Castanea sativa shells: Is cosmetic industry a prominent opportunity to valorise this agro-waste?

Sustainability arises as a pivotal concept in different industries. Chestnut industry is one of the primary motors of the Portuguese fruit economy [1]. During chestnut processing, large amounts of by-products are produced, mostly shells. The wealth of chestnut shells in bioactive compounds, including vitamin E, amino acids and polyphenols, endowed with interesting biological activities, underlines its potential valorization as a substrate of natural antioxidants with attractive applications in the cosmetic field [1-3]. The implementation of eco-innovative technologies, such as supercritical fluids extraction (SFE), to recover bioactives has arisen as a priority for the industrial valorization of agro-residues.

The purpose of this study was to recover antioxidants from chestnut shells by SFE, aiming their reuse as new cosmetic principles. The extraction was performed at 60 °C, 350 bar and 15% co-solvent (ethanol) for 90 minutes. The extract was characterized regarding antioxidant and antiradical activities, elastase and hyaluronidase inhibition and in-vitro safeness on dermal cells (HaCaT and HFF-1). The skin permeation of polyphenols was screened using Franz cells coupled to human skin.

The antioxidant/antiradical properties (ABTS: 124.8 mg AAE/g dw; DPPH: 53.0% inhibition; FRAP: IC₅₀ = 204.8 μg/mL), and inhibitory activities on hyaluronidase (IC₅₀=54.4 mg/mL) and elastase (33.6%) reinforce the potential use of chestnut shells extract as an effective source of anti-aging ingredients. The in-vitro assay proved that the extract up to 100 µg/mL did not lead to a significant decrease of HaCaT and HFF-1 viability. Regarding ex-vivo assay, two polyphenols from SFE extract – ellagic acid (779.6 µg/g) and epicatechin (35.3 µg/g) – permeated the human skin after 8 h.

In conclusion, this study emphasizes the skin health effects and safety of C. sativa shells extract obtained by a green technology and proposes its incorporation in cosmetic formulations as an anti-aging ingredient.

Acknowledgements: This research was funded by FCT/MCTES through national funds (UIDB/50006/2020) and project PTDC/ASP-AGR/29277/2017 - Castanea sativa shells as a new source of active ingredients for Functional Food and Cosmetic applications: a sustainable approach, financially supported by national funds by FCT/MCTES and co-supported by Fundo Europeu de Desenvolvimento Regional (FEDER) throughout COMPETE 2020 - Programa Operacional Competitividade e Internacionalização (POCI-01-0145-FEDER-029277). Diana Pinto is thankful for her PhD grant (SFRH/BD/144534/2019) financed by POPH-QREN and subsidized by the European Science Foundation and Ministério da Ciência, Tecnologia e Ensino Superior. Francisca Rodrigues is thankful for her contract (CEECIND/01886/2020) financed by FCT/MCTES—CEEC Individual 2020 Program Contract.

References:

1. Pinto, D., et al., Castanea sativa shells: A review on phytochemical composition, bioactivity and waste management approaches for industrial valorization. Food Research International, 2021. 144: p. 110364.

2. Pinto, D., et al., Valorisation of underexploited Castanea sativa shells bioactive compounds recovered by supercritical fluid extraction with CO2: A response surface methodology approach. Journal of CO2 Utilization, 2020. 40: p. 101194.

3. Pinto, D., et al., Optimizing the extraction of phenolic antioxidants from chestnut shells by subcritical water extraction using response surface methodology. Food Chemistry, 2021. 334: p. 127521.