ABSTRACTThe use of cell and plant tissue culture techniques to produce economically important active metabolites has been growing. Among these substances are total limonoid aglycones, which are produced by "pera" orange (Citrus sinensis (L.) Osbeck, Rutaceae) and have received considerable attention because of their anticancer actions. The main objective of the present study was to analyze and compare the levels of limonoid aglycones in seeds, callus cultures (originating from seeds), callus cultures (originating from hypocotyls), cell suspensions from hypocotyls cells, and cell suspensions from cotyledons. The cell cultures or C. sinensis were obtained by inoculating two strains of callus in MS medium supplemented with 2.0 µM 2,4-dichlorophenoxyacetic acid, 7.0 µM benzyl aminopurine, and 3% (w/v) sucrose in the dark. The highest concentrations of limonoid aglycone that were obtained were observed in cotyledon cell lines (240 mg/100 g dry weight) that were produced on day 21 of culture and hypocotyl cell lines on day 7 (210 mg/100 g dry weight). Explants of different origins under the same culture conditions had different limonoid aglycone content. The present results may suggest strategies for enhancing the productivity of biologically important limonoid aglycones and investigating the complex pathways of these secondary metabolites in plant tissue cultures.

Os estudos dos metabólitos secundários de plantas se desenvolveram aceleradamente nos últimos 50 anos. Estes compostos são conhecidos por desempenharem um papel importante na adaptação das plantas aos seus ambientes e também representam uma fonte importante de substâncias farmacologicamente ativas. As técnicas de cultura de células de plantas iniciaramse na década de 1960 como uma possível ferramenta para estudar e produzir os metabólitos secundários de plantas. O uso de cultura de células de planta para a produção de substâncias de interesse contribuiu grandemente para avanços em diversas áreas da fisiologia e bioquímica vegetal. Diferentes estratégias, usando sistemas de cultura in vitro, foram estudadas com o objetivo de aumentar a produção de metabólitos secundários. As plantas dos gêneros Aspidosperma e Tabernaemontana são importantes fontes de alcalóides indólicos biologicamente ativos, sendo que no Brasil existe um número considerável de espécies destes gêneros. As culturas de células de Aspidosperma e Tabernaemontana foram iniciadas há pelo menos 16 anos, as quais produzem um grande número de alcalóides, o que estimulou o desenvolvimento de diversas técnicas para sua produção, extração e identificação.

Studies on plant secondary metabolites have been increasing over the last 50 years. These compounds are known to play a major role in the adaptation of plants to their environment and an important source of active pharmaceuticals. Plant cell culture technologies were introduced at the end of the 1960s as a possible tool for both studying and producing plant secondary metabolites. Different strategies, using in vitro systems, have been extensively studied with the objective of improving the production of secondary plant compounds. The Aspidosperma and Tabernaemontana genera are an important source of biologically active alkaloids and in Brazil there is a considerable number of species of these genera. About 16 years ago cell cultures of Tabernemontana and Aspidosperma were initiated. These cell cultures did produce a number of alkaloids of pharmaceutical interest that stimulated the development of several techniques to production, extraction and identification.