Nahyun Kim

Metabolomic Approach for Age Discrimination of Panax ginseng Using UPLC-Q-Tof MS

An ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-Tof MS)-based metabolomic technique was applied for metabolite profiling of 60 Panax ginseng samples aged from 1 to 6 years. Multivariate statistical methods such as principal component analysis and hierarchical clustering analysis were used to compare the derived patterns among the samples. The data set was subsequently applied to various metabolite selection methods for sophisticated classification with the optimal number of metabolites. The results showed variations in accuracy among the classification methods for the samples of different ages, especially for those aged 4, 5, and 6 years. This proposed analytical method coupled with multivariate analysis is fast, accurate, and reliable for discriminating the cultivation ages of P. ginseng samples and is a potential tool to standardize quality control in the P. ginseng industry.

Ursolic acid is a PPAR-α agonist that regulates hepatic lipid metabolism

In this study, we confirmed that ursolic acid, a plant triterpenoid, activates peroxisome proliferator-activated receptor (PPAR)-α in vitro. Surface plasmon resonance and time-resolved fluorescence resonance energy transfer analyses do not show direct binding of ursolic acid to the ligand-binding domain of PPAR-α; however, ursolic acid enhances the binding of PPAR-α to the peroxisome proliferator response element in PPAR-α-responsive genes, alters the expression of key genes in lipid metabolism, significantly reducing intracellular triglyceride and cholesterol concentrations in hepatocytes. Thus, ursolic acid is a PPAR-α agonist that regulates the expression of lipid metabolism genes, but it is not a direct ligand of PPAR-α.

Design and discovery of plasmepsin II inhibitors using an automated workflow on large-scale grids.

Novel and potent inhibitors of Plasmodium falciparum plasmepsin II were identified by post‐processing the results of a docking screening with BEAR, a recently reported procedure for the refinement and rescoring of docked ligands in virtual screening. FRET substrate degradation assays performed on the 30 most promising compounds resulted in 26 inhibitors with IC50 values ranging from 4.3 nM to 1.8 μM.

Nontargeted Metabolomics Approach for Age Differentiation and Structure Interpretation of Age-Dependent Key Constituents in Hairy Roots of Panax ginseng

The age of the ginseng plant has been considered as an important criterion to determine the quality of this species. For age differentiation and structure interpretation of age-dependent key constituents of Panax ginseng, hairy root (fine root) extracts aged from four to six years were analyzed using a nontargeted approach with ultraperformance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS). Various classification methods were used to determine an optimal method to best describe ginseng age by selecting influential metabolites of different ages. Through the metabolite selection process, several age-dependent key constituents having the potential to be biomarkers were determined, and their structures were identified according to tandem mass spectrometry and accurate mass spectrometry by comparing them with an in-house ginsenoside library and with literature data. This proposed method applied to the hairy roots of P. ginseng showed an improved efficiency of age differentiation when compared to previous results on the main roots and increases the possibility of the identification of key metabolites that can be used as biomarker candidates for quality assurance in ginseng.

Bioactive triterpenoids from Callistemon lanceolatus.

A new triterpenoid, 30-hydroxyalphitolic acid 1, and eight known triterpenoids, alphitolic acid 2, lupenol 3, 3-acetoxy-olean-18-en-28-oic acid 4, betulinic acid 5, ursolic acid 6, betulinic acid 3-O-caffeate 7, morolic acid 3-O-caffeate 8, and ursolic acid 3-O-caffeate 9, were isolated from Callistemon lanceolatus. Their structures were determined using spectroscopic techniques, which included 1D- and 2D-NMR. All compounds were evaluated for the inhibition of LPS-induced nitric oxide production in murine macrophage RAW264.7 cells. Betulinic acid 3-O-caffeate 7 showed a moderate inhibitory effect on nitric oxide production with IC50 value of 15.4 μM.

Ursolic acid improves lipid and glucose metabolism in high‐fat‐fed C57BL/6J mice by activating peroxisome proliferator‐activated receptor alpha and hepatic autophagy

SCOPE This study investigated metabolic effects of ursolic acid (UA), a peroxisome proliferation-activated receptor (PPAR)-α activator, in vivo. METHODS AND RESULTS High-fat diet (HFD)-fed C57BL/6J mice were orally administered UA (50 or 200 mg/kg body weight) for 8 wk. UA reduced liver and adipose tissue mass, adipocyte size, and plasma leptin concentrations, plasma triglyceride and low-density-lipoprotein cholesterol concentrations, while it elevated the high-density-lipoprotein cholesterol and adiponectin concentrations significantly compared with controls. UA induced the expression of PPARα and its responsive genes involved in fatty acid uptake and β-oxidation in the livers, whereas genes involved in lipogenesis, including sterol regulatory element-binding proteins-1c, were downregulated. UA administration improved glucose tolerance and insulin sensitivity significantly compared with the HFD-fed control livers. UA administration also activated hepatic autophagy as assessed by the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II and other key proteins in the autophagy pathway. CONCLUSION Our findings suggest that UA ameliorates lipid and glucose metabolism in HFD-fed mice primarily by the activation of PPARα and induction of the hepatic autophagy pathway. Thus, intake of UA in the diet or in an isolated form may ameliorate lipid and glucose metabolism.

Polyhydroxylated macrolides from Seimatosporium discosioides and their effects on the activation of peroxisome proliferator-activated receptor gamma

Two new polyhydroxylated macrolides, seimatopolides A (1) and B (2), were isolated from an EtOAc extract of Seimatosporium discosioides culture medium. The structures of the new compounds were established on the basis of spectroscopic analysis, including 1D and 2D NMR, and their absolute configurations were determined using the modified Moshers method. Seimatopolides A (1) and B (2) activated peroxisome proliferator-activated receptor (PPAR)-γ with EC(50) values of 1.15 and 11.05 μM, respectively. The expression of PPAR-γ target genes in HepG2 hepatocytes was significantly altered; in particular, expression of the gluconeogenic genes glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) was reduced upon stimulation with 1, supporting the proposal that compound 1 is both a PPAR-γ agonist and a possible therapeutic candidate for treatment of diabetes.

Cytotoxic 6-Alkylsalicylic Acids from the Endophytic Streptomyces laceyi

Two new 6-alkylsalicylic acids, salaceyins A and B were isolated by bioassay-guided fractionation from the culture of the endophytic Streptomyces laceyi MS53 and their structures were determined on the basis of spectroscopic data. Salaceyins A and B exhibited modest cytotoxicity against a human breast cancer cell line (SKBR3) with IC50 values of 3.0 and 5.5 μg/ml, respectively.

A metabolomic approach to determine the geographical origins of Anemarrhena asphodeloides by using UPLC–QTOF MS

An ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF MS) method was developed for metabolite profiling of Anemarrhena asphodeloides Bunge from two different geographical origins. In this study, the metabolite profile data obtained using UPLC-QTOF MS was subjected to multivariate statistical analyses, such as the principal component analysis and the hierarchical clustering analysis, to compare metabolite patterns among A. asphodeloides samples. Furthermore, a metabolite selection method known as significance analysis of microarrays (SAM) was applied to further select metabolites and to identify key constituents to efficiently distinguish between geographical origins. The UPLC-QTOF MS analysis successfully classified 21 samples into two distinct groups according to their geographical origins. The validation method used to assess the analytical stability and accuracy of these data is also described. These results suggest that this proposed method is reliable, accurate, and effective for geographic classification of A. asphodeloides, thus guiding its proper use for therapeutic purposes.

Metabolomics approach for the discrimination of raw and steamed Gastrodia elata using liquid chromatography quadrupole time-of-flight mass spectrometry

A liquid chromatography quadrupole time-of-flight mass spectrometry-based metabolomics approach was applied to metabolite profiling of Gastrodia elata in order to identify raw and steamed G. elata and explore potential biomarkers for each processing state. A statistical classification method, significant analysis of microarrays, was used to select influential metabolites from the different forms. Through metabolite selection, several potential biomarkers were determined and assigned by matching mass information with that of reference compounds or by comparing it with data in the literature. Furthermore, the developed method was cross-checked using two validation procedures. The first validation was performed simultaneously with the metabolite profiling of G. elata using all detected metabolites, and the second was performed after the metabolite profiling using representative standard compounds of G. elata. Overall, this study can be applied to quality assurance of G. elata.