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Withanolides from Vassobia lorentzii

2000; American Chemical Society; Volume: 63; Issue: 10 Linguagem: Inglês

10.1021/np000022z

1520-6025

Rosana I. Misico, Roberto R. Gil, Juan C. Oberti, Adriana S. Veleiro, Gerardo Burton,

Heavy metals in environment

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)-5β,6β:18,20-diepoxy-18-hydroxy-1-oxowitha-2,5,24-trienolide (1); (17S,20R,22R)-18,20-epoxy-4β,18-dihydroxy-1-oxowitha-2,5,24-trienolide (2); (17S,18R,20R,22R)-4β-hydroxy-18,20-epoxy-18-methoxy-1-oxowitha-2,5,24-trienolide (3); (17S,18S,20R,22R)-4β-hydroxy-18,20-epoxy-18-methoxy-1-oxowitha-2,5,24-trienolide (4); (17S,20R,22R)-4β-hydroxy-18,20-epoxy-1,18-dioxowitha-2,5,24-trienolide (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)-5β,6β-epoxy-4β,18,20-trihydroxy-1-oxowitha-2,24-dienolide (8). Compounds 1 and 2 were obtained as epimeric mixtures at C-18.