Leaf extract from Mount Amiata chestnut as a novel anti-photoaging and skin care agent

Modern cosmetic industry is approaching medicinal plants with ethnobotanical tradition and pre-validated use (1). We studied the Italian chestnut (Castanea sativa Mill., Fagaceae) from Monte Amiata's forests, Tuscany (2), focusing on its byproducts, such as leaves. In different Italian regions, fresh leaves of chestnut have a long history of use by local people for dermatologic and cosmetic applications: e.g. as external poultice against sores in Tuscany (3), to make washes for skin diseases and inflammations in Sardinia and Calabria (4, 5), as infusion against dandruff in Liguria (6) and in the Abruzzo, Lazio and Molise National Park (7). In addition, the inhibitory activity against Staphylococcus aureus of refined European chestnut leaf extracts has been reported, with possible applications for treatment of skin and soft tissue infections (8). Driven by recent studies reported in literature, suggesting a scavenger and antioxidant activity of chestnut leaf extracts (9), our experimental protocol was focused on a 75% V/V ethanol extract obtained from Mount Amiata chestnut leaves, proposing its possible topical application as functional product in skin aging. Antioxidant and antiradical agents are, in fact, a useful strategy for the prevention of skin photoaging and oxidative stress-mediated skin diseases (10). C. sativa leaf extract contains flavonoids and hydroxycinnamic derivatives, with hyperoside being the most abundant constituent of the extract. Biological tests conducted on human keratinocytes showed that the extract protects cells from chemical (hydrogen peroxide) and physical (UVA irradiation) oxidative damage. The extract activity seems to be primarily related to free-radical scavenging, since cell levels of malondialdehyde, carbonylated proteins and reactive oxygen species decreased when cells were treated with 0.1% V/V extract, while superoxide dismutase activity and Nrf-2 mRNA expression were not affected by the extract at the same concentration. The extract, incorporated in an oil/water emulsion exhibited sun protection factor booster activity. Given these results, the Mount Amiata chestnut leaf extract could be an efficient opportunity in the treatment of extrinsic aging, in which one of the main targets is the neutralization of free radicals.