The effect of silver nanoparticles (Ag NPs) obtained in the presence of royal jelly (RJ) on the growth of yeast Candida guilliermondii NP-4, on the total and H⁺-ATPase activity, as well as lipid peroxidation process and antioxidant enzymes (superoxide dismutase (SOD), catalase) activity was studied. It has been shown that RJ-mediated Ag NPs have a fungicide and fungistatic effects at the concentrations of 5.4 µg mL⁻¹ and 27 µg mL⁻¹, respectively. Under the influence of RJ-mediated Ag NPs, a decrease in total and H⁺-ATPase activity in yeast homogenates by ~ 90% and ~ 80% was observed, respectively. In yeast mitochondria total and H⁺-ATPase activity depression was detected by ~ 80% and ~ 90%, respectively. The amount of malondialdehyde in the Ag NPs exposed yeast homogenate increased ~ 60%, the catalase activity increased ~ 70%, and the SOD activity—~ 30%. The obtained data indicate that the use of RJ-mediated Ag NPs have a diverse range of influence on yeast cells. This approach may be important in the field of biomedical research aimed at evaluating the development of oxidative stress in cells. It may also contribute to a more comprehensive understanding of antimicrobial properties of RJ-mediated Ag NPs and help control the proliferation of pathogenic fungi.

Modern telecommunication technologies use the high frequency microwave radiation, the application of which continues to expand rapidly. Exposure to non-ionizing radiation can induce oxidative stress in cells. The biochemical processes involved in overcoming this stress are highly energy-consuming and require additional energy expenditure which consequently enhances the ATP hydrolysis. The indicator of oxidative stress is the intensification of lipid peroxidation, with malondialdehyde (MDA) serving as a key biomarker. In eukaryotic cells, various bioactive dietary supplements, including royal jelly (RJ), may exert beneficial effects on mitigating oxidative stress due to their antioxidant and other biologically active components. Yeasts represent a convenient model for studying the development of oxidative stress and the mechanisms of its overcoming in eukaryotic cells, because they are similar to higher eukaryotes by their structural, reproductive, and functional peculiarities. This study aimed to investigate the effect of 51.8 GHz microwave radiation on ATPase activity, lipid peroxidation, and antioxidant enzyme activity in homogenates and mitochondria of Candida guilliermondii NP-4, as well as to assess the potential role of RJ in migtigating of oxidative stress in yeast cells. The results demonstrated that the exposure to millimeter waves of 51.8 GHz and the following repair period led to intensification of lipid peroxidation, evidenced by an increase in MDA level by 75%. In repaired cells, the MDA content was reduced by ≈27%. Microwave radiation also stimulated catalase and superoxide dismutase (SOD) activity by 65% and 30%, respectively, in repaired cells the SOD activity increased by 13%, while catalase activity - by 25%.

Investigation of fluorescence, electrophoretic and melting parameters of DNA of yeasts Candida guilliermondii NP-4 after X-radiation and posradiation repair was carried out. It was shown that under influence of X-radiation the rate of saturation of DNA by ethidium bromide and the melting temperature of yeast DNA was increased, and the melting interval was decreased. After repair period the rate of saturation of DNA by ethidium bromide and the melting temperature of yeast DNA were the highest, and the melting interval was the lowest, and in the electrophoregramms or repaired DNA there were additional low molecular fractions which testify about possible changes in DNA primary and secondary structures under influence of X-radiation and postradiation repair.

This study aimed to investigate the effect of X-radiation on the ATPase activity and the activity of antioxidant enzymes, including enzymes of proline biosynthesis, in C. guilliermondii NP-4 yeast cells after X-irradiation and the post-irradiation repair of cells. It has been shown that the X-irradiation of yeasts C. guilliermondii NP-4 at a dose of 300 Gy causes the increase of activity of the enzymes catalase and SOD and the ratio of catalase/SOD. The repair of radiation-induced damages requires a lot of energy, so the demand for ATP increases in irradiated and repaired yeasts. The total and FoF ₁ -ATPase activity in yeast homogenates and mitochondria increases after X-irradiation and post-irradiation repair. Amino acid proline is an antioxidative defense molecule and plays a significant role in the adaptation of cells to stress. So higher proline levels in yeasts can protect them from oxidative damage. There are still no systematic studies of the antioxidant properties of proline. In this study, it has been shown that the activity of enzymes of proline biosynthesis (ornithine transaminase and proline-5-carboxylate reductase) in yeasts C.guilliermondii NP-4 increases after X-irradiation and remains higher after post-irradiation repair. Connected with it, the proline amount in X-irradiated and repaired yeasts also is higher than in non-irradiated cells. We suppose that proline has a radioprotective effect on X-irradiated yeasts C. guilliermondii NP-4.