Pentagalloyl glucose and gallotannins from mangifera Indica L. seed kernel extract as a promising antifungal feed additive, in vitro, and in silico studies

Recently, the valorization of agro-industrial wastes through their exploration of their bioactive compounds has become a necessary trend to maximize their applications in various production sectors, particularly animal feeding. In the study, mango seed kernels were used as agro-industrial wastes to extract gallotannins fraction (GF) and pentagalloyl glucose (PGG). The GF and PGG were mixed with poultry feeds to investigate their potential ability to control Aspergillus flavus (A. flavus) growth and inhibit its production of aflatoxins (AFs). Ketoconazole was used as an antifungal standard. GF and PGG combat the growth of A. flavus, with minimum inhibition concentration (MIC) of 21.7 ± 1.7 and 20 ± 0 mg/mL, respectively. Moreover, GF and PGG showed promising results in preventing the production of AFs (AFB1, AFB2, AFG1, and AFG2) at 5 and 10 mg/100-g feed. Furthermore, to explain the mode of action of PGG as an antifungal agent, a molecular docking study has been performed against Type 1 Polyketide Synthase (PKS), which is found in many toxigenic Aspergillus species and has a highly active Acyl Carrier Protein (ACP) domain that is implicated in thiol ester-bound intermediates involved in fungal polyketides, fatty acids, and other non-ribosomal peptide formation, which are highly implicated in the construction of aflatoxin biosynthesis. The promising results prompt us to use mango seed extract as a cheap source of gallotannin components as a safe feed additive for reducing fungal and mycotoxin contamination in animal feeds.