Novel Stimulants of Medicinal Basidiomycetes Growth Based on Nanoparticles of N-monosubstituted Amino Acid Derivatives of Fullerene C 60

: The inﬂuence of nanoparticles of hydrated C 60 fullerene and its N-monoamino acid derivatives on the oxidative metabolism and growth of the mycelial biomass of basidiomycetes during their submerged cultivation was studied. It was found that the supplementation of culture media with nanoparticles of the studied compounds at their ﬁnal concentration range of 10 − 7 to 10 − 11 M signiﬁcantly increased the resulting biomass, while the severity of the effect in this concentration range changed slightly. That prompted the use of nanomolar concentrations of compounds as reasonable. The most pronounced stimulating effect (an increase in biomass of about 240% with respect to control) was observed when culturing Laetiporus sulphureus , the intrinsically high level of oxidative metabolism of which was signiﬁcantly lowered by the presence of the studied additives. It was shown that the growth-enhancing action of nanoparticles of fullerene C 60 and its derivatives could not be attributed to photochemical reactions, particularly fullerene photoexcitation. Fullerene and its derivatives manifest a growth regulatory effect on bio-objects from different kingdoms of the living world (plants and fungi), which is indicative of these compounds’ mechanism of action based on a direct impact on fundamental, universal for all living beings, biophysical processes, primarily chain free-radical oxidation.

In addition to the above mushrooms, the possibilities of applying others are widely examined. It is shown that the water-soluble polysaccharide Flammulina velutipes I-A shows inhibitory activity in relation to hydroxyl radical and superoxide anion radical, as well as stimulates NO production and enhances the secretion of tumor necrosis factor-α, interleukin-1β and interleukin-6 by macrophages RAW264.7 [10]. A large number of studies derivatives on the growth and oxidative metabolism of three commonly used types of medicinal basidiomycetes.
Most of the researchers agree that the growth-stimulating effect of fullerene derivatives should be attributed to their ability to prevent oxidative stress development by trapping reactive oxygen species (ROS) [28,29]. ROS are universal chemical agents mediating the adverse effects of different types of stress (temperature, osmotic, acid-base, excessive lighting, ultraviolet radiation). For instance, in the course of exploring stress-induced transcription in the cyanobacterium Synechocystis sp., a number of genes have been identified as being induced in response to numerous abiotic stresses [30]. It was found that most of the genes encoding various protection factors are expressed not only in response to the corresponding adverse environmental factor but also in response to exogenous administration of hydrogen peroxide [30]. Thus, by regulating free radical processes, it seems possible to improve the adaptogenic and growth characteristics of cultivated organisms.
It is known that fullerene C 60 and its various derivatives are able to participate in the regulation of free radical processes [31]. The most extensively studied is the antiradical activity of hydroxylated derivatives of fullerene C 60 (fullerenols) and carboxylated derivatives of fullerene C 60 (carboxyfullelenes). Thus, it is shown that fullerenols C 60 (OH) [18][19][20] inhibit 59 and 70% of radical anions generated by the xanthine/xanthine oxidase system at their concentrations of 50 and 100 µM, respectively [32]. The inhibitory effect of hydroxy and other derivatives of fullerene C 60 exerted in relation to hydroxyl radical (•OH) [33], nitroxyl radical (NO•) [34], solvated electron (e aq -), and singlet oxygen ( 1 O 2 ) is also described [35].
I.M. Andreev et al. have found [36] that fullerene C 60 derivatized with such amino acids as proline, ε-aminocaproic acid, and arginine, displays membranotropic activity and penetrates cell membranes in the ionized form, thereby causing their depolarization. Evidence from a single study [37] indicates that basidiomycetes are capable of metabolizing the fullerene derivatives. In the present work, nanoparticles of fullerene C 60 and its amino acid derivatives are considered from the viewpoint of their prospects for being mycelial growth stimulants in mushrooms.

Preparation of Fullerene C 60 Water Dispersion
Water dispersion of fullerene C 60 was obtained in accordance with the methodology described by Andrievsky G.V. et al. [38] by obtaining a saturated solution in toluene, to which water was poured and treated in the dark in an ultrasound bath (42 kHz, 50 W) for several hours with interruptions for cooling.

Strains and Cultivation Conditions
The following strains of the basidiomycetes were used: Flammulina velutipes (Curtis) Singer (strain 0535); Ganoderma applanatum (Persoon) Patouillan (strain 0154), both received from the Collection of the Department of Mycology and Algology of the M.V. Lomonosov Moscow State University (Moscow, Russia); and Laetiporus sulphureus (Bull.) Murrill (strain 120707) was obtained from the Collection of the Department of Botany of the Irkutsk State University (Irkutsk, Russia). Mushroom cultures were maintained on wort agar (4 degrees Balling) at 4 °C in the dark, pH 6-6.5.
After the complete overgrowth of Petri dishes, the mycelium-covered blocks from the agar medium were used as an inoculum of a liquid nutrient medium. The latter was composed of an aqueous solution of the dissolved nutritive agents (carbon and nitrogen sources), supplemented by the substances under investigation, i.e., water dispersion of nanoparticles of fullerene C60 or its amino acid derivatives. The following compositions of media (g/L of water) were used for culture: medium A-D-glucose 10; yeast extract 1; medium B-D-glucose 20; yeast extract-2; peptone 0. For that, solutions of these compounds were prepared in a 50% (v/v) water-ethanol mixture to obtain concentrations of 1.0 × 10 -4 M, 1.0 × 10 -5 M, 1.0 × 10 -6 M, 1.0 × 10 -7 M, 1.0 × 10 -8 M, 1.0 × 10 -9 M, and then transferred to a nutrient medium under aseptic conditions at a volume ratio of 1:99. In the control experiments (in the absence of functionalized fullerene supplements), a corresponding portion of aqueous ethanol was introduced. The ethanol solutions implemented made it possible to avoid autoclaving the added compounds and their destruction under the influence of high temperatures and to exclude contamination by foreign microorganisms. Ultimately, the ethanol level in nutrient media ranged from 0.26 to 0.88%, i.e., at concentrations non-toxic for mushrooms.
The concentration dependence studies of the growth-stimulating effect of fullerene C60 and its amino acid derivatives under the conditions of a submerged culture of winter mushroom (F. velutipes), flat polypore (G. applanatum), and sulfur-yellow polypore (L. sulphureus) were carried out in the dark at a temperature of 25 °C for 18 days.
Since fullerene C60 is known as a compound capable of transferring photoexcitation energy to oxygen [40,41], the experiments were conducted to elucidate the role of light in the biostimulating properties of fullerene C60 and its amino acid derivatives when

Strains and Cultivation Conditions
The following strains of the basidiomycetes were used: Flammulina velutipes (Curtis) Singer (strain 0535); Ganoderma applanatum (Persoon) Patouillan (strain 0154), both received from the Collection of the Department of Mycology and Algology of the M.V. Lomonosov Moscow State University (Moscow, Russia); and Laetiporus sulphureus (Bull.) Murrill (strain 120707) was obtained from the Collection of the Department of Botany of the Irkutsk State University (Irkutsk, Russia). Mushroom cultures were maintained on wort agar (4 degrees Balling) at 4 • C in the dark, pH 6-6.5.
After the complete overgrowth of Petri dishes, the mycelium-covered blocks from the agar medium were used as an inoculum of a liquid nutrient medium. The latter was composed of an aqueous solution of the dissolved nutritive agents (carbon and nitrogen sources), supplemented by the substances under investigation, i.e., water dispersion of nanoparticles of fullerene C 60 or its amino acid derivatives. The following compositions of media (g/L of water) were used for culture: medium A-D-glucose 10; yeast extract 1; medium B-D-glucose 20; yeast extract-2; peptone 0. The concentration dependence studies of the growth-stimulating effect of fullerene C 60 and its amino acid derivatives under the conditions of a submerged culture of winter mushroom (F. velutipes), flat polypore (G. applanatum), and sulfur-yellow polypore (L. sulphureus) were carried out in the dark at a temperature of 25 • C for 18 days.
Since fullerene C 60 is known as a compound capable of transferring photoexcitation energy to oxygen [40,41], the experiments were conducted to elucidate the role of light in the biostimulating properties of fullerene C 60 and its amino acid derivatives when growing the basidiomycetes. These experiments were carried out at the following parameters of

Mushroom Mycelium Biomass
Mushroom mycelium grown in submerged culture was separated from nutrient liquid, washed with distilled water, and then, dried to a constant mass in a laboratory oven at a temperature of 40 • C to collect dry mycelium [42]. Both fresh and dry mass values were obtained accordingly after weighing on analytical scales.

Hydrodynamic Radius of Particles
The hydrodynamic radius of nanoparticles formed by the studied compounds in aqueous solutions was determined by dynamic light scattering (DLS) with a Zetasizer Nano ZS (Malvern Instruments, GB) device. This method allows one to calculate the hydrodynamic radius (R) of spheres that would move in liquids at the same speed as the studied particles. Measurements of R were carried out by assessing the correlation function of intensity fluctuations of laser radiation at λ = 633 nm scattered on the particles of fullerene C 60 or its N-monosubstituted amino acid derivatives at the angle of 173 • . Measurements were carried out at a compound concentration of 1 × 10 −4 M and a temperature of 25 • C. For each sample, 5 intensity distributions by particle size were recorded; each of them included an average of 10 measurements.

DPPH Scavenging Activity
To measure the content of antiradical antioxidants (AO) in the grown mycelium of basidiomycetes, this dry-ground raw material was extracted with 70% ethanol at a temperature of 24 • C for 24 h at a mass ratio of raw material to extracting agent of 1:300. The extracts were clarified by centrifugation at 4000 rpm for 15 min.
The absorption spectra were recorded using an Agilent Cary 60 spectrophotometer (USA).
Quantitative analysis of AO was performed based on a spectrometric observation of their interaction with the stable chromogen radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) [43,44]. 2.7 mL of 8.1 × 10 −5 M DPPH solution in ethanol was added to the test sample, and the reaction system volume was brought to 3.6 mL with ethanol. The optical density was measured at the wavelength of 517 nm at 1 cm optical path length for the first 30 min of the experiment at 5 min intervals, and then every hour during the experiment. The last measurement was made 24 h after the reaction started, and this value was used for calculating the AO concentration. By varying the test sample volume, the radical DPPH conversion degree at experiment termination was controlled to be from 15 to 70% as measured by its optical absorption. The DPPH conversion degree was calculated by the formula: where D exp is the optical density of the reaction system 24 h after the reaction started; D contr is the optical density of the control solution; ζ is the DPPH conversion degree 24 h after mixing the reagents.
In the control experiment, 70% ethanol was introduced into the reaction system instead of the extract solution.
Here is the formula for calculating the AO concentration (M) in the units of the reference compound gallic acid: where [DPPH] 0 is the initial concentration of DPPH in the reaction system, mol/L; V syst is the volume of the reaction system, mL; V al is the volume of the extract introduced into the Processes 2023, 11, 1695 6 of 15 reaction system, mL; 5 is the stoichiometric coefficient of the DPPH inhibition by gallic acid. The results were presented as the C AO quantities normalized to a weighed mass (mM/g).

Lipid Peroxidation
For determining the level of lipid peroxidation (LP) in the mycelial extracts under study, the content of malonic dialdehyde (MDA) was measured by a reaction with thiobarbituric acid (TBA). Extraction of the LP products from a dry-ground raw material was performed using 70% ethanol at a temperature of 24 • C for 24 h, with the mass ratio of raw material and extracting agent being 1:40. After extraction, the extracts were diluted with 1 mL of distilled water and clarified by centrifugation at 4000 rpm for 15 min.
MDA concentration was determined according to a widespread method [45]. Briefly, 1 mL of extract was mixed with 1 mL of a 0.65% solution of TBA in a 20% solution of trichloroacetic acid, heated in a water bath at a temperature of 96 • C, then cooled and centrifuged twice at 4000 rpm for 15 min. The resulting solution's optical density value was measured at 440, 532, and 600 nm, and the MDA concentration was calculated by the formula: where D 440 , D 532 , and D 600 are optical densities at 440, 532, and 600 nm, respectively; 0.0571 is a ratio of molar extinction coefficients of the sucrose-TBA complex at 532 nm and 440 nm, 157,000 is a molar extinction coefficient of MDA. The results were presented as the quantities normalized to a weighed mass (microM/g).

Statistical Processing of Results
The results were statistically processed using Microsoft Excel software. The data were presented as an average mean with a standard deviation or as a percentage. The values of the parametric Student criterion were found for a 95% level of significance.

Results and Discussion
Fullerene possesses hydrophobic properties, which is why in the aqueous medium, the hydrated fullerene C 60 and its N-monosubstituted amino acid derivatives tend to form not true but colloidal solutions. In this case, the chemical and biological properties of fullerene C 60 and its derivatives should be considered in conjunction with data on the sizes of nanoparticles that they form in water. The DLS data on the average size of particles formed by the compounds used in this study are presented in Table 1. Table 1. The average hydrodynamic radius of particles of fullerene C 60 and its derivatives in studied water solutions.

The Name of the Compound
Hydrodynamic Radius r, nm C 60 55.0 ± 22.7 C 60 -L-Ala-OK 4.5 ± 0.8 C 60 -D-Ala-OK 2.9 ± 1 C 60 -D-Val-OK 15.1 ± 2.7 C 60 -D-ε-ACA-OK 6.8 ± 3.5 Previously, we discovered a significant stimulating effect on the growth and development of pea (Pisum sativum L.) seeds resulting from their treatment with 10 −9 M AAFD solutions [46]. In the present work, we have explored the AAFD impact on the biological productivity of some medicinal basidiomycetes during their submerged cultivation and the parameters associated with the level of lipid peroxidation (Table 2).
For most samples, the introduction of the studied compounds into the submerged growth medium led to an increase in the mycelial mass harvested on the 18th day of cultivation. Simultaneously with the increase in biomass, in most experiments, a decrease in the level of secondary products of lipid peroxidation reacting with TBA (TBA-reactive species, TBARS) was observed. Furthermore, the most pronounced decrease in the LP level, as well as an increase in biomass yield, was observed in the Laetiporus sulphureus mushroom, which has an intrinsically high level of oxidative metabolism and LP products. The LP processes regulation is the key component of the growth-stimulating mechanism of solubilized forms of fullerene C 60 . A high level of oxidative processes is characteristic of the oxidative stress state. Table 2. The influence of hydrated fullerene C 60 and its amino acid derivatives at a concentration of 10 −9 M on biomass and parameters of the oxidative metabolism of mycelium grown in the dark for 18 days on medium A at 25 • C.

Sample
Biomass, mg The key role played by plant and mushroom extracts in scavenging the free radicals is played by phenolic compounds [47,48]. It is known that fullerene and its derivatives can affect the phenolic composition of plants. The authors of the work [49] showed that a presowing soaking of wheat seeds in 40 and 80 nM fullerenol solutions led to a decrease in the concentration of phenolic compounds in the 30-day seedlings grown under salt stress conditions. The addition of fullerene derivatives to the submerged cultivation medium was not followed by a noticeable tendency to increase or decrease the antioxidant content (C AO ) of water-ethanol mycelial extracts from the grown mushrooms. Since the DPPH radical reacts mainly with the antioxidants acting via the hydrogen atom transfer mechanism, data on C AO could be interpreted as the total content of low-molecular-weight non-enzymatic antioxidants expressed in standard antioxidant units. The dynamics of the fungal low-molecular-weight antioxidants interaction with the DPPH radical obey an exponential function for a prolonged period before entering a plateau (Figure 2). Most of the basidiomycetes' phenolic compounds are represented by phenolic acids [50,51]. The antioxidant capacity of phenolic acids, as well as other phenolic compounds, is known to be determined by hydroxyl groups, while their reactivity increases sharply with two hydroxyl substituents in orthoor para-positions. Therefore, for example, it was shown that caffeic acid is a stronger antioxidant than ferulic acid and p-coumaric acid owing to the presence of the second OH group in an ortho position in relation to the first one [52].
In the scientific literature, there is some information on the interaction of other fullerene-containing compounds with free radicals. By the EPR method implementing a spin trap 13 C, benzyl radical addition to the fullerene C60 molecule in a toluene medium was shown [57]. The pulse radiolysis technique confirmed the efficient interaction of different carboxylated fullerenes with solvated electrons, hydroxyl radicals and singlet oxygen. When interacting with solvated electrons, the carboxylated derivatives of fullerene, according to the authors, form the monoanion radical [35]. Regarding the binding of the hydroxyl radical •OH by the fullerene hydroxylated derivatives, the proposed mechanisms are divisible into two types: (1) •OH captures H from a hydroxyl group with the formation of an etheric bond on the surface of the fullerene nucleus; (2) •OH attaches to the double bond of the fullerene skeleton [33]. Thus, fullerene C60 and its various derivatives are able to effectively bind various free radicals. However, on the Data on the component composition of the antioxidants of the studied fungi indicate the presence in them of monophenols and polyphenols with meta-substitution, along with the structures described above. Their presence, along with the formation of C-Cdimers by the oxidized AO forms, could explain the prolonged period before entering the plateau of the radical DPPH interaction kinetic curves. In the extracts from the edible mushroom Flammulina velutipes fruit bodies, the presence of pyrogallol, homogentisic acid, sulfosalicylic acid, gallic acid, 5-caffeoylquinic acid, quercetin, and ferulic acid were found [53]. HPLC analysis of ethyl acetate and ethanol fractions of the L. sulphureus fruit bodies showed the presence of para-coumaric acid, quercetin, kaempferol, caffeic acid, (+)-catechin, gallic acid, 5-caffeoylquinic acid [54]. In the Ganoderma applanatum mushroom mycelium, by means of the HPLC-MS/MS method, para-hydroxybenzoic acid, protocatechuic acid, para-coumaric acid, vanillic acid, gallic acid, esculetin, caffeic acid, and syringic acid were found [55].
Earlier, we demonstrated that AAFDs have the ability to inhibit free-radical oxidation in various model systems, which seems to be one of the apparent mechanisms of their influence on oxidative homeostasis [56].
In the scientific literature, there is some information on the interaction of other fullerene-containing compounds with free radicals. By the EPR method implementing a spin trap 13 C, benzyl radical addition to the fullerene C 60 molecule in a toluene medium was shown [57]. The pulse radiolysis technique confirmed the efficient interaction of different carboxylated fullerenes with solvated electrons, hydroxyl radicals and singlet oxygen. When interacting with solvated electrons, the carboxylated derivatives of fullerene, according to the authors, form the monoanion radical [35]. Regarding the binding of the hydroxyl radical •OH by the fullerene hydroxylated derivatives, the proposed mechanisms are divisible into two types: (1) •OH captures H from a hydroxyl group with the formation of an etheric bond on the surface of the fullerene nucleus; (2) •OH attaches to the double bond of the fullerene skeleton [33]. Thus, fullerene C 60 and its various derivatives are able to effectively bind various free radicals. However, on the other hand, there is evidence that fullerene is C 60 and its derivatives are capable of transmitting excitation energy to oxygen with the formation of its reactive species, in particular, singlet oxygen [40]. In order to find out whether photochemical processes are involved in the mechanism of the growth-regulatory effect of fullerene C 60 amino acid derivatives, an additional series of experiments on growing the basidiomycetes G. applanatum and L. sulphureus in the absence other hand, there is evidence that fullerene is C60 and its derivatives are capable of transmitting excitation energy to oxygen with the formation of its reactive species, in particular, singlet oxygen [40]. In order to find out whether photochemical processes are involved in the mechanism of the growth-regulatory effect of fullerene C60 amino acid derivatives, an additional series of experiments on growing the basidiomycetes G. applanatum and L. sulphureus in the absence of light and under the conditions of 11-hour daylight periods at a temperature of 28 °C (Figure 3) was carried out. The results of these experiments demonstrated that within the concentration range of 10 -7 -10 -11 M, despite a slight decrease in the biomass accumulation in a few modes of the "light" experiment compared to the "dark" experiment, the growth-regulatory activity of fullerene C60 and its amino acid derivatives is not associated with the potential ability of the studied compounds to generate singlet oxygen in the presence of light with the subsequent activation of the endogenous antioxidant protection system. Moreover, the capability of the fullerene C60 solubilized forms for growth stimulation in the absence of light is also indicative of the irrelevance of this activity in our earlier experiments with plants [46] to the fullerene's impact on the photosynthetic apparatus of the plant cell.
The fullerene C60 solubilized forms being the growth stimulants for taxonomically distant groups representing the distinct kingdoms of the living world (plants and mushrooms) is indicative of these compounds' activity mechanism based on the direct effect on fundamental, universal for all living organisms' biophysical processes, primarily chain free radical oxidation, as well as effects on the physicochemical properties of biological membranes. The results of these experiments demonstrated that within the concentration range of 10 −7 -10 −11 M, despite a slight decrease in the biomass accumulation in a few modes of the "light" experiment compared to the "dark" experiment, the growth-regulatory activity of fullerene C 60 and its amino acid derivatives is not associated with the potential ability of the studied compounds to generate singlet oxygen in the presence of light with the subsequent activation of the endogenous antioxidant protection system. Moreover, the capability of the fullerene C 60 solubilized forms for growth stimulation in the absence of light is also indicative of the irrelevance of this activity in our earlier experiments with plants [46] to the fullerene's impact on the photosynthetic apparatus of the plant cell.
The fullerene C 60 solubilized forms being the growth stimulants for taxonomically distant groups representing the distinct kingdoms of the living world (plants and mushrooms) is indicative of these compounds' activity mechanism based on the direct effect on fundamental, universal for all living organisms' biophysical processes, primarily chain free radical oxidation, as well as effects on the physicochemical properties of biological membranes.
The observed growth-stimulating effects of hydrated fullerene C 60 and its amino acid derivatives were not downregulated appreciably by varying their concentration in culture medium from 10 −7 to 10 −11 M (Figures 4-6). culture medium from 10 -7 to 10 -11 M (Figures 4-6).
In the work [58], it was found by the radioactive labeling method that the carboxylated derivative of C61(CO2H)2, despite its solubility in water, was located in the membrane, as well as in the membranous cell organelles, including mitochondria, the main primary source of free radicals. The possibility of amino acid derivatives of fullerene C60-Ala, C60-Ala-Ala to penetrate through model phosphatidylcholine membranes was demonstrated [59].  The observed growth-stimulating effects of hydrated fullerene C60 and its amino acid derivatives were not downregulated appreciably by varying their concentration in culture medium from 10 -7 to 10 -11 M (Figures 4-6).
In the work [58], it was found by the radioactive labeling method that the carboxylated derivative of C61(CO2H)2, despite its solubility in water, was located in the membrane, as well as in the membranous cell organelles, including mitochondria, the main primary source of free radicals. The possibility of amino acid derivatives of fullerene C60-Ala, C60-Ala-Ala to penetrate through model phosphatidylcholine membranes was demonstrated [59].    We experimentally confirmed the assumption that the reason for the observed stimulating effect of the studied fullerene C60 water-soluble forms lies in their ability to participate in the regulation of oxidative metabolism. In line with this supposition are the results of F. velutipes culturing on nutrient media A and B, with the different content of nutrients at other conditions being equal. Fullerene C60 amino acid derivatives at high concentrations exerted a profound effect of an increase in biomass on nutrient medium A with a relatively low content of carbon and nitrogen sources (Figure 7), i.e., under the stress conditions induced by poor nutrition. When using the AAFD on medium B enriched with nutritive components, the biomass increment parameters turned out to be lower than the control values at the experiment modes with AAFD concentrations of In the work [58], it was found by the radioactive labeling method that the carboxylated derivative of C 61 (CO 2 H) 2 , despite its solubility in water, was located in the membrane, as well as in the membranous cell organelles, including mitochondria, the main primary source of free radicals. The possibility of amino acid derivatives of fullerene C 60 -Ala, C 60 -Ala-Ala to penetrate through model phosphatidylcholine membranes was demonstrated [59].
We experimentally confirmed the assumption that the reason for the observed stimulating effect of the studied fullerene C 60 water-soluble forms lies in their ability to participate in the regulation of oxidative metabolism. In line with this supposition are the results of F. velutipes culturing on nutrient media A and B, with the different content of nutrients at other conditions being equal. Fullerene C 60 amino acid derivatives at high concentrations exerted a profound effect of an increase in biomass on nutrient medium A with a relatively low content of carbon and nitrogen sources (Figure 7), i.e., under the stress conditions induced by poor nutrition. When using the AAFD on medium B enriched with nutritive components, the biomass increment parameters turned out to be lower than the control values at the experiment modes with AAFD concentrations of 10 −6 -10 −8 M. Therefore, it is reasonable to implement AAFD at their nanomolar concentrations.

Conclusions
Thus, the studied amino acid derivatives of fullerene C60 could serve as efficient stimulants of medicinal xylotrophic basidial fungi growth, with the highest effects found at the AAFD nanomolar concentrations. The observed growth-stimulating effects are associated with the regulation of oxidative metabolism by the studied water-soluble

Conclusions
Thus, the studied amino acid derivatives of fullerene C 60 could serve as efficient stimulants of medicinal xylotrophic basidial fungi growth, with the highest effects found at the AAFD nanomolar concentrations. The observed growth-stimulating effects are associated with the regulation of oxidative metabolism by the studied water-soluble forms of fullerene C 60 , since in almost all cases, the positive AAFD action on fungal growth is accompanied by a decrease in the level of LP secondary products. Furthermore, the greatest increase in the biomass accumulation parameter caused by AAFD application takes place in mushrooms with a high level of oxidative metabolism. The fact that the AAFD growth-stimulating effect is manifested in representatives of both the higher plants and the kingdom of fungi is indicative of the relationship of this effect's mechanism with the fundamental biophysical processes, such as free radical chain peroxidation. The AAFD under study can be of interest as additives to the nutrient medium when growing medicinal basidiomycetes aimed at enhanced mycelial biomass yield. The results of this research provide new information that supports the key role of free radical processes in regulating the positive influence of the fullerene C 60 water-soluble derivatives on the organism's growth and development.