Biological activities of Greek bee-honeys
As a part of a systematic research on the chemical composition of Greek bee-honeys and, as it has been observed, an increasing interest in the use of honey in traditional Mediterranean food, in this study we report the chemical analyses and biological activities of 49 Greek honey samples produced in different regions of Greece.
All the samples were extracted with CH²Cl² and BuOH, and several chemical compounds have been isolated and identified from them. Among these: the triol E-4-(1',2',4'-Trihydroxy-2',6',6'-trimethylcyclohexyl)-but-3-en-2-one which have been shown to be unique to samples with the higher percentages from Thymus sp., the rare natural compound 3-hydroxy-4-phelyl-2-butanone just in three of our studied honey samples. Besides, the extracts as well as pure isolated compounds were assayed for their antimicrobial and antioxidative activities. The antimicrobial activities of all studied samples and of pure isolated compounds were determined, using the diffusion-dilution techniques, by measuring the MIC of them against the Gram-positive bacteria: S.aureus and S.epidermidis, and the Gram negative: P.aeruginosa, E.coli, E.cloacae, K.pneumoniae, the oral pathogens S.mutans and S.viridans, the pathogenic fungi: Candida albicans, C. tropicalis and C. glabrata as well as against the food pathogenic Listeria monocytogenes. All strains were standard of American Type Culture Collection. Standard antibiotics were used in order to control the sensitivity of the tested bacteria and fungi.
All the tested bee-honeys samples exhibited moderate to strong activities against the assayed microorganisms. The isolated triol and 8-hydroxy linalool showed very strong activities (MIC values ranges from 0.04-0.57 mg/ml), while the isolated butanone appeared to be less active. The samples have also been tested for their ability to protect cellular DNA from H²O²-induced single strand breaks in a T-lemphocytic cell-line (Jurkat cells). Formation of single strand breaks was estimated by using the highly sensitive methodology of comet assay (single cell gel electrophoresis). The results obtained from these experiments indicated that honey from Abies trees of Karpenissi and Vitina, orange trees of Lakonia and from Pinus of the island of EVia exhibited the best protective activities. Bioactivity-guided fractionation and isolation of the active compounds in these samples is in progress.
Acknowledgments
This study was supported by the General Secretariat of Resrearch and Technology of Greece (PAVET project) by Attiki, as well as for PENED project, and "Korres" Natural Products, S.A.
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E. Melliou, I. B. Chinou, University of Athens, Athens, Greece
M. Melidou, D. Galaris, University of Ioannina Medical SChool, Greece
S. Karabournioti, "Attiki" Bee-Culturing Company, Greece |
