quinta-feira, 11 de dezembro de 2014

Identification of Phenolic Compounds and Evaluation of Antioxidant and Antimicrobial Properties of Euphorbia Tirucalli L.

de Araújo, K.M.; de Lima, A.; Silva, J.N.; Rodrigues, L.L.; Amorim, A.G.N.; Quelemes, P.V.; dos Santos, R.C.; Rocha, J.A.; de Andrades, É.O.; Leite, J.R.S.A.; Mancini-Filho, J.; da Trindade, R.A. Identification of Phenolic Compounds and Evaluation of Antioxidant and Antimicrobial Properties of Euphorbia Tirucalli L.. Antioxidants 2014, 3, 159-175.

Abstract

Bioactive compounds extracted from natural sources can benefit human health. The aim of this work was to determine total phenolic content and antioxidant activity in extracts of Euphorbia tirucalli L. followed by identification and quantification of the phenolic compounds, as well as their antibacterial activities. Antioxidant activities were determined by DPPH and ABTS•+ assay. Identification of phenolic compounds was performed using high-performance liquid chromatography (HPLC), and antimicrobial activities were verified by agar dilution methods and MIC values. Total phenolic content ranged from 7.73 to 30.54 mg/100 g gallic acid equivalent. Extracts from dry plants showed higher antioxidant activities than those from fresh ones. The DPPH EC50 values were approximately 12.15 μg/mL and 16.59 μg/mL, respectively. Antioxidant activity measured by the ABTS method yielded values higher than 718.99 μM trolox/g for dry plants, while by the Rancimat® system yielded protection factors exceeding 1 for all extracts, comparable to synthetic BHT. Ferulic acid was the principal phenolic compound identified and quantified through HPLC-UV in all extracts. The extracts proved effective inhibitory potential for Staphylococcus epidermidis and Staphylococcus aureus. These results showed that extracts of Euphorbia tirucalli L. have excellent antioxidant capacity and moderate antimicrobial activity. These can be attributed to the high concentration of ferulic acid. 

Conclusions

Based on our results, it is possible to conclude that the dry extracts showed higher values than fresh extracts, mainly due to their higher concentration of phenolics, possibly caused by dehydration before the extraction process. The methodology used to study the different extracts from Euphorbia tirucalli L. allowed identification and quantification of the phenolic compounds, of which ferulic acid was the most prominent. This phenolic compound was the most visible peak of the samples, which were associated with the high antioxidant potential of this plant as analyzed by different and specific methods. Additional studies must be performed for isolation and further characterization of bioactive compounds present in Euphorbia tirucalli L., as well as purification and enrichment of ferulic acid. Once the concentration of ferulic acid in this plant is identified, other antimicrobial assays can be performed, such as those for antiparasitic activity. These results justify the use of this plant in traditional medicine to treat infections and injuries, as well as some diseases. Furthermore, our results indicate that “aveloz” shows a good and viable alternative for both the treatment of diseases and a possible replacement for the traditional synthetic antioxidants.

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