engleski

Determination of tyrosol, hydroxytyrosol and oleuropein derivatives in Croatian olive oils

Introduction. The Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, neurodegenerative diseases and certain types of cancer. The apparent health benefits have been partially ascribed to the dietary consumption of virgin olive oil, typically between 25-50 mL per day. Much research has been focused on the biologically active phenolic compounds naturally present in extra virgin olive oils. Hydroxytyrosol and tyrosol are especially important, taking into account their antioxidant, anti-inflammatory, antimicrobial, anticancer and other activity. The amount of polyphenols in extra virgin olive oil (EVOO) vary, depending on several factors such as geographical zone, cultivar, agro-climatic conditions, degree of fruit ripeness and the oil-extraction process. There are many different classes of polyphenols, the most representative being: simple phenols, phenolic acids and their derivatives, secoiridoids, lignans and flavonoids. The level and composition of the phenolic fraction is a very important parameter in the evaluation of the quality and health benefits of EVOO. Materials and methods. Three different EVOO from Istra (Bjelica, Buža and Žižolera) and from Ugljan island have been analysed in this study. Extraction of phenols has been carried out using the ultrasound-assisted liquid-liquid extraction (US-LLE) method. Phenolic compounds content has been determined following the HPLC- DAD analysis. The most abundant secoiridoid, decarboxymethyl-oleuropein aglycon (3, 4-DHPEA- EDA) was confirmed by ESI-MS fragmentation profile of molecular [M-H]- ions with those from the literature. Results. Results show that EVOO contain significant amount of simple phenols hydroxytyrosol and tyrosol, comparable to the values earlier determined in Croatian olive oils. It has been determined especially high content of secoiridoid 3, 4-DHPEA-EDA. Conclusion. Analysed samples of EVOO from Istra and Ugljan island are rich in important phenolic compounds hydroxytyrosol and tyrosol showing significant potential of Croatian EVOO in disease prevention and health preservation.

Olive oil ; phenolic compounds ; hydroxytyrosol ; tyrosol ; secoiridoid

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