acylfulvene and irofulven

Acylfulvenes are a class of antitumor agents derived from illudin S, a sesquiterpenoid toxin isolated from mushrooms of the genus Omphalotus. Although DNA appears to be their major target, no data concerning mutagenicity of acylfulvenes are available in the literature, and limited data have been published on illudin S. Enzyme-mediated biotransformations have been demonstrated to influence the cytotoxicity of acylfulvenes. Illudin S and some acylfulvenes [e.g., (-)-6-hydroxymethylacylfulvene (HMAF)] are allylic alcohols with potential for enhanced cytotoxicity and genotoxicity by means of metabolic sulfation. Therefore, we studied the influence of various heterologously expressed human sulfotransferases (SULTs) on biological activities of illudin S and HMAF in bacterial and mammalian cells. (-)-Acylfulvene (AF) was tested as a congener lacking an allylic hydroxyl group. We found: (1) all three compounds were mutagenic in standard Salmonella typhimurium strains TA98, TA100 and TA104; (2) they induced gene mutations (at the hypoxanthine phosphoribosyl transferase locus) and sister chromatid exchange (SCE) in Chinese hamster V79 cells; (3) these effects were practically unaffected when human SULTs were expressed in the target bacteria or mammalian cells (using SCE as the endpoint); (4) illudin S demonstrated 40-600 times higher genotoxic activities than the semisynthetic acylfulvenes studied; it was positive in the SCE test even at a concentration of 0.3 nM; (5) genotoxicity in mammalian cells was observed at substantially lower concentrations of the compounds than required for a positive result in the bacterial test (400 nM with illudin S). We conclude that illudin S, HMAF and AF are potent genotoxicants and human SULTs do not play a significant role in their bioactivation.

Topics: Animals; Arylsulfotransferase; Cell Line; Cricetinae; Cricetulus; Dose-Response Relationship, Drug; Humans; Mutagenicity Tests; Mutagens; Mutation; Polycyclic Sesquiterpenes; Salmonella typhimurium; Sesquiterpenes; Sister Chromatid Exchange; Spiro Compounds; Sulfotransferases

We report our full account of the enantioselective total synthesis of (-)-acylfulvene (1) and (-)-irofulven (2), which features metathesis reactions for the rapid assembly of the molecular framework of these antitumor agents. We discuss (1) the application of an Evans Cu-catalyzed aldol addition reaction using a strained cyclopropyl ketenethioacetal, (2) an efficient enyne ring-closing metathesis cascade reaction in a challenging setting, (3) the reagent IPNBSH for a late-stage reductive allylic transposition reaction, and (4) the final RCM/dehydrogenation sequence for the formation of (-)-acylfulvene (1) and (-)-irofulven (2).

Topics: Allyl Compounds; Antineoplastic Agents; Catalysis; Copper; Hydrogen; Magnetic Resonance Spectroscopy; Models, Chemical; Sesquiterpenes; Spiro Compounds; Stereoisomerism

The primary hydroxyl group in hydroxymethylacylfulvene, a potent antitumor drug, is readily replaced by thiols including cysteine, N-acetylcysteine, homocysteine, and glutathione. Best yields are obtained when reaction is carried out in the presence of dilute sulfuric acid. A variety of sulfur-containing analogues have been prepared, and their toxicity to tumor cells was examined.

Topics: Amino Acids; Animals; Antineoplastic Agents; Drug Screening Assays, Antitumor; Inhibitory Concentration 50; Peptides; Rats; Sesquiterpenes; Tumor Cells, Cultured

Reaction of the fungal sesquiterpene illudin S with excess paraformaldehyde in dilute H2SO4 gives (hydroxymethyl)acylfulvene. The primary allylic hydroxyl thus formed can undergo very facile replacement by a variety of nucleophiles. (Hydroxymethyl)acylfulvene (MGI.114) was more toxic than a precursor, acylfulvene, but less toxic than the parent compound illudin S to HL 60 cells.

Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Basidiomycota; Chromatography, Thin Layer; Crystallography, X-Ray; Drug Screening Assays, Antitumor; HL-60 Cells; Humans; Lung Neoplasms; Magnetic Resonance Spectroscopy; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Polycyclic Sesquiterpenes; Sesquiterpenes