Structure-antioxidant activity relationships of flavonoids and phenolic acids

http://amborella.net/2010PlantSystematics/DATA/3-24-APG%202003%20Bot%20J%20Linn%20Soc%20APGII.pdf

An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II

Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.

The Effects of Plant Flavonoids on Mammalian Cells:Implications for Inflammation, Heart Disease, and Cancer

Estimation of total flavonoid content in propolis by two complementary colorimetric methods

Antimicrobial activity of flavonoids

Isoflavones, flavanones and dihydroflavonols all give similar UV spectra as a result of their having little or no conjugation between the A- and B-rings. They are all readily distinguished from flavones and flavonols by their UV spectra, which typically exhibit an intense Band II absorption with only a shoulder or low intensity peak representing Band I.

The Ultraviolet Spectra of Isoflavones, Flavanones and Dihydroflavonols

6-methoxyflavonoids from Brickellia laciniata (Compositae)

Sesquiterpene lactones and diterpenoids from Helianthus argophyllus

Restriction site and length variations of nrDNA were examined for 51 populations of seven species ofKrigia. The nrDNA repeat ranged in size from 8.7 to 9.6 kilobase (kb). The transcribed region, including the two ITSs, was 5.35 kb long in all examinedKrigia populations. In contrast, the size of the nontranscribed IGS varied from 3.35 to 4.25 kb. Eight different types of length-variations were identified among the 51 populations, including distinct nrDNA lengths in the tetraploid and diploid populations of bothK. biflora andK. virginica. However, a few variations were detected among populations of the same species or within a cytotype. All populations ofKrigia sect.Cymbia share a 600 bp insertion in IGS near the 18 S gene, and this feature suggests monophyly of the section. AllKrigia spp. had a conjugated type of subrepeat composed of approximately 75 basepairs (bp) and 125 bp. Base modifications in the gene coding regions were highly conserved among species. Forty-five restriction sites from 15 enzymes were mapped, 24 of which were variable among populations. Only four of the variable sites occurred in the rRNA coding region while 20 variable sites were detected in the noncoding regions. Collectively, 25 enzymes generated about 66 restriction sites in each nrDNA; this amounts to about 4.3% of the nrDNA repeat. A total of 50 restriction sites was variable, 28 of which were phylogenetically informative. Phylogenetic analyses of site mutations indicated that two sections ofKrigia, sect.Cymbia and sect.Krigia, are monophyletic. In addition, relationships among several species were congruent with other sources of data, such as cpDNA restriction site variation and morphology. Both length and restriction site variation supported an allopolyploid origin of the hexaploidK. montana. The average sequence divergence value inKrigia nrDNA was 40 times greater than that of the chloroplast DNA. The rapid evolution of nrDNA sequences was primarily due to changes of the IGS sequences.

Phylogenetic and evolutionary implications of nuclear ribosomal DNA variation in dwarf dandelions (Krigia, Lactuceae, Asteraceae)

11,13-Dehydrodesacetylmatricarin and other sesquiterpene lactones from Artemisia ludoviciana var. ludoviciana and the identity of artecanin and chyrsartemin B

Tom J. Mabry

Papers

The Ultraviolet Spectra of Isoflavones, Flavanones and Dihydroflavonols

6-methoxyflavonoids from Brickellia laciniata (Compositae)

Sesquiterpene lactones and diterpenoids from Helianthus argophyllus

Phylogenetic and evolutionary implications of nuclear ribosomal DNA variation in dwarf dandelions (Krigia, Lactuceae, Asteraceae)

11,13-Dehydrodesacetylmatricarin and other sesquiterpene lactones from Artemisia ludoviciana var. ludoviciana and the identity of artecanin and chyrsartemin B