Phytochemical study and pharmaceutical properties of essential oils and organic extracts of two Eucalyptus species: E. stricklandii Maiden and E. brevifolia F.Muell

ABSTRACT

Essential oils and solvent extracts of E. brevifolia F.M and E. strickalndii M. were screened for their chemical composition, and biological activities. 39 compounds were identified in, E. brevifolia F. M. EOs, whereas 41 volatile compounds were identified in E. stricklandii M. EOs. The organic extracts were rich on polyphenols and tannins. The IC₅₀ of the ME of E. stricklandii M. using DPPH· assay was 4.4 ± 0.2 µg/mL. Concerning AChE, the aqueous extract of E. brevifolia F.M. exhibited the highest IC₅₀ value 10.0 ± 0.0 µg/mL. Regarding the anti-inflammatory capacity, E. brevifolia F.M. EOs and E. stricklandii M. ME showed the best IC₅₀ (7.3 µg/mL and 9.7 µg/mL) against the inhibition of 15-LOX. Both plants exhibited a good activity against gram-negative bacteria. Finally, E. stricklandii M. ME was the best cytotoxic extract against HCT116 and K562 with IC₅₀s of 18.0 ± 0.1 µg/mL and 1.8 ± 0.0 µg/mL.

HIGHLIGHTS

• Eucalyptus leaves EOs were extracted using Clevenger type apparatus.

• Chemical composition of E. stricklandii Maiden and E. brevifolia F. Muell EOs was studied.

• Antimicrobial activity was more efficient on Gram negative bacteria.

• Methanolic extracts exhibited a strong antioxidant power (IC₅₀ = 4.4 µg/mL).

• Polar extracts were the most active one against 15-Lox, AChE.

• A strong cytotoxic effect against leukemia cell lines was shown (IC₅₀ = 1.8 µg/mL).

KEYWORDS:

• Eucalyptus
• essential oils
• extracts
• biological activities
• antimicrobial effect
• cytotoxicity

Acknowledgments

We are very grateful to Pr. Mohamed Larbi Khouja (INRGREF, B.P10, Ariana Tunisia) for providing us with plant material. The authors are also grateful to the Tunisian Ministry of Higher Education and Scientific Research as well as to the University of Carthage for the grant adressed to Dr. Ben Hassine, which allowed the realization of this work. Our sincere thanks are addressed to Pr. Jacob Lorenzo-Morales, associate professor of parasitology at the Canarian Tropical Disease Department and Public Health Institute, La Laguna, Spain for checking English writing of this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).