Abdulmagid Alabdul Magid

Triterpenoid saponins from the fruits of Caryocar villosum.

Fourteen new triterpenoid saponins (1-14) were isolated from the methanol extract of the fruits of Caryocar villosum along with 10 known saponins. Their structures were established on the basis of extensive NMR (1H, 13C, COSY, TOCSY, ROESY, HSQC, and HMBC) and ESIMS studies. The toxicity of the methanolic extracts of the peel and the pulp of fruits and the crude saponin fraction of the peel was assessed using the Artemia salina test. The antimicrobial activities of caryocarosides IV-21 (14), II-1 (16), III-1 (17), and IV-9 (20) and of saponin 23 were also studied in vitro on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Mycobacterium smegmatis, and Enterococcus faecalis bacteria.

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.

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).

Diterpenoids and triterpenoids from Euphorbia retusa.

Six new ent-abietane lactones (1-6), three new esterified tetracyclic triterpenes (7-9), and seven known diterpenoids and triterpenoids were isolated from the roots of Euphorbia retusa. Their structures were elucidated by means of spectroscopic studies including 1D and 2D NMR, mass spectrometry, chemical transformation, and comparison with literature data.

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).

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%.

Two new bis-iridoids isolated from Scabiosa stellata and their antibacterial, antioxidant, anti-tyrosinase and cytotoxic activities

This study presents the chemical profile investigation of a 70% ethanol extract obtained from Scabiosa stellata, a medicinal herbaceous traditionally used to treat heel cracks. A 13C NMR-based dereplication methodology was firstly applied on centrifugal partition chromatography-generated fractions in order to quickly identify the major compounds of the extract. The dereplication process was then completed by semi-preparative high-performance liquid chromatography in order to identify unknown or minor compounds. Two new bis-iridoids, namely 7-O-caffeoyl-sylvestroside I (1) and 7-O-(p-coumaroyl)-sylvestroside I (2), together with ten known compounds (3-12) were isolated. Their structures were elucidated by spectroscopic methods including NMR and HR-ESI-MS. The antibacterial, anti-tyrosinase and DPPH radical scavenging activities of the crude extract, fractions, and isolated compounds were evaluated. A significant antibacterial activity was observed for nine isolated compounds, particularly 1 and 2 which yielded MIC values of 31.2μg/mL against Enterococcus faecalis and 62.5μg/mL against Staphylococcus epidermidis. The cytotoxic activity of these new bis-iridoids was evaluated on a fibrosarcoma cell line (HT1080) and only compound 1 exhibited a moderate cytotoxic activity (IC50 35.9μg/mL).

Phenolic Glycosides from the Stem Bark of Caryocar villosum and C. glabrum

Mushroom tyrosinase inhibitory activity of methanol extracts and polar fractions of the stem bark of Caryocar villosum and C. glabrum has been assessed. Seven new phenolic glycosides (1-7) were isolated from the most active fractions, along with 15 known compounds (8-22). The structures of these compounds were established on the basis of spectroscopic methods including 1D and 2D NMR analysis, HRESIMS, and comparison with literature experimental data for known compounds.

Chemical composition, antioxidant and antibacterial activities of Tamarix balansae J. Gay aerial parts

Abstract A previously undescribed phenolic sulphate ester, potassium 34-dihydroxy-3-methoxybenzoic acid methyl ester-5-sulphate (1), along with nine known flavonoids, kaempferol-3-O-potassium sulphate-4′,7-dimethyl ether (2), kaempferol-4′,7-dimethyl ether (3), rhamnocitrin-3-O-potassium sulphate (4), rhamnocitrin (5), kaempferol (6), quercetin (7), afzelin (8), quercetin-3-O-α-l-rhamnopyranoside (9) and luteolin-3′-O-potassium sulphate (10) were isolated from the aerial parts of Tamarix balansae. Structures elucidation was performed by comprehensive 1D and 2D NMR analyses, mass spectrometry and by comparison with literature data. The antibacterial assay against Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa bacteria showed a good activity for 2, 3, 7 and 9, with MICs ranging from 62.5 to 250 μg/mL. The abilities of these compounds to scavenge the DPPH were evaluated. Compounds 1, 7, 9 and 10 exhibited a good antiradical activity potential with IC50 values ranging from 3.0 to 115.5 μg/mL, compared with ascorbic acid (IC50 7.4 μg/mL) which was used as positive control.

Triterpenoid saponins from Scabiosa stellata collected in North-eastern Algeria

Eight undescribed triterpenoid saponins, scabiostellatosides A-H, together with three known compounds were isolated from the whole plant of Scabiosa stellata L. Their structures were established by spectroscopic analyses (1D, 2D-NMR and HRESIMS) and chemical methods. Scabiostellatosides A-H were evaluated for their cytotoxicity against human fibrosarcoma cell line (HT1080). Scabiostellatoside F, a heptasaccharide derivative of oleanolic acid, exhibited moderate cytotoxicity against HT1080 cell line with IC50 value of 12.0 μM.