Comparison of different extraction methods of Pistacia lentiscus var. chia leaves: Yield, antioxidant activity and essential oil chemical composition

In the present study, four different extraction methods were employed to recover extracts from Pistacia lentiscus var. chia (mastic tree) leaves. The methods include conventional Soxhlet extraction (SE), green extraction processes such as microwave assisted (MAE) and ultrasound assisted extraction (UAE), as well as the innovative supercritical fluid extraction (SFE). Extractions were carried out in both fresh and freeze-dried leaves. Traditional hydrodistillation process (HD) was also applied for the recovery of the essential oil from fresh and dried mastic tree leaves. The efficiency and selectivity of processes were determined in terms of extraction yield and antioxidant activity. Antioxidant activity of the extracts was measured using the DPPH assay. The essential oil from HD was analyzed by GC-MS. The initial moisture of the leaves was 49.6 +/- 1.31% on wet basis (w.b.), while final moisture after drying was 2.7 +/- 0.27% (w.b.). The results showed that the extraction techniques and the drying procedure significantly affected the extractive yield and antioxidant activity of the extracts. Specifically, fresh mastic tree leaves showed better performance in both yield and antioxidant potential. MAE of fresh leaves using water presented the greatest extraction yield (48.11 +/- 0.56% on dry basis (d.b.)) followed by UAE (39.39 +/- 1.13% d.b.) and SE both using water as solvent (31.99 +/- 1.55% d.b.). UAE water extracts exhibited the highest antioxidant activity (IC50=37.13 +/- 2.7 tig/mL) followed by MAE water extracts (37.18 +/- 0.99 tig/mL) and UAE ethanol extracts (38.46 +/- 1.91 tig/mL). SFE had an extraction yield of 22.3%f 0.25% (w.b.) for fresh leaves but no antioxidant activity was attributed to the extract. HD's performance was 0.06 mL/100 g dry plant matter for the fresh leaves and 0.03 mL/100 g dry plant matter for the dried ones. The presence of Myrcene, Limonene, S-Germacrene, trans-Caryophyllene, S-Cadinene and alpha-Amorphene was confirmed in the essential oils obtained by HD.(C) 2014 Elsevier GmbH. All rights reserved.