Unraveling the Antifungal Activity of Hernandulcin: Protective Effect on the Postharvest Rot of Strawberry Receptacles

ABSTRACT The antifungal properties of the natural sesquiterpenoid hernandulcin on two postharvest phytopathogens of strawberry receptacles ( Fragaria × ananassa cv. Camino real) are reported. Benomyl‐resistant strains of Botrytis cinerea (isolate FI2) and Rhizopus stolonifer (isolate FI3) were characterized as natural agents of receptacle postharvest rot. From these phytopathogens, R. stolonifer isolate FI3 triggered faster and more devastating rot than that caused by B. cinerea isolate FI2. According to the resazurin reduction assay, hernandulcin (HE) exhibited cytotoxic activity against the isolates of B. cinerea and R. stolonifer , with minimum inhibitory concentrations of 100 ± 0.5 and 200 ± 0.7 µg/mL, respectively. HE exerted mixed‐type inhibition (IC 50 , 189.6 µg/mL) on 3‐hydroxy‐3‐methylglutaryl‐CoA reductase, suggesting its possible action through blocking early steps of ergosterol biosynthesis. Mixed‐type inhibition was endorsed by enzyme kinetics and the docking approach. The effect of HE splattering (100‐250 mg/L) on receptacles inoculated by both fungal species revealed a significant delay ( p < 0.01) in phytopathogen sign emergence and rot development for at least 8 days post‐inoculation. HE splatter substantially preserved ( p < 0.05 ‐ p < 0.01) receptacle quality parameters such as total phenol content, antioxidant capacity, protein, fat, fiber, and reducing sugars, as well as the levels of cyanidin‐3‐O‐glucoside, pelargonidin‐3‐O‐glucoside, and pelargonidin‐3‐O‐rutinoside determined by HPLC‐ESI/MS. Our results sustain the potential use of HE for controlling the incidence of some phytopathogens linked to the soft rot of strawberry receptacles. Practical Applications This investigation demonstrates the antifungal properties of hernandulcin, a non‐caloric sweetener accumulated in the leaves of the Mexican medicinal plant Phylla scaberrima . This natural sesquiterpene may be used to avoid the simultaneous contamination of strawberry fruit by gray mold ( Botrytis cinerea ) and Rhizopus rot. Thus, the application of hernandulcin to extend the shelf life of strawberry fruits is feasible.