A series of 12 3-(4-bromobenzyl)-5-(arylmethylene)-5 H-furan-2-one lactones, designed using the naturally occurring toxin nostoclides as a lead structure, were synthesized and screened as potential inhibitors of photosynthetic electron transport. The structures were confirmed by (1)H and (13)C NMR, MS, and IR analyses. Their biological activity was evaluated both in vitro, as the ability to interfere with light-driven reduction of ferricyanide by isolated spinach chloroplasts, and in vivo, as the capability to inhibite the oxygen production by intact Chlorella cells. Some of the compounds exhibited inhibitory properties in the micromolar range against basal and phosphorylating electron flow from water to K 3[Fe(CN) 6], with no effect on uncoupled electron flow. Thus, they seem to behave as energy-transfer inhibitors. Although poor solubility in water may limit their effectiveness, the active derivatives could present structures to be exploited for the design of new substances endowed with herbicidal activity.

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3-Benzyl-furan-2(5H)-one (2a) and 3-(4-bromobenzyl)-furan-2(5H)-one (2b) were treated with TBDMSOTf and converted into the corresponding tert-butyldimethylsilylfuran ethers. These furans were further condensed with several aromatic aldehydes affording compounds 5-14 with general 3-benzyl-5-arylidene-furan-2(5H)-one structures in 31% to 98% yields. Such compounds are analogues of the naturally occurring nostoclide lactones, reported to present moderate cytotoxic activity. Compounds 5-14 were submitted to an in vitro bioassay against the HL-60, HCT-8, SF295 and MDA-MB-435 cancer cell lines using the MTT cytotoxicity assay.

Aquatidial, um novo bis-norsesquiterpenóide assimétrico, hipoteticamente derivado da isoemigossipolona, foi isolado da casca externa das raízes de Pachira aquatica (Bombacaceae), juntamente com os compostos conhecidos isoemigossipolona, p-cumarato de triacontila e lupeol. As estruturas do aquatidial e dos demais compostos foram determinadas por análises espectroscópicas (EM-FAB, IV, RMN 1D e 2D) ou por comparação com dados publicados na literatura.Aquatidial, a new asymmetric bis-norsesquiterpenoid, hypothetically derived from isohemigossypolone, was isolated from the outer bark of Pachira aquatica (Bombacaceae) roots, along with the known compounds isohemigossypolone, triacontyl p-coumarate and lupeol. The structures of aquatidial and the known compounds were established by spectroscopic analyses (HRFABMS, IR, 1D and 2D NMR) or comparison with published data from literature.

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