5988-99-8Relevant articles and documents
Structure-cytotoxicity relationships of some helenanolide-type sesquiterpene lactones
Beekman, Aaeron C.,Woerdenbag, Herman J.,Van Uden, Wim,Pras, Niesko,Konings, Antonius W. T.,Wikstroem, Hakan V.,Schmidt, Thomas J.
, p. 252 - 257 (2007/10/03)
This study deals with the cytotoxicity of helenanolide-type (10α- methylpseudoguaianolide) sesquiterpene lactones. We determined the influence of substitution patterns on the toxicity of 21 helenanolides to a cloned Ehrlich ascites tumor cell line, EN2. Within a series of helenalin esters, the acetate (2) and isobutyrate (3) were more toxic than helenalin itself (1). Esters with larger acyl groups (tiglate 4 and isovalerate 5) exhibited a decreased toxicity compared with the parent alcohol (1). Similar relationships were observed between the 6,8-diastereomer of helenalin, mexicanin I (6) and its acetate (7) and isovalerate (8). In contrast, cytotoxicity within a series of 11α,13-dihydrohelenalin esters (9-12) was shown to be directly related to the size and lipophilicity of the ester side chain, dihydrohelenalin (9) being the least toxic compound in this group. Investigation of several 2,3-dihydrohelenalin derivatives (13-21) with 2α- hydroxy-4-oxo- and 2α,4α-dihydroxy- or -O-acyl-substituted cyclopentane rings (arnifolins and chamissonolides, respectively), for which no pharmacological data have been reported so far, revealed further interesting influences of the substitution pattern on cytotoxicity. The results may be interpreted in terms of lipophilicity and steric effects on the accessibility of the reactive sites considered responsible for biological activity.
Helenanolides: Stereocontrolled Total Synthesis of dl-Bigelovin, dl-Mexicanin I, and dl-Linifolin A
Grieco, Paul A.,Ohfune, Yasufumi,Majetich, George F.
, p. 360 - 366 (2007/10/02)
Stereocontrolled total syntheses of the sesquiterpene lactones dl-bigelovin (11), dl-mexicanin I (12), and dl-linifolin A (13) are described.The syntheses start with the hydroazulenone 4 and proceed via the key epoxy alkohol 9.Elaboration of 9 into the tricyclic γ-lactone 14 dl-bigelovin. α-methylenation.Subsequent oxidation at C(4) completes the synthesis of dl-bigelovin.Epoxide opening of 9 with dilithioacetate provides access to tricyclic lactone 23 which gives way to 24 via reduction of ketone 25.Cleavage of the benzyl ether in 24 followed by α-methylenationand oxidation generates dl-mexicanin I.Acetylation of 12 affords dl-linifolin A.