Pharmacognosy with the Basics of Plant Biochemistry - Kovalyov V. M. 2004

Special Part
Phenolic Compounds
Quinones

Quinones are cyclic diketones whose molecules contain keto groups integrated into a system of conjugated bonds. Benzoquinones, naphthoquinones, and anthraquinones are of the greatest practical importance.

BENZOQUINONES

Benzoquinones exist as two isomers: 1,2-benzoquinone and 1,4-benzoquinone.

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1,2-Benzoquinone

1,4-Benzoquinone

General formula of ubiquinones

Substituted 1,4-benzoquinones act as oxidizing agents that undergo reversible reduction to hydroquinones. They participate in electron transport during cellular Respiration. Ubiquinone belongs to this group.

Ubiquinone (coenzyme Q, KoQ_n, 2,3-dimethoxy-6-methyl-5-polyprenylbenzoquinones). The number of polyprenyl residues (n) can range from 1 to 15. In nature, Q₆–Q₁₀ are the most common. The Human Body primarily utilizes Q₁₀.

Ubiquinones play a vital role in the Bioenergetics of most prokaryotes and all eukaryotes. Their primary function is The transport of electrons and protons from various substrates to Cytochromes during respiration and Oxidative Phosphorylation. Additionally, ubiquinones—mainly in their reduced form as ubiquinols—function as antioxidants.

For the industrial extraction of KoQ, microbial biomass (Bacteria, Yeast, Fungi) is utilized. Efficient biotechnological Methods for obtaining Q₉ and Q₁₀ have been developed.

Ubiquinone Q₁₀ is used abroad in dietary supplements under the name coenzyme Q₁₀ or Co Q₁₀. As an oxygen carrier, ubiquinone reduces hypoxic Damage caused by oxygen deprivation in cardiovascular diseases, making it recommended for the Prevention of cardiovascular disorders. Due to its low toxicity, coenzyme Q₁₀ is effective in chronic conditions, in pediatric Treatment, and for mitigating the cardiotoxic effects of antitumor drugs. Ko Q₁₀ also exhibits immunomodulatory properties. It enhances the body's tolerance to overload and stress, strengthens The Immune System, and supplies Cells with energy.

NAPHTHOQUINONES

Naphthoquinone derivatives are predominantly found in plants of the families Juglandaceae, Plumbaginaceae, Droseraceae, etc.; they have also been isolated from bacteria and serve as structural fragments of numerous natural substances. Certain naphthoquinones exhibit high biological activity. Phylloquinone (vitamin K₁) is a naphthoquinone involved in Photosynthesis. Derivatives of 1,4-naphthoquinone—such as juglone, shikonin, and droserone—play a significant role in the pharmacological activity of walnut leaves, gromwell herb and roots, sundew herb, and other plants.