RESUMO
The alkaloid extract and five alkaloids isolated from subterranean stem bark of Duguetia furfuracea (Annonaceae) were investigated for the following activities: antitumoral, trypanocidal and leishmanicidal. Dicentrinone showed weak cytotoxicity, but it had the strongest leishmanicidal activity (IC(50) 0.01 microM). Duguetine and duguetine beta-N-oxide caused considerable antitumoral activity in every cell lines evaluated, although duguetine was more active against trypomastigote forms (IC(50) 9.32 microM) than other alkaloids tested.
Assuntos
Alcaloides/farmacologia , Annonaceae/química , Antineoplásicos Fitogênicos/isolamento & purificação , Leishmania braziliensis/efeitos dos fármacos , Tripanossomicidas/isolamento & purificação , Alcaloides/isolamento & purificação , Aporfinas/isolamento & purificação , Aporfinas/farmacologia , Linhagem Celular Tumoral , Humanos , Estrutura Molecular , Extratos Vegetais/farmacologia , Trypanosoma cruzi/efeitos dos fármacosRESUMO
The cytotoxic effects of seven constituents isolated from Duguetia glabriuscula were evaluated against Hep2 human larynx carcinoma cells. The cytotoxicity exhibited by beta-sitosterol was as strong as that of cis-platin. (+)-Alloaromadendran-10,14beta-diol caused inhibition of cellular growth with IC50 values lower than 25 microg/ml, a feature that was considered as revealing significant activity. Polycarpol showed borderline cytotoxicity, whereas the other compounds were inactive.
Assuntos
Annonaceae/química , Antineoplásicos Fitogênicos/toxicidade , Sitosteroides/toxicidade , Linhagem Celular Tumoral , Cisplatino/toxicidade , Humanos , Concentração Inibidora 50 , Casca de Planta/química , Extratos Vegetais/química , Extratos Vegetais/toxicidade , Folhas de Planta/química , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Testes de Toxicidade/métodosRESUMO
Anhydrotetracycline (AHTC), one of the major toxic decomposition products of the antibiotic tetracycline, contains several potential binding sites to metal ions. The acidity constants of the ligand were calculated in aqueous medium (I = 0.1 M) at 25 and 37 degrees C. We found pKa1 = 3.23 +/- 0.08, pKa2 = 5.94 +/- 0.09, and pKa3 = 8.48 +/- 0.02 at 25 degrees C and pKa1 = 3.12 +/- 0.09, pKa2 = 5.86 +/- 0.03, and pKa3 = 8.38 +/- 0.04 at 37 degrees C. The coordination of AHTC to Cu(II) and Ni(II) ions was studied in the solid state as well as in buffered aqueous solution at pH 10.0. At this pH, the formation of the two CuL2 and CuL species was indicated (log beta 1 = 8.41 +/- 0.04 and log beta 2 = 12.55 +/- 0.05), but only the formation of the NiL complex (log beta = 5.74 +/- 0.04) was identified. Spectroscopic data confirm the previous assignment of the C11 and C12 oxygens as the coordination sites, yielding six-membered ring chelates and excluding complexation through any of the potential binding positions on ring A.