[Naphthoquinones--biosynthesis, occurrence and metabolism in plants].

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.