We have selected the mediterranean shrub Euphorbia characias as an experimental model to study the complexity of plant latex chemistry. Latex is a mixture with diversified composition, that includes alkaloids, terpenoid compounds, polymeric substances such as resins and gums, starch, oil and a large number of proteins and enzymatic activities. The aim of the present study is to contribute to the knowledge of this plant product evaluating the antioxidant properties of extracts of E. characias and searching for polymeric substances as natural rubber. We analyzed different extracts from the latex of E. characias and performed a new extraction method (involving the use of trichloacetic acid, TCA) that turned out to be easier, faster and higher reproducible if compared to common extraction methods involving organic solvents like methanol, ethanol, and petroleum ether/methanol. TCA extract of E. characias latex exhibits antioxidant activities determined as total content of free-radical scavenging, polyphenols and total flavonoids. GC-MS analysis confirms the presence of several compound identified as antioxidant molecules. E. characias latex contains a natural rubber. The optimum rubber extraction is achieved with acetic acid followed by cyclohexane/ ethanol treatment. The rubber content was shown to be 14% (w/v) of the E. characias latex and the gel content is 2.5% of the rubber weight. E. characias natural rubber showed a molecular weight of 93000 and Mw/Mn of 2.9. On the basis of 1H NMR, 13C NMR and FT-IR spectroscopy, the structure of this rubber can be identified as cis-1,4-polyisoprene.
Natural rubber and antioxidants in Euphorbia characias latex
PINTUS, FRANCESCA;MASCIA, CLAUDIA;MEDDA, ROSARIA
2012-01-01
Abstract
We have selected the mediterranean shrub Euphorbia characias as an experimental model to study the complexity of plant latex chemistry. Latex is a mixture with diversified composition, that includes alkaloids, terpenoid compounds, polymeric substances such as resins and gums, starch, oil and a large number of proteins and enzymatic activities. The aim of the present study is to contribute to the knowledge of this plant product evaluating the antioxidant properties of extracts of E. characias and searching for polymeric substances as natural rubber. We analyzed different extracts from the latex of E. characias and performed a new extraction method (involving the use of trichloacetic acid, TCA) that turned out to be easier, faster and higher reproducible if compared to common extraction methods involving organic solvents like methanol, ethanol, and petroleum ether/methanol. TCA extract of E. characias latex exhibits antioxidant activities determined as total content of free-radical scavenging, polyphenols and total flavonoids. GC-MS analysis confirms the presence of several compound identified as antioxidant molecules. E. characias latex contains a natural rubber. The optimum rubber extraction is achieved with acetic acid followed by cyclohexane/ ethanol treatment. The rubber content was shown to be 14% (w/v) of the E. characias latex and the gel content is 2.5% of the rubber weight. E. characias natural rubber showed a molecular weight of 93000 and Mw/Mn of 2.9. On the basis of 1H NMR, 13C NMR and FT-IR spectroscopy, the structure of this rubber can be identified as cis-1,4-polyisoprene.
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