Effect of geographical origin on yield and secondary metabolite content of extracts of Moroccan Juniperus thurifera

Abstract

The thuriferous juniper (Juniperus thurifera) is an important species in the Mediterranean region due to its ecological and economic values. It plays a significant role in preventing soil erosion and desertification, as well as being used in traditional medicine and as a source of essential oils for various industries. In addition, its extracts are considered as a source of bioactive compounds with various pharmacological activities, such as antioxidant, anti-inflammatory and antimicrobial effects. However in Morocco, it is considered as one of the undervalued and least preserved species. Its stands continue to be vigorously degraded. The present work aims to study the effect of the origin on the yield, the phenolic compounds, flavonoids and tannins contents and the antioxidant activity of the leaves extracts of this species. In order to accomplish this study, we carried out the extraction by soxhlet from the leaves of J. thurifera, coming from three geographical origins, using two solvents (hexane and ethanol). Then the dosage of different compounds (polyphenols, flavonoids and condensed tannins) and the evaluation of the antioxidant activity were carried out. The results show a significant variability between the samples coming from three different biogeographical zones, namely: the Eastern, Central and Western High Atlas in terms of yield and levels of polyphenols, flavonoids and condensed tannins. This allowed to demonstrate the effect of geographical origin and the interaction between environmental conditions and genotype on the production of secondary metabolites. In fact, we found that the Midelt population has a good yield in ethanolic extracts (9.41% ± 0.59) and hexane 6.57% ± 0.29. Furthermore, the El Haouz population is the richest in polyphenols in ethanolic extracts (191.30 ± 4.27 mg GAE /g Extract), as well as it has an important reducing potential (IC50 = 0.98 ± 0.05 mg/ml). These results can be exploited as bioindicators in all programs of valorization and conservation of Moroccan Juniperus thurifera