Chestnut (Castanea Sativa Miller.) Burs Extracts And Functional Compounds: Uhplc-Uv-Hrms Profiling, Antioxidant Activity, And Inhibitory Effects On Phytopathogenic Fungi

Chestnut (Castanea sativa Miller.) burs (CSB) represent a solid waste produced during the edible fruit harvesting. Their usual disposal in the field increases the environmental and economic impact of the agricultural process. HPLC-UV-HRMS profiling revealed that CSB organic and aqueous extracts (CSB-M, CSB-H, CSB-A) contain several hydrolyzable tannins, mainly ellagitannins, and glycoside flavonols. Ellagic acid (EA) and chestanin are predominant components (5-79 and 1-13 mg/g dry extract, respectively). NMR analysis confirmed the chemical structures of the major constituents from CSB-M. The extracts displayed a significant scavenging activity against DPPH center dot (EC50 12.64-24.94 mu g/mL) and ABTS(center dot+) radicals (TEAC value 2.71-3.52 mM Trolox/mg extract). They were effective in inhibiting the mycelial growth (EC50 6.04-15.51 mg/mL) and spore germination (EC50 2.22-11.17 mg/mL) of Alternaria alternata and Fusarium solani. At the highest concentration, CSB-M was also active against Botrytis cinerea both in mycelium and spore form (EC50 64.98 and 16.33 mg/mL). The EA contributed to the antifungal activity of extracts (EC50 on spore germination 13.33-112.64 mu g/mL). Our results can support the upgrading of chestnut burs from agricultural wastes to a resource of natural fungicides for managing fruit and vegetable diseases.