Abstract
Nowadays, there is a growing interest in botanicals for human nutrition and care. Arbutus unedo wild berries are edible and medicinal fruits that contain many healthy bioactive components, which can be considered a valuable resource for the food ingredient market and for nutraceutical and cosmetic sectors. In the present study, the polyphenols and in vitro antiradical and hypoglycemic activities of five wild Italian accessions of A. unedo were investigated, and their chemical profiles were treated by means of unsupervised chemometric techniques like the hierarchical and principal component analysis. Moreover, Fourier-transformed mid-infrared spectroscopy was used to provide a rapid assessment of the phytochemical composition of different accessions. Samples differed mainly in their anthocyanin content and overall nutraceutical potential. Anthocyanins were present mainly as glycosides of cyanidin and delphinidin, with delphinidin-3-O-glucoside being the most abundant one, ranging from 49 ± 1 to 111 ± 3 mg g−1 (for P1 and P2, respectively; p < 0.05). Extracts were screened for their in vitro biological activities by using the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), 2,2-diphenyl-1-picrylhydrazyl (DPPH•) antiradical tests, while their hypoglycemic activity was investigated by the α-glucosidase inhibition test. In both in vitro antiradical tests, the highest capacity was recorded for P2 (EC50: 1.17 and 0.064 mg mL−1, for DPPH• and ABTS•+, respectively), with values higher than those reported in the literature for A. unedo fruit extracts. P2 also showed the highest inhibition power towards α-glucosidase (about 70%). Moreover, the nonparametric correlation analysis pointed out a very high significant correlation between the percentage of α-glucosidase inhibition and cyanidin-3-O-rutinoside (r: 0.973; p < 0.01). Finally, the application of hierarchical analysis to samples analyzed provided three different clusters based on the average phytochemical content coded as low, medium and high. Moreover, principal component analysis made it possible to establish similarities among the accessions depending on their overall nutraceutical characteristics and on the relative anthocyanin content.
Highlights
Arbutus unedo L. (Ericaceae family), commonly known as the strawberry tree, is a wild evergreen shrub native to the Mediterranean region, which grows spontaneously in other regions characterized by hot summers and mild and rainy winters [1]
To the best of our knowledge, there is very limited information on the antiradical potential and nutraceutical attributes of wild A. unedo fruits growing in Italy [14] and on the relationships among these attributes and the biological activity linked to them, whereas the search for new resilient crops able to adapt to the strong climate change is increasingly pressing. In light of these considerations, the present study aimed to evaluate the content of phenols and anthocyanins in fruit extracts from five spontaneous accessions of Arbutus unedo L., growing in Central Italy, through a comparative analysis of their phenolic profile, antiradical potential and hypoglycemic activity
Attenuated Total Reflectance (ATR)-Fourier–Transform Infrared Spectroscopy (FTIR) analysis of A. unedo wild berries was carried out, for the first time, time, to provide effective information about the qualitative composition of the plant matrix by to provide effective information about the qualitative composition of the plant matrix by analyzing the analyzing the relation between the spectral fingerprints and molecular structures of the samples
Summary
Arbutus unedo L. (Ericaceae family), commonly known as the strawberry tree, is a wild evergreen shrub native to the Mediterranean region, which grows spontaneously in other regions characterized by hot summers and mild and rainy winters [1]. From an ecological point of view, A. unedo L. is a hardy plant, and this plays a key role in reforestation programs in southern European countries such as Greece, Italy, Portugal and Spain, where forest fires are common during the dry season [2]. A. unedo L. produces red spherical fruits, having a diameter of about 2–3 cm These fruits are rarely eaten fresh, despite their pleasant taste when fully ripe, because they are rich in seeds and not very appreciated by the modern consumer [3]. They have some importance in local agricultural communities, which use them for the production of alcoholic beverages, jams, jellies and marmalades [4]. These fruits have been known since ancient times for their healthy properties, being used in folk medicine for diverse purposes [5] and the Food and Agriculture Organization (FAO)
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