Significance and Impact of the Study: In the present study, the bioactive metabolite Mellein was represented as a broad-spectrum antimicrobial agent produced by Lasiodiplodia theobromae strain (SJF-1) isolated from the medicinal plant Syzygium cumini. In addition, Mellein exhibited drug-like characteristics through in silico absorption, distribution, metabolism, and excretion pharmacological studies. Hence, from the above studies, Mellein could be considered as a potential drug candidate and also a biocontrol agent in the medical, agricultural and pharmaceutical sectors.

Abstract

In an on-going investigation of bioactive metabolites producing potential endophytic fungi, the strain Lasiodiplodia theobromae (SJF-1) was isolated from a medicinal plant Syzygium cumini. The cultural, morphological and molecular identification was done with the SJF-1 strain. The obtained gene sequence was deposited in NCBI with accession number MG 938644. The methanolic extract of SJF-1 strain possessed one major bioactive fraction, and it was purified by column chromatography. Further, it was identified as Mellein by various spectroscopic studies (¹H, ¹³C, DEPT-135°, FT-IR, ESI-HR-MS and 2D NMR). Biologically, Mellein showed potent anti-Xanthomonas activity with minimum inhibitory concentration (MIC) values ranging from 1·9 to 62·5 μg ml⁻¹ against 11 Xanthomonas strains, a broad-spectrum antimicrobial activity with MIC 7·8–31·25 μg ml⁻¹ and 1·9–31·25 μg ml⁻¹ towards both bacterial and fungal strains, respectively. The scanning electron microscope analysis proved the antimicrobial efficacy of a Mellein by rupturing the cell walls of Xanthomonas sp. Molecular docking studies further supported that the Mellein showed good binding interactions with the proteins of Xanthomonas sp. to reduce pathogenicity. Further, in silico pharmacological studies showed that this metabolite exhibited high gastrointestinal absorption properties and promising oral drug bioavailability. We report, anti-Xanthomonas, in silico docking and pharmacological studies of Mellein from (SJF-1) strain for the first time.