The main objective of this work is to determine the effect of the harvest period on the yield and chemical quality of the essential oils of the Eucalyptus sideroxylon A. Cunn. leaves of the Mamora forest, Dayet Zerzour Bnifdel region, Rabat. Essential oil yields are remarkably high above 2.3%, with an ultimate rate of 5.48% for the month of April. The chemical quality of these essential oils is characterized by the presence of two major monoterpenes, 1,8-cineole (eucalyptol) and α-terpineol, which are proportionally inverted in terms of quantity. During the wet months between September and March, the cineole predominates with levels ranging from 72.67% to 86.11% and the other dry months are characterized by an increase of α-terpineol rate from 12.05% to 25.61%. This inverted chemical variability reveals a change in the orientation of cineole and α-terpineol biosynthesis under the control of climatic factors. This work allows us to discern favorable periods for the harvest of Eucalyptus sideroxylon leaves in terms of yield and quality of essential oils.
The present work aimed to determine the difference in the chemical composition of essential oils isolated from two parts of Cupressus arizonica and to evaluate their in vitro antimicrobial and antioxidant effects. The yields of the essential oil obtained by hydrodistillation from the leaves and cones were 0.85% and 1.29%, respectively. The chemical analysis of the constituents of the two essential oils of Cupressus arizonica was carried out by using the GC and GC/MS techniques. The results of this analysis show that the leaves are dominated by cis-muurola-4 (14), 5-diene (21.27%), umbellulone (19.88%), α-pinene (9.39%), and α-muurolene (7.87%7); on the other hand, the cones are rich in α-pinene (51.07%) accompanied by other variable content constituents, myrcene (17.92%), limonene (9.66%), β-pinene (4.92%), meta-cymenene (2.6%), and α-terpineol (2.38%). The antimicrobial activity against four bacterial strains, four wood decay fungi, and three mould strains were determined using the agar-agar dispersion method. The studied essential oils exhibited moderate antimicrobial properties, which demonstrates the sensibility of all strains tested with the exception of wood rot fungi to which they do not have activity against all concentrations tested. The dosage of antioxidant activity was evaluated using DPPH scavenging and ferric ion reducing power (FRAP). The results indicate that the essential oils from cones of Cupressus arizonica possess a strong antioxidant activity (lower IC50) IC50 = 0.098 ± 0.008/EC50 = 0.646 ± 0.02) in comparison with those from the leaves (IC50 = 5.297 ± 0.09/EC50 = 2.335 ± 0.36). The results suggest that both essential oils could be used as a source of treatment for bacterial infections and also as natural antioxidant substances.
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