Vernoguinamide: A new ceramide and other compounds from the root of Vernonia guineensis Benth. and their chemophenetic significance

Wouamba SCN, Happi Mouthe G, Lenta BN, Sewald N, Kouam SF. Vernoguinamide: A new ceramide and other compounds from the root of Vernonia guineensis Benth. and their chemophenetic significance. BIOCHEMICAL SYSTEMATICS AND ECOLOGY. 2020;88: UNSP 103988.The chemical investigation of the roots of Vernonia guineensis Benth. (Asteraceae) resulted in the isolation of a new ceramide, named vernoguinamide (1), together with fifteen known compounds, including three anthraquinones, physion (2), erythroglaucin (3) and emodin (4), three triterpenoids, hop-17(21)-en-3 beta-yl acetate (5), lupeol (6) and betulinic acid (7), six steroids, vernoguinoside A (8), vernoguinoside (9), beta-sitosterol 3-O-beta-D-glucoside (10), stigmasterol 3-O-beta-D-glucoside (11), stigmasterol (12) and beta-sitosterol (13) and three fatty acid derivatives, tetracosanoic acid (14), tricosanic acid (15) and arachidic acid glycerol ester (16). The structure of the new compound as well as those of the known compounds were established by spectrometric analysis including HRESI-MS, 1D and 2D-NMR and by comparison with the previously reported data. Among these compounds, the anthraquinones 2-4 and the triterpene 5 were isolated for the first time from Vernonia genus and compounds 6, 7 and 14-16 were extracted for the first time from the species. The isolated compounds were tested for their antibacterial activity and 3, 8 and 9 were the most active compounds against the tested bacteria. Furthermore, the chemophenetic relationships of the isolated compounds and their significance were also discussed

Ergostane-type steroids from the Cameroonian 'white tiama' Entandrophragma angolense.

Happi GM, Wouamba SCN, Ismail M, et al. Ergostane-type steroids from the Cameroonian 'white tiama' Entandrophragma angolense. Steroids. 2020;156: 108584.Two new ergostane-type steroids named tiamenones A and B (1-2) were isolated from the bark of Entandrophragma angolense (Meliaceae) along with ten known compounds identified as 20S-hydroxy-4,6,24(28)-ergostatrien-3-one (3), 3beta,7alpha,20beta-trihydroxyergosta-5,24(28)-diene (4), 3beta,5alpha-dihydroxyergosta-7,22-diene (5), stigmasterol, beta-sitosterol, beta-amyrin, oleanolic acid, asperphenamate, sucrose and daucosterol. The structures of the isolated compounds have been established using NMR spectroscopic and mass spectrometric analyses. The assignment of relative and absolute configurations of compound 1 was achieved by a NOESY experiment and comparison of its NMR data with those of known compound reported in literature. Compounds 1-3, beta-amyrin and asperphenamate were evaluated for their antibacterial potencies against five bacterial model strains viz. Escherichia coli DSMZ 1058, Pseudomonas agarici DSMZ 11810, Bacillus subtilis DSMZ 704, Micrococcus luteus DMSZ 1605 and Staphylococcus warneri DSMZ 20036 and their cytotoxicity on two cell lines KB3-1 and HT-29. No potencies were exhibited by the tested compounds even at the highest concentration of 0.5 mg/mL. Compounds 1-3 were found to be potential HIV-1 inhibitors based on their molecular docking analyses. Copyright © 2020. Published by Elsevier Inc

Bioactive Secondary Metabolites from Fungi of the Genus <i>Cytospora</i> Ehrenb. (Ascomycota)

Cytospora is a genus of fungi belonging to the Cytosporaceae family (Sordariomycetes, Ascomycota) considered as a prolific source of specialized metabolites due to their ability to produce diverse secondary metabolites with a broad range of biological activities. Since the first chemical investigation of this genus in the 1980s, further studies have led to the isolation and structural elucidation of several bioactive compounds including cytosporones, nonanolides, macrocyclic dilactones, and terpenoids. This review summarizes, for the first time, the chemical diversity of bioactive secondary metabolites from the genus Cytospora and highlights its potential as an alternative source of secondary metabolites for pharmacological studies. Moreover, this review will serve as a basis for future investigations of compounds of this genus

Furanocoumarins from the twigs of Ficus chlamydocarpa (Moraceae)

Wandji NT, Bitchagno GTM, Tchamgoue J, et al. Furanocoumarins from the twigs of Ficus chlamydocarpa (Moraceae). Phytochemistry Letters. 2022;47:38-41.Two furanocoumarin derivatives, 3-methoxypsoralen (1) and 3,5-dimethoxypsoralen (2), along with nine known compounds, friedelinol (3), 3-oxo-11β-hydroxyoleanan-12-ene (4), lupeol (5), taraxer-3-one (6), a mixture of β-sitosterone (7a) and stigmast-4,22-dien-3-one (7b), ergosterol (8), 9,19-cyclolanost-3-one-24,25-diol (9), oleanan-12-ene-3,11-dione (10), and β-sitosterol 3-O-β-D-glucopyranoside (11) were isolated from the twigs of Ficus chlamydocarpa. Their structures were established by NMR spectroscopic analyses and HRESIMS. The structure of 1 was further confirmed from its single crystal X-ray diffraction. The crude extract, fractions and some isolated compounds were assessed for their preliminary antibacterial activity and cytotoxicity. One of the fractions (FB-B3) exhibited inhibition against the bacterial strain Pseudomonas agarici and induced a remarkable cytotoxic activity toward the human cervix carcinoma cell line KB-3-1 (IC50 0.166 mg/mL), and compounds 1, 6, and 7 showed moderate antibacterial activity against Bacillus subtilis and Micrococcus luteus

Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance

Tseme Wandji N, Bitchagno GTM, Mawabo Kamga I, et al. Polyoxygenated Stigmastane-Type Steroids from Vernonia kotschyana Sch. Bip. ex Walp. and Their Chemophenetic Significance. Molecules. 2023;28(13): 5278.Four polyoxygenated stigmastanes (1–4) alongside known analogues (7–8) and flavonoids (5–6) were isolated from a dichloromethane/methanol (1:1, v/v) extract of the whole plant of Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae). Their structures were determined by means of spectroscopic and spectrometric analysis. The relative stereochemistry of the new compounds was established and confirmed via biosynthesis evidence and cyclization of 1 under acidic conditions. A plausible biosynthetic pathway to the new compounds and the chemophenetic significance of the isolated constituents were also discussed. The crude extract, fractions, and compounds (1–3) were assessed for their antibacterial activity against five highly prevalent bacterial strains. The fractions and compounds showed low to moderate activity with minimal inhibitory concentrations (MICs) > 125 µg/mL

Chemical constituents from the bark of the Cameroonian mahogany Trichilia emetica Vahl (Meliaceae)

Tsopgni WDT, Happi GM, Stammler H-G, et al. Chemical constituents from the bark of the Cameroonian mahogany Trichilia emetica Vahl (Meliaceae). Phytochemistry Letters. 2019;33:49-54.Phytochemical investigation of the stem bark extract of Trichilia emetica led to the isolation of two new naturally occurring compounds including a prieurianin-class limonoid named trichirokin (1) and the steroid ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4), along with nine known compounds characterized as rohituka-3 (3), rohituka-9 (2), scopoletin, benzoic acid, protocatechuic acid, lignoceric acid, beta-sitosterol, stigmasterol and beta-sitosterol-3-O-beta-D-glucopyranoside. The crystal structures of rohituka-3 (3) and ergosta-5,24(28)-diene-3S, 16S, 20S-triol (4) are reported here for the first time. The structures of the compounds were elucidated by extensive spectroscopic and spectrometric data interpretation. The stereochemistry of compound 1 was established on the basis of its NOESY spectrum and the comparison of its optical rotation value with that of its congener 2. None of the reported compounds displayed antibacterial or cytotoxic activity

Antiplasmodial and Cytotoxic Triterpenoids from the Bark of the Cameroonian Medicinal Plant <i>Entandrophragma congoënse</i>

Eight new triterpenoids, prototiamins A–G (<b>1</b>–<b>6</b>, <b>9</b>) and <i>seco</i>-tiaminic acid A (<b>10</b>), were isolated along with four known compounds from the bark of <i>Entandrophragma congoënse</i>. Their structures were elucidated by means of HRMS and different NMR techniques and chemical transformations. Assignments of relative and absolute configurations for the new compounds were achieved using NOESY experiments and by chemical modification including the advanced Mosher’s method. Additionally, the structure and relative configuration of compound <b>3</b> were confirmed by single-crystal X-ray diffraction analysis. Compounds <b>1</b>, <b>3</b>, and <b>5</b> displayed significant in vitro antiplasmodial activity against the erythrocytic stages of chloroquine-sensitive <i>Plasmodium falciparum</i> strain NF54. Prototiamin C (<b>3</b>) was the most potent of the compounds isolated, with an IC₅₀ value of 0.44 μM. All compounds tested showed low cytotoxicity for the L6 rat skeletal myoblast cell line

Three phragmalin-type limonoids orthoesters and the structure of odoratone isolated from the bark of Entandrophragma candollei (Meliaceae)

Happi GM, Mouthe Kemayou GP, Stammler H-G, et al. Three phragmalin-type limonoids orthoesters and the structure of odoratone isolated from the bark of Entandrophragma candollei (Meliaceae). Phytochemistry. 2020;181: 112537.The phytochemical exploration of the Entandrophragma candollei stem bark extract led to the isolation and identification of twenty compounds including three undescribed phragmalin-class limonoids named encandollens C-E (1-3), the undescribed protolimonoid 5 together with sixteen known compounds. The structures of all the isolated compounds were determined by interpretation of their spectroscopic and spectrometric data including HRMS, 1D and 2D NMR analyses. The assignment of the absolute and relative stereochemistry of the undescribed compounds was achieved using SC-XRD analyses as well as NOESY experiments. The previously reported structure of odoratone (5a) was corrected as 23R,24S-dihydroxy-22S,25-epoxytirucall-7-en-3-one (5) based on its NMR and SC-XRD data. Prieurianin (4) exhibited high cytotoxic activity on KB3-1cell lines with an IC50 of 1.47muM compared to the reference griseofulvin (IC50=17-21muM). The results of the in silico docking of compound 4 supported and delivered further insights on its cytotoxicity. Copyright © 2020 Elsevier Ltd. All rights reserved

Two new triterpenoid fatty acid esters from Schefflera barteri Harms (Araliaceae)

Mbougnia JFT, Bitchagno Mbahbou GT, Wouamba SCN, et al. Two new triterpenoid fatty acid esters from Schefflera barteri Harms (Araliaceae). Natural product research. 2020.Two new fatty acid esters of triterpenoids (1-2) together with eleven known compounds (3-13) were obtained after investigation of the CH2Cl2-MeOH (1:1) crude extract from the leaves of Schefflera barteri Harms. All these compounds (1-13) were isolated for the first time from this plant among which compounds 3, 4, 6 and 9-13 were also isolated from the genus Schefflera for the first time. The structures of the isolated compounds were elucidated by analyses of their spectroscopic data (1D and 2D NMR, and MS). The antibacterial and cytotoxic activities of crude extracts, fractions and compounds (1, 2, 5, 6, 8 and 9) were investigated against both Gram-negative and Gram-positive bacteria strains as well as on human cervix carcinoma and colon adenocarcinoma cancer cell lines, respectively. They showed weak to significant activity towards the strains and malignant cells used