Riad Elias

Toward the chemical ecology of medicinal plant use in chimpanzees: The case ofVernonia amygdalina, a plant used by wild chimpanzees possibly for parasite-related diseases

The bitter and related constituents have been isolated fromVernonia amygdalina (Compositae), a plant ingested by wild chimpanzees possibly suffering from parasite-related diseases in the Mahale Mountains National Park, Tanzania. Isolated from the plant were four known sesquiterpene lactones, seven new steroid glucosides, and two aglycones of the glucosides. The sesquiterpene lactones showed significant in vitro antischistosomal, plasmodicidal, and leishmanicidal activities. Antischistosomal activity was also found for the major steroid glucoside, vernonioside B1. A trend in the glucosides to show significant antischistosomal, plasmodicidal, and amebicidal activities when the sugar moiety was removed, was observed. Vernodalin, judged as the most significant constituent for antiparasitic activities in vitro, was tested for in vivo antischistosomal effect. It was, however, highly toxic to the cercaria-infected mouse. Chimpanzees have been only rarely observed to ingest anything but the pith of the young stem. The occurrence of vernonioside B1 and its aglycone vernoniol B1, the major constituents among the steroid-related constituents, were detected at significant levels in the pith. However, vernodalin was abundant only in the leaves and bark. Thus, chimpanzees at Mahale were hypothesized to control parasite-related diseases by ingesting the young pith of this tree containing steroid-related constituents.

In vitro Antimicrobial Activity of Plants used in Cambodian Traditional Medicine

The purpose of the present study was to screen 27 plant species used in the traditional medicine of Cambodia for in vitro antibacterial and antifungal activities. Thirty-three methanolic extracts were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Mycobacterium smegmatis and Candida albicans. Screened by disk diffusion assay, the extracts showed antimicrobial activity especially on Gram-positive bacteria. None of the crude methanolic extracts showed activity against P. aeruginosa. Twenty-five selected extracts were evaluated using a micro-dilution test. Harrisonia perforata (roots) and Hymenodictyon excelsum (bark) exhibited a bactericidal effect against S. aureus at a concentration of 500 microg/ml. Azadirachta indica (bark), Harrisonia perforata (roots and stem) and Shorea obtusa (roots) exhibited a bactericidal effect against M. smegmatis at 250 microg/ml.

Cytotoxic Steroidal Saponins from the Flowers of Allium leucanthum

Allium leucanthum C. Koch is an endemic Caucasian species that grows in Georgia. The flowers are used in traditional medicine. Phytochemical investigation allowed the isolation of seven spirostanol type saponins from the flowers. Their structures were elucidated on the base of NMR and HRESIMS spectrometry data. A new compound, which we have named leucospiroside A (5), has been identified as (25R)-5α-spirostane-2α,3β,6β-triol 3-O-β-glucopyranosyl-(1→3)-β-glucopyranosyl-(1→2)-[β-glucopyranosyl-(1→3)]-β-glucopyranosyl-(1→4)-β-galactopyranoside. The six others were known substances, but are described in this plant for the first time. The crude extract, spirostanol and furostanol fractions, as well as isolated compounds, were evaluated for their in vitro cytotoxic activity. Compounds 1-3 and 5 were found to be the most active, with relatively similar IC50 values ranging from 3.7 to 5.8 µM for a lung cancer cell line (A549) and 5.6 to 8.2 µM for a colon cancer cell line (DLD-1).

The protective activity of α-hederine against H2O2 genotoxicity in HepG2 cells by alkaline comet assay

Abstract This study was designed to evaluate the protective effect of α-hederine (α-hed) against H 2 O 2 -mediated DNA damage on HepG2 cell line by the alkaline comet assay. For the protective effect of α-hed study, cells were treated according to three protocols: pre-treatment, simultaneous treatment and post-treatment. The effect of α-hed on catalase activity was evaluated after treating the cells with 3.36 mg/ml of 3-amino-1,2,4-triazole (AMT) singly or in combination with α-hed (1.5 or 3 μg/ml) and H 2 O 2 (8.8 μM) during 1 h. The catalase activity was also biochemically measured after treating cells with α-hed at 1.5, 3, or 15 μg/ml during 1 h. Additionally, the influence of α-hed on membrane RedOx potential, pool of reduced glutathione and total protein content was evaluated by flow cytometry. In the pre-treatment, the two concentrations of α-hed (1.5 and 3 μg/ml) decreased the lesions induced by H 2 O 2 (8.8 μM) significantly. This decrease was about 57.2% and 66.1%, respectively. Similar results were observed when cells were treated with α-hed and H 2 O 2 simultaneously. The decrease of H 2 O 2 -induced lesions was about 78.2% and 83.2% (α-hed 1.5 and 3 μg/ml, respectively). In the post-treatment protocol, this decrease was not significant. The combination of AMT and H 2 O 2 induced more DNA damage than H 2 O 2 alone (tail moment (TM) means was 31.4% and 21.8%, respectively). When α-hed was added to this mixture, TM means were reduced significantly (17.4% for α-hed 1.5 μg/ml and 15.5% for α-hed 3 μg/ml). Up to 6.9 μg/ml, α-hed enhanced catalase activity (60.5%), followed by a decrease of the activity. Total protein content and membrane RedOx potential were slightly increased up to 11 μg/ml (14% and 3.6%, respectively) followed by a drop and a plateau. Pool of reduced glutathione remained unchanged up to 10 μg/ml then dropped and reached a plateau. In conclusion, α-hed could exert its protective effect against H 2 O 2 -mediated DNA damage by scavenging free radicals or by enhancing the catalase activity.

Two sesquiterpenoids, lucinone and glutinone, from Jasonia glutinosa

Two new sesquiterpenoids—lucinone (1) and glutinone (2)—isolated from the aerial parts of Jasonia glutinosa have been characterized by 1D and 2D NMR techniques. The complete structure of these sesquiterpene compounds have been determined as 5β,11,12-trihydroxy-iphionan-4-one and 2-[5′-(2′-oxopentyl)]-2-methyl-5-(1′-hydroxy-1′-methylethanol)-cyclohexanone, respectively.

Cytotoxic Activity of Alkaloids Isolated from Stephania rotunda In vitro cytotoxic activity of cepharanthine

Three major alkaloids: cepharanthine (1), tetrahydropalmatine (2) and xylopinine (3) isolated from Stephania rotunda tuber were investigated for their cytotoxic activity in a panel of human cancer cells (HT29, LS174T, SW620 and HepG2) using MTT assay. In the present study, cepharanthine (1) exerted potent cytotoxicity against colon and hepatoma cancer cell lines with IC(50) values between 2.4 and 5.3 microM while tetrahydropalmatine (2) and xylopinine (3) displayed weak cytotoxicity. In addition, the mutagenic activity of cepharanthine (1) was investigated using a modified liquid incubation technique of the Salmonella/microsomal assay. This alkaloid (1) was found to be non-mutagenic for doses up to 8.2 microM.

Genotoxic and clastogenic activity of saponins extracted from Nauclea bark as assessed by the micronucleus and the comet assays in Chinese Hamster Ovary cells

ETHNOPHARMACOLOGICAL RELEVANCE Bark extracts of Nauclea latifolia, Nauclea diderrichii, Nauclea pobeguinii and Nauclea vandergutchii are used in traditional medicine in West and South Africa for the treatment of fevers, diarrhea and malaria. AIM OF THE STUDY To estimate the possible long-term toxicity and genotoxicity of plant extracts (dichloromethane, methanol, water/methanol, water) and saponins. MATERIALS AND METHODS The clastogenicity of plant extracts and saponins was assessed by the micronucleus assay performed on Chinese Hamster Ovary cells. The DNA-damaging activity of saponin mixture was assessed by the comet assay on Chinese Hamster ovary cells. RESULTS Hydromethanolic extracts from Nauclea latifolia, Nauclea diderrichii and Nauclea pobeguinii exhibited a significant clastogenic/aneugenic activity without S9 mix. The hydromethanolic extract from Nauclea diderrichii was the most clastogenic/aneugenic fraction with a Minimal Active Concentration (MAC) of 23.1 μgm L(-1). It was submitted to a separation step leading to six main saponins identified as quinovic acid glycosides (saponins A, D, E, G, J, K). None of the isolated saponins exerted a significant clastogenic/aneugenic activity by the micronucleus assay, however a mixture made with equal quantities of each of the six saponins exhibited a direct genotoxic/clastogenic activity as assessed by both the micronucleus assay and the comet assay on Chinese Hamster Ovary cells. CONCLUSION Saponins present in the hydromethanolic extracts of Nauclea induced synergistic in vitro DNA-damage and chromosome mutations in mammalian cells. This genotoxic activity was probably due to the capacity of Nauclea saponins to reduce cell defense against oxidative stress through the inhibition of glutathione-S-transferase activity.

α‐hederin potentiates 5‐FU antitumor activity in human colon adenocarcinoma cells

The aim of this study was to investigate the ability of α‐hederin to improve the efficacy of widely prescribed 5‐fluorouracil (5‐FU) in a human colon adenocarcinoma model. Drug combinations of α‐hederin and 5‐FU using both fixed‐concentration and combination index methods were performed in vitro in HT‐29 cells. The results showed that α‐hederin at sub‐IC50 cytotoxic concentrations enhanced 5‐FU cytotoxicity about 3.3‐fold (p < 0.001). Simultaneous combination of α‐hederin and 5‐FU at their IC50 ratio showed either a synergistic effect at a moderate cytotoxic range (25% of cell growth inhibition) or an antagonistic effect at a high level of growth inhibition. The data indicate therefore that it is possible to optimize colorectal cancer cell sensitivity to 5‐FU with α‐hederin. Copyright

DNA-Damaging, Mutagenic, and Clastogenic Activities of Gentiopicroside Isolated from Cephalaria kotschyi Roots

Gentiopicroside (1) is the major secoiridoid glucoside constituent of Cephalaria kotschyi roots. The mutagenicity, DNA-damaging capacities, and clastogenicity of this molecule were evaluated by the Salmonella typhimurium mutagenicity assay (Ames test) on tester strains TA97a, TA98, TA100, and TA102, the alkaline comet assay, and the micronucleus assay on CHO cells. All tests were performed with and without the metabolization mixture, S9 mix. In the Ames test, the mutagenicity of 1 was limited to TA102 without S9 mix (2.3 rev microg(-1)). The genotoxicity was more evident without S9 mix (0.78 OTMchi(2) units microg(-1) mL) than with the metabolic mixture (0.16 OTMchi(2) units microg(-1) mL) with the comet assay. Similarly, the clastogenicity without S9 mix was 0.99 MNC microg(-1) mL and 0.38 MNC microg(-1) mL with S9 mix in the micronucleus assay. The interaction of 1 with DNA is probably through the involvement of oxidative DNA lesions.

Pores formation on cell membranes by hederacolchiside A1 leads to a rapid release of proteins for cytosolic subproteome analysis.

Hederacolchiside A1 was used to progressively permeabilize the membrane of human melanoma MEL-5 cells. Holes formation was followed by Scanning Electron Microscopy and interaction of the saponin with cholesterol and phospholipids by TOF-SIMS. 2D-LC-MS/MS and 2D-SDS-PAGE show that the release of soluble proteins into serum-free culture media increases with time. This can lead to a new rapid and efficient strategy to analyze the cytosolic subproteome and it opens the door to get information from the cytosolic compartment for clinical proteomic studies.