Open analogues of arcyriaflavin A. Synthesis through Diels-Alder reaction between maleimides and 1-aryl-3-tert-butyldimethylsiloxy-1, 3-butadienes.

The preparation of a range of open analogues of arcyriaflavin A is described. The synthetic approach is based on the use of perhydroisoindole-1,3,5-triones as key intermediates, which were obtained via Diels-Alder methodology using 1-aryl-3-siloxy-1, 3-butadienes as starting materials. Fischer indolization and aromatization processes afforded different methoxy-substituted arylpyrrolocarbazoles. The stereochemistry and conformation of the Diels-Alder products and the regiochemistry of the indolization reactions are supported by NMR and molecular modeling studies.

Synthesis and pharmacological activity of diarylindole derivatives. Cytotoxic agents based on combretastatins.

Taking into account the structure of Combretastatins, we have synthesized and assayed for cytotoxic activity of new indole derivatives. Two aryl groups are maintained in the cis orientation required for activity by means of an indole moiety built up on less active ketoderivatives used as starting materials.

Synthesis, antitumoral and antiviral evaluation of halo- and demethyl-yatein derivatives.

Several chloro- and iodo-lignanolides have been obtained by direct halogenation of aromatic rings from yatein and 4'-O-demethylyatein. They were assayed as antineoplastics, in order to check the influence in the activity of substitution in both aromatic rings. Although these compounds show a modest antineoplastic activity, it is far from that displayed by yatein and podophyllotoxin. These results confirm that demethylation and the introduction of halo substituents diminish the activity of lignans of the dibenzylbutyrolactone type.

Heterolignanolides: antitumor activity of furyl-, thienyl-, and pyridyl analogs of lignanolides.

A new class of heteroaromatic analogs of lignans, called heterolignanolides, have been tested against several tumor cell lines. These compounds carry diverse heterocyclic rings, instead of the trimethoxyphenyl ring found in the natural lignans yatein and podorhizol. They have moderate antineoplastic activity (P-388, A-549, HT-29) compared with that of yatein. None of the tested compounds has discernible antiviral (HSV-1, VSV) or enzyme inhibitor (ADA, DHFR, GST) activity.

A versatile approach to the synthesis of combretastatins.

A new and versatile synthesis of combretastatins has been developed. Starting from commercially available materials, 2-phenyl-2-benzyl-1,3-dithianes were easily prepared and used as intermediates in the synthesis of several families of combretastatins. This approach facilitates the preparation of representative intermediates in a few steps, with or without an oxygenated function in the ethylenic residue. Many different analogues suitable for pharmacological evaluation can also be obtained from some of these intermediates.

Synthesis and biological activity of bromolignans and cyclolignans.

Nine lignan derivatives (4-12) have been obtained from (-)-yatein by treatment with DDQ and NBS. They showed moderate antineoplastic activity (P-388, A-549, HT-29) compared with podophyllotoxin, but some of them have a better therapeutic index. None of the tested compounds shows anti-viral (HSV-1, VSV) or enzyme inhibitor (ADA, DHFR, GST) activities.