Publications by authors named "Tapondjou L"

Article Synopsis
  • - A new saponin called diosgeninoside and a new fatty acid named betacic acid were discovered alongside six known compounds in a methanolic extract.
  • - The chemical structures of these compounds were determined using 1D and 2D NMR spectrometry and other methods.
  • - Both the methanolic extract and one of its fractions demonstrated moderate antibacterial activity against specific bacteria, with minimum inhibitory concentrations (MIC) measured at 128 µg/mL and 64 µg/mL for certain compounds.
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Article Synopsis
  • Four new triterpenoid saponins (manniosides G, H, I, and J) were identified from the leaves of a plant, alongside several known compounds.* -
  • Their structures were determined using advanced techniques like NMR analysis and mass spectrometry.* -
  • The extracts and some isolated compounds were tested for antibacterial properties but showed no significant antioxidant activity.*
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The genus is a rich source of physiologically active secondary metabolites, including a novel compound named 21-methylene-24-ethylidene lophenol, alongside 15 known compounds. These compounds were characterized using different spectroscopic techniques. They exhibited promising antimicrobial activity, particularly against bacteria causing gastrointestinal infections.

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Five unusual alkaloids featuring a pyrrolo[1,2-a]quinolone skeleton (pyrroloquinolones B-F, 1-5) were isolated from the ethanol extract of the whole plant of Vernonia glabra (Steetz) Vatke, along with sixteen known compounds. Their structures were established by means of spectroscopic (1D and 2D NMR, UV, IR, and ECD) and high resolution mass spectrometric techniques as well as by comparison of their spectroscopic data with those reported in the literature. The ethanol extract and some isolated compounds were assessed for their antibacterial activity against four bacterial strains.

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Article Synopsis
  • A new phenolic glucoside was isolated from the methanol extract of leaves, alongside fifteen known secondary metabolites with potential health benefits.
  • The structures of these compounds were determined using 1D and 2D NMR analysis and mass spectrometry.
  • The extracts and isolated compounds were tested for antibacterial activity, showing that some were highly effective against certain bacteria, while others had moderate activity.
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Article Synopsis
  • * This new compound is made up of 4'-O-methylgallocatechin linked by a specific bond to another 4'-O-methylgallocatechin.
  • * The structures of both olasubscorpioside C and the known compound 4'-O-methylgallocatechin were determined using advanced techniques like NMR and mass spectrometry, confirming their identities through comparisons with existing data.
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Chemical investigation of the ethanol extract from the stems and roots of the medicinal plant Lavigeria macrocarpa led to the isolation and structure elucidation of three previously unreported 21-nordammarane-type saponins namely 6α,27-dihydroxy-3,20-dioxo-21-nordammar-24-(Z)-ene 27-O-[α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside] (1), 6α,27-dihydroxy-3-oxo-21-nordammar-24-(Z)-ene 27-O-β-D-glucopyranoside (2), and 2α,3β,6α,27-tetrahydroxy-21-nordammar-24-(Z)-ene 27-O-β-D-glucopyranoside (3) trivially named lavigemacrocarposide A-C, along with eight known secondary metabolites. Acid hydrolysis of lavigemacrocarposide A yielded a new prosapogenin namely 6α,27-dihydroxy-3,20-dioxo-21-nordammar-24-(Z)-ene 27-O-β-D-glucopyranoside (1a) and the previously unreported artefactual aglycones 1b and 1c. Their structures were elucidated by spectroscopic analyses including mass spectrometry, 1D and 2D NMR as well as chemical evidence.

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A new 3-arylcoumarin, 7-hydroxy-6-(1,1-dimethylallyl)-2',5'-dihydroxy-4'-(3,3dimethylprenyl)-3-arylcoumarin (desmoarylcoumarin) , a previously unreported oleanane-type triterpenoid, 3,22,23-trihydroxyolean-12-en (episoyasapogenol B) , together with five known flavonoids including darbergioidin (), isoferreirin (), quercetin (), vitexin (), swertizin (), and one carbohydrate, sucrose () were isolated from the methanolic extract of the roots of . Their structures were elucidated mainly by extensive spectroscopic analysis (1D and 2D) and mass spectrometric (HRFAB-MS) data. The methanolic extract, EtOAc and -BuOH fractions as well as some isolated compounds were assessed for their antibacterial and antioxidant activities.

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Eleven previously undescribed arylnaphthalide lignans (-) together with seven known compounds were isolated from the whole plant of . The structures of - were elucidated by spectroscopic analysis and mass spectrometry. Compounds (IC = 4.

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Article Synopsis
  • The paper identifies eight new triterpenoid saponins, including afzeliioside A and several pairs of acetylated regioisomers (B/C, D/E) along with afzeliiosides F-H and the known impatiprin C, all isolated from a specific liana species.
  • Their structures were determined through advanced techniques like NMR and mass spectrometry, supported by comparative spectral analysis with similar compounds.
  • The cytotoxic activity of these compounds was evaluated against CAL-27 oral squamous carcinoma cells, revealing that only one compound showed moderate activity (EC = 36.0 μg/mL).
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A previously unreported gallocatechin glycoside, (2 ,3) 4'--methyl-gallocatechin-3--α-ʟ-rhamnopyranoside () and an unseparable mixture of two previously undescribed dihydromyricetin glycosides, (2 ,3) 4'--methyl-dihydromyricetin-3--α-ʟ-rhamnopyranoside () and (2 ,3) 4'--methyl-dihydromyricetin-3--α-ʟ-rhamnopyranoside () along with three known compounds were isolated from the -butanol soluble fraction of the stem bark of Oliv. Their structures were elucidated by detailed spectroscopic analyses, including H NMR, C NMR, H-H COSY, HSQC, HMBC, NOESY, HR-ESI-MS and chemical methods. The crude ethanol extract, the fractions, and some of the isolated compounds were screened for their antioxidant and antibacterial activities.

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In our previous study, we reported the isolation of pennogenin-3--α--rhamnopyranosyl-(1→2)-[α--rhamnopyranosyl-(1→3)]-β--glucopyranoside (spiroconazol A), a steroidal saponin, from the flowers of L. var. .

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The use of natural products for medicinal purposes is becoming more and more common nowadays, as evidenced by the presence in plants of secondary metabolites with different potentials such as antioxidant and antibacterial properties. We evaluated in this work the antimicrobial activities of the extracts and some isolated compounds from the seeds of Hiern. (Rubiaceae), a Cameroonian medicinal plant traditionally used to cure microbial infections.

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Microbial infections are leading causes of death and morbidity all over the world due to the development of the resistance to antibiotics by certain microorganisms. In this study, the chemical exploration of the ethanol (EtOH) extract of the aerial part of (Dracaenaceae) led to the isolation of one previously unreported chalcone derivative, i.e.

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Phytochemical investigation of the methanol extracts from the leaves and bark of resulted in the isolation of one new flavone -glycoside: apigenin-8--[6''-feruloyl]---glucopyranoside] (), together with sixteen known compounds including quercetin-3----rhamnoside (), vitexin (), isovitexin (), quercetin-3----glucopyranoside (), quercetin-3----arabinopyranoside (), quercetin (), kaempferol (), methyl inositol (), sucrose (), betulinic acid (), vanillic acid (), stigmastane-3,6-diol (), aurantiamide acetate (), robinetinidol (), catechin () and epicatechin (). The structures of these compounds were established on the basis of their spectroscopic (1 D and 2 D NMR) and mass spectrometric (ESI-TOF-MS) data. The methanol extracts, fractions and some of the isolated compounds were screened for their antimicrobial properties against five microbial strains.

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Ripe figs, barks, and wood of Ficus vallis-choudae are used in traditional medicine against several conditions including nausea and malaria. However, its use is still to be scientifically documented and validated. Hence, the aim of the present work was to evaluate the antiplasmodial activity of the dichloromethane-methanol (DCM-MeOH (1:1)) crude extract, their hexane, dichloromethane, ethyl acetate, and methanoli fractions, as well as the isolated chemical constituents.

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A new triterpenoid saponin (Mimonoside D: 3---L-arabinopyranosyl-3-hydroxyolean-12-en-28-oic acid 28---D-xylopyranosyl-(1→2)--D- glucopyranoside ester ()) was isolated from the aerial parts of Sauvalle together with nine known compounds: 7,4'-dihydroxyflavone (), kaempferol (), lupeol (), betulinic acid (), -sitosterol (), -sitosterol-3---D-glucopyranoside (), lutein (), 5,2'-dihydroxy-7,4',5'-trimethoxyflavone () and vitexin (). Their structures were elucidated on the basis of spectroscopic (1D and 2D nuclear magnetic resonance) and high-resolution mass spectrometric data as well as by comparison of their spectral data with those of related compounds. Compounds , and had already been isolated from , while compounds , , and have been isolated from other species.

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Coronavirus disease 2019 (COVID-19) is an ongoing pandemic instigated by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) which changed the daily train of the world's population and cause several dead. Despite the significant efforts made in developing vaccines and therapeutic drugs, there is currently no available effective treatment against this new coronavirus infection, hence the need to continue research which is aimed at limiting the progression of this virus. The present study which has as objective to carry out studies on the metabolites of some Cameroonian medicinal plants of the family with a view to propose potential molecules to fight against COVID-19.

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Aim: To identify the bioactive hepatoprotective components of the ethanol extract of Pentaclethra macrophylla stem bark using in vitro and in vivo approaches.

Methods: The bioguided-fractionation of the ethanol extract was based on the substances' capacity to prevent in vitro, the lipid peroxidation of hepatocytes' membranes induced by hydrogen peroxide. For the in vivo hepatoprotective test, mice were treated orally with the ethyl acetate (EtOAc) fraction of the ethanol extract at doses of 50 and 75 mg/kg/day for one week and subjected to d-galactosamine/lipopolysaccharide (GaIN/LPS)-induced hepatotoxicity.

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Article Synopsis
  • A new tetraoxygenated xanthone was isolated from the methanol extract of leaves, along with eleven other known compounds.
  • The structural identification of these compounds was conducted using techniques like NMR, UV, IR, and MS, along with comparisons to existing literature.
  • The new xanthone demonstrated weak antibacterial activity against eight bacterial strains, with minimum inhibitory concentration (MIC) values between 64 and 128 µg/mL.
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The use of chemical pesticides to preserve food commodities is a global issue of concern due to their negative effect on the environment and public health. In recent years, the European Union is trying to reduce their use, favoring alternative or complementary approaches based on natural products. In this scenario, plant-borne essential oils (EOs) represent valid options for Integrated Pest Management (IPM) programs.

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In this work, the essential oils (EOs) from Litchi chinensis, Clausena anisata, Heracleum sphondylium, Pimpinella anisum, Lippia alba, Crithmum maritimum and Syzygium aromaticum were tested for their contact toxicity against the poultry red mite, Dermanyssus gallinae, a deleterious ectoparasite of aviary systems. In addition, in order to give insights on their mode of action and effectiveness, the vapor phase and residual toxicity tests were also performed. Results showed that amongst all the tested EOs, that of S.

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A new saponin, 3-O-β-d-3-oxo-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (1), was isolated from the methanol extract of stem bark of Crossopteryx febrifuga together with the known 3β-d-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (2), shanzhiside methyl ester (3), shanzhiside (4), β-sitosterol (5), β-sitosterol-3-O-β-d-glucopyranoside (6), ursa-12,20(30)-diene-27,28-dioic acid (7), hederagenin (8), and oleanolic acid (9). The structures were established by comprehensive interpretation of their spectral data 1D- (1H and 13C), 2D-NMR (1H-1H COSY, HMQC, HMBC), spectroscopic, and electrospray ionisation time-of-flight mass spectrometry analysis. The isolated compounds and extracts were screened for their antibacterial properties.

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