Southern China and Northern Thailand. This species is well known for its fruit, which is commonly called “luo han guo” or “luo han kuo” in Chinese; “la han qua” in Vietnamese; or arhat, Buddha, or monk fruit in English. Phytochemical research has shown that the fruit of this species is rich in triterpene glycosides that are very sweet, low in calories, and may be used as a substitute for sugar. In addition, many compounds have been isolated from the vines and leaves of S. grosvenorii, including β-amyrin, aloe emodin, aloe-emodin acetate, 5α,8α-epidioxy-24(R)-methylcholesta-6,22-dien-3β-ol, p-hydroxyl benzyl acid, n-hexadecaoic acid, 12-methyltetradecanoic acid, β-sitosterol, and daucosterol. Moreover, a new flavandiol, siraitiflavandiol, has been obtained from ripe S. grosvenorii fruit, while 2 kaempferol glycosides have been isolated from the unripe fruit. Pharmacological results have also shown that S. grosvenorii extracts and purified mogrosides exhibit antidiabetic, anticarcinogenic, antibacterial, antioxidant, and antiallergic effects. Overall, S. grosvenorii could potentially serve as an important source of pharmaceutical and sweetener compounds for a wide range of food products.

Ligand Binding Affinities of Arctigenin and Its Demethylated Metabolites to Estrogen Receptor Alpha

Phytoestrogens are defined as plant-derived compounds with estrogen-like activities according to their chemical structures and activities. Plant lignans are generally categorized as phytoestrogens. It was reported that (−)-arctigenin, the aglycone of arctiin, was demethylated to (−)-dihydroxyenterolactone (DHENL) by Eubacterium (E.) sp. ARC-2. Through stepwise demethylation, E. sp. ARC-2 produced six intermediates, three mono-desmethylarctigenins and three di-desmethylarctigenins. In the present study, ligand binding affinities of (−)-arctigenin and its seven metabolites, including DHENL, were investigated for an estrogen receptor alpha, and found that demethylated metabolites had stronger binding affinities than (−)-arctigenin using a ligand binding screen assay method. The IC50 value of (2R,3R)-2-(4-hydroxy-3-methoxybenzyl)-3-(3,4-dihydroxybenzyl)-butyrolactone was 7.9 × 10−4 M.

The Antiinflammatory Mechanism of Igongsan in Mouse Peritoneal Macrophages via Suppression of NF-κB/Caspase-1 Activation

Igongsan (IGS), which is an herbal prescription composed of five different herbs, Ginseng Radix (root of Panax ginseng, Araliaceae), Atractylodis Rhizoma Alba (rhizome of Atractylodes Macrocephala, Compositae), Poria Sclerotium (sclerotium of Poria cocos, Polyporaceae), Glycyrrhizae Radix et Rhizoma (root and rhizome of Glycyrrhiza uralensis, Leguminosae), and Citri Unshius Pericarpium (Peel of Citrus unshiu, Rutaceae), has been traditionally used in Korea to treat a variety of inflammatory diseases. In this study, we investigated to elucidate the mechanism responsible for IGSs antiinflammatory effect in mouse peritoneal macrophages. The findings demonstrate that IGS inhibited the production of inflammatory cytokine and prostaglandins E2. IGS inhibited the enhanced levels of cyclooxygenase‐2 and inducible NO synthase caused by lipopolysaccharide (LPS). Additionally, it was shown that the antiinflammatory effect of IGS is through regulating the activation of nuclear factor‐kappa B and caspase‐1 in LPS‐stimulated mouse peritoneal macrophages. These results provide novel insights into the pharmacological actions of IGS as a potential candidate for development of new drugs to treat inflammatory diseases. Discussion and conclusion: These results provide novel insights into the pharmacological actions of IGS as a potential candidate for development of new drugs to treat inflammatory diseases. Copyright

Cinnamomi Cortex (Cinnamomum verum) Suppresses Testosterone-induced Benign Prostatic Hyperplasia by Regulating 5α-reductase.

Cinnamomi cortex (dried bark of Cinnamomum verum) is an important drug in Traditional Korean Medicine used to improve blood circulation and Yang Qi. Benign prostatic hyperplasia (BPH) is a common chronic disease in aging men. This study was conducted to determine the effect of Cinnamomi cortex water extract (CC) on BPH. BPH was induced by a pre-4-week daily injection of testosterone propionate (TP). Six weeks of further injection with (a) vehicle, (b) TP, (c) TPu2009+u2009CC, (d) TPu2009+u2009finasteride (Fi) was carried on. As a result, the prostate weight and prostatic index of the CC treatment group were reduced. Histological changes including epithelial thickness and lumen area were recovered as normal by CC treatment. The protein expressions of prostate specific antigen, estrogen receptor α (ERα), androgen receptor (AR), 5α-reductase (5AR), and steroid receptor coactivator 1 were suppressed by treatment of CC. Immunohistochemical assays supported the western blot results, as the expressions of AR and ERα were down-regulated by CC treatment as well. Further in vitro experiments showed CC was able to inhibit proliferation of RWPE-1 cells by suppressing 5AR and AR. These results all together suggest CC as a potential treatment for BPH.

Anti-obesity effects of Arctii Fructus (Arctium lappa) in white/brown adipocytes and high-fat diet-induced obese mice

Arctii Fructus is traditionally used in oriental pharmacies as an anti-inflammatory medicine. Although several studies have shown its anti-inflammatory effects, there have been no reports on its use in obesity related studies. In this study, the anti-obesity effect of Arctii Fructus was investigated in high-fat diet (HFD)-induced obese mice, and the effect was confirmed in white and primary cultured brown adipocytes. Arctii Fructus inhibited weight gain and reduced the mass of white adipose tissue in HFD-induced obese mice. Serum levels of triglyceride and LDL-cholesterol were reduced, and HDL-cholesterol was increased in the Arctii Fructus treated group. In 3T3-L1 cells, a water extract (WAF) and 70% EtOH extract (EtAF) of Arctii Fructus significantly inhibited adipogenesis and suppressed the expression of proliferator-activated receptor gamma and CCAAT/enhancer-binding protein alpha. In particular, EtAF activated the phosphorylation of AMP-activated protein kinase. On the other hand, uncoupling protein 1 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha, known as brown adipocytes specific genes, were increased in primary cultured brown adipocytes by WAF and EtAF. This study shows that Arctii Fructus prevents the development of obesity through the inhibition of white adipocyte differentiation and activation of brown adipocyte differentiation which suggests that Arctii Fructus could be an effective therapeutic for treating or preventing obesity.

Veratri Nigri Rhizoma et Radix (Veratrum nigrum L.) and Its Constituent Jervine Prevent Adipogenesis via Activation of the LKB1-AMPKα-ACC Axis In Vivo and In Vitro

This study was performed in order to investigate the antiobese effects of the ethanolic extract of Veratri Nigri Rhizoma et Radix (VN), a herb with limited usage, due to its toxicology. An HPLC analysis identified jervine as a constituent of VN. By an Oil Red O assay and a Real-Time RT-PCR assay, VN showed higher antiadipogenic effects than jervine. In high-fat diet- (HFD-) induced obese C57BL/6J mice, VN administration suppressed body weight gain. The levels of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT-enhancer-binding protein alpha (C/EBPα), adipocyte fatty-acid-binding protein (aP2), adiponectin, resistin, and LIPIN1 were suppressed by VN, while SIRT1 was upregulated. Furthermore, VN activated phosphorylation of the liver kinase B1- (LKB1-) AMP-activated protein kinase alpha- (AMPKα-) acetyl CoA carboxylase (ACC) axis. Further investigation of cotreatment of VN with the AMPK agonist AICAR or AMPK inhibitor Compound C showed that VN can activate the phosphorylation of AMPKα in compensation to the inhibition of Compound C. In conclusion, VN shows antiobesity effects in HFD-induced obese C57BL/6J mice. In 3T3-L1 adipocytes, VN has antiadipogenic features, which is due to activating the LKB1-AMPKα-ACC axis. These results suggest that VN has a potential benefit in preventing obesity.