title: Cytoprotective effects of 5 benzophenones and a xanthone from Hypericum annulatum in models of epirubicin-induced cytotoxicity: SAR-analysis and mechanistic investigations.
abstract: A new benzophenone O-glucoside neoannulatophenonoside (1) together with the known pinocembrin-7-O-glucoside were isolated from the aerial parts of Hyperium annulatum Moris (Guttiferae). The former was identified as 3',5',6-trihydroxy-4-methoxybenzophenone-2-O-beta-D-glucopyranoside by means of chemical and physical evidence. The cytoprotective effects of the new compound together with the previously isolated from this species hypericophenonoside (2), annulatophenone (3), annulatophenonoside (4), acetylannulatophenonoside (5) and 1,3,7-trihydroxyxanthone (6) were evaluated in a model of epirubicin-induced cellular toxicity in K-562 cells. While the benzophenone O-glycosides 1, 2, 4 and 5 exerted substantial cytoprotective effects against the epirubicin cytotoxicity in K-562 cells the aglycones 3 and 6 lacked any significant cytoprotective activity. Biochemical investigations aimed at evaluating the free-radical scavenging activity of the tested compounds as well as their effects on the cellular glutathione stores were carried out as well, aiming at unravelling the mechanisms of cytoprotection. Finally, the ability of 1, 4 and 5 to ameliorate epirubicin-induced anticlonogenic effects on bone marrow cells colony forming units, in vitro were also evaluated. Taken together, the experimental data indicate that the benzophenone glycosides isolated from H. annulatum have a substantial cytoprotective potential against the toxic effects induced by epirubicin and necessitates further detailed pharmacological evaluation of these compounds as possible chemoprotective/radioprotective agents.
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Pharmacy, Medical University-Sofia, 2 Dumav St., 1000 Sofia, Bulgaria. gmomekov@satline.net
authors.forename: Georgi
authors.initials: G
authors.lastname: Momekov
authors.forename: Paraskev T
authors.initials: PT
authors.lastname: Nedialkov
authors.forename: Gerassim M
authors.initials: GM
authors.lastname: Kitanov
authors.forename: Dimitrina
authors.initials: D
authors.lastname: Zh Zheleva-Dimitrova
authors.forename: Tzvetomira
authors.initials: T
authors.lastname: Tzanova
authors.forename: Ulrich
authors.initials: U
authors.lastname: Girreser
authors.forename: Margarita
authors.initials: M
authors.lastname: Karaivanova
mesh_terms: D000818:Animals; D001577:Benzophenones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D003114:Colony-Forming Units Assay; D019610:Cytoprotection / Q000187:drug effects*; D015251:Epirubicin / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D020902:Hypericum / Q000737:chemistry*; D020014:K562 Cells; D051379:Mice; D015394:Molecular Structure; D023461:Myeloid Progenitor Cells / Q000187:drug effects / Q000378:metabolism; D035261:Plant Components, Aerial / Q000737:chemistry; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D044004:Xanthones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D001577:Benzophenones; D016166:Free Radical Scavengers; D011994:Recombinant Proteins; D044004:Xanthones; D015251:Epirubicin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor