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Tom J. Mabry

Bio: Tom J. Mabry is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Kaempferol & Sesquiterpene lactone. The author has an hindex of 42, co-authored 459 publications receiving 13375 citations. Previous affiliations of Tom J. Mabry include University of Illinois at Urbana–Champaign & Minia University.


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TL;DR: In this article, a 3,2'-dioxygenated flavonoids with planarity reduction and reduced conjugation of the B-ring chromophore with the A-ring was studied.
Abstract: C20H20O10, Mr = 420.37, triclinic, P1, a = 8.771 (3), b = 13.508 (3), c = 15.970 (4) A, alpha = 86.04 (2), beta = 81.77 (2), gamma = 84.17 (2) degrees, V = 1860.0 (8) A3, Z = 4 (two molecules per asymmetric unit), Dm (by flotation in ZnCl2/H2O solution at 298 K) = 1.491, Dx = 1.503 g cm-3, Mo K alpha radiation, lambda = 0.71069 A, mu = 1.14 cm-1, F(000) = 880, T = 163 K. Full-matrix least-squares refinement converged to R = 0.039 and wR = 0.037 using 5198 reflections with I greater than 3 sigma (I). The two molecules in the asymmetric unit differ in the torsion angles involving the methoxy groups and in the dihedral angle between the planes of rings B and C, 33.31 (7) and 40.83 (7) degrees in molecules (I) and (II), respectively. This compound belongs to a class of 3,2'-dioxygenated flavonoids whose ultraviolet (UV), mass spectroscopic (MS) and chromatographic properties indicate that in solution these compounds have reduced planarity (and thus reduced conjugation) of the B-ring chromophore with the A, C-ring chromophore.
Journal ArticleDOI
TL;DR: The planar A ring has a typical chair conformation and the C and D rings assume 13 beta, 14 alpha-half-chair and 13 beta-envelope conformations, respectively.
Abstract: C24H30O4, Mr = 382.5, orthorhombic, P212121, a = 13.091 (2), b = 19.711 (1), c = 8.242 (1) A, V = 2126.7 (5) A3, Z = 4, Dx = 1.195 Mg m-3, lamba (Cu K alpha) = 1.54184 A, mu(Cu K alpha) = 0.56 mm-1, F(000) = 824, T = 295 K. Final R = 0.045 for 2446 unique reflections. The planar A ring is bent relative to the rest of the steroid skeleton. The B ring has a typical chair conformation and the C and D rings assume 13 beta,14 alpha-half-chair and 13 beta-envelope conformations, respectively. The conformation of the progesterone side chain is similar to the conformation observed in other 17 alpha-ester pregnanes: C16-C17-C20-O20 torsion angle -27.4(3) degrees.
01 Jan 1995
TL;DR: Cl cladistic analyses of chloroplast DNA variation were used to investigate evolutionary relationships within Iva s.
Abstract: Cyclachaena, and Iva s. str.), while others recognize only a single genus Iva s. 1. Although chemical, pollen ultrastructure, and other morphological data have challenged the latter concept, relationships among the segregate taxa are still unclear. The current study used cladistic analyses of chloroplast DNA variation to investigate evolutionary relationships within Iva s. 1., especially within the controversial section Cyclachaena. Nuclear rDNA was also utilized to test for hybrid origin of selected taxa. The results support the dismemberment of Iva s. 1. and recognition of Iva s. str., largely because Iva s. 1. is shown to be paraphyletic. Most members of the section Cyclachaena were found to have relatively close interspecific relationships. Nevertheless, cpDNA data strongly support two lineages within Cyclachaena. One lineage, including L xanthifolia, L acerosa, L nevadensis, and I. dealbata, has a close relationship with the genus Euphrosyne. The second lineage includes only one species, L ambrosiaefolia, which is closely related to Dicoria. The origin of L ambrosiaefolia was shown to be monophyletic, not involving hybridization. One of the major systematic problems in the Asteraceae has been generic circumscription (Lane and Turner, 1985). The family has apparently undergone rapid radiation and differentiation over a relatively short period of time (Raven and Axelrod, 1974). The complex variation pattern has made generic delineation difficult, especially in the subtribe Ambrosiinae. The generic concepts have long been argued, especially the circumscription of Iva and related genera (Miao, Turner, and Mabry, in press; Miao et al., in press) Iva was established by Linnaeus in 1753 in his Species Plantarum. At that time, only two species, I. annua and I. frutescens, were recognized. With the increasing number of new species discovered in New World, controversy as to generic limits of Iva arose. Fresenius (1838) established the genus Cyclachaena based upon Iva xanthifolia; Gray (1853), however, placed it in the genus Euphrosyne. Later, Gray (1886) repositioned this in Iva. Instead of splitting Iva into several smaller genera, Gray (1886) and Hoffmann (1890) treated these as sections Euiva, Cyclachaena, and Chorisiva within an expanded Iva. This arrangement widely influenced subsequent taxonomic workers, but the controversy of generic status for various sectional units

Cited by
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TL;DR: The factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase.

8,513 citations

Journal ArticleDOI
TL;DR: A revised and updated classification for the families of the flowering plants is provided in this paper, which includes Austrobaileyales, Canellales, Gunnerales, Crossosomatales and Celastrales.

7,299 citations

Journal Article
TL;DR: Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional, and suggestions are made where such possibilities may be worth pursuing.
Abstract: 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.

4,663 citations

Journal ArticleDOI
TL;DR: In this article, two complementary colorimetric methods, aluminum chloride method and 2,4-dini trophenylhydrazine method, were used to determine the real content of total flavonoids in propolis.

3,899 citations

Journal ArticleDOI
TL;DR: Several high-quality investigations have examined the relationship between flavonoid structure and antibacterial activity and these are in close agreement, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.

3,630 citations