Title: Bioflavonoids
Additional Names: Vitamin P complex; citrus flavonoid compounds
Trademarks: Arliflav; Pecitrol Veinogène; C.V.P. (USV)
Literature References: A group of compounds which contribute to the maintenance of normal blood vessel conditions by decreasing capillary permeability and fragility. Widely distributed among plants: J. B. Harborne, Comparative Biochemistry of the Flavonoids (Academic Press, New York, 1967). Biosynthesis: Grisebach, Barz, Naturwissenschaften 56, 538 (1969). High concentrates can be obtained from all citrus fruits, rose hips, and black currants. Commercial methods extract the rinds of oranges, tangerines, lemons, limes, kumquats, and grapefruits. Solvents used in the extraction processes are aqueous alkalies, hot water, or water-miscible organic solvents, such as isopropanol: Freedman et al., US 2888381 (1959 to U.S. Vitamin). Early interest in the compounds developed because of their synergistic effect with ascorbic acid. Other pharmacologic effects such as inhibition of adrenaline autooxidation and of enzyme action are also under study: several authors in The Pharmacology of Plant Phenolics, J. W. Fairbairn, Ed. (Academic Press, New York, 1959); several authors in Angiologica 9, 133-446 (1972). Metabolism: DeEds, "Flavonoid Metabolism" in Comprehensive Biology Vol. 20, M. Florkin, E. H. Stotz, Eds. (Elsevier, New York, 1968). Reviews: Scarborough, Bacharach, Vitam. Horm. 7, 1-55 (1949); Baier et al., Ann. N.Y. Acad. Sci. 61, (Art. 3), 637-736 (1955); T. Robinson, The Organic Constituents of Higher Plants (Burgess, Minneapolis, 1967) pp 178-209; H. Geiger, C. Quinn in Flavonoids, J. B. Harborne et al., Eds. (Academic Press, New York, 1975) pp 692-742.
Therap-Cat: Capillary protectant.
Keywords: Vasoprotectant.
Biopterin Bioresmethrin Biotin l-Sulfoxide Biperiden Biphenamine

Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone)
Isoflavan structure
Neoflavonoids structure

Flavonoids (or bioflavonoids) (from the Latin word flavus meaning yellow, their colour in nature) are a class of plant secondary metabolites. Flavonoids were referred to as Vitamin P [1] (probably because of the effect they had on the permeability of vascular capillaries) from the mid-1930s to early 50s, but the term has since fallen out of use.[2]

According to the IUPAC nomenclature,[3][4] they can be classified into:

  • flavonoids or bioflavonoids.
  • isoflavonoids, derived from 3-phenylchromen-4-one (3-phenyl-1,4-benzopyrone) structure
  • neoflavonoids, derived from 4-phenylcoumarine (4-phenyl-1,2-benzopyrone) structure.

The three flavonoid classes above are all ketone-containing compounds, and as such, are anthoxanthins (flavones and flavonols). This class was the first to be termed bioflavonoids. The terms flavonoid and bioflavonoid have also been more loosely used to describe non-ketone polyhydroxy polyphenol compounds which are more specifically termed flavanoids. The three cycle or heterocycles in the flavonoid backbone are generally called ring A, B and C. Ring A usually shows a phloroglucinol substitution pattern.