The ethyl acetate solvent extract of the soft coral Xenia macrospiculata, collected from the Red Sea coast of Eritrea, has been investigated for novel bioactive compounds against the two most prevalent postharvest fungal pathogens, Aspergillus niger and Aspergillus flavus , which damage the fruits and cause significant yield losses and quality degradation. The crude extract was fractionated using column chromatography; separated fractions were screened for antifungal activity both in vitro and in vivo, applying Citrus reticulata fruits. The active molecules were characterized, and their mechanism of antifungal activity was predicted using molecular docking. Finally, the in silico analysis was conducted to study the toxicity of the molecules against human beings. Three fractions, such as ethyl acetate fraction 9 (EAF 9), EAF 47, and EAF 56, have shown potential antifungal activity both in vitro and in vivo. Among these fractions, EAF 9 has shown the highest zone of inhibition against A. flavus, and EAF 47 has shown the highest activity against A. niger at a concentration of 100 μg/mL. The molecular characterization results confirmed that all three molecules are diterpenes, in which one compound was characterized earlier (EAF 9 = Xenicinedial); the other two, EAF 56 (Xeniculin moiety) and EAF 47, were reported to be new compounds. The ligand fraction EAF 9 has shown potential interaction with the antifungal target 14α‐demethylase, with the voriconazole inhibitor (PDB: 4UYM) suppressing the selected fungi. Toxicity assessment by using the computational tool ProTox‐III predicted that EAF 9 was nontoxic to humans and categorized in Class VI; the other two molecules are grouped in the Class IV category. This study contributes to the ongoing search for novel natural products with agricultural and pharmaceutical applications. The in silico toxicity evaluation further supports the potential use of these compounds as safe and effective antifungal agents to augment food security.
Kasimala et al. (Thu,) studied this question.