Résumé:
The antioxidant activity and phenolic content of
extracts and solvent–solvent partition fractions
from the aerial parts of three medicinal plants
were evaluated. Aerial parts of Hammada elegans,
Plantago ciliata and Thymelaea microphylla were
extracted using the polarity gradients of different
solvents. The samples were extracted by liquid–
liquid partition with different organic solvents to
obtain 16 fractions. Next, the phenolic contents of
all fractions were analysed using the Folin-Ciocalteu
method and their inhibition of the peroxidation
of linoleic acid and sunflower oil was evaluated
by the lipid peroxide ammonium thiocyanate
method.
The total phenolic content of the different Hammada
elegans fractions varied from 0.045 to
0.0714 mg/g dry weight, expressed as gallic acid
equivalents (GAE). The percentage inhibition of
peroxidation of linoleic acid and sunflower oil was
found to be higher in methanolic fractions and
was comparable to that of α-tocopherol, Trolox,
butylated hydroxytoluene (BHT) and butylated
hydroxyanisole (BHA). In this study, a direct re-lationship between total phenolic content and inhibition
of lipid peroxidation was observed. This
indicates that phenolics are the main contributors
to the observed antioxidant activities of the different
plant extracts.
These results indicate that the level of antioxidant
activity in these plants varies greatly. They also
suggest that the phenolics in these plants provide
a substantial amount of antioxidants. Additional
research may reveal further benefits of these medicinal
plants. The flora of Algeria appears to be a
rich and interesting source of plants for ethnomedicinal
and phytochemical studies.
