Sicilian myrtle diversity: evaluation of leaf total phenols content and antioxidant properties

Myrtle (Myrtus communis L.) is an aromatic plant spontaneously growing and increasingly cultivated in Mediterranean area. Recently, interest on myrtle plant is growing due to the pharmacological and antioxidant properties since myrtle leaves are important sources of phenolic and antioxidant compounds with health-promoting effects. Plant genotype is the primary factor affecting antioxidant activity and phenol content. For this reason, a core collection of local selected myrtle accessions from Sicily was evaluated with the aim to identify genotypes with high antioxidant value. Thirty-six myrtle individuals belonging to seven populations were studied for leaf total phenols, tannins and antioxidant activity. Results of quantitative determination of total phenols, tannins and antioxidant activity measured with two protocols (DPPH and ABTS radical scavenging activity) revealed a high variability of myrtle genotypes for these parameters. Leaves of the accession MTR11 belonging to Scopello population had the highest total phenol content as catechin equivalents (5495 mg CE 100 g-1 dw) and the highest antioxidant activity (DPPH: 53.7 mmols Trolox 100 g-1 dw; ABTS: 61.6 mmols Trolox 100 g-1 dw). On the contrary, the lowest phenols content (1540.7 mg CE 100 g-1 dw) and the lowest antioxidant activity (DPPH: 13.9 mmols Trolox 100 g-1 dw; ABTS: 16.7 mmols Trolox 100 g-1 dw) were determined in the genotype MTR7 belonging to Zingaro population. The concentration of tannins in the leaves of myrtle analyzed ranged from 78.3 mg CE 100 g-1 dw to 356.9 mg CE 100 g-1 dw, in MRT7 of Zingaro and in 2MRT6 of Misilmeri populations respectively.