engleski

Tepals of native Crocus taxa as a promising antioxidant biomaterial rich in flavonoid kaempferol

Most of the pharmacological activities of cultivated Crocus sativus have mainly been related to its stigmas (spice saffron) and their major bioactive compounds - carotenoids. Tepals, which are dominant part of C. sativus flowers in terms of mass (93% of the flower mass), are still considered as a waste material. In this work we compared, using high- performance liquid chromatography method, qualitative and quantitative composition of flavonoids in tepals, stigmas and stamens of native Crocus taxa water extracts, spectrophotometrically measured antioxidant activities of tepals extracts, and statistically correlated obtained data mutually. The results revealed that Crocus tepals contained similar or higher concentration of flavonoid-glycosides than stigmas and stamens. Out of the tested tepal extracts, C. vernus ssp. vernus from the Botanical Garden Zagreb showed the best biological potential: the highest amount of identified flavonoids (5054.6 mg of identified flavonoid-glycosides/kg dw) and showed the highest antioxidant activity (ABTS - 82%, FRAP - 99.2% , and DPPH - 62.7% of Trolox antioxidant activity). In this taxon we also recorded significantly higher concentration of kaempferol-rutinoside (3581 mg/kg dw) than in other taxa. This flavonoid showed very strong or strong correlation with antioxidant assays results. Therefore, we presume that kaempferol- rutinoside is one of the main antioxidant phenolic component in Crocus tepals. High flavonoid content and strong antioxidant activity add value to the, so far, neglected native C. vernus ssp. vernus taxon. To the best of our knowledge, this is the first study on native Croatian Crocus taxa flavonoid content, and their bioactivity at all. The results contribute to the phytochemical description and dietary potential of native Crocus taxa.

cytotoxicity ; dietary potential ; HPLC ; phenolics ; phytochemical analysis ; saffron

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