Jaehong Han

Jaehong Han
Chung-Ang University · College of Biotechnology and Natural Resources

Doctor of Philosophy

About

117
Publications
22,150
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Introduction
Jaehong Han currently works at the College of Biotechnology and Natural Resources, Chung-Ang University. Jaehong does research in Phytochemistry, Bioinorganic Chemistry and Natural Products. Jaehong's Interestes also include Public Engagement through The Asian Society of Natural Products. His current project is 'Biotransformation of natural products by human intestinal bacteria'. Jaehong's research group emphasizes and practices strong Chemistry to perform research at the advanced level.
Additional affiliations
September 2004 - February 2015
Chung-Ang University
Position
  • Professor (Full)
September 2003 - April 2004
Ewha Womans University
Position
  • Professor
August 2001 - July 2003
Virginia Polytechnic Institute and State University
Position
  • PostDoc Position

Publications

Publications (117)
Article
Full-text available
Tyrosinase (TYR) is a type III copper oxidase present in fungi, plants and animals. The inhibitor of human TYR plays a vital role in pharmaceutical and cosmetic fields by preventing synthesis of melanin in the skin. To search for an effective TYR inhibitor from various plant extracts, a kinetic study of TYR inhibition was performed with mushroom TY...
Article
Gut metabolism of natural products is of great interest due to the altered biological activity of the metabolites. To study the gut metabolism of the dietary furanocoumarins, the biotransformation of Angelica dahurica was studied with human gut microbiota. The major components of Avenula dahurica, including xanthotoxin (1), bergapten (2), imperator...
Article
Full-text available
For the functional food applications, antioxidant properties and the bioactive compounds of the 23 Curcuma species commercially cultivated in Thailand were studied. Total phenolic content and DPPH radical scavenging activity were determined. The concentrations of eight bioactive compounds, including curcumin (1), demethoxycurcumin (2), bisdemethoxy...
Article
Full-text available
The intestine is a small world where all the chemical reactions are operated by gut microbiota. Study on the gut metabolism of natural products is a new and expanding research area that leads to new bioactive metabolites, as well as novel chemical reactions. To provide exemplary cases, flavonoid biotransformation by intestinal bacteria with focus o...
Article
Kaempferia parviflora (KP) is a famous medicinal plant from Thailand, and is a rich source of various kinds of methoxyflavones (MFs). Many kinds of food products such as tea, capsule, and liquor are manufactured from the rhizomes of KP. In this study, KP infusions were prepared with different brewing conditions, and the amounts of three major metho...
Article
Full-text available
Whereas Korean ginseng, Panax ginseng Meyer, is harvested in the fall, the variation of ginsenoside content in field-grown ginseng across seasonal development has never been investigated in Korea. Thus, ultra-high performance liquid chromatography (UHPLC) analysis of nine major ginsenosides, including ginsenoside Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rd,...
Article
Objective: Thai medicinal plants were used as the traditional medicines and as part of everyday plants diet. Plants contain a mixture of phytochemical and exhibit a lot of functional food and medicinal properties. This project aims to investigate the potential of selected Thai medicinal plants according to the properties of their antioxidant and an...
Article
For biotechnological production of high valued β-D-hexyl glucoside, catalytic properties of Hanseniaspora thailandica BC9 β-glucosidase purified from the periplasmic fraction was studied, and the transglycosylation activity for the production of β-D-hexyl glucoside was optimized. The constitutive BC9 β-glucosidase exhibited maximum specific activit...
Article
Curcumin and other curcuminoids from Curcuma longa are important bioactive compounds exhibiting various pharmacological activities. In addition to the known reductive metabolism of curcuminoids, an alternative biotransformation of curcuminoids by human gut microbiota is reported herein. A curcuminoid mixture, composed of curcumin (1), demethoxycurc...
Article
Full-text available
Indonesia is one of the richest countries with respect to plants resources. People from various ethnic, language, and religious groups have used the plants as alternative medicines, health foods and beverages for hundreds of years. To establish modern application for these understudied plant resources, ethnopharmacological data from more than 40 le...
Article
Polymethoxyflavones (PMFs) were biotransformed to various demethylated metabolites in the human intestine by the PMF-metabolizing bacterium, Blautia sp. MRG-PMF1. Because the newly formed metabolites can have different biological activities, the pathways and regioselectivity of PMF bioconversion were investigated. Using an anaerobic in vitro study,...
Article
(E)-4-Hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) reductase (IspH, HDR or LytB) is an Fe/S enzyme catalyzing the reductive dehydroxylation of HMBPP to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) in the last step of methylerythritol phosphate (MEP) pathway. The MEP pathway is known to produce 4–6:1 ratio of IPP and DMAPP m...
Article
Full-text available
Icariin is a major bioactive compound of Epimedii Herba, a traditional oriental medicine exhibiting anti-cancer, anti-inflammatory and anti-osteoporosis activities. Recently, the estrogenic activities of icariin drew significant attention, but the published scientific data seemed not to be so consistent. To provide fundamental information for the s...
Article
Full-text available
Plant-derived compounds are an important source of clinically useful anti-cancer agents. Chrysin, a biologically active flavone found in many plants, has limited usage for cancer chemotherapeutics due to its poor oral bioavailability. 5-Hydroxy-7-methoxyflavone (HMF), an active natural chrysin derivative found in various plant sources, is known to...
Article
Daidzin, daidzein 7-O-glucoside, is a major isoflavone in soybean and acts as a phytoestrogen. By intestinal bacteria dietary, daidzin is hydrolyzed to the aglycone daidzein and further converted to the more reduced metabolites, such as dihydrodaidzein, tetrahydrodaidzein, and equol. Human intestinal bacteria Enterococcus sp. MRG-2 and Lactococcus...
Poster
5, 3’-Dihydroxy-3, 7, 4’-trimethoxyflavone (QD) is a novel chemically synthesized quercetin derivative by the reaction between quercetin and the corresponding alkyl halides. As quercetin is a well-known flavonoid has diverse biological activities such as anti-inflammatory, anti-cancer, antiviral and anti-melanogenic. To check the altered biological...
Article
Full-text available
Biological Fe/S clusters play various important roles, such as electron transfer and substrate transformation. In the study of the electronic properties of biological and chemical Fe/S clusters, 57 Fe-Mössbauer spectroscopy provides imperative information. In this review, practical aspects of 57 Fe-Mössbauer spectroscopy,with an emphasis on the iso...
Article
Full-text available
Series of alkyl quercetin derivatives were synthesized from the reactions between quercetin (1) and the corresponding alkyl halides. Three methyl quercetin derivatives, 5,3′-dihydroxy-3,7,4′-trimethoxyflavone (2), 5-hydroxy-3,7,3′,4′-tetramethoxyflavone (3), 3,5,7,3′,4′-pentamethoxyflavone (4), three ethyl quercetin derivatives, 5,3′-dihydroxy-3,7,...
Article
Full-text available
GbIspH1, IspH type 1 in Ginkgo biloba chloroplast, is the Fe/S enzyme catalyzing the reductive dehydroxylation of HMBPP to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) at the final step of methylerythritol phosphate pathway in chloroplast. Compared to the bacterial IspH, plant IspH, including GbIspH1, has an additional polype...
Data
Supplementary Material containing experimental details and more supporting data.
Article
Poylmethoxyflavones (PMFs) are major bioactive flavonoids which exhibit27 various biological activities such as anti-cancer effects. The biotransformation of PMFs and characterization of a PMF-metabolizing human intestinal bacterium were studied herein for the first time. Hydrolysis of aryl methyl ether functional groups by human fecal samples was...
Article
Polymethoxyflavones (PMFs) are a group of polymethoxylated bioactive flavones with diverse biological activities, including anticancer, anti-inflammatory, antibacterial, and antiviral activities. PMFs are found from various plants such as orange, tangerine, and krachaidum. To establish the simple quantitative analytical methods for PMFs, chromatogr...
Article
To elucidate the hitherto unknown absolute configuration of (-)-O-desmethylangolensin ((-)-O-DMA), an intestinal bacterial metabolite produced from daidzein, chiroptical study, including specific optical rotation and electronic circular dichroism (ECD), of (R)-O-DMA was carried out by Time-Dependent Density Functional Theory (TD-DFT) calculations....
Article
Background Plant isoflavones are mostly present in the glycoside form. Isoflavone aglycones produced by intestinal microflora are reported to be more bioactive than the glycoside form. However, the deglycosylation of isoflavone C-glycosides is known to be rare, and is less studied.ResultsThree new bacteria were isolated from human fecal samples, tw...
Article
Full-text available
E-mail: jaehongh@cau.ac.krReceived February 3, 2014, Accepted February 24, 2014Key Words : Bioconversion, Chiroptical, Isoflavone, 2-HPPA, TD-DFTBiotransformation of natural products by human intestinalbacteria has recently drawn a significant interest, due to theemerging strong correlation between gut microbiota andhuman health.
Article
Isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), biochemical precursors of the isoprenoids, are biosynthesized by mevalonate pathway and methylerythritol phosphate (MEP) pathway. Because these two pathways are mutually exclusive in most organisms, inhibition of MEP pathway has become a target for the development of new bioactive...
Article
Carboxymethyl starch was modified by the incorporation of an azidophenyl group to prepare photoreactive starch, and characterized by Fourier transform infrared reflectance (FT-IR), proton nuclear magnetic resonance (1H-NMR), and ultraviolet (UV) spectroscopy. Photo-irradiation immobilized the Az-starch on a polystyrene plate and it was stably retai...
Article
Full-text available
Steroid 5α-reductase inhibition was studied using eleven polymethoxyflavones (PMFs). Homologous eleven PMFs showed wide range of steroid 5α-reductase inhibitory effects. Among the tested PMFs, 5-hydroxy-7,4′-dimethoxyflavone (5) was found to be the most potent inhibitor of steroid 5α-reductase with the IC50 of 20 μM. These results showed PMFs could...
Article
Titanium (Ti) is widely used as an implant material. There are various kinds of Ti surface modification methods to facilitate effective osseointegration. In this study, UV‐curable azido‐LMC (azidophenyl low molecular weight chitosan) was used to modify the Ti surface. Here we suggest a novel Ti coating material that confers complex, diverse improve...
Article
Azotobacter vinelandii, a strict aerobic nitrogen-fixing bacterium, has been extensively studied with regard to the ability of N2-fixation due to its high expression of nitrogenase and fast growth. Because nitrogenase can also reduce cyanide to ammonia and methane, cyanide degradation by A. vinelandii has been studied for the application in the bio...
Article
4-Hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) is the ultimate enzyme in 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway converting (E)-4-hydroxy-3-methylbut-2-enyl pyrophosphate (HMBPP) into isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Burkholderia glumae, a Gram-negative rice-pathogenic bacterium, harbors 2 hdr...
Article
Full-text available
To investigate anticancer effects of Kaempferia parviflora, rhizomes of K. parviflora were extracted with supercritical CO2 fluid and ethanol under various extraction conditions. Antiproliferative activity of these extracts was evaluated against human cervical cancer HeLa and human gastric adenocarcinoma AGS cell lines. Supercritical CO2 fluid extr...
Article
Full-text available
Although several studies covered anti-proliferative and cytotoxic effects of the rhizome extracts of Kaempferia parviflora Wall. Ex. Baker towards cancer cells, cytotoxicity of its pure methoxyflavone components remains undetermined. The present study was aimed to evaluate the cytotoxicity of 3,5,7,4′-tetramethoxyflavone (TeMF), 5,7,4′-trimethoxyfl...
Article
Wild-type naphthalene dioxygenase (NDO) from Pseudomonas sp. strain NCIB 9816-4 transforms relatively planar flavone and isoflavone to cis-dihydrodiols. However, this enzyme cannot catalyze the transformation of flavanone and isoflavanone in which a phenyl group bonds to the stereogenic C2 or C3 of the C-ring. Protein modeling suggested that Phe224...
Article
Full-text available
The [Fe 4 S 4 ] 2+ clusters with 2-, 3-, and 4-pyridinemethanethiolate (S2-Pic, S3-Pic, and S4-Pic, respectively) terminal ligands have been synthesized from the ligand substitution reaction of the (n Bu 4 N) 2 [Fe 4 S 4 Cl 4 ] (I) cluster. The new (n Bu 4 N) 2 [Fe 4 S 4 (SR) 4 ] (R = 2-Pic; II, 3-Pic; III, 4-Pic; IV) clusters were characterized by...
Article
Full-text available
To ensure polymethoxyflavone (PMF) extract from krachaidum, Kaempferia parviflora rhizome, supercritical CO2 extraction was attempted as an efficient and nontoxic method. Extraction yields and composition of PMFs in the supercritical fluid extracts (SFEs) were obtained under the different extraction conditions of pressure and temperature. Nine PMFs...
Article
Cyanobacterial aldehyde decarbonylase (cAD) is, structurally, a member of the di-iron carboxylate family of oxygenases. We previously reported that cAD from Prochlorococcus marinus catalyzes the unusual hydrolysis of aldehydes to produce alkanes and formate in a reaction that requires an external reducing system but does not require oxygen [Das et...
Article
The root of Korean ginseng, Panax ginseng C. A. Meyer, has been known worldwide as a panacea for many centuries. Contradictory weight gain and loss effects in Korean ginseng led to the adoption of supercritical carbon dioxide extraction to assure the quality of food-grade anti-obesity ginseng products. Among different extraction conditions of CO2 p...
Data
Crystallographic data and refinement statistics. (DOC)
Data
Thin-layer chromatographic analysis of toxoflavin degradation under various conditions. The enzyme reaction was carried out using three different enzymes: wild-type enzyme (WT), TxDE with the F94S mutation, and TxDE with the mutation D175A. For the reaction in the absence of DTT or Mn2+, the purified WT enzyme was dialyzed against buffer in the pre...
Data
EPR spectrum of the purified TxDE. Sample contains 290 uM TxDE. EPR parameters: 100 K, 1-mW microwave power at 9.18 GHz, modulation amplitude 3.2G. (TIF)
Data
Stereoscopic view of the active site of the TxDE–toxoflavin complex. This view, obtained by a rotation of about 90° along the vertical axis of Figure 4A, illustrates that the possible sixth coordinating ligand is missing in this complex. The electron density of 2Fo-Fc contoured at 1 σ is shown for a bound Mn(II) (black sphere), water molecule (red...
Data
UV-Vis absorption spectra of toxoflavin in the absence and presence of DTT. Two different absorption spectra of toxoflavin (25 µM), which was dissolved in 50 mM HEPES, pH 6.8, and 10 µM MnCl2, were recorded under aerobic conditions. In the absence of DTT (solid line), toxoflavin exhibits two absorption peaks, at 258 and 393 nm. Upon the addition of...
Data
1H-NMR experiments in deuterated methanol (99% CD3OD). 1H-NMR chemical shifts under aerobic conditions at 22°C for (A) pure toxoflavin (1), (B) pure 4,8-dihydrotoxoflavin (2), and (C) pure DTT (3) are shown with peak assignments for each proton in the compounds. (D) The 1H-NMR experiment was performed in deuterated methanol after a 10-min reaction...
Data
Details for distances and angles (degrees) between a bound metal and its ligands. (DOC)
Data
Overall structure of glyoxalase and 2,3-dihyroxybiphenyl 1,2-dioxygenase (DHBD). (A) As described in the text, a dimer of glyoxalase (PDB ID 1FRO) [37] generates two independent active sites at the intersubunit interface. Each monomer is indicated in a different color, and the active sites are presented with a bound metal ion (black sphere). (B) Th...
Article
Just add water: Structurally, cyanobacterial aldehyde decarbonylases are members of the non-heme diiron oxygenase family of enzymes. However, the enzyme catalyzes the hydrolysis of aliphatic aldehydes to alkanes and formate (see scheme), in an oxygen-independent reaction. This unusual and chemically difficult reaction most likely involves free radi...
Article
Full-text available
Pathogenic bacteria synthesize and secrete toxic low molecular weight compounds as virulence factors. These microbial toxins play essential roles in the pathogenicity of bacteria in various hosts, and are emerging as targets for antivirulence strategies. Toxoflavin, a phytotoxin produced by Burkholderia glumae BGR1, has been known to be the key fac...
Article
Full-text available
This review details recent progresses in the flavonoid biotransformation by bacterial non-heme dioxygenases, biphenyl dioxygenase (BDO), and naphthalene dioxygenase (NDO), which can initially activate biphenyl and naphthalene with insertion of dioxygen in stereospecfic and regiospecific manners. Flavone, isoflavone, flavanone, and isoflavanol were...
Article
Full-text available
A Gram-negative anaerobic microorganism, MRG-1, isolated from human intestine showed high activities of deglycosylation and reduction of daidzin, based on rapid TLC analysis. A rod-shaped strain MRG-1 was identified as a new species showing 91.0% homology to Coprobacillus species, based on 16S rRNA sequence analysis. The strain MRG-1 showed β-gluco...
Article
Full-text available
Naphthalene dioxygenase (NDO) from Pseudomonas sp. strain NCIB 9816-4 is a multicomponent enzyme system that carries out the initial step in the degradation of naphthalene. This enzyme has broad substrate range and catalyzes several types of reactions including cis-dihydroxylation, monooxygenation, and desaturation. 1-Phenylpyrazole and 1-phenylpyr...
Article
Full-text available
In this study, we investigated the effect of dietary supplementation of Cu-Met chelate (Cu-Met) and Cu-soy proteinate (Cu-SP) on the performance, blood parameters, liver mineral content, and intestinal microflora in broiler chickens. A total of 1,008 hatched Ross broiler chickens were randomly assigned to 1 of 6 dietary treatments (T): T1, control;...
Article
Full-text available
For vibrational and electronic spectroscopic characterizations of α-amino acid mineral chelates, nine water-soluble α-amino acids of Ala, Asn, Gln, His, Ile, Lys, Pro, Thr, and Val were used to prepare metal complexes with Fe(II), Fe(III), Cu(II), and Zn(II) ions. The α-amino acid-metal complexes were characterized by FT-IR and UV-Vis spectrometers...
Article
Full-text available
Biphenyl dioxygenase from Pseudomonas pseudoalcaligenes strain KF707 expressed in Escherichia coli was found to exhibit monooxygenase activity toward four stereoisomers of isoflavan-4-ol. LC-MS and LC-NMR analyses of the metabolites revealed that the corresponding epoxides formed between C2' and C3' on the B-ring of each isoflavan-4-ol substrate we...
Article
A water-soluble photo-reactive chitosan derivative was synthesized as a novel anti-adhesive agent by combining low molecular O-carboxymethyl chitosan and photo-reactive N-(4-azidobenzoyloxy) succinimide. Photoreactive low molecular O-carboxymethyl chitosan was analyzed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear resonance s...
Article
Full-text available
Compositional changes in ginsenosides and crude saponin during enzymatic biotransformation of red ginseng were studied on three commercial polysaccharide-hydrolyzing enzymes, Pectinex, Termamyl, and Celluclast. Considerable enhancement of crude saponin production was observed with Pectinex, whereas hydrothermally processed black ginseng showed sign...
Article
The dichloride-bridged [TPA2Mn2(μ-Cl)2]2+ complex (I) was synthesized as a structural and functional model complex of the chloride-inhibited manganese catalase, and its catalytic properties in MeCN have been studied. Complex I shows sigmoidal kinetics and the activity is significantly inhibited in the presence of water. The kinetic parameters of th...
Article
Full-text available
This study investigated the effects of Fe-soy proteinate (Fe-SP) and magnesium oxide (MgO) dietary supplements on eggshell quality in laying hens. A total of 800 26-wk-old Hy-Line Brown hens were assigned to four dietary treatments: control (C), Fe-SP 100 (100 ppm Fe-soy proteinate), MgO (3 g MgO/kg diet), and Fe-SP 100+MgO. Each treatment had five...
Article
Elucidation of the correct stereochemistry of the metabolite is essential for the mechanistic study of bioactive compounds. Isoflavan-4-ol has the same chiropical chromophore as THD, the biosynthetic precursor of the potent phytoestrogen S-equol. Interested in the correct absolute configuration of isoflavan-4-ol stereoisomers and to compare the ava...
Article
To elucidate the mechanism of (3S)-equol biosynthesis, (2,3,4-d(3))-trans-THD was synthesized and converted to (3S)-equol by THD reductase in Eggerthella strain Julong 732. The position of the deuterium atoms in (3S)-equol was determined by (1)H NMR and (2)H NMR spectroscopy, and the product was identified as (2,3,4(alpha)-d(3))-(3S)-equol. All the...
Article
Full-text available
Naphthalene dioxygenase (NDO) from Pseudomonas sp. strain NCIB 9816-4 incorporated dioxygen at the C7 and C8 positions on the A-rings of flavone and isoflavone with different stereoselectivity, resulting in the formation of (7S,8S)-dihydroxy-2-phenyl-7,8-dihydro-4H-chromen-4-one (flavone-cis-(7S,8S)-dihydrodiol) and (7R,8R)-dihydroxy-3-phenyl-7,8-d...
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