Background:
Eucalyptus belongs to the Myrtaceae family. It is the most planted hardwood
forest crop worldwide, representing a global renewable resource of fiber, pharmaceuticals and energy.
Objective:
To compare the five species, E. maidenii, E. robusta, E. citriodora, E. tereticornis and
E. camaldulensis, seeking for the richest source of nutrients and pharmaceuticals.
Methodology:
Eucalyptus samples were subjected to some chemical determinations for both primary
and secondary metabolites to verify their nutritional and pharmaceutical importance related to different
extracts. GC-MS analysis was applied to detect the presence of some individual phenolic constituents
in their leaves.
Results:
E. robusta recorded the maximum contents of carbohydrates (40.07%) and protein (31.91%).
While E. camaldulensis contained the highest contents of total phenolic compounds (46.56 mg/g), tannins
(40.01 mg/g) and antioxidant activities assayed by the phosphomolybednum method (57.60
mg/g), followed by E. citridora. However, E. tereticornis exhibited the highest reducing power ability
(151.23 mg/g). The GC-MS highlighted 20 phenolic constituents and antioxidants which varied in their
abundance in Eucalyptus leaves, 8 individual phenolics (hydroquinone, hesperitin, pyrogallol, resorcinol,
protocatechuic acid, naringenin, chlorogenic acid and catechin) were maximally recorded with E.
camaldulensis and secondly, with E. citridora in case of at least 5 components. Nevertheless, gallic
and quinic acids were more abundant in the leaves of E. tereticornis, which may explain its high corresponding
reducing powers.
Conclusion:
Acetone-water combination has enhanced phenolics extraction from Eucalyptus tissues.
This is the first report aiming to compare between the aforementioned Eucalyptus species highlighting
either their nutritional or medicinal importance.
