Laurence Voutquenne-Nazabadioko

Triterpenoid Saponins from Symplocos lancifolia

Three new bidesmosidic saponins (1-3) and a new ursane triterpenoid, 2α,3β,11α,23-tetrahydroxyurs-12-en-28-oic acid (4), along with seven known compounds, were isolated from a methanolic extract of the leaves of Symplocos lancifolia. The bidesmosidic saponins were found to possess the same sugar unit part, composed of two β-d-glucose moieties and one α-l-rhamnose moiety, linked to maslinic acid, arjunolic acid, and asiatic acid, respectively. Their structures were elucidated by interpretation of their 1D and 2D NMR spectra and completed by analysis of the HRESIMS data. The antibacterial activity of the isolated triterpenoids was evaluated against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, and several showed activity against Gram-positive bacteria.

Triterpenoid saponins from the roots of Gypsophila trichotoma Wender.

Eleven triterpenoid saponins were isolated from the roots of Gypsophila trichotoma Wender. (G. trichotoma Wender. var. trichotoma) (Caryophyllaceae), together with one known compound. The structures were established on the basis of extensive NMR analysis ((1)H, (13)C NMR, COSY, TOCSY, ROESY, HSQC, and HMBC), completed by analysis of HR-ESI-MS and ESI-MS(n). The saponins have the commonly found gypsogenin as the aglycone substituted at C-3 with trisaccharide and at C-28 with oligosaccharide through a fucose residue, as saponins isolated from Gypsophila perfoliata L. originated from China. The oligosaccharide attached to C-28 is substituted with acetyl and (or) sulfate groups. Тhe cytotoxicity of the saponin extract from G. trichotoma was evaluated against a rat alveolar macrophage-like cell line NR8383 and human leukemia cell lines U937 and BV-173. The synergistic effect of the aminoacyl saponins, previously isolated from G. trichotoma, was tested for its ability to enhance the cytotoxicity of the targeted toxin in HER14 cells.

Triterpenoids from Salvia argentea var. aurasiaca (Pomel) Batt. & Trab. and their chemotaxonomic significance

Ten triterpenoids were isolated from the exudate of Salvia argentea L. var. aurasiaca (Pomel) Batt. & Trab. Their structures were elucidated by 1D and 2D NMR and HRESIMS analyses as 11α-methoxyurs-12-ene-1β,3β,15α-triol (1), urs-12-ene-1β,3β,11α,15α-tetraol (2), 11α-methoxyurs-12-ene-1β,3β-diol (3), 1β,3β,15α-trihydroxy-11α-methoxyurs-12-en-28-al (4), 1β,3β,15α-trihydroxyurs-12-en-28-al (5), urs-12-ene-1β,3β,15α,28-tetraol (6), 11α-methoxyurs-12-ene-1β,3β,28-triol (7), 13β,28-epoxyurs-12-ene-1β,3β-diol (8), urs-12-ene-3β,7β,15α,28-tetraol (9) and olean-12-ene-3β,7β,15α,28-tetraol (10). A chemotaxonomic survey of the triterpenoids of Salvia species show that triterpenoids from the exudate of S. argentea var. aurasiaca (Pomel) Batt. & Trab., provide some features, such as hydroxylation at C-15, and hydroxylation at C-7. On this basis, S. argentea L. var. aurasiaca (Pomel) Batt. & Trab., is quite different from S. argentea L.

Evaluation of the biological activity of the molluscicidal fraction of Solanum sisymbriifolium against non target organisms.

The evaluation of the biocidal activity of the fruit of Solanum sisymbriifolium involving non target organisms such as aquatic insects, fish and snails lead to the isolation of the steroidal alkaloids, solamargine and β-solamarine, from the active fractions. The fractions A3 and C, with biological activity against fish, snail and aquatic insect and larvae, are able to affect the good functioning of ecosystem found on alimentary chain. The fraction B seems to be less toxic to fish and aquatic insect and larvae. The fraction B could thus be used as molluscicide in the future.

Tyrosinase inhibitors and sesquiterpene diglycosides from Guioa villosa.

Through a bioassay-guided phytochemical investigation involving mushroom tyrosinase inhibitory activity, seven farnesyl diglycosides ( 1 - 7), five flavonoids ( 8 - 12), one trimeric proanthocyanidin ( 13), two triterpenes ( 14 and 15), and one cerebroside ( 16), were isolated from the leaves of Caledonian Guioa villosa. Among them, crenulatosides E, F and G ( 1 - 3) were new acyclic sesquiterpene diglycosides. The sesquiterpene diglycosides isolated from the active EtOAc extract showed no inhibitory activity, whereas betulin ( 14), lupeol ( 15) and soyacerebroside I ( 16) demonstrated a potent tyrosinase inhibitory activity.

Antibacterial and cytotoxic triterpenoids from the roots of Combretum racemosum

A new pentacyclic triterpenoid glucoside, together with fourteen known compounds, was isolated from the roots of Combretum racemosum. Combretaceae). The structure of the new compound was established as 28-O-β-d-glucopyranosyl-2α,3β,21β,23-tetrahydroxyolean-18-en-28-oate (1) on the basis of detailed spectroscopic data including MS, 1D, and 2D NMR. The inhibitory activity of compounds 1-15 against promyelocytic leukemia HL-60 and human erythromyeloblastoid leukemia K562 cell lines was evaluated. Compounds 11 (3-O-β-acetyl-ursolic acid), 14 (betulinic acid), and 15 (quadranoside II) exhibited significant cytotoxicity, with IC50 values of 13 to 50 μM. Among the isolated triterpenes, compounds 1, 3 (arjungenin), 5 (terminolic acid), and 11 exhibited moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Enterococcus faecalis (MICs within a range of 64 and 256 μg/mL).

Glycosidase inhibitors from the roots of Glyphaea brevis.

Ten phenylalkyl-substituted iminosugars (1-10) and a cinnamic acid derived glucoside (11) were isolated from the roots of Glyphaea brevis (Malvaceae). Their structures were elucidated by 1D and 2D NMR analysis, as well as by HR-ESIMS. Compounds 1-10 retain an unprecedented structure composed of an iminosugar-like core identified as 1-deoxyfuconojirimycin in glyphaeaside A1-A4 (1, 2, 5, 6), 1-deoxygalactonojirimycin in glyphaeaside B1-B5 (3, 4, 7-9) or 1-deoxynojirimycin in glyphaeaside C (10), substituted by a β-d-glucopyranose in compounds 2, 4, 6 and 9. These compounds feature a di-, tri- or tetra-hydroxylated nine-carbon chain at the pseudo-anomeric position, substituted by a terminal phenyl group. All alkyl C-iminosugars displayed potent and selective inhibition towards β-glucosidase with IC50 values ranging from 0.15 to 68μM. Compound 10 with an 1-deoxynojirimycin backbone was the most active and was found to act as a competitive inhibitor with Ki=31nM, therefore emerging as one of the most potent inhibitor of β-glucosidase reported to date. Inhibition of β-mannosidase was observed with compounds 1, 3, 7 and 10, but only weak inhibition could be detected with the alkyl-C-iminosugars on the other tested glycosidases (α-glucosidase, α-fucosidase, α- and β-galactosidase).

Triterpene saponins of Genista ulicina Spach

From the n-BuOH extract of the aerial parts of Genista ulicina, six triterpene saponins, 3-O-β-D-glucopyranosyl-olean-12-ene-3β,27,28,30-tetraol, 3-O-β-D-glucopyranosyl-olean-12-ene-3β,27,28,29-tetraol, 3,29-di-O-β-D-glucopyranosyl-olean-12-ene-3β,27,28,29-tetraol, 3-O-β-D-glucopyranosyl-olean-12-ene-3β,28,29-triol-27-oic acid, 3-O-β-D-glucopyranosyl-olean-12-ene-3β,27,28-triol-29-oic acid, and 3-O-β-D-glucopyranosyl-14-H-27-nor-olean-12-ene-3β,28,29-triol, were isolated together with eight known triterpene saponins and six flavonoids. Their structures were established mainly by means of spectroscopic methods (1D and 2D-NMR as well as HR-ESI-MS). The n-BuOH extract, investigated for its antitumor growth inhibition of human colon cancer HT-29 cells, presented no significant activity (IC50>100 μg).

Fast Identification of Radical Scavengers from Securigera varia by Combining 13C-NMR-Based Dereplication to Bioactivity-Guided Fractionation

Securigera varia (Fabaceae) is a common herbaceous perennial plant widely growing in Europe and Asia and purposely established for erosion control, roadside planting, and soil rehabilitation. The aim of this study was to determine the radical scavenging activity of a crude methanol extract of S. varia aerial parts by using the free radical DPPH (1,1-diphenyl-2-picrylhydrazyl) and to rapidly identify the compounds involved in this activity. The crude extract was initially separated in five fractions on Diaion HP20 resin and the most active part was fractionated by Centrifugal Partition Extraction (CPE). Known compounds were directly identified by a 13C-NMR-based dereplication method. Semi-preparative high performance liquid chromatography purification experiments were further performed to identify unknown or minor active compounds. As a result, one new (13) and twelve known flavonoid glycosides together with three nitropropanoylglucopyranoses were isolated, including astragalin (1), kaempferol-3-O-(6-O-acetyl)-β-d-glucopyranoside (2), kaempferol-3,4′-di-O-β-d-glucopyranoside (3), trifolin (4), isoquercitrin (5), hyperoside (6), isovitexin (7), isoorientin (8), isovitexin 4′-O-β-d-glucopyranoside (9), apigenin 7-O-β-d-glucuronopyranoside (10), luteolin 7-O-β-d-glucuronopyranoside (11), apigenin 7-O-α-l-rhamnopyranosyl-(1→2)-β-d-glucuronopyranoside (12), apigenin 7-O-β-d-glucopyranosyl-(1→2)-β-d-glucuronopyranoside (13), 6-O-(3-nitropropanoyl)-β-d-glucopyranoside (14), coronillin (16) and coronarian (15). 120 mg of the most active compound isoorientin against the free radical DPPH was recovered by CPE with an HPLC purity of 99%.

Leptocarposide: a new triterpenoid glycoside from Ludwigia leptocarpa (Onagraceae).

A new triterpenoid bidesmoside (leptocarposide) possessing an acyl group in their glycosidic moiety (1), together with the known luteolin‐8‐C‐glucoside (2) and 1‐O‐β‐d‐glucopyranosyl‐(2S,3R,8E)‐2‐[(2′R)‐2‐hydroxypalmitoylamino]‐8‐octadecen‐1,3‐diol (3) was isolated from the n‐butanol‐soluble fraction of whole plant of Ludwigia leptocarpa (Nutt) Hara (Onagraceae). Structure of compound 1 has been assigned on the basis of spectroscopic data (1H and 13C NMR, 1H‐1H COSY, HSQC, HMBC, and ROESY), mass spectrometry, and by comparison with the literature. This compound was further screened for its potential antioxidant properties by using the radical scavenging assay model 2,2‐diphenyl‐1‐picrylhydrazyl and reveals non‐potent antioxidant activities, while compound 2 shows SC50 of 0,038 mM. Copyright