Ana Carina da Silva Cândido

Composição química e atividade alelopática do óleo volátil de Hydrocotyle bonariensis Lam (araliaceae)

Os oleos essenciais sao liquidos aromaticos obtidos de materiais vegetais (flores, folhas, ramos, sementes, ervas, madeira, frutos, raizes e cascas), sendo constituidos por misturas complexas, dentre outras, de terpenoides que podem conter ate 100 ou mais compostos orgânicos. Os terpenos encontrados com maior frequencia nos oleos essenciais sao os monoterpenos, sesquiterpenos e com menor frequ-encia os diterpenos. Seus constituintes terpenicos podem apresentar diversas funcoes orgânicas, como alcoois, cetonas, eteres, esteres e aldeidos. Os terpenos possuem, tambem, diversas funcoes nas plantas atuando como fitoalexinas, repelentes de insetos, agentes de atracao polinica, agentes de defesa contra herbivoros, feromonios, hormonios vegetais, moleculas de sinalizacao e aleloquimicos.

Atividade fitotóxica de Croton doctoris S. Moore

The aim of this study was to verify the phytotoxic effect of the crude ethanol extract and semipurified fractions from the stem and leaves of Croton doctoris on the germination, growth and cell division of roots cells of lettuce (Lactuca sativa) and onion (Allium cepa), in the laboratory. The bioassays was conducted in using completely randomized design, with four concentrations (0, 250, 500, 1.000mg L-1) and four replications. The crude extract and the fractions from the stem and leaves inhibited germination and seedling growth of lettuce and onion, with greater phytotoxic effect observed in the ethyl acetate fraction (EAF) from the stems and leaves that significantly affected the growth and mitotic index of root cells of lettuce and onions. With these results it appears that C. doctoris contains substances capable of influencing the germination, growth and cell division of the species studied.