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Recebido em 12/11/02; aceito em 19/5/03 CHEMICAL CONTITUENTS OF Alchornea glandulosa (EUPHORBIACEAE). Chemical investigation of the leaves of Alchornea glandulosa (Euphorbiaceae) afforded a mixture of β-sitosterol and stigmasterol, the terpenoid loliolide, the guanidine alkaloid N-1,N-2,N-3-triisopentenylguanidine and the phenolic compound corilagin. The structures of these compounds were elucidated by spectroscopic analysis. The antimicrobial and antiproliferative properties of the crude methanolic extract of the leaves and of fractions from its fractionation, were investigated against a series of bacteria and fungi, as well as against four human cancer cell lines.

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Titanate nanotubes (TiNTs) with the chemical composition Na 2 Ti 3 O 7 .nH 2 O (NaTiNT) were obtained through a hydrothermal method in highly alkaline medium. Protonated titanates nanotubes (H-TiNTs), with the composition H 2 Ti 3 O 7 .nH 2 O, were prepared by ion exchange reaction through a suspension of Na 2 Ti 3 O 7 nH 2 O nanotubes in HCl medium, promoting the exchange of Na + ions by H +. Both Na 2 Ti 3 O 7 .nH 2 O and H 2 Ti 3 O 7 .nH 2 O products, as well the TiO 2 used as raw material for the nanotubes processing, were used as starting material for the solar cells photoelectrodes sensitized using mesoporphyrin extracted from a precursor of cashew nut shell. Exposing the NaTiNT sample to solar radiation of 1258 W/m 2 , a short-circuit current density (I SC) of 13 A/cm 2 and an open-circuit voltage (V OC) of 370 mV were registered and, a current density of 7.6 A/cm 2 and a voltage of 256 mV for the prototype cell based on H-TiNTs. A current density of 1.1 A/cm 2 and an open-circuit voltage of 1.6 mV were obtained for the cell using TiO 2 as electrode.

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