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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.


Papers
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Journal ArticleDOI
TL;DR: The conformations of the two conformational isomers of isabelin (1), a germacranolide dilactone isolated from Ambrosia psilostachya DC. (Compositae), have been determined in chloroform solution by use of the intramolecular nuclear Overhauser effect; and further, the configuration of the endocyclic double-bond in its ten-membered ring has been confirmed as mentioned in this paper.
Abstract: The conformations of the two conformational isomers of isabelin (1), a germacranolide dilactone isolated from Ambrosia psilostachya DC. (Compositae), have been determined in chloroform solution by use of the intramolecular nuclear Overhauser effect; and further, the configuration of the endocyclic double-bond in its ten-membered ring has been confirmed. It has been concluded that the major and minor isomers of isabelin mainly adopt the conformations (A) and (B), respectively, which have a trans-orientation of the endocyclic double-bond. Since isabelin has been correlated with artemisiifolin (3), salonitenolide (4), and cnicin (5), the results obtained here have also established a trans configuration for these three germacranolide monolactones. In addition, isoisabelin (2), a geometrical isomer of isabelin, has been examined to determine the configuration of its C(9)–C(10) double-bond and its conformation.

4 citations

Journal ArticleDOI
TL;DR: It was shown that xylulose does not inhibit or otherwise influence the Hill reaction in this alga and is not implicated in the growth of Chlorococcum echinozygotum.
Abstract: SUMMARY We previously established that xylulose inhibits the growth of the green alga Chlorococcum echinozygotum. Utilizing experiments involving exposure of the alga to NaHC14O3, it was possible to show by counting the C14 activity of methanolic extracts of the algal cells that xylulose inhibited CO2 uptake. Subsequently it was shown that xylulose does not inhibit or otherwise influence the Hill reaction in this alga. Several enzymes related to xylulose metabolism were investigated. It was found that xylulokinase was active in C. echinozygotum while phosphoketolase activity was absent. Transketolase was present but its activity was not notably affected by xylulose. Crude carboxydismutase preparations were found to be inhibited by xylulose and xylulose 5-phosphate. However, as carboxydismutase was purified further, this inhibition was relatively less. When xylulose 1,5-diphosphate was prepared synthetically, this compound was found to be the most effective inhibitor of purified algal carboxydismutase. We conclude that d-xylulose enters the cells of C. echinozygotum where it is converted to d-xylulose 1,5-diphosphate which acts as a competitive inhibitor of carboxydismutase.

4 citations

Journal ArticleDOI
TL;DR: 2-(3,4-Dimethoxyphenyl)-5,7-dihydroxy-6,8-dimethoxy-4H-chromen-4-o ne, C19H18O8, Mr = 374.38, monoclinic, P2(1)/n, a = 9.026(4), b = 15.054(6), c = 12.829(6) A, beta = 100.98
Abstract: 2-(3,4-Dimethoxyphenyl)-5,7-dihydroxy-6,8-dimethoxy-4H-chromen-4-o ne, C19H18O8, Mr = 374.38, monoclinic, P2(1)/n, a = 9.026(4), b = 15.054(6), c = 12.829(6) A, beta = 100.98(4) degrees, V = 1711(1) A3, Z = 4, Dx = 1.450 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.07 cm-1, F(000) = 784, T = 295 K, R = 0.0778 for 2280 independent reflections. The nearly planar AB ring system (0.04 A r.m.s.d.), O(1) to C(10), and the planar C ring (0.001 A r.m.s.d.) are almost coplanar with an interplanar angle of only 4.4(4) degrees. The methyl groups at C(6) and C(8) are rotated out of the molecular plane on opposite sides with torsion angles C(5)C(6)O(6)C(11) = -94.5(4) and C(7)C(8)O(8)C(12) = 109.0(4) degrees. The methyl groups of ring C are coplanar with the ring, C(3')C(4')O(4')"(13) = 0.2(5) and C(6')C(5')O(5')C(14) = 1.3(5) degrees. The carbonyl group forms an intramolecular hydrogen bond with O(5), O(5)...O(4) = 2.612(5), H(5O)...O(4) = 1.85(4) A, O(5)-H(5O)...O(4) = 151.9(8) degrees, and an intermolecular hydrogen bond with O(7) of an adjacent molecule, O(7)...O(4) (-0.5 + x, -0.5 - y, 0.5 + z) = 2.689(5), H(7O)...O(4) = 1.92(4) A, and O(7)-H(7O)...O(4) = 163.2(8) degrees.

4 citations

Journal ArticleDOI
TL;DR: Hasakol, an inhibitor against Ba++-induced contraction of smooth muscles, has been synthesized in six steps starting from 7-O-geranylumbelliferone via an improved Claisen rearrangement as mentioned in this paper.
Abstract: Hasakol, an inhibitor against Ba++-induced contraction of smooth muscles, has been synthesized in six steps starting from 7-O-geranylumbelliferone via an improved Claisen rearrangement.

3 citations


Cited by
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Journal ArticleDOI
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