Natural Pigments from the Endophyte Aspergillus westerdijkiae and Evaluation of their Bioactivities

Background: The growing consumer preference for natural and sustainable products has heightened interest in biopigments across pharmaceutical, cosmetic, and food industries. In this study, we investigate endophytic fungi as a viable and eco-friendly source for the production of bioactive natural pigments.

Methods and results: A promising strain, Aspergillus westerdijkiae 17P, was isolated from Betula pendula and assessed for its pigment-producing potential and associated bioactivities. The biomass extract was fractionated, and the resulting components were evaluated for antimicrobial, antioxidant, anticancer, neuroprotective, and peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist activities. Among the fractions, 17P2 exhibited broad-spectrum antimicrobial effects, notable antioxidant activity (83% DPPH radical scavenging at 1000 mg/mL), and cytotoxicity against MCF-7 and HepG2 cancer cell lines, with IC₅₀ values of 250 mg/mL. Isothermal titration calorimetry (ITC) demonstrated strong binding affinities of 17P2 to acetylcholinesterase (Kd = 1.63 µM) and butyrylcholinesterase (Kd = 0.03 µM), indicating potential anti-Alzheimer's properties. Additionally, significant interactions with monoamine oxidase A and PPAR-γ suggest possible antidepressant and antidiabetic applications. Four major pigment fractions (17P1-17P4) were purified and structurally characterized using UHPLC-MS and NMR, revealing key metabolites such as aluminium and iron aspergillic acid complexes, penicillic acid, and preussin. Notably, gamma irradiation at 2000 Gy significantly enhanced the red, yellow, and orange pigments yield compared to the non-irradiated control cultures.

Conclusions: Collectively, these findings position A. westerdijkiae 17P as a valuable and versatile biotechnological resource for the sustainable production of multifunctional fungal pigments with potential industrial and therapeutic applications.