Bioprocessing of Talaromyces purpurogenus for production of dihydromonascorubrin with a powerful antioxidant and antimicrobial activities integrated with the network-guided target prediction and molecular docking analyses.

The antibiotic resistance of pathogenic microorganisms due to the irresponsible use in healthcare and agricultural practices is one of the global threats for the human, especially immune-compromised patients. Thus, searching for a novel compounds from fungi with unique affinity to combat the drug-resistant microorganisms was the objective. Talaromyces purpurogenus # PZ292970.1, an endophyte of palm tree Elaeis guineensis, has the highest productivity of azaphilone pigment (25.5 AU410/ml), with a strong activity against E. coli (MIC value 6.8 µg/ml), S. aureus and C. albicans (MIC value 12.5 µg/ml). The extracted pigment of T. purpurogenus has a strong antibiofilm activity for S. aureus (86.2%), C. albicans (85.8%) and E. coli (79.7%), compared to the control. The TLC purified-pigment of T. purpurogenus had a maximum absorbance at λ410 nm, with a small one at λ510 nm, revealing the identity of the major peak as orange azaphilone pigment. The purified pigment gave a distinct single peak by HPLC, ensures their structural homogeneity. From the FT-IR analyses, the absorption and stretching vibration of the target compound functional groups ensures their spectral identity as polyketide azaphilone. The 1HNMR and 13CNMR spectra revealed characteristic proton signals for the aromatic polyketide related to dihydromonascorubrin derivatives. From LC-MS/MS, the purified compound had 385.2 m/z that were matched to the molecular mass of dihydromonascorubrin, compared the authentic dihydromonascorubrin (382.4 m/z) as suggest from the fragmentation pattern by CFM-ID software. The yield of azaphilone pigment was increased by 2 folds upon bioprocessing by Plackett-Burman design, and by 2.4 folds by γ-irradiation at 1.0 kGy. The pigment showed a powerful antioxidant activity with free radical scavenging and reducing properties as reported by DPPH, ABT and FRAP assays. Integrating target prediction and molecular docking in silico analyses, dihydromonascorubrin exhibited multi-target mechanisms linked to efflux-associated resistance in E. coli and peptidoglycan remodeling in S. aureus.