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 (13)C-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)-ß-D-glucopyranoside (2), kaempferol-3,4'-di-O-ß-D-glucopyranoside (3), trifolin (4), isoquercitrin (5), hyperoside (6), isovitexin (7), isoorientin (8), isovitexin 4'-O-ß-D-glucopyranoside (9), apigenin 7-O-ß-D-glucuronopyranoside (10), luteolin 7-O-ß-D-glucuronopyranoside (11), apigenin 7-O-α-L-rhamnopyranosyl-(1→2)-ß-D-glucuronopyranoside (12), apigenin 7-O-ß-D-glucopyranosyl-(1 → 2)-ß-D-glucuronopyranoside (13), 6-O-(3-nitropropanoyl)-ß-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%.

Cytotoxicity and apoptosis induced by alfalfa (Medicago sativa) leaf extracts in sensitive and multidrug-resistant tumor cells.

Alfalfa (Medicago sativa) has been used to cure a wide variety of ailments. However, only a few studies have reported its anticancer effects. In this study, extracts were obtained from alfalfa leaves and their cytotoxic effects were assessed on several sensitive and multidrug-resistant tumor cells lines. Using the mouse leukaemia P388 cell line and its doxorubicin-resistant counterpart (P388/DOX), we showed that the inhibition of cell growth induced by alfalfa leaf extracts was mediated through the induction of apoptosis, as evidenced by DNA fragmentation analysis. The execution of programmed cell death was achieved via the activation of caspase-3, leading to PARP cleavage. Fractionation of toluene extract (To-1), the most active extract obtained from crude extract, led to the identification of 3 terpene derivatives and 5 flavonoids. Among them, (-)-medicarpin, (-)-melilotocarpan E, millepurpan, tricin, and chrysoeriol showed cytotoxic effects in P388 as well as P388/DOX cells. These results demonstrate that alfalfa leaf extract may have interesting potential in cancer chemoprevention and therapy.

New diterpenoids and phenolic amides from Icacina mannii Oliv.

Fourteen undescribed compounds including five neoclerodanes (1-5), three labdanes (12-14), three pimarane (15-17) derivatives, one carbamate (24) and two clovamide-type amides (25 and 26), along with twenty-two known compounds (6-11, 18-23 and 27-36) were isolated from the tuber and stem of Icacina mannii. Their structures were elucidated by 1D and 2D NMR and HR-ESI-MS data analysis, and by comparing their NMR data with those of the literature.

Inhibition of stromelysin-1 by caffeic acid derivatives from a propolis sample from Algeria.

Stromelysin-1 (matrix metalloproteinase-3: MMP-3) occupies a central position in collagenolytic and elastolytic cascades, leading to cutaneous intrinsic and extrinsic aging. We screened extracts of a propolis sample from Algeria with the aim to isolate compounds able to selectively inhibit this enzyme. A butanolic extract (B (3)) of the investigated propolis sample was found to potently inhibit MMP-3 activity (IC (50) = 0.15 ± 0.03 µg/mL), with no or only weak activity on other MMPs. This fraction also inhibited plasmin amidolytic activity (IC (50) = 0.05 µg/mL) and impeded plasmin-mediated proMMP-3 activation. B (3) was fractionated by HPLC, and one compound, characterized by NMR and mass spectroscopy and not previously identified in propolis, i.e., (+)-chicoric acid, displayed potent IN VITRO MMP-3 inhibitory activity (IC (50) = 6.3 × 10 (-7) M). In addition, both caffeic acid and (+)-chicoric acid methyl ester present in fraction B (3) significantly inhibited UVA-mediated MMP-3 upregulation by fibroblasts.

New Oleanane-type glycosides and secoiridoid glucoside from Aptandra zenkeri.

Four new saponins, camelliagenin A and B derivatives, and one new secoiridoid glucoside were isolated from the stem bark of Aptandra zenkeri Engl. (Aptandraceae) together with two known secoiridoid glucosides. Their structures were determined based on a combination of 1D- and 2D-NMR experiments techniques and HR-ESI-MS analysis. This is the first report on saponins in genus Aptandra.

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.

Isolation and structure elucidation of cyclopeptide alkaloids from the leaves of Heisteria parvifolia.

Heisteria parvifolia Sm. is prescribed in traditional medecine against numerous diseases in Côte d'Ivoire. Due to the shortcoming in scientifical knowledge of use of this species, our investigations revealed five undescribed cyclopeptide alkaloids added to one known derivative namely anorldianine. These compounds were elucidated by 1D and 2D-NMR experiments and comparison with literature data, and confirmed by HR-ESI-MS. Cytotoxic activity evaluation of these compounds against the chronic myeloid leukemia (K565) cell line exhibited an antiproliferative activity with cell growth inhibition from 13% to 46%.

Triterpene saponins from the roots of Parkia bicolor A. Chev.

Five undescribed triterpene-type saponins, parkibicolorosides A-E, a cassane-type diterpene, and a known trimethoxy benzene glucoside were isolated from the roots of Parkia bicolor A. Chev. Their structures were elucidated by different spectroscopic methods including 1D- and 2D-NMR experiments as well as HR-ESI-MS analysis. Their cytotoxic activity against the chronic myeloid leukemia (K562) cell line was evaluated. The monosaccharides saponins exhibited a moderate antiproliferative activity with IC50 ranging from 48.49 ±â€¯0.16 to 81.66 ±â€¯0.17 µM.

Isoflavonoid glycosides from the roots of Baphia bancoensis.

Chemical investigation of the methanol extract of the roots of Baphia bancoensis led to the isolation and characterization of three new isoflavonoid glycosides (1-3). Their structures were determined on the basis of spectroscopic studies andchemical evidence. Antibacterial activity of isolated compounds was evaluated against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa.

Dihydroisocoumarin glucosides from stem bark of Caryocar glabrum.

Two dihydroisocoumarin glucosides have been isolated from the stem bark of Caryocar glabrum (Aubl.) Pers. Their structures and absolute stereochemistry were established on the basis of extensive 1D and 2D NMR, UV, IR, HRESIMS, and CD studies. These compounds represent the first members of a new biogenetic pathway for the isocoumarins nucleus involving shikimate derived A-ring coupling with a phenyl propanoid derivative.

A New Cardenolide and Other Compounds from Salsola tetragona.

One new cardenolide, 3-O-ß-D-allopyranosylcoroglaucigenin (salsotetragonin) (1), was isolated from the aerial parts of Salsola tetragona Delile with four known cardenolides (2-5); two known flavonoids (6-7), three known phenolic compounds (8-10) and two known fatty acids (11-12). Their structures were identified by spectroscopic analyses and by comparison of their spectral data with those reported in the literature. Compounds 1-5, 7, 10 and 12 were isolated from the genus Salsola for the first time. This is the first report on cardenolides identified in the Amaranthaceae family.

Acylated farnesyl diglycosides from Guioa crenulata.

Chemical investigation of the methanol extract of the leaves of Caledonian Guioa crenulata led to the isolation and characterisation of four farnesyl diglycosides, crenulatosides A, B, C and D, along with three known flavonol glycosides and one known trimeric proanthocyanidin possessing a doubly linked structure. The structures of these compounds were determined on the basis of spectroscopic studies and chemical evidence. The ethanol and ethyl acetate extracts of the leaves exhibited no cytotoxic activity and no inhibition of acetylcholinesterase.

Medicarpin and millepurpan, two flavonoids isolated from Medicago sativa, induce apoptosis and overcome multidrug resistance in leukemia P388 cells.

BACKGROUND: High consumption of flavonoids has been associated with a decrease risk of cancer. Alfalfa (Medicago sativa) leaves have been widely used in traditional medicine and is currently used as a dietary supplement because of their high nutrient content. We previously reported the cytotoxic activity of alfalfa leaf extracts against several sensitive and multidrug resistant tumor cell lines. HYPOTHESIS/PURPOSE: We aimed to determine whether medicarpin and millepurpan, two isoflavonoids isolated from alfalfa leaves, may have pro-apoptotic effects against drug-sensitive (P388) and multidrug resistant P388 leukemia cells (P388/DOX). STUDY DESIGN/METHODS: Cells were incubated with medicarpin or millepurpan for the appropriate time. Cell viability was assessed by the MTT assay. DNA fragmentation was analyzed by agarose gel electrophoresis. Cell cycle analysis was realized by flow cytometry technics. Caspases 3 and 9 activities were measured using Promega caspACE assay kits. Proteins and genes expression were visualized respectively by western-blot using specific antibodies and RT-PCR assay. RESULTS: P-glycoprotein-expressing P388/DOX cells did not show resistance to medicarpin (IC50 ≈ 90 µM for P388 and P388/DOX cells) and millepurpan (IC50 = 54 µM and 69 µM for P388 and P388/DOX cells, respectively). Treatment with medicarpin or millepurpan triggered apoptosis in sensitive as well as multidrug resistant P388 cells. These effects were mediated through the mitochondrial pathway by modifying the balance pro/anti-apoptotic proteins. While 3 µM doxorubicin alone could not induce cell death in P388/DOX cells, concomitant treatment with doxorubicin and subtoxic concentration of medicarpin or millepurpan restored the pro-apoptotic cascade. Each compound increased sensitivity of P388/DOX cells to doxorubicin whereas they had no effect in sensitive P388 cells. Vinblastine cytotoxicity was also enhanced in P388/DOX cells (IC50 = 210 nM to 23 and 25 nM with medicarpin and millepurpan, respectively). This improved sensitivity was mediated by an increased uptake of doxorubicin in P388/DOX cells expressing P-gp. P-gp expression was not altered by exposure to medicarpin and millepurpan. CONCLUSION: These data indicate that medicarpin and millepurpan possess pro-apoptotic properties and potentiate the cytotoxicity of chemotherapy drugs in multidrug resistant P388 leukemia cells by modulating P-gp-mediated efflux of drugs. These flavonoids may be used as chemopreventive agents or as sensitizer to enhance cytotoxicity of chemotherapy drugs in multidrug resistant cancer cells.

New Flavonol Glycoside from the Leaves of Ventilago africana.

A new flavonol diglycoside, rhamnocitrin-3-O-α-L-rhamnopyranosyl-(1-->6)-ß-D-galactopyranoside, was isolated from the leaves of Ventilago Africana, in addition to 11 known flavonoids. Their structures were determined by spectroscopic methods including 1D- and 2D-NMR, and HR-ESI-MS analysis. The isolated compounds were evaluated for their antioxidant activity by using DPPH radical-scavenging assay. Compounds 4, 7-9 have discrete to good antioxidant potential with EC50 values ranging from 20.9 to 40.4 µM, compared with ascorbic acid (EC50 60 µM) used as positive control.

Cytotoxic triterpenoid saponins from the stem bark of Antonia ovata.

Phytochemical investigation of the MeOH extract of the stem bark of Antonia ovata led to the isolation of four triterpenoid saponins, along with eleven known compounds. Their structures were established by extensive 1D and 2D NMR, as well as HR-MS analysis and acid hydrolysis. All isolated saponins contained the same tetrasaccharide chain O-beta-d-xylopyranosyl-(1-->2)-O-beta-d-glucopyranosyl-(1-->3)-O-[beta-d-glucopyranosyl-(1-->2)]-beta-d-glucuropyranoside linked to C-3 of esterified derivatives of R(1)-barrigenol, A(1)-barrigenol, barringtogenol C, or camelliagenin. Biological evaluation of the compounds against KB cell line revealed a potent cytotoxic activity with IC(50) values ranging from 3.1 to 6.6microM. The known compounds were found to be inactive at 10microg/ml concentration.

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.

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.