Giardia lamblia is the causative agent of giardiasis, a common parasitic infection of the human and animal digestive tract. Although several drugs have been available to treat this infection, they present unpleasant side effects or cytotoxicity. In order to find a more natural treatment for the disease, we analyzed the effects of the methanolic extract and three fractions obtained from Hovenia dulcis Thunb. (Rhamnaceae) leaves on G. lamblia. Comparing all fractions, dichloromethane was more efficient in reducing Giardia growth. The exposition of G. lamblia to this fraction lead to degenerations in the surface, modifications in the cell shape and alterations in the localization of nuclei. Besides that, the adhesion of G. lamblia was also altered. Experiments revealed that the obtained fraction did not present cytotoxic effects in mammalian cells. In summary, dichloromethane fraction has strong antigiardial effects and could become an important new substance for the treatment of giardiasis.

A protocol for in vitro propagation of Rollinia mucosa, an important medicinal plant, was developed. The presence of 500 mg l 21 polyvinylpyrrolidone (PVP) during explant excision was important to avoid browning. Axillary buds, adventitious buds, and shoot cluster proliferation were achieved from epicotyl and hypocotyl explants from nursery-grown seedlings. The highest direct organogenesis percentage from hypocotyl explants was obtained upon culture of explants on Murashige and Skoog medium supplemented with 2.2 mM benzyladenine (BA) plus 2.32 mM kinetin. Epicotyl explants display highest regeneration frequency on a medium containing 8.8 mM BA and 0.54 mM naphthaleneacetic acid. Gibberellic acid was necessary for shoot elongation. Root induction was observed when shoots were pretreated with activated charcoal for 7 d in the dark before culture on Woody Plant Medium supplemented with 49.21 mM indolebutyric acid for 10 d. Root development was observed when 20 g l 21 sucrose was used. Rooted plantlets were acclimatized and grown in the greenhouse.

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Resumo Calos não-homogêneos e compactos foram induzidos a partir de explantes Internodais de Datura insignis Barb. Rodr. cultivados em meio B5 (Gamborg, 1968) suplementado com 1mg/l BAP + 0,25 e 1mg/1 NAA. A análise histológica do calo revelou que, embora tenham ocorrido divisões periclinais na epiderme, no colênquima e no parênquima cortical, interfascicular e medular, apenas os tecidos situados entre a epiderme e o cilindro central transformaram-se em tecido calogênico. Constatou-se a diferenciação de elementos xilemáticos e centros meristemáticos dispersos pelo calo. Em meio com 1mg/l BAR + 0,25mg de NAA observou-se a presença de estruturas globulares constituídas de células em divisão periclinal com arranjo radial e inúmeros centros meristemáticos. Não foi possível identificar a presença de embriões somáticos, considerando-se os calos como não-embriogênicos.