Document Type : Original Article
Laboratory of Biotoxicology, Department of Biology, Faculty of Natural and Life Sciences, Djillali Liabes. 12 Rue Oulhaci Mokhtar. University of Sidi-bel-Abbes, 22000, Algeria.
Laboratory of Inorganic Materials, Chemistry and Application, Oran University of Science and Technology, Faculty of Chemistry, Department of Physical Chemistry, Post Box 1505, 31000 El-M’naouar, Oran, Algeria.
Laboratory of Biotoxicology, Department of Biology, Faculty of Natural and Life Sciences, Djillali Liabes. 12 Rue Oulhaci Mokhtar. University of Sidi-bel-Abbes, 22000, Algeria
In Algeria, many plant resources, including ginger (Zingiber officinale), are experiencing a revival of interest in the dietary habits of local populations who associate them with their ancestral culinary and curative traditions. The aim of this study was to extract and characterize some physicochemical parameters of the essential oils (EO) of the fresh and dry ginger rhizomes and to evaluate, in-vitro, their antioxidant activity by scavenging the free radical DPPH. The extraction of the EO was realized by the hydrodistillation method.
Steam distillation of the EO from the fresh and dry ginger samples provided yields of 0.42±0.017 and 1.55±0.034 %, respectively. The evaluation of their physicochemical characteristics, in the same order, according to AFNOR standards made it possible to find the following results: refractive index: 1.4707±0,001 and 1.4853±0.0011; density 0.8748±0.0005 and 0.8837±0.0005; acid number: 1.4707±0.0086 and 1.4853±0.017mg KOH / g; ester index: 15,732±0.24 and 18,36±0,41 mg KOH / g.
The evaluation of the antioxidant activity by the DPPH free radical scavenging method shows that the fresh rhizomes of Zingiber officinale EOs displayed significantly (p < 0,01) higher activity than the dried ones. Nevertheless, both Ginger forms EOs had lower activity than vitamin E (p < 0,001) which remains the best with EC50 =309,5, namely (EO of fresh ginger, EC50 = 723 μg / ml; EO of dry ginger, IC50 = 774 μg / ml), all the statistical results of the parameters studied showed significant differences between the two types of ginger.