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.
PROTOCATECHUIC ACID OXIDASE
