title: Withanolides from Vassobia lorentzii.
abstract: Eight new withanolides were isolated from the aerial parts of Vassobia lorentzii and characterized by spectroscopic methods and with the aid of molecular modeling. The compounds were identified as (17S,20R,22R)-5beta,6beta:18,20-diepoxy-18-hydro xy-1-oxowitha-2,5, 24-trienolide (1); (17S,20R,22R)-18,20-epoxy-4beta, 18-dihydroxy-1-oxowitha-2,5,24-trienolide (2); (17S,18R,20R, 22R)-4beta-hydroxy-18,20-epoxy-18-methoxy-1-oxowitha-2,5, 24-trienolide (3); (17S,18S,20R,22R)-4beta-hydroxy-18, 20-epoxy-18-methoxy-1-oxowitha-2,5,24-trienolide (4); (17S,20R, 22R)-4beta-hydroxy-18,20-epoxy-1,18-dioxowitha-2,5,24-tri enolide (5); (17S,18R,20R,22R)-18,20-epoxy-18-methoxy-1,4-dioxowitha++ +-2,5, 24-trienolide (6); (17S,18S,20R,22R)-18,20-epoxy-18-methoxy-1, 4-dioxowitha-2,5,24-trienolide (7); and (17S,20R,22R)-5beta, 6beta-epoxy-4beta,18,20-trihydroxy-1-oxowitha-2,24-die nolide (8). Compounds 1 and 2 were obtained as epimeric mixtures at C-18.
authors.affiliation: Departamento de Química Orgánica and IMBIV, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina.
authors.forename: R I
authors.initials: RI
authors.lastname: Misico
authors.forename: R R
authors.initials: RR
authors.lastname: Gil
authors.forename: J C
authors.initials: JC
authors.lastname: Oberti
authors.forename: A S
authors.initials: AS
authors.lastname: Veleiro
authors.forename: G
authors.initials: G
authors.lastname: Burton
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000302:isolation & purification / Q000494:pharmacology; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification*; D006801:Humans; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D010963:Plasmodium falciparum / Q000187:drug effects; D019657:Solanaceae / Q000737:chemistry*
chemical_list: D000962:Antimalarials; D007783:Lactones; D004875:Ergosterol