engleski

Evaluation of melatonin of blueberry cultivars (Vaccinium corymbosum L.) grown in the northwest Croatia

Besides polyphenols, blueberry fruits contained melatonin (N-acetyl-5-methoxytryptamine) which is a derivative of tryptophan mainly synthesized in the pineal gland of mammals. Only few authors reported about melatonin presence in higher plants, and a number of studies have shown that melatonin has many different physiological functions due to its efficacy as a strong antioxidant. There are not reports documenting presence of melatonin in blueberry. The occurrence of melatonin in four blueberry cultivars (Duke, Sierra, Elliot, Bluecrop) grown in the Northwest Croatia, harvested at three period and at two growing seasons (2006, 2007) were confirmed by HPLC-FD. Determination of melatonin was performed using HPLC-FD on a Nucleosil C-18 column (250 x 4.6 mm i.d., 5 m), andmprotected with a Nucleosil C-18 guard column (10 x 4.6 mm i.d., 5 detection was performed at excitation wavelength 280 nm and emission wavelength 348 nm. Identification of melatonin was carried out by comparing retention times with those of authentic standard of melatonin. Melatonin was quantified using the external standard method and quantification was based on peak area. This is the first report about presence of melatonin in blueberry fruits. Among the researched cultivars, Sierra contained the highest amounts of melatonin (120, 24-134, 99 ng/100g) followed by Duke> Bluecrop>Elliott. The statistical analysis ( ANOVA) showed significant differences in concentrations of melatonin among four blueberry cultivars (p<0.05) as well as between two growing seasons (p<0.05). Growing and climate conditions in Northwest Croatia are convenient for introducing blueberry cultivars (Duke, Elliott, Bluecrop and Sierra). This was proved with good quality of blueberry fruits, which contained remarkable concentrations of melatonin during two consecutive growing seasons.

blueberry; Vaccinium corymbosum; melatonin; HPLC-FD

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