Enhancement of antioxidant activity and total phenolic content of Fomitopsis pinicola mycelium extract.

Background: Fomitopsis pinicola is one of the most common fungi found in temperate zone of Europe, widely distributed spread in Asia and North America. Fungus has a wide range of therapeutic activity: antitumor, antimicrobial, anti-inflammatory, antidiabetic, antifungal, hepatoprotective, hemostatic action. A number of studies have confirmed the significant antioxidant activity of F. pinicola fruiting bodies. However, the controlled cultivation conditions that influence fungal growth and metabolite production of F. pinicola, particularly the mycelial growth and biosynthesis of metabolites in its culture broth, as well as the antioxidant activity of its mycelium, remain poorly understood.

Results: This study investigated the impact of cultivation conditions on F. pinicola mycelium growth, phenols synthesis and antioxidant activity. Difference in the biosynthetic activity of F. pinicola under tested cultivation conditions was established. A highest value of 2,2-diphenyl-1-picryl-hydrazyl (DPPH•) inhibition (78.2 ± 0.9%) was found for a mycelium cultivated at 30 ºC, while cultivation at a lower temperature (20 ºC) was suitable for biomass growth (8.5 ± 0.3 g/L) and total phenolic content (TPC) 11.0 ± 0.6 mg GAE/g. Carbon and nitrogen sources in a cultivation broth significantly influenced the studied characteristics. Xylose supported the highest DPPH• inhibition (89.91 ± 0.5%) and TPC (16.55 ± 0.4 mg GAE/g), while galactose yielded the best biomass (4.0 ± 0.3 g/L). Peptone was the most effective nitrogen source for obtaining the mycelium with high potential of DPPH• radical inactivation (90.42 ± 0.5%) and TPC (17.41 ± 0.5 mg GAE/g), while the maximum biomass yield (7.8 ± 0.6 g/L) was found with yeast extract in cultivation medium. F. pinicola demonstrated the ability to grow and produce bioactive metabolites across a wide pH range from 2.5 to 7.5. Shaking cultivation resulted in the highest TPC (21.44 ± 0.10 mg GAE/g), though the same level of antioxidant activity (93%) was achieved under both shaking and static cultivation on the 7th and 28th days, respectively.

Conclusion: Controlling cultivation parameters makes it possible to regulate the metabolic and biochemical processes of F. pinicola, facilitating the balance needed to obtain optimal biomass, phenols and antioxidant activity. The findings show the potential to increase phenol production by 2.25 and 2.23 times under shaking and static conditions, respectively, while maintaining a high level of activity.