InfluÃncia da radiaÃÃo gama em extratos vegetais ricos em taninos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Popular known as cashew and angico, Anacardium occidentale Linn. and Anadenanthera colubrina (Vell.) Brenan are species found in the Northeast of Brazil and they are well known for containing high concentration of secondary metabolites, in special tannins, utilized as substance cousin in association with phytotherapeutic products, being of economical and ecological interest. Gamma radiation is used in products of vegetal origin for microbiological control. However, the process of radiation exposure can increase or reduce phenolic composite contents, as total phenols and tannins, in raw and cooked materials. The aim of this work was to perform a preliminar study in order to chemically evaluate contents of total phenols and tannins of extracts from bark and leaves of cashew and angico, before and after gamma irradiation with 60Co. Extracts obtained in the laboratory were divided in control and exposed groups, the later to doses of 5, 7,5 and 10 kGy. Total phenols were quantified by the method of Folin-Ciocalteau and the tannins, by precipitation of casein. Afterwards, the antimicrobial potential from cashew and angico and the moluscicide action from cashew were investigated. The percentuals of total phenols and tannins in barks from cashew did not suffer statiscally significant changes with the absorbed dose of radiation, presenting values of concentration of 5,73Â0,14 e 5,20Â0,14, respectively. In leaves from cashew, the levels of chemical compounds were statiscally influenced (p<0.05) by radiation, with averages of total phenois between 3,13Â0,04 (0 kGy) and 3,50Â0,08 (10 kGy), and for tannins 2,47Â0,06 (0 kGy) and 2,93Â0,04 (10 kGy). The concentrations of total phenols and tannins in barks and leaves from angico did not present significant alterations with the dose of radiation. Gamma radiation influenced in the antimicrobial activity only for cashew extracts, in case of Gram-positives, Staphylococcus aureus, showing averages of halos of inhibition for barks of: 14,33Â058 (0 kGy) and 22,33Â0,58 (10 kGy); and for leaves of: 11,33Â 0,58 (0 kGy) and 19,00Â1,00 (10 kGy). Cashew extracts presented, additionally, an increase in embryonic letality of B. glabrata, aproximatelly five times higher, when they are in contact with irradiated extracts than unirradiated ones, with averages for barks of 25mg/L, between 1,3Â0,6 (0 kGy) and 3,0Â0,02 (10 kGy) and 50 mg/L, beween 5,9Â2,3 (0 kGy) and 28,6Â0,1 (10 kGy); for leaves of 100mg/L, between 13Â5 (0 kGy) and 27Â 2,5 (10 kGy) and 200 mg/L, between 11Â4 (0 kGy) and 57Â14(10 kGy). The exposure to radiation caused physical-chemical alterations in phenol compounds from leaves extracts of cashew, increasing the concentration of tannins. One hypothesis for this increase in the concentration of tannins is that gamma radiation acts like a catalyser for the condensation of poliphenols. The results indicate a potential utilization of leaves extracts from cashew as main product for the obtaining antimicrobial and moluscicides agents, from renewable sources ecologically correct.

ASSUNTO(S)

atividade moluscicida fenÃis totais anacardium occidentale linn atividade antimicrobiana anacardium occidentale linn antimcrobial activity radiaÃÃo gama taninos anadenanthera colubrina (vell.) brenan gamma radiation total phenols taninnes anadenanthera colubrina (vell.) brenan engenharia nuclear moluscicide activity

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