Global Advanced Research Journal of Agricultural Science (GARJAS) ISSN: 2315-5094
November 2014 Vol. 3(11): pp. 356-366
Copyright © 2014 Global Advanced Research Journals

Full Length Research Paper

Evaluation of the antibacterial activity of the essential oil and antioxidant activity of aqueous extracts of the Eucalyptus globulus Labill. leaves

S. Pombal, J. Rodilla, A. Gomes, L. Silva*, P. Rocha

Fiber Materials and Environmental Technologies, Chemistry Department, University of Beira Interior, Rua Marquês d’Ávila e Bolama, 6201-001- Covilhã.

Corresponding Author’s Email: rodilla@ubi.pt;  mlas@ubi.pt

Accepted 28 October, 2014

Abstract

The purpose of this study was valorizing Eucalyptus globulus Labill. (Myrtaceae) residues in terms of phenolic compounds extracted to aqueous extract and essential oils extract to leaves. The leaves were studied are collected in Gardunha Mountains near Alpedrinha (Portugal). Essential oil was extracted of leaves in Clevenger apparatus and the hot-water was used for tested the phenolic content. The essential oils were obtained and analyzed by GC-MS and tested for antibacterial activity using a Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. These tests were performed using two different techniques: agar diffusion with cylindrical cavities and vapor diffusion in agar plate. The aqueous extract is submitted to study antioxidant activity. This way the phenolic content was determined by the Folin-Ciocalteu method, flavonoid content was also determined by colorimetric method and antioxidant activity was measured by DPPH method. These results show that E. globulus leaves have a high amount of compounds derived from monoterpene allowing show good antibacterial activity. For other side the aqueous extract has a very strong antioxidant activity and been possible to identify six components by HPLC-DAD: gallic, caffeic and ellagic acids, rutine, luteolin and quercetin. To our knowledge this is the first report on flavonoid content, antioxidant activity and composition of the aqueous phase from E. globulus leaves.

Keywords: Eucalyptus globulus; leaves; aqueous extract; oil composition; antimicrobial activity; phenolic content; antioxidant activity.