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Showing papers by "Tom J. Mabry published in 1970"



Book ChapterDOI
01 Jan 1970
TL;DR: The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 - 400 nm1 as discussed by the authors, and these two peaks are commonly referred to as Band I (usually 300 − 380 nm, Table V-1 records the λmaxvalues for Band I for all flavones examined in the present investigation), and Band II (usually 240 - 280 nm).
Abstract: The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 – 400 nm1. These two peaks are commonly referred to as Band I (usually 300 – 380 nm, Table V-1 records the λmaxvalues for Band I for all flavones and flavonols examined in the present investigation), and Band II (usually 240 – 280 nm). Band I is considered to be associated with absorption due to the B-ring cinnamoyl system, and Band II with absorption involving the A-ring benzoyl system (see III) [1].

208 citations


Journal ArticleDOI
H. Yoshioka1, W. Renold1, N.H. Fischer1, Akio Higo1, Tom J. Mabry1 
TL;DR: In this paper, the isolation and chemistry of four eudesmanolides, reynosin (III), santamarine (IV), α-epoxysantamarine(V), and isotelekin (VII) from Ambrosia confertiflora collected in Mexico were described.

84 citations


Book ChapterDOI
01 Jan 1970
TL;DR: In this paper, fresh cut metallic sodium (2.5 g) was added cautiously in small portions to dry spectroscopic methanol (100 ml), stored in a glass container with a tightly fitting plastic stopper.
Abstract: Sodium methoxide (NaOMe). Freshly cut metallic sodium (2.5 g) was added cautiously in small portions to dry spectroscopic methanol (100 ml). The solution was stored in a glass container with a tightly fitting plastic stopper.

69 citations


Journal ArticleDOI
TL;DR: Distributional data for sixty-two flavonoids and two coumarins in all 17 spp.

42 citations


Book ChapterDOI
01 Jan 1970
TL;DR: 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.
Abstract: 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.

40 citations


Journal ArticleDOI
01 Dec 1970-Taxon
TL;DR: All evidence indicates that the two classes of plant pigments, betalains and anthocyanins, are mutually exclusive.
Abstract: In 1949 betalains were reported to possibly co-occur with an anthocyanidin (cyanidin) in Carpobrotus edulis; however, upon re-examination of this plant, only betalains and leucoanthocyanidins were detected. Thus, to date, all evidence indicates that the two classes of plant pigments, betalains and anthocyanins, are mutually exclusive. The detection of betalains in seven species belonging to the family Amaranthaceae and ten species of the Chenopodiaceae are also reported.

31 citations



Journal ArticleDOI
TL;DR: The structure assigned to artemisiifolin was previously ascribed to a salonitenolide, a germacranolide from Centaurea saloitana Vis, but preliminary studies suggest that the structure of salonitanolide should be revised to formula II.

21 citations


Book ChapterDOI
01 Jan 1970
TL;DR: Two-dimensional paper chromatography represents one of the best methods for the rapid separation of mixtures of flavonoids from crude methanol or methanoline-water extracts of dried plant material.
Abstract: Two-dimensional paper chromatography represents one of the best methods for the rapid separation of mixtures of flavonoids from crude methanol or methanol-water extracts of dried plant material. Furthermore, sufficient quantities of the separated compound for both hydrolytic and ultraviolet spectral analyses often can be isolated from about 30 chromatograms. The present discussion will emphasize the chromatographic techniques routinely employed in this laboratory for the analysis of flavonoids; however, a number of other procedures and variations have been published elsewhere [1, 2]

19 citations



Journal ArticleDOI
TL;DR: The major flavonoid of Oenothera speciosa has been shown to be a new natural product, myricetin 3-O-methyl ether 3′-Oβ-d -glucoside as mentioned in this paper.


Journal ArticleDOI
TL;DR: In this article, phenylalanine-1-14 C-labeled vitexin (I) and isovitexins (II) were obtained from Spirodela species cultured on a medium containing phenYLalanine 1- 14 C, and were introduced in separate experiments into the growth media for Lemna minor plants, a species which normally produces both of these C -glycosylflavones.

Book ChapterDOI
01 Jan 1970
TL;DR: In this article, NMR spectra are presented in order of increasing oxidation and substitution of the flavonoid nucleus for flavones, flavonols, isoflavones, dihydroflavonol, flavanones, chalcones and aurones.
Abstract: NMR spectra are presented in order of increasing oxidation and substitution of the flavonoid nucleus for flavones, flavonols, isoflavones, dihydroflavonols, flavanones, chalcones and aurones.


Book ChapterDOI
01 Jan 1970
TL;DR: In this article, the UV spectra of both chalcones and aurones are characterized by an intense Band I and a diminished Band II absorption, which is consistent with the spectral properties of chalcone and aurone pigments.
Abstract: Chalcones and aurones, which are often referred to as the “anthochlor” pigments because many turn red on contact with alkali, are relatively rare types of flavonoids [1]. Detailed spectral analyses, in particular of synthetic chalcones and aurones, have been published elsewhere [2 – 5], but for completeness a number have been included here. The UV spectra of both chalcones and aurones are characterized by an intense Band I and a diminished Band II absorption.

Book ChapterDOI
01 Jan 1970
TL;DR: The application of NMR spectroscopy to the structure analysis of flavonoids is now well established as discussed by the authors, however, most naturally occurring flavonoid glycosides have low solubility in CDC13; therefore most workers were limited to the NMR analysis of the more soluble methyl, ethyl and acetyl derivatives.
Abstract: The application of nuclear magnetic resonance (NMR) spectroscopy to the structure analysis of flavonoids is now well established. Many flavonoid aglycones, in particular isoflavones and highly methylated flavones and flavonols, are sufficiently soluble in the commonly used solvent, deuteriochloroform (CDC13) for direct NMR analysis. However, most naturally occurring flavonoids, including all of the flavonoid glycosides, have low solubility in CDC13; therefore, prior to 1964 most workers were limited to the NMR analysis of the more soluble methyl, ethyl and acetyl derivatives (see for example reference [1]). However, the signals observed for the substituent groups in these derivatives often obscure signals of other protons in the flavonoid.

Book ChapterDOI
01 Jan 1970
TL;DR: The procedures discussed in Chapters I and II were concerned with the isolation and purification of flavonoids as discussed by the authors, and the standard procedure is to hydrolyze it and proceed with the identification of the aglycone and sugar (or sugars) so produced.
Abstract: The procedures discussed in Chapters I and II were concerned with the isolation and purification of flavonoids. If the pure flavonoid is suspected to be a glycoside (e.g. from solubility and paper chromatographic properties), the standard procedure is to hydrolyze it and proceed with the identification of the aglycone and sugar (or sugars) so produced.

Journal ArticleDOI
TL;DR: The structures of two new pseudoguaianolides, tetraneurin-B (2 ) and -C (3 ), first isolated from Parthenium alpinum var. tetranuris, have been established as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, the structure revision of the germacranolide salonitenolide and the preferential C-8 relactonization of GCLs containing C-6 and C8 lactonizable α-oxygen groups are described.
Abstract: The structure revision of the germacranolide salonitenolide and the preferential C-8 relactonization of germacranolides containing C-6 and C-8 lactonizable α-oxygen groups are described.

Book ChapterDOI
01 Jan 1970
TL;DR: A typical charcoal procedure for the preliminary purification of the flavonoid glycosides in a crude extract obtained from Baptisia lecontei plant material is presented in this paper.
Abstract: Charcoal is useful for the preliminary purification of a mixture of flavonoids, particularly flavonoid glycosides, which are usually present in a crude aqueous or aqueous-methanolic extract of plant material [1]. The charcoal procedure described below separates flavonoids from most non-aromatic plant constituents such as the common carbohydrates. The method is especially useful for flavonoid glycosides which are readily recovered almost quantitatively from the charcoal with water containing 7% phenol (i. e. a saturated aqueous solution at room temperature). Although many aglycones can also be recovered, at least in part, from the charcoal, the procedure is not recommended for their purification. Aglycones can often be extracted directly from a crude syrup obtained from a plant extract with a solvent such as ethyl acetate, while their complete recovery from charcoal many require the use of pyridine as eluent. A typical charcoal procedure is presented below for the preliminary purification of the flavonoids in a crude extract obtained from Baptisia lecontei plant material.

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.