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Showing papers by "Tom J. Mabry published in 1968"


Journal ArticleDOI
TL;DR: It is concluded that the aromatic ring of dopa is cleaved and that re-cyclization involving the nitrogen generates the dihydropyridine moiety.
Abstract: During studies on the biogenesis of betalains (I) in cactus fruits (Opuntia sp.). DL-dopa-1-[14C] and -2-[14C] were incorporated into betanin (III) which was obtained radiopure after crystallization. The specific activity remained constant after conversion to betanidin (IV) and to a neobetanidin derivative (IX). Reaction of radiobetanin with proline afforded indicaxanthin (V) carrying more than 90% of the radioactivity. Dopa (VI) is thus an efficient precursor for betalamic acid (VIII) but not for cyclodopa (VII). Decarboxylation of radiobetanidin and radioindicaxanthin showed that the carboxyl group of dopa remained a carboxyl group in the biotransformation to betalamic acid. It is concluded that the aromatic ring of dopa is cleaved and that re-cyclization involving the nitrogen generates the dihydropyridine moiety. Under the same conditions mevalonic acid, aspartic acid and phenylalanine showed low incorporations. Studies with beet seedlings and DL-dopa-1-[14C], -2-[14C] and DL-tyrosine-1-[14C] afforded similar results but with low incorporations.

46 citations


Journal ArticleDOI
TL;DR: In this paper, a spectroscopic procedure using anhydrous AlCl 3 and AlCl3 /HCl was described for the detection of ortho-dihydroxyl groups in flavonoids.

42 citations


Journal ArticleDOI
TL;DR: Lecontin and (+)-fustin glucoside, two new members of the rare group of flavonoids the dihydroflavonol 3-O-glycosides, are shown to have structures I and II, respectively.

34 citations


Journal ArticleDOI
TL;DR: The structure and stereochemistry of tamaulipin-A (Ia), a new germacranolide isolated from Ambrosia confertiflora, was determined in part by conversion to a product also derived from saussurea lactone, a sesquiterpene lactone of known absolute structure as mentioned in this paper.

33 citations





Journal ArticleDOI
TL;DR: A new flavone, scaposin, has been isolated from Hymenoxys scaposa (Compositae) and its structure established as 5,5',7-trihydroxy-3,4,6,8-tetramethoxyflavone by synthesis as discussed by the authors.

15 citations


Journal ArticleDOI
TL;DR: The isolation of 2 inhibitory compounds derived from xylose during autoclaving, and the identification of one of them as xylulose are reported.
Abstract: The growth of Chlorococcum echinozygotum was previously known to be inhibited by an autoclaved solution of xylose in Bold's modified Bristol's medium. We now report the isolation of 2 inhibitory compounds derived from xylose during autoclaving, and the identification of one of them as xylulose. Two strains of C. echinozygotum were isolated, one of which had physiologically adapted to xylulose. The growth rates of both strains were studied using varying amounts of xylulose. Cell counting studies indicated that the zoospores of the unadapted strain were most severely affected by xylulose inhibition and that the zygospores were most resistant.

4 citations