Plant extracts : biological activity, composition and application. / Extratos vegetais : atividade biologica, composição e aplicação.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this work the biological activity (antioxidant and antimicrobial), as well as the composition of several plant extracts were studied. For cocklebur (Xanthium strumarium), 18 different extracts were studied, including supercritical extraction, hydrodistillation, maceration, dynamic maceration and soxhlet with different extracting solvents, including methanol, ethanol, ethyl acetate and chloroform/dichloromethane (1/1), while clove (Caryophillus aromaticus L.), citronella (Cymbopogon winterianus) and palmarosa (Cymbopogon martinii) only the essential oil. The isolated fractions eucalyptol and eugenol were analyzed too. To the antioxidant activity evaluation, a new Antioxidant Activity Index (AAI) using the DPPH radical (2,2-diphenyl-1-picrylhydrazyl) was proposed, that use was possible to compare the antioxidant strength between plant extracts, as well as between pure compounds. The antimicrobial activity of samples was evaluated by the determination of the minimal inhibitory concentration (MIC), by the way the extracts were compared with antibiotics against the microorganisms Staphylococcus aureus, Escherichia coli, Salmonella thyphimurium, Pseudomonas aeruginosa e Clostridium perfringens. The composition of the volatile fractions was carried out using a gas chromatography coupled with mass spectrometer detector for the identification and coupled with flame ionization detector (FID) for the quantification of the compounds. For non-volatile fractions, a liquid chromatography coupled with diode array detector and coupled with mass spectrometer detector was used in the phenolic compounds analysis. The results showed that the composition of the X. strumarium extracts obtained by supercritical extraction and by hydrodistillation presented little qualitative difference, but they did differ quantitatively, 79.6% of _-guaiene was found in the hydrodistilled, while as 0.2 to 0.5% in the supercritical extracts. Hydrodistilled and supercritical extracts of X. strumarium presented poor antioxidant activity, but strong antimicrobial activity, however, the non-volatile fractions exhibit strong antioxidant and antimicrobial activities. In the non-volatile fractions, two phenolic compounds was indentified, the ferulic and chlorogenic acids, since that the concentrations were higher in methanolic and ethanolic extracts than the ethyl acetate and chloroform/dichloromethane extracts, moreover, high correlation between these compounds and antioxidant activity was found. The results show that carboxyatractyloside, a high liver toxic compound, is indeed present in the seeds and in the cotiledonary stage (two leaves stage) but not in adult leaves, therefore for medicinal use, only the adult leaves should be used. The clove oil and the eugenol presented very strong antioxidant activity and strong to moderate antimicrobial activity against tested microorganisms. The citronella and palmarosa oils and the eucalyptol showed poor antioxidant activity and strong to moderate antimicrobial activity. The eugenol was found as the majority compound in the clove oil followed by B-caryophyllene, while as in the citronella and palmarosa oils the B-citronellal and geraniol were the majority compounds, respectively. Considering that the eucalyptol and eugenol showed good antimicrobial activity and are isolated compounds, that make easy the control quality and the acquisition of the homogeneous samples batches, they are chosen compounds to be tested as alternative growth promoters in broilers from 1 to 21 days of age. In this experiment were used 392 male broilers (Ross), distributed in 7 treatments where used eucalyptol and eugenol microencapsulated and the antibiotic avilamicyn. The results showed that the association of the two compounds had negative effect in the broilers performance, however, when the eucalyptol (500 mg/kg) or eugenol (500 mg/kg) was used, the broilers performance were better than control group, and no significant difference to 10 mg/kg of avilamicyn was observed. So, the avilamycin can be substituted by the tested plant extracts without to lose the performance of birds in the growing phase.

ASSUNTO(S)

biological activity desempenho de frangos broilers performance espectrometria de massas chromatography cromatografia mass spectrometry atividade biologica plant extracts extratos vegetais

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