Revisão: Jatropha curcas L.: aspectos morfofisiológicos e químicos

Resumo Jatropha curcas L. (pinhão-manso) é uma espécie vegetal oleaginosa cujo óleo, extraído de suas sementes, apresenta múltiplas aplicações para comunidades locais, além da sua potencial aplicação em diferentes setores industriais, dentre os quais a indústria de biodiesel, constituindo-se, assim, em mais uma fonte de matéria-prima dentro do elenco de espécies oleaginosas úteis. Aspectos morfofisiológicos e físico-químicos são de grande importância quando se tem interesse na prospecção de espécies vegetais visando sua domesticação e exploração comercial. O objetivo deste estudo foi realizar uma revisão do estado da arte sobre a J. curcas, compilando estudos acerca da caracterização morfofisiológica, assim como acerca da composição química das sementes, gerando assim informações que auxiliem na exploração do potencial de produção e cultivo da espécie, a fim de subsidiar estudos que propiciem a exploração comercial sustentável dessa cultura. O conhecimento morfológico disponível sobre J. curcas possibilita o entendimento preciso do ciclo biológico da planta, entretanto, estudos fisiológicos ainda necessitam ser desenvolvidos para uma melhor compreensão do comportamento dela, principalmente em termos de armazenamento, condições ótimas de germinação e formação de mudas, assim como sobre o comportamento da espécie quando sob condições adversas, tais como excessiva insolação, restrição hídrica e temperaturas elevadas, dentre outras. A descrição da composição química, caracterização de compostos tóxicos e fatores antinutricionais da semente já existentes forneceram informações que podem dar suporte a produção e exploração comercial de J. curcas, porém estudos e testes com animais devem ser conduzidos para confirmar com maior segurança suas aplicações comerciais.

Phytochemical screening, antioxidant and antibacterial activities of extracts prepared from different tissues of Schinus terebinthifolius Raddi that occurs in the coast of Bahia, Brazil

BACKGROUND

Schinus terebinthifolius is widely used in traditional medicine by Brazilian quilombola and indigenous communities for treatment of several diseases. Extracts from different tissues are being used to produce creams to treat cervicitis and cervicovaginitis. However, most studies are limited to the assessment of the essential oils and extracts obtained from the leaves.

OBJECTIVE

The aim was to evaluate antioxidant and antibacterial activities, to assess the phytochemical profile and to quantify total phenolic compounds of various extracts prepared from S. terebinthifolius grown in the coast of Bahia, Brazil.

MATERIALS AND METHODS

Extracts were obtained by hot continuous extraction (soxhlet) and by maceration. Quantification of phenolic compounds was performed using the Folin-Ciocalteu method and antioxidant properties were assessed by 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Phytochemical screening was performed as described by in the literature and antibacterial activity against Enterococcus faecalis (ATCC 29212) was determined by the microdilution broth assay.

RESULTS

Extraction method greatly affected the metabolite profile of the extracts. Antioxidant activity varied between 21.92% and 85.76%, while total phenols ranged between 5.44 and 309.03 mg EAG/g of extract. Leaf extract obtained with soxhlet showed minimum inhibitory concentration (MIC) of 15.62 μg/mL, while stem extract obtained by maceration was able to inhibit the growth of E. faecalis at 62.5 μg/mL. Stem bark extracts showed a MIC of 500 μg/mL for both extraction methods, while no inhibition was observed for fruit extracts.

CONCLUSION

In general, total phenolic content, antioxidant and antibacterial activities were higher in samples obtained by soxhlet. Our results provide important clues in order to identify alternative sources of bioactive compounds that can be used to develop new drugs.

Physiological and biochemical responses of Ricinus communis seedlings to different temperatures: a metabolomics approach

BACKGROUND

Compared with major crops, growth and development of Ricinus communis is still poorly understood. A better understanding of the biochemical and physiological aspects of germination and seedling growth is crucial for the breeding of high yielding varieties adapted to various growing environments. In this context, we analysed the effect of temperature on growth of young R. communis seedlings and we measured primary and secondary metabolites in roots and cotyledons. Three genotypes, recommended to small family farms as cash crop, were used in this study.

RESULTS

Seedling biomass was strongly affected by the temperature, with the lowest total biomass observed at 20°C. The response in terms of biomass production for the genotype MPA11 was clearly different from the other two genotypes: genotype MPA11 produced heavier seedlings at all temperatures but the root biomass of this genotype decreased with increasing temperature, reaching the lowest value at 35°C. In contrast, root biomass of genotypes MPB01 and IAC80 was not affected by temperature, suggesting that the roots of these genotypes are less sensitive to changes in temperature. In addition, an increasing temperature decreased the root to shoot ratio, which suggests that biomass allocation between below- and above ground parts of the plants was strongly affected by the temperature. Carbohydrate contents were reduced in response to increasing temperature in both roots and cotyledons, whereas amino acids accumulated to higher contents. Our results show that a specific balance between amino acids, carbohydrates and organic acids in the cotyledons and roots seems to be an important trait for faster and more efficient growth of genotype MPA11.

CONCLUSIONS

An increase in temperature triggers the mobilization of carbohydrates to support the preferred growth of the aerial parts, at the expense of the roots. A shift in the carbon-nitrogen metabolism towards the accumulation of nitrogen-containing compounds seems to be the main biochemical response to support growth at higher temperatures. The biochemical changes observed in response to the increasing temperature provide leads into understanding plant adaptation to harsh environmental conditions, which will be very helpful in developing strategies for R. communis crop improvement research.