Antioxidant activity, chemical diversity and in-silico molecular docking studies of the endophyte Alternaria alternata and host plant Schleichera oleosa

The endophytic fungal and medicinal plant systems are the potential sources of secondary metabolites with wide pharmacological activities. In the present study, Alternaria alternata fungus endophytic in Schleichera oleosa was characterized based on ITS1-5.8s-ITS4 regions of rDNA. Metabolites of A. alternata and host plant S. oleosa exhibited high antioxidant activity was assayed by the cyclic voltammetric method to determine the free radical scavenging and electrochemical activity. The metabolite profiling of fungal and plant extracts was analyzed by Q-TOF-HR-LC/MS. Catechin, griseofulvin, epigallocatechin and epicatechin in A. alternata extract, while isoreserpin, dihydrogambogic acid, irigenin dibenzyl ether and rutilantinone in S. oleosa extract are major compounds with antimicrobial, anti-inflammatory, antioxidant and anti-cancer properties. Two similar amino-acid derivative compounds like 2-amino-8-oxo-9, 10- epoxy-decanoic acid, weredetected in A . alternata and 12-amino-dodecanoic acid was detected in S. oleosa . Compounds that obeyed the rule of five and that were subjected to molecular docking, in which epigallocatechin and isoreserpin showed potential binding affinity against bacterial DNA gyrase, penicillin-binding antibacterial and antioxidant target tyrosinase. In this study, endophytic fungal and host plant revealed their potential to produce bioactive compounds which hold possible future keys for their application in the clinical industries involved in novel drug discovery. • The present study provides information on metabolites produced by the endophytic fungus Alternaria alternata and the host plant Schleichera oleosa , in which metabolites exhibited significant antioxidant activity. • In-silico drug-likeness analysis and bioactivity prediction of compounds epigallocatechin and isoreserpine exhibited significant binding affinity against DNA gyrase and penicillin-binding bacterial proteins. • The medicinal plant produces a treasure trove of incredible secondary metabolites, and the endophytic fungus colonizes as a closely guarded potential source of plant bioactive compounds. • The present study demonstrated that in vitro testing of endophytic fungal and host extracts for antibacterial and antioxidant activities, followed by metabolite characterization and in-silico and molecular docking analyses, could be employed for the identification of novel compounds of biological origin with pharmacological activities.