[Naphthoquinones--biosynthesis, occurrence and metabolism in plants]. / Naftochinony--biosyntéza, výskyt a metabolizmus v rostlinách.

Naphthoquinones are relatively widely occurring natural substances, products of secondary metabolism of some actinomycetes, fungi, lichens, and higher plants. The importance of these substances for the producers proper is, due to their wide biological activity, still discussed. In most cases they act as phytoalexines. In the case of fungi, they may play a significant role in the pathogenicity of moulds--naphthoquinones interact with mitochondria, microsomes and cytoplasmic proteins, in the form of radicals they are bound to DNA and RNA, and they do damage to them. Naphthoquinones are highly cytotoxic substances; their antimicrobial, antifungal, antiviral and antiparasitic effects have been observed. In traditional medicines, particularly in some parts of Asia (China) and South America, naphthoquinones-containing plants are widely used primarily in the treatment of various tumoral and parasitic diseases.

Exogenous regulators in the mycelium of Pleurotus ostreatus after exogenous application.

The mycelium of the fungus Pleurotus ostreatus was cultured on a synthetic medium with growth regulators. Best growth was observed on media with 100 ppm IAA, 200 ppm GA3 and 200 ppm of kinetin. Growth of terminal hyphae and the appearance of colonies differed characteristically. Auxin bio-assays showed that the content of substances in younger mycelium slowly increased during cultivation without conspicuous changes in the medium. After exogenous application of IAA the content of auxins in younger mycelium increased and the content of IAA decreased gradually in the culture medium. Gibberellin bio-assays showed their content in the mycelium fell during cultivation and while it increased in the medium. Application of GA3 to the medium leads to a significant increase in these substances in the young mycelium and in the medium their level remains the same. Cytokinin bio-assays showed their content to vary during cultivation. An addition to kinetin to the nutrient medium results in an increase of cytokinins in the mycelium while in the medium the level of cytokinins is maintained. Addition of one substance thus influences the levels of other endogenous regulators.