Phenolic compounds in leaves of seagrass Posidonia oceanica (L.) Delile in the costal area of Zadar

Posidonia oceanica (L.) Delile je morska cvjetnica koja je važan primarni producent u obalnom području Sredozemnog mora te u Jadranskom moru. Zbog svoje rasprostranjenosti u litoralnoj zoni, dugog životnog vijeka i posebne osjetljivosti na promjene okolišnih uvjeta pogodan je bioindikator. Cilj ovog istraživanja bio je utvrditi postoje li razlike u količini fenolnih spojeva (ukupnih fenola, tanina, flavonoida, antocijana) i aktivnosti enzima gvajakol peroksidaze i polifenol oksidaze u intermedijarnim listovima posidonije prikupljenim u različitim godišnjim dobima u uvali Brbišćica i u Zadarskom kanalu na dubini 10 m. Dobiveni rezultati su pokazali da su se vrijednosti spomenutih pokazatelja mijenjale ovisno o godišnjem dobu, tj. okolišnim uvjetima. Udjeli ukupnih fenola, tanina i flavonoida pokazali su sličan obrazac porasta i pada vrijednosti kroz različita godišnja doba te su u travnju i listopadu bili veći u uzorcima iz Brbišćice. Udio antocijana bio je na oba lokaliteta najveći u uzorcima prikupljenim u listopadu. Aktivnosti enzima gvajakol peroksidaze i polifenol oksidaze u ekstraktima listova posidnije također su se mijenjali tijekom godine. U uzorcima s pojedinog lokaliteta oba su enzima imala sličan obrazac promjena aktivnosti tijekom godine.Marine phanerogam Posidonia oceanica (L.) Delile is a seagrass which is one of the most important primary producers in the coastal area of the Mediterranean and Adriatic sea. As a widely spread and long-living specie sensitive to environmental conditions, P. oceanica is a good biondicator of coastal areas. The aim of this study was to determine differences between the amount of phenolic compounds (total phenols, tannins, flavonoids, anthocyanins) and activity of guaiacol peroxidase and polyphenol oxidase in intermediate leaves of P. oceanica collected during four seasons in Brbišćica bay and Zadarski kanal at 10 m depth. Results have shown that the amount of measured markers in the leaves of P. oceanica changed due to seasonal period and environment conditions.The content of total phenols, tannins and flavonoids showed the same pattern of increase and decrease during four seasons and their amount was higher in samples collected in April and October in Brbišćica bay. Anthocyanins content was significantly higher in samples collected in October at the both locations. The activity of enzyms guaiacol peroxidase and polyphenol oxidase in leaves of P. oceanica also changed during the year. They showed the similar pattern of changing activity during four seasons in the leaves from both locations