Aikaterini Termentzi

From Olive Drupes to Olive Oil. An HPLC-Orbitrap-based Qualitative and Quantitative Exploration of Olive Key Metabolites

The aim of the current study was the qualitative exploration and quantitative monitoring of key olive secondary metabolites in different production steps (drupes, paste, first and final oil) throughout a virgin olive oil production line. The Greek variety Koroneiki was selected as one of the most representative olives, which is rich in biological active compounds. For the first time, an HPLC-Orbitrap platform was employed for both qualitative and quantitative purposes. Fifty-two components belonging to phenyl alcohols, secoiridoids, flavonoids, triterpenes, and lactones were identified based on HRMS and HRMS/MS data. Nine biologically and chemically significant metabolites were quantitatively determined throughout the four production steps. Drupes and paste were found to be rich in several components, which are not present in the final oil. The current study discloses the chemical nature of different olive materials in a successive and integrated way and reveals new sources of high added value constituents of olives.

Natural Resins and Bioactive Natural Products thereof as Potential Anitimicrobial Agents

Natural products and their derivatives have historically been invaluable as a source of therapeutic agents and have contributed to the discovery of antimicrobial agents. However, today with the development of drug-resistant strains, new scaffolds and new sources of bioactive compounds are needed. To this end, plant derived natural resins are reviewed for their potential application as antimicrobial agents. Natural gums, extracts of the whole resins, as well as specific extracts, fractions, essential oils and isolated compounds from the above resins are discussed in terms of their antifungal, antibacterial, and antiprotozoal activity.

The bite of the honeybee: 2-heptanone secreted from honeybee mandibles during a bite acts as a local anaesthetic in insects and mammals.

Honeybees secrete 2-heptanone (2-H) from their mandibular glands when they bite. Researchers have identified several possible functions: 2-H could act as an alarm pheromone to recruit guards and soldiers, it could act as a chemical marker, or it could have some other function. The actual role of 2-H in honeybee behaviour remains unresolved. In this study, we show that 2-H acts as an anaesthetic in small arthropods, such as wax moth larva (WML) and Varroa mites, which are paralysed after a honeybee bite. We demonstrated that honeybee mandibles can penetrate the cuticle of WML, introducing less than one nanolitre of 2-H into the WML open circulatory system and causing instantaneous anaesthetization that lasts for a few minutes. The first indication that 2-H acts as a local anaesthetic was that its effect on larval response, inhibition and recovery is very similar to that of lidocaine. We compared the inhibitory effects of 2-H and lidocaine on voltage-gated sodium channels. Although both compounds blocked the hNav1.6 and hNav1.2 channels, lidocaine was slightly more effective, 2.82 times, on hNav.6. In contrast, when the two compounds were tested using an ex vivo preparation–the isolated rat sciatic nerve–the function of the two compounds was so similar that we were able to definitively classify 2-H as a local anaesthetic. Using the same method, we showed that 2-H has the fastest inhibitory effect of all alkyl-ketones tested, including the isomers 3- and 4-heptanone. This suggests that natural selection may have favoured 2-H over other, similar compounds because of the associated fitness advantages it confers. Our results reveal a previously unknown role of 2-H in honeybee defensive behaviour and due to its minor neurotoxicity show potential for developing a new local anaesthetic from a natural product, which could be used in human and veterinary medicine.

From Drupes to Olive Oil: An Exploration of Olive Key Metabolites

Publisher Summary The literature data concerning the qualitative and quantitative alterations of olive key metabolites during the process of olive oil production are often contradictory and it seems that the parameters, such as the production procedure, the variety, the origin, the harvesting season, and so forth, play a crucial role. However, in spite of the existent discrepancies in the literature, it seems that there are specific trends followed by bioactive molecules during olive oil production that are accepted by the majority of researchers. It is a fact that from all molecules, even the more lipophilic ones, such as the triterpenic acids, only a small percentage ends up in the olive oil. In the three-phase systems, most of the valuable constituents are lost in the waste water. In the two-phase olive mills, a greater percentage of biophenols is lost in the solid wastes and the final product contains only a small portion of secoiridoids and triterpenes, making the waste an ideal raw material for their isolation. Research is proceeding and focuses on the identification of genotypes with particular interest in terms of phenolic composition, while innovative methods for the production of olive oil, beyond traditional milling, are being developed and patented. More integrated studies that allow the qualitative evaluation and the quantitative monitoring of olive minor constituents of different varieties in the various stages of maturation and during extraction and malaxation are expected to provide a better insight into the chemistry and biochemistry of olives and olive oil constituents. This, in turn, may contribute to the production of oil with a higher nutritional value and to a better exploitation of waste products for the recovery of bioactive ingredients.

The application of highly centrifuged honey as an improved diet for experimentally caged honey bees

Summary Whilst sucrose syrup appears to be the most commonly used diet applied during honey bee cage experiments, dead honey bees may occur within the first week of feeding. However, sucrose syrup remains the dominant food supplement for cage experiments since past research has proved that all alternative hydrocarbon diets, including honey, decrease the lifespan of honey bees when compared to syrup. In this study we tested feeding caged honey bees with honey from which all pollen grains and possibly all pathogenic spores were removed through high speed centrifugation. This preparation significantly extended the lifespan of honey bees in cages compared with sucrose syrup and honey. The analysis of the glycoside content of centrifuged honey and of the honey from which it was produced showed that the two products were identical. The 1H NMR spectra of the two samples displayed an identical resonance pattern. This refers to the qualitative content, as well as the ratio of the constituent sugars of the two samples. This study showed that highly centrifuged honey could be applied as an improved reliable diet for experimentally caged honey bees.