Publications by authors named "Turibio Kuiate Tabopda"

A new triterpene, aculeastrumone A (), a new triterpene saponin aculeastrumoside A (), and eleven known compounds () were isolated from MeOH/Water (80/20) extract of the fruits of (Solanaceae). Their structures were established by detailed 1D and 2D NMR spectroscopic studies and mass spectrometry. The isolated compounds were evaluated against three human cancer cells ((MCF-7 (breast cancer), NCI-H460 (lung cancer), and Hela (cervical cancer)) and normal human fibroblast (BJ) cell lines.

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The phytochemical investigations of the tuber roots of led to the isolation of a new alkaloid, schweinfurthiamide () and eight known compounds. The structures of the isolated compounds were elucidated using spectroscopic techniques 1D and 2D NMR (H, C, COSY, HMBC, HMQC, HSQC-TOCSY). The absolute configuration of was unambiguously determined using DP4+ calculations.

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is a tropical plant noticeable for its variegated leaves and exploited for various medicinal purposes. In this study, seven compounds, including three furanolabdane diterpenoids, i.e.

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commonly known as Bang Bali in Bali-Nguemba, Cameroon is used in traditional medicine against various diseases. The leaves and stem bark extracts were subjected to silica gel and Sephadex LH column chromatography to yield pure compounds. The structures of the compounds were determined by detail analysis of NMR and Mass spectroscopic data and by comparison with data reported in the literature.

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Four new oleanane-type saponins, macrostachyaosides A, B, C, and D (1-4) were isolated from the roots of Acacia macrostachya. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR data and HR-ESI-MS analyses. At concentrations of 100 μM of each compounds, none of the tested compounds caused a significant growth reduction against HL60 cells.

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Two new triterpene saponins, albidosides H (1) and I (2), along with the three known saponins were isolated from the barks of Acacia albida. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry. Albidosides H (1) and I (2) were assayed for their cytotoxicity against HeLa and HL60 cells using MTT method.

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Seven previously undescribed bidesmosidic triterpenoid saponins named albidosides A - G, were isolated from a methanol extract of the roots of Acacia albida. Their structures were elucidated using 1D and 2D NMR spectroscopy and mass spectrometry and determined to be bidesmosides of oleanolic acid and of 16α-hydroxyoleanolic acid. Albidosides B - G were assayed for their cytotoxicity against HeLa and HL60 cells using MTT method and microscopic observation.

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Phytochemical investigation of the roots of Albizia chevalieri led to the isolation of two new 5-deoxyflavan-3,4-diol glucosides from roots of A. chevalieri, Chevalieriflavanosides A and B. Their structures were established by 2D NMR techniques, UV, IR, CD, and mass spectrometry.

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Phytochemical investigation of the aerial parts of Chlorophytum deistelianum led to the isolation of four previously undescribed steroidal saponins called chlorodeistelianosides A-D with five known ones. Their structures were established mainly by extensive 1D and 2D NMR spectroscopic techniques and mass spectrometry as (25R)-3β-[(β-D-glucopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→4)]-β-D-xylopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-spirostan-12-one, (24S,25S)-24-[(β-D-glucopyranosyl)oxy]-3β-[(β-d-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-spirostan-12-one, (25R)-26-[(β-D-glucopyranosyl)oxy]-2α-hydroxy-22α-methoxy-5α-furostan-3β-yl β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside, and (25R)-26-[(β-D-glucopyranosyl)oxy]-3β-[(β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranosyl)oxy]-5α-furost-20(22)-en-12-one. Cytotoxicity of most compounds was evaluated against one human cancer cell line (SW480) and one rat cardiomyoblast cell line (H9c2).

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During a study on the chemistry and biological activity of Antrocaryon klaineanum Pierre, six new sterols including 4,24(28)-ergostadiene-6α,7α-diol (1), 6α-methoxy-4,24(28)-ergostadiene-7α,20S-diol (2), 6α-methoxy-4,24(28)-ergostadien-7α-ol (3), 20S-hydroxy-24(28)-ergosten-3-one (4), 7α-hydroxy-4,24(28)-ergostadien-3-one (5), and 24(28)-ergostene-3β,6α-diol (6) were characterized by physical and spectroscopic means. The known steroids 7 and 8 were also isolated. The crude extract and the isolated compounds were evaluated for their ability to inhibit the 3D7 strain of Plasmodium falciparum.

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Three new steroidal saponins, named diospreussinosides A-C (1-3), along with two known ones (4, 5) were isolated from rhizomes of Dioscorea preussii. Their structures were elucidated mainly by 1D and 2D NMR spectroscopic analysis and mass spectrometry as (25S)-17α,25-dihydroxyspirost-5-en-3β-yl-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranoside (1), (25S)-17α,25-dihydroxyspirost-5-en-3β-yl-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (2), and (24S,25R)-17α,24,25-trihydroxyspirost-5-en-3β-yl-O-α-L-rhamnopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (3). The spirostane-type skeleton of compound 3 possessing an unusual dihydroxylation pattern on the F-ring is reported for the first time.

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Seven known secondary metabolites were isolated from the methanol extract of the branches of Piper umbellatum. The identification of these compounds was mainly achieved by 2D NMR spectroscopic techniques and FAB-MS. Among them, the known cepharadiones A and B can be considered aschemotaxonomic markers of the genus Piper.

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Phytochemical investigation of the under-ground parts of Hydrocotyle bonariensis led to the isolation of five oleanane-type triterpenoid saponins, 3-O-{β-D-glucopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl}-21-O-(2-methylbutyroyl)-22-O-acetyl-R(1)-barrigenol, 3-O-{β-D-glucopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl}-21-O-(2-methylbutyroyl)-28-O-acetyl-R(1)-barrigenol, 3-O-{β-D-glucopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl}-21-O-acetyl-R(1)-barrigenol, 3-O-{β-D-glucopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl}-R(1)-barrigenol, and 3-O-{β-D-glucopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl}-22-O-(2-methylbutyroyl)-A(1)-barrigenol, together with the known saniculoside-R1. Their structures were established by 2D NMR techniques and mass spectrometry. Six compounds were evaluated against two human colon cancer cell lines, HCT 116 and HT-29.

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Phytochemical investigation of the methanol extract of the twigs of Garcinia staudtii yielded four new prenylated xanthones, staudtiixanthones A-D (1-4), along with eleven known compounds. Their structures were determined by analysis of 1D and 2D NMR spectra and by comparison of spectroscopic data with those previously reported. Some of these compounds have been evaluated for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).

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A bioassay-guided fractionation of methanol extracts of stem barks, combined with screening based on Epidermal Growth Factor (EGF)-responsive neural stem cells (erNSCs) differentiation assay, has been used. This study resulted in the isolation of 3,3'-di-O-methylellagic acid 1, 3,3'-di-O-methyl ellagic acid-4-O-beta-D-xylopyranoside 2, ellagic acid 3, and arjunolic acid 4. Among them, compounds 1 and 2 exhibit potent induction of neuronal differentiation in neurosphere stem cells with no cytotoxic effect.

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Antibacterial bioassay-guided fractionation of the methanol extract of the stem bark of Terminalia superba led to the isolation of four new triterpene glucosides (1-4) which were characterized as 2 alpha,3 beta-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranoside (1), 2 alpha,3 beta, 21 beta-trihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranoside (2), 2 alpha,3 beta, 29-trihydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranoside (3) and 2 alpha,3 beta,23,27-tetrahydroxyolean-12-en-28-oic acid 28-O-beta-D-glucopyranoside (4) together with the known triterpene 2 alpha,3 beta,23-trihydroxyolean-12-en-28-oic acid (5). Structures were established by spectroscopic methods including one- and two-dimensional NMR, EI-MS and HR-EI-MS. The antibacterial activity of 1-5 was also investigated against two gram-positive (Bacillus subtilis, Staphylococcus aureus), and four gram-negative (Escherichia coli, Shigella flexenari, Pseudomonas aeruginosa, Salmonella typhi) bacterial strains.

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In our continuous search for alpha-glucosidase inhibitors from plants, four new depsidones named brevipsidones A-D (1-4) were isolated from stem bark of Garcinia brevipedicellata together with known damnacanthal, scopoletin and a mixture of stigmasterol and beta-sitosterol. Structural elucidations were made by spectroscopic analyses including 2D-NMR data.

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Fractionation of stem barks of Terminalia superba yielded two new ellagic acid derivatives, 3,4'-di-O-methylellagic acid 3'-O-beta-D-xylopyranoside (1) and 4'-O-galloy-3,3'-di-O-methylellagic acid 4-O-beta-D-xylopyranoside (2) together with known 3,3'-di-O-methylellagic acid, ellagic acid and 3,3'-di-O-methylellagic acid 4'-O-beta-D-xylopyranoside. Compounds (1) and (2) showed significant alpha-glucosidase inhibition activity and possessed significant immunoinhibitory activities with no cytotoxic effects.

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Four alkaloids named piperumbellactams A-D (1-4) were isolated from branches of Piper umbellatum together with known N-hydroxyaristolam II (5), N-p-coumaroyl tyramine (6), 4-nerolidylcatechol (7), N-trans-feruloyltyramine, E-3-(3,4-dihydroxyphenyl)-N-2-[4-hydroxyphenylethyl]-2-propenamide, beta-amyrin, friedelin, apigenin 8-C-neohesperidoside, acacetin 6-C-beta-d-glucopyranoside, beta-sitosterol, its 3-O-beta-d-glucopyranoside and its 3-O-beta-d-[6'-dodecanoyl]-glucopyranoside. Glycosidase inhibition, antioxidant and antifungal activities of these compounds were evaluated. Compounds 1-3 showed moderate alpha-glucosidase enzyme inhibition with IC50 values 98.

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Three new sesquiterpene lactones, (4betaH)-5alpha-hydroxy-8alpha-(2-methylbut-2-enoyloxy)-2-oxo-1(10),11(13)-guaiadien-12,6alpha-olide (1), (4betaH)-8alpha-(2-methylbut-2-enoyloxy)-2-oxo-1(5),10(14),11(13)-guaiatrien-12,6alpha-olide (2) and 2,5-epoxy-2beta-hydroxy-4alpha-methoxy-8alpha-(2-methylbut-2-enoyloxy)-4(15),10(14),11(13)-germacratrien-12,6alpha-olide (3), have been isolated from roots and stems of Elephantopus mollis together with two known sesquiterpene lactones (4, 5). The identification of the isolates was accomplished by spectroscopic methods. Compounds (1-5) exhibited significant cytotoxic activities against mouse neuroblastoma B104 cells.

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Activity-guided fractionation of root and leaf extracts from Elephantopus mollis led to the isolation of a new triterpene (1) and a new sesquiterpene lactone (2) together with five known sesquiterpene lactones (3-7). The structures of compounds 1 and 2 were determined based on their spectroscopic data. The cytotoxic activity of the isolated compounds was evaluated against neuroblastoma B104 cells.

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