Publications by authors named "Yan-Qiong Guo"

Glutathione S-transferases (GSTs) are multifunctional enzymes, and insect GSTs play a pivotal role in the metabolism of insecticides. Grapholita molesta is a worldwide pest that causes substantial economic losses to the fruit industry. However, it remains unclear how imidacloprid, a commonly used insecticide in orchards, is metabolized by G.

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Stably expressed reference genes are critical internal standards for the quantification of gene transcription levels using quantitative real-time PCR. Housekeeping genes are commonly used as reference genes but their expressions were variable depending on experimental conditions in many insect species studied. Here we report the identification and evaluation of 10 housekeeping genes in alligator weed flea beetle, Agasicles hygrophila Selman & Vogt (Coleoptera: Chrysomelidae), a biocontrol agent of alligator weed.

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Mulberry Diels-Alder-type adducts (MDAAs) are a group of structurally unique natural products biosynthetically derived from the intermolecular [4 + 2] cycloaddition of a dehydroprenylphenol and a chalcone. In the current study, ten MDAAs, including an undescribed one, inethermulberrofuran C, were isolated from the root bark of Morus alba. The anti-Alzheimer's disease (anti-AD) properties of these isolates were systematically screened for a series of potential targets (Aβ self-aggregation, tau aggregation, and ChEs) as well as the anti-neuroinflammatory and neuroprotective activities.

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Chromatographic fractionation of the EtOH extracts of the Traditional Chinese Medicine (TCM) Chloranthus japonicus, has led to the isolation of a new lindenane-type sesquiterpenoid lactone derivative (1). Rosmarylchloranthalactone E (1), which consists of lindenane sesquiterpenoid lactone and rosmarinic acid moieties linked via an ester bridge, was structurally elucidated by 1D and 2D NMR and HRMS data. Compound 1 was a potent phosphodiesterase-4 (PDE4) inhibitor with an IC value of 0.

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The bioassay-guided phytochemical study of a traditional Chinese medicine Morus alba led to the isolation of 18 prenylated flavonoids (1-18), of which (±)-cyclomorusin (1/2), a pair of enantiomers, and 14-methoxy-dihydromorusin (3) are the new ones. Subsequent structural modification of the selected components by methylation, esterification, hydrogenation, and oxidative cyclization led to 14 more derivatives (19-32). The small library was screened for its inhibition against phosphodiesterase-4 (PDE4), which is a drug target for the treatment of asthma and chronic obstructive pulmonary disease (COPD).

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Bioassay-guided fractionation of the ethanolic extract of the leaves of Psidium guajava led to the isolation of 11 new Psidium meroterpenoids, psiguajadials A-K (1-11), along with 17 known ones (12-28). Their structures and absolute configurations were elucidated by spectroscopic methods and comparison of experimental and calculated ECD. Compounds 1 and 2 represent two unprecedented skeletons of 3,5-diformyl-benzyl phloroglucinol-coupled sesquiterpenoid, while 3 is the first example of Psidium meroterpenoids coupling via an oxepane ring.

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Bioassay-guided fractionation of an ethanolic extract of Chloranthus japonicus led to the isolation of the known lindenane-type sesquiterpenoid chlojaponilactone B (1). This compound exhibited pronounced inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages.

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Eight new lindenane sesquiterpenoid dimers, chlojapolides A-H (1-8), along with 11 known analogues were isolated from the whole plant of Chloranthus japonicus. Their structures including absolute configurations were elucidated by spectral and chemical methods. All the compounds were examined for their inhibitory effects on the nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW 264.

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Fifteen taxanes (1-15) including a new taxane glucoside, 7β,9α,10β-triacetoxy-13α-hydroxy-5α-O-(β-d-glucopyranosyl)taxa-4(20),11-diene (1), were isolated from the barks of Taxus wallichiana var. mairei. Compounds 1-15 representing three sub-types of 6/8/6-taxane were evaluated in vitro for anti-proliferative activity against a panel of parental and drug-resistant cancer cells.

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Bioassay-guided fractionation of the ethanol extract of the Chinese folk medicine Crotalaria ferruginea led to the isolation of a new isoflavonoid, 4'-hydroxy-2'-methylalpinum-isoflavone (1), and eight known analogs (2-9). Their structures were elucidated by spectroscopic analysis. Compounds 1, 2, 5, and 8 showed inhibitory activities against phosphodiesterase-4 (PDE4), a therapeutic target of asthma, with IC50 values ranging from 2.

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A new apotirucallane-type triterpenoid with an unusual 22,23-epoxy group in the side chain, 22,23-epoxy-apotirucalla-14-ene-3alpha,7alpha,24alpha,25-tetraol (1), was isolated from the leaves and twigs of Orophea yunnanensis. The structure of 1 was established on the basis of HRESIMS, 1D, and 2D NMR spectroscopic methods. This is the first phytochemical study of Orophea yunnanensis, and the biogenetic origin of 1 was postulated.

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