Publications by authors named "Dai Jun-Gui"

is widely used in traditional Chinese medicine and contains rich bioactive compounds. These compounds often have a methyl group at their 4'-OH position catalyzed by methyltransferases. Therefore, studying methyltransferases in plants is of great significance.

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Article Synopsis
  • Sesquiterpene synthases (STPSs) are enzymes that create diverse hydrocarbons through carbocation-driven reactions, with deprotonation-reprotonation processes contributing significantly to this diversity.
  • Research focused on two STPSs, AhCS and AhIS, showing they produce different compounds by selectively protonating at different positions of germacrene A (GA).
  • Structural analyses and site-directed mutagenesis identified specific active site residues that control regioselectivity, allowing researchers to successfully interchange the functions of AhCS and AhIS, paving the way for designing STPSs with varied structural outputs.
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Short-chain dehydrogenase/reductases (SDRs) belong to the NAD(P)(H)-dependent oxidoreductase superfamily, which have various functions of catalyzing oxidation/reduction reactions and have been generally used as powerful biocatalysts in the production of pharmaceuticals. In this study, ScSDR1 and ScSDR2, two new SDRs have been identified and characterized from 3.5365.

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Anhydroicaritin (), baohuoside () and icariin () were recognized as major pharmacologically active ingredients of plants. Their primary means of acquisition were chemical isolation from plants. However, it suffers from low yield, environmental pollution and shortage of plants.

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Peridecalins C and D ( and ), one decalin and one oxygen-decalin containing polyketide-amino acid hybrids with 5/6/6 ring system, was isolated from a genetic mutant of sp. F-31. Their structures were elucidated through extensive spectroscopic data analysis, including 1 D/2D NMR and HR-MS spectra.

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One new eremophilane sesquiterpene periconianone L (), together with four known guaiane-type sesquiterpenes 4,10,11-trihydroxyguaiane (), (-)-guai-1(10)-ene-4,11-diolhydroxymecuration (), guaidiol A (), and epi-guaidiol A () were isolated from the endophytic fungus sp. F-31. The structure of the new compound was established by spectroscopic methods, including UV, IR, HRESIMS, and extensive NMR techniques.

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Nineteen compounds were isolated and structurally characterized from an ethanol extract of Dendrobium gratiossimum, including dendrogratiol A(1), DDB-1(2), 3,4-dihydroxyl-5,3',4'-trimethoxybibenzyl(3), amoenylin(4), chrysotoxine(5), DTB(6), 3,4,4'-trihydroxyl-5,3'-dimethoxybenzyl(7), 3-methylgiga(8), aloifol(9), gigantol tetramethyl ether(10), batatasin Ⅲ(11), moscatilin(12), moniliformine(13), gigantol(14), DMB(15), flavanthrinin(16), cannithrene-2(17), 3,4-dihydroxyl-5,4'-dimethoxystilbene(18) and 4-hydroxy-3,5,4'-trimethoxystilbene(19). 1 was a new compound, and 2-10, 16, 18 and 19 were obtained from this plant species for the first time. In vitro cytotoxic and antiviral activities of these isolates were evaluated, which displayed that 4 showed moderate cytotoxicity against human hepatoma cell line HepG2 with the IC_(50) of 10.

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Objective: In order to obtain new glycosyltransferases with highly efficient catalysis, the glycosyltransferases from which contains diverse types of glycosides were mined. A new glycosyltransferase gene (UGT88B2) with full length was obtained by PCR and further transformed into for heterologous expression. The catalytic activity of recombinant UGT88B2 was determined by HPLC-MS.

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Various bioactive polyketides have been found in However, the polyketide synthases (PKSs), which participate in biosynthesis of polyketides in remain unknown. In this study, two type III PKSs (AbPKS1 and AbPKS2) were identified from . AbPKS1 and AbPKS2 were able to utilize malonyl-CoA to yield heptaketides (TW93a and aloesone) and octaketides (SEK4 and SEK4b), respectively.

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Bistachybotrysin K (), one new phenylspirodrimane dimer with a central 6/7 oxygen heterocycle core, was isolated from the fungus CGMCC 3.5365. Its structure was elucidated by extensive spectroscopic data and single-crystal X-ray diffraction.

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Three new phenylspirodrimanes derivatives named stachybotrysins H and I ( and ) and stachybotrin E (), together with one known compound stachybotrylactam (), were isolated from CGMCC 3.5365. Their structures were determined by extensive NMR data and mass spectroscopic analysis.

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Glucuronidation is an important and popular metabolic reaction in vivo of drugs. The further evaluation of biological activity and toxicity of glucuronides is necessary in the course of the drug research and development. However, the synthesis of glucuronides is limited by the lack of efficient approach.

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Seven new phenolic bisabolane sesquiterpenoids, (7R,10S)-7,10-epoxysydonic acid (1), (7S,10S)-7,10-epoxysydonic acid (2), (7R,11S)-7,12-epoxysydonic acid (3), (7S,11S)-7,12-epoxysydonic acid (4), 7-deoxy-7,14-didehydro-12-hydroxysydonic acid (5), (Z)-7-deoxy-7,8-didehydro-12-hydroxysydonic acid (6), and (E)-7-deoxy-7,8-didehydro-12-hydroxysydonic acid (7), along with five known analogues (8-12), were obtained from the culture of an endophytic fungus Aspergillus sp. xy02 isolated from the leaves of a Thai mangrove Xylocarpus moluccensis. All structures were assigned on the basis of detailed spectroscopic analyses.

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Bysspectin A (1), a polyketide-derived octaketide dimer with a novel carbon skeleton, and two new precursor derivatives, bysspectins B and C (2 and 3), were obtained from an organic extract of the endophytic fungus Byssochlamys spectabilis that had been isolated from a leaf tissue of the traditional Chinese medicinal plant Edgeworthia chrysantha, together with a known octaketide, paecilocin A (4). Their structures were determined by HRMS, 1D and 2D NMR spectroscopic analysis. A plausible route for their biosynthetic pathway is proposed.

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Two new lanostane triterpenoids (1 and 2), two new ergostane-type steroids (3 and 4) together with two known lanostane triterpenoids (5 and 6) and one known steroid (7) were isolated from the cultured mycelia of Ganoderma capense (CGMCC 5.71). Their structures were determined on the basis of extensive spectroscopic (HRESIMS, 1D NMR, 2D NMR) data analyses.

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Secoisolariciresinol dehydrogenase (SDH) is a key enzyme involved in the biosynthetic pathway of podophyllotoxin.In this study, two SDH candidate genes,SO282 and SO1223, were cloned from callus of Dysosma versipellis by homology-based PCR and rapid amplification of cDNA end (RACE).The SDH candidate genes were expressed in Escherichia coli and the subsequent enzyme assay in vitro showed that recombinant SO282 had the SDH activity.

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The glycosides of 4'-demethylepipodophyllotoxin (DMEP) possess various pharmacological activities; however, the chemical synthesis of these glycosides faces challenges in regioselectivity, stereoselectivity, and the protection and de-protection of functional groups. In this work, a novel glycosyltransferase (GT) gene AbGT5 from Aloe barbadensis was successfully cloned, heterogeneously expressed and purified. Recombinant AbGT5 was able to catalyze the glycosylation of DMEP and the glycosylated product, which was separated from the preparative scale reaction, was characterized as DMEP 4'-O-β-D-glucoside via MS, 1H-NMR, 13C-NMR, HSQC and HMBC.

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Three new xanthone dimers, named phomoxanthones C-E (1-3), were obtained from the Thai mangrove fungus Phomopsis sp. xy21, together with four known ones. The structures of these compounds were elucidated by the analysis of HRESIMS and extensive NMR spectroscopic data.

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Five monoterpenoids were isolated from the endophytic fungus Periconia sp. F-31, including three new carene-type monoterpenoids, 2-carene-5,8-diol (1), 2-carene-8,10-diol (2), 2-carene-8-acetamide (3), one new menthene-type monoterpenoid 8-hydroxy-1,7-expoxy-2-menthene (4), and one known monoterpenoid anethofuran (5). The structures of all compounds were elucidated based on a comprehensive spectroscopic data analysis, electronic circular dichroism (ECD), and calculated ECD.

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A new steroid glucoside (1), along with nine known steroids (2-10) and four known sorbicillinoids (11-14), were isolated from the endophytic fungus Trichoderma sp. Xy24. Their structures were elucidated on the basis of spectroscopic data analyses and by comparison with reported data.

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Three new sesquiterpenoids trichoacorenols B-C and cyclonerodiol B (1-3), along with three known ones (4-6), were isolated from the mangrove plant endophytic fungus Trichoderma sp. Xy24 using various column chromatography techniques. The structures of these compounds were determined on the basis of extensive spectroscopic data analyses.

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A study on the microbial transformation of glycyrrhetinic acid (GA) was conducted by a fungus, Cunninghamella blakesleeana CGMCC 3.970 systematically. After incubation with the cell cultures of C.

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Various chromatographic techniques, including silica gel column chromatography, Sephadex LH-20, preparative thin-layer chromatography, and preparative HPLC, were employed to isolate the chemical constituents from callus cultures of Dysosma versipellis. Structures of the compounds were elucidated based on UV, IR, MS and NMR spectroscopic data analysis. Totally, seven flavonoid glycosides were isolated from the 95% ethanol extract of the callus cultures and identified as kaempferol-3-O-[6″-(3″'-methoxy)-malonyl]-β-D-glucopyranoside(1), kaempferol-3-O-(6″-O-acetyl)-β-D-glucopyranoside(2), kaempferide-3-O-β-D-glucopyranoside(3), kaempferol-3-O-β-D-glucopyranoside(4), isoquercitrin(5), quercetin-4'-O-β-D-glucopyranoside(6) and kaempferol-3-(6″-malonyl)-β-D-glucopyranoside(7), respectively.

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To investigate the secondary metabolites of endophytic fungi Pericinia sp. F-31. Column chromatography on silica gel, Sephadex LH-20 and semi-preparative HPLC were used to separate and purify the compounds.

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Two new flavonoids (1 and 2), along with 14 known ones (3-16), were isolated from the cultured cells of Glycyrrhiza uralensis. Most of them were prenylated flavonoids. Their structures were elucidated on the basis of spectroscopic data analysis.

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