Further Constituents of Alphitonia Species

Guise, G. Bruce; Ritchie, E; Taylor, WC

doi:10.1071/ch9620314

Cited by 28 publications

(21 citation statements)

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“…The structure of alphitonin, isolated from the heartwood of Alphitonia excelsa, was reported in 1960 (1). The compound was also identified in the wood of Alphitonia petriei but not in that of Alphitonia whitei (7). Remarkably, no studies on the biological activity of alphitonin have been reported so far.…”

Section: Discussionmentioning

confidence: 89%

Degradation of Quercetin and Luteolin byEubacterium ramulus

Braune

Gütschow

Engst

et al. 2001

Appl Environ Microbiol

210

155

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The degradation of the flavonol quercetin and the flavone luteolin by Eubacterium ramulus, a strict anaerobe of the human intestinal tract, was studied. Resting cells converted these flavonoids to 3,4-dihydroxyphenylacetic acid and 3-(3,4-dihydroxyphenyl)propionic acid, respectively. The conversion of quercetin was accompanied by the transient formation of two intermediates, one of which was identified as taxifolin based on its specific retention time and UV and mass spectra. The structure of the second intermediate, alphitonin, was additionally elucidated by 1 H and 13 C nuclear magnetic resonance analysis. In resting-cell experiments, taxifolin in turn was converted via alphitonin to 3,4-dihydroxyphenylacetic acid. Alphitonin, which was prepared by enzymatic conversion of taxifolin and subsequent purification, was also transformed to 3,4-dihydroxyphenylacetic acid. The coenzyme-independent isomerization of taxifolin to alphitonin was catalyzed by cell extract or a partially purified enzyme preparation of E. ramulus. The degradation of luteolin by resting cells of E. ramulus resulted in the formation of the intermediate eriodictyol, which was identified by high-performance liquid chromatography and mass spectrometry analysis. The observed intermediates of quercetin and luteolin conversion suggest that the degradation pathways in E. ramulus start with an analogous reduction step followed by different enzymatic reactions depending on the additional 3-hydroxyl group present in the flavonol structure.Flavonoids are polyphenolic compounds which are present in foods and beverages of plant origin. The daily intake of flavonoids calculated on the basis of the aglycones was estimated to range from approximately 3 to 70 mg in different countries, and it may well exceed these values in regions with a very high intake of tea and vegetables (5, 10, 13). In vivo data on absorption and metabolism after oral intake are contradictory. However, a major part of ingested flavonoids are not absorbed and are largely degraded by the intestinal microflora.It was shown in vitro that flavonoids are potent antioxidants and inhibitors of ubiquitous enzymes, and their anticarcinogenic properties were demonstrated with different cell lines (for a review, see reference 8). Due to these properties, flavonoids are reported to protect against cancer, coronary heart disease, and stroke. In order to judge the potential beneficial health effects of flavonoids in humans, studies on their fate in the gastrointestinal tract, including transformation by bacteria, are necessary. Intestinal bacteria play important roles not only in deconjugation of flavonoids but also in their further degradation. The bacterial metabolites, which possibly exert biological activities different from those of the original flavonoids, may be absorbed and further metabolized in the human body. Therefore, it is essential to study their conversion by intestinal bacteria and to identify and characterize the fermentation products formed. Although some flavonoid-degrading species...

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Section: Discussionmentioning

confidence: 89%

Degradation of Quercetin and Luteolin byEubacterium ramulus

Braune

Gütschow

Engst

et al. 2001

Appl Environ Microbiol

210

155

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“…3 Alphitolic acid (2a-hydroxybetulinic acid, 3), which possesses various pharmacological properties such as antibacterial, anti-inflammatory, antiproliferative, antiplasmodial, anti-HIV activities, [4][5][6][7][8] was firstly isolated from the ethereal extract of Alphitonia whitei Braid. 9,10 In this study, we developed efficient synthetic approaches to 3 and related isomeric 2,3-dihydroxy lupanes 4-10 11,12 so as to assist further pharmaceutical research on these biologically important molecules. To the best of our knowledge, this is the first synthesis of 3.…”

Section: Introductionmentioning

confidence: 99%

Efficient access to isomeric 2,3-dihydroxy lupanes: first synthesis of alphitolic acid

Jia¹,

Zhang²,

Zhang³

et al. 2009

Tetrahedron

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“…This genus is composed of approximately 20 species growing in tropical regions of Southeast Asia, Oceania and Polynesia (Correa et al, 2010, Richardson et al, 2000. A range of phenolic compounds has already been identified from various Alphitonia species (Branch et al, 1972, Guise et al, 1962, Jou et al, 2004. More precisely, flavonoids have been identified in the leaves (Lin et al, 1995) and fruit (Muhammad et al, 2015) of A. neocaledonica.…”

Section: Introductionmentioning

confidence: 99%