title: Transcriptional response of genes involved in cell defense system in human cells stressed by H2O2 and pre-treated with (Tunisian) Rhamnus alaternus extracts: combination with polyphenolic compounds and classic in vitro assays.
abstract: The ability of three Rhamnus alaternus leaves extracts on antigenotoxic and gene expression level effects was respectively investigated in a bacterial assay system, i.e. the SOS chromotest with Escherichia coli PQ37 and in human K562 lymphoblast cell line. Total oligomers flavonoids (TOF) enriched, methanol and ethyl acetate extracts were prepared from powdered R. alaternus leaves and characterized quantitatively for the presence of polyphenolic compounds. We explored the response to oxidative stress using the transcriptional profile of genes in K562 cells stressed with H2O2 after incubation with plant extracts. For this purpose, we used a cDNA microarrays containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair genes. Analysis revealed that SOD1, AOE 372, TXN genes involved in the antioxidant defense system and XPC, LIG4, POLD2, PCNA genes implied in the DNA repair system were among the most expressed ones in the presence of the tested extracts. These results were in accordance with those obtained when we tested the antigenotoxic and antioxidant effects of the same extracts with, respectively the SOS chromotest and the xanthine/xanthine oxidase enzymatic assay system. The effect of the tested extracts on SOS response induced by both Aflatoxin B1 (AFB1: 10 microg/assay) and nifuroxazide (20 microg/assay) showed that the TOF extract exhibited the highest antimutagenic level towards the indirect mutagen AFB1. Whereas ethyl acetate extract showed the highest antimutagenic effect towards the direct mutagen, nifuroxazide. None of the tested extracts induced mutagenic activity. However all the tested extracts exhibited xanthine oxidase inhibiting and superoxide anions scavenging effects. R. alaternus extracts contain compounds with significant antioxidant and antigenotoxic activities. These compounds modulate gene expression as detected by using cDNA arrays.
authors.affiliation: Unité de Pharmacognosie/Biologie Moléculaire 99/UR/07-03, Faculté de Pharmacie/Médecine Dentaire de Monastir, Rue Avicenne 5000 Monastir, Tunisie.
authors.forename: Rebai Ben
authors.initials: RB
authors.lastname: Ammar
authors.forename: Ines
authors.initials: I
authors.lastname: Bouhlel
authors.forename: Kita
authors.initials: K
authors.lastname: Valenti
authors.forename: Mohamed Ben
authors.initials: MB
authors.lastname: Sghaier
authors.forename: Soumaya
authors.initials: S
authors.lastname: Kilani
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Mariotte
authors.forename: Marie-Geneviève
authors.initials: MG
authors.lastname: Dijoux-Franca
authors.forename: François
authors.initials: F
authors.lastname: Laporte
authors.forename: Kamel
authors.initials: K
authors.lastname: Ghedira
authors.forename: Leila
authors.initials: L
authors.lastname: Chekir-Ghedira
mesh_terms: D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009152:Mutagenicity Tests; D020411:Oligonucleotide Array Sequence Analysis; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D059808:Polyphenols; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism; D012313:RNA / Q000235:genetics / Q000378:metabolism; D031955:Rhamnus / Q000737:chemistry*; D013481:Superoxides / Q000378:metabolism; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D005419:Flavonoids; D016166:Free Radical Scavengers; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D013481:Superoxides; D012313:RNA; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase