title: Improving the MDR reversal activity of 6,17-epoxylathyrane diterpenes.
abstract: Aiming to optimize macrocyclic lathyrane-type diterpenes as effective Pgp modulators, the phytochemical study of the methanolic extract of Euphorbia boetica aerial parts was carried out. Two new macrocyclic 6,17-epoxylathyrane-type diterpenes, named epoxyboetiranes A (1) and B (2), along with three known analogues (3-5) were isolated. Epoxyboetirane A (1), a triacetate isolated in large amounts, was hydrolyzed to give epoxylathyrol (6). In order to study the effect of the substitution pattern of the macrocyclic scaffold on MDR reversal, 6 was acylated with aroyl, phenylacetyl, cinnamoyl and alkanoyl chlorides/anhydrides, yielding eight new esters, epoxyboetiranes C-J (7-14). The ability of compounds 1-14 as P-glycoprotein (Pgp, ABCB1) modulators was evaluated through combination of transport and chemosensitivity assays, using L5178Y mouse T lymphoma cell line transfected with the human MDR1 gene. In the transport assay, excepting 1, 3 and 6, the compounds, at non-cytotoxic concentrations, displayed strong MDR reversing activity in a dose-dependent mode, exhibiting all the new acyl derivatives (7-14) a many fold increase in the activity when compared with 1. Apart from 11 and 12, all compounds exhibited remarkable synergistic effects in combination with doxorubicin. An ATPase assay, using membrane vesicles from mammalian cells overexpressing Pgp, was also performed with two representatives of the modulators (4 and 5). The results suggest that both compounds compete with substrates for the Pgp drug-binding sites.
authors.affiliation: Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
authors.forename: Cátia
authors.initials: C
authors.lastname: Vieira
authors.affiliation: Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
authors.forename: Noélia
authors.initials: N
authors.lastname: Duarte
authors.affiliation: Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
authors.forename: Mariana A
authors.initials: MA
authors.lastname: Reis
authors.affiliation: Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, Dóm tér 10, H-6720 Szeged, Hungary.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Spengler
authors.affiliation: Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
authors.forename: Ana Margarida
authors.initials: AM
authors.lastname: Madureira
authors.affiliation: Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, Dóm tér 10, H-6720 Szeged, Hungary.
authors.forename: Joseph
authors.initials: J
authors.lastname: Molnár
authors.affiliation: Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal. Electronic address: mjuferreira@ff.ul.pt.
authors.forename: Maria-José U
authors.initials: MJ
authors.lastname: Ferreira
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D028481:Euphorbia / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D051379:Mice; D035261:Plant Components, Aerial / Q000737:chemistry / Q000378:metabolism; D012235:Rhodamines / Q000737:chemistry / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004224:Diterpenes; D012235:Rhodamines; C530347:lathyrane
keywords: ATPase activity; Euphorbia boetica; Macrocyclic diterpenes; Multidrug resistance; P-glycoprotein