Antioxidant effects and phytochemical analysis of crude and chromatographic fractions obtained from Eucalyptus globulus bark
Eucalyptus globulus is extremely used in traditional medicine in Algeria and its leaf extract is included as one of the antioxidant in the list of existing food additives in Japan. In the present study, the crude extract from bark of this plant and its fractions obtained by Sephadex LH-20 column were studied to quantify their levels of phenolic compounds and their antioxidant activity (ferric reducing power, 1,1-diphenyl-2-picryl hydroxyl (DPPH•) radical scavenging activity and scavenging of hydrogen peroxide). All extracts exhibited a reducing power effect higher than that of á-tocopherol. It was observed that crude extract displayed the highest DPPH• scavenging ability (IC50115.40 ìg/ml) followed by á- tocopherol (IC50 233.78 ìg/ml). Crude extract also displayed the highest ability to neutralize hydrogen peroxide at 65 ìg/ml (75.55%), followed by á-tocopherol (20.07%) at the same concentration. The results show that fractions b and c exhibited lower antioxidant activities for the three antioxidant tests comparatively to that of crude extract. Fraction a exhibited the lowest antioxidant capacity.
Key words: Eucalyptus globulus, bark extract, phenolic compounds, antioxidant effect, Sephadex LH-20 column.