Known as sweet chestnut, Castanea sativa is a member of the Fagaceae family, and is found in abundance in Southern and Southeastern Europe and Asia.1 In traditional medicine, chestnut tree flower preparations have been used for various indications.2 Chestnut has been used in French folk medicine as a tea to treat severe cough, colds, and bronchitis as well as diarrhea.2-6 In modern times, C. sativa leaf extract has been described as having the capacity to scavenge various free radicals associated with oxidative stress induced by ultraviolet exposure.7
Traditional uses
A 2014 study of the therapeutic and traditional uses of the plants native to the Western Italian Alps revealed that C. sativa has long been important in the region, typically for food and wood.8 But medical uses have been uncovered in that region as well. In fact, ancient Romans found C. sativa to exhibit antibacterial, astringent, antitoxic, and tonic qualities, with chestnut honey used then to dress chronic wounds, burns, and skin ulcers.9 A 2014 study by Carocho et al. of the phytochemical profile and antioxidant activity of C. sativa flowers is noteworthy for buttressing the reported health benefits of the use of chestnut flower infusions and decoctions in traditional medicine.2
Antioxidant activity
In 2005, Calliste et al. investigated the antioxidant potential of C. sativa leaf to act against the stable free radical 2,2-diphenyl-1-pycrylhydrazyl, superoxide anion, and hydroxyl radical. Using electronic spin resonance, the investigators showed that C. sativa exhibited high antioxidant potential equivalent to reference antioxidants quercetin and vitamin E.3
Dr. Leslie S. Baumann
Three years later, Almeida et al. conducted an in vitro assessment of an ethanol/water (7:3) extract from C. sativa leaves and an ethanol/water (2:3) extract from Quercus robur (English oak) leaves, finding that both plants demonstrated a high potency to scavenge various reactive oxygen and nitrogen species. The researchers concluded that these findings supported the burgeoning interest in these extracts for use in topical antioxidant formulations.4 An in vivo investigation using an ethanol/water (7:3) extract from C. sativa conducted by the same team later in the year yielded similar results, with the researchers concluding that chestnut extract has the potential to confer benefits against photoaging and other oxidative stress–mediated conditions when included in an appropriately formulated topical antioxidant preparation.6 Subsequently, Barreira et al. demonstrated that chestnut skin and leaves exhibited sufficient antioxidant potency to warrant use in novel antioxidant formulations.10
In 2015, Almeida et al. characterized an antioxidant semisolid surfactant-free topical formulation featuring C. sativa leaf extract. In the process of ascertaining the physical, functional, and microbiologic stability of the antioxidant formulation, the investigators identified a hydrating effect and good skin tolerance, which they concluded suggested a capacity to prevent or treat cutaneous conditions in which oxidative stress plays a role.11
Photoprotective potential
In 2010, Sapkota et al. evaluated the antioxidant and antimelanogenic characteristics of several prebloom and full-bloom chestnut flower extracts, finding that a prebloom methanol extract and an ethanol extract evinced the greatest levels of phenolic and flavonoid compounds. These extracts also displayed the best radical scavenging and mushroom tyrosinase–inhibiting activities. Notably, the prebloom extract was effective in protecting the skin from the deleterious impact of UV radiation. The investigators also observed that all of the tested extracts lowered the tyrosinase activity and melanin formation of SK-MEL-2 cells similarly to arbutin. They ascribed the antimelanogenic effects of chestnut flower extracts to their antioxidant-mediated inhibitory effects on tyrosinase. They concluded that chestnut flower extracts have considerable potential as cosmetic agents.12
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Recently, Almeida et al. studied the protective effects in a human keratinocyte cell line of C. sativa extract at various concentrations (0.001-, 0.01-, 0.05-, and 0.1-mcg/mL) against UV-induced DNA damage. They found that the chestnut extract concentration dependently protected against UV-mediated DNA damage, with the 0.1-mcg/mL concentration affording maximum protection (66.4%). This result was considered to be a direct antioxidant effect attributed to various phenolic antioxidants present in C. sativa. In addition, the investigators observed no phototoxic or genotoxic effects on HaCaT cells incubated with up to 0.1 mcg/mL of chestnut leaf extract. They concluded that C. sativa leaf extract has the potential to prevent or mitigate UV-induced harm to the skin.7
Other benefits and bioactivity
Assessments of C. sativa by-products have shown a favorable profile of bioactive constituents that demonstrate antioxidant, anticarcinogenic, and cardioprotective activity. Braga et al. conducted a 2015 review that concluded these compounds, as part of agro-industrial waste, offer value to the pharmaceutical, cosmetics, and food industries, with the potential to lower pollution costs and raise profits while enhancing social, economic, and environmental sustainability in growing regions.1