Antioxidant and Gene Protective Effects of Medicinal Mushrooms Inonotus obliquus (Pers.:Fr.) Pilat and Phellinus robustus (P. Karst.) Bourd. et Galz.
Nina A. Bisko
Institute of Food Biotechnology and Genomics of the National Academy of Sciences of Ukraine, Kiev
Victor V. Shcherba
Institute of Microbiology, National Academy of Sciences of Belarus, Minsk, 220141, Belarus
Nadezda Yu. Mitropolskaya
M. G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, Tereschenkivska Str. 2, Kiev, 252601, Ukraine
Victor T. Bilay
N. G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine. 2 Tereshchenkivskaya Str., Kiev 01601, Ukraine
Fungal melanin pigments were shown to display high antioxidant activity. This work was designed to isolate melanin pigments from Inonotus obliquus and Phellinus robustus to study their antioxidant and gene protective properties during metabolic activation of aromatic amines by the peroxidase pathway of oxidation.
Investigation of the element composition of exo-and endomelanins of Inonotus obliquus and Phellinus robustus showed that these species distinguish one from another insignificantly. However, it has been demonstrated that the content of carboxyl groups in endomelanins of both investigated species was two times higher in comparison with exomelanins. IR- spectra of exo- and endomelanins of I. obliquus and Ph. Robustus were also similar. The molecular weight of exo- and endomelanines from I. obliquus was 35−60 kDa, and from Ph. Robustus 40−60 kDa.
The obtained data indicate that the alkaline fraction of exo- and endomelanins of I. obliquus had a molecular mass of 55−60 kDa, Ph. Robustus 65−70 kDa, the alcohol fraction of >I. obliquus 25−30 kDa, and Ph. robustus 40−45 kDa. The melanins of both species also contained a small quantity of substances with the molecular mass of 100−120 kDa.
Melanins isolated from both mushrooms and applied at a concentration above 20 μg/mL inhibited the reaction of peroxidase-mediated oxidation of o-dianisidine (DA). It was demonstrated that the ability of melanin isolated from Ph. Robustus to inhibit peroxidase-mediated free radical oxidation of DA was considerably lower than that of the pigment from I. obliquus. The highest degrees of inhibition of peroxidase-mediated DA oxidation with melanins isolated from Ph. Robustus (75 μg/mL) and I. obliquus (75 μg/mL) mushrooms were 75% and 80%, respectively. Our data showed that melanin isolated from I. obliquus inhibited peroxidase-mediated oxidation of DA more efficiently than it prevented damage to DNA induced by oxidation products. In contrast, melanin from Ph. Robustus applied at a lower concentration inhibited the formation of DNA/DNA crosslinks more readily than it prevented DA oxidation. Such properties of melanins can be used in developing new anticarcinoganic drugs.