Absolute configurations of isoflavans

Kurosawa, Kazu; Ollis, W. D.; Redman, B. T.; Sutherland, I. O.; Alves, Herbert M.; Gottlieb, Otto R.

doi:10.1016/s0031-9422(00)94602-8

Cited by 46 publications

(22 citation statements)

References 20 publications

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“…Our ECD data and the sign of optical rotation were in good agreement with [21], which corroborates the (3R)-configuration of 4. As to compound 5 the negative sign of optical rotation agrees with the data reported before for the (3S)-enantiomer prepared by semisynthesis starting from (3S)duartin [23].…”

supporting

confidence: 89%

Antiprotozoal Isoflavan Quinones from Abrus precatorius ssp. africanus

et al. 2013

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A library of 206 extracts from selected South African plants was screened in vitro against a panel of protozoan parasites, Plasmodium falciparum, Trypanosoma brucei rhodesiense, and Leishmania donovani. A CH2Cl2/MeOH (1 : 1) extract of Abrus precatorius L. ssp. africanus strongly inhibited P. falciparum (98 %), T. b. rhodesiense (100 %), and L. donovani (76 %) when tested at a concentration of 10.0 µg/mL. The active constituents were tracked by HPLC-based activity profiling and isolated by preparative and semipreparative RP-HPLC chromatography. Structures were established by HR-ESIMS, and 1D and 2D NMR (1H, 13C, COSY, HMBC, HSQC, and NOE difference spectroscopy). Five compounds were obtained and identified as two isoflavan hydroquinones, abruquinone H (1) and abruquinone G (2), and three isoflavan quinones, abruquinone I (3), abruquinone B (4), and 7,8,3''5'-tetramethoxyisoflavan-1',4'-quinone (5). Compounds 1 and 3 were new natural products. The absolute configuration of compounds was determined by comparison of electronic circular dichroism spectra with calculated ECD data. Compounds 3 and 4 showed strong activity against T. b. rhodesiense (IC50 values of 0.30 and 0.16 µM, respectively) and good selectivity (selectivity indices of 73.7 and 50.5, respectively).

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confidence: 89%

Antiprotozoal Isoflavan Quinones from Abrus precatorius ssp. africanus

et al. 2013

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“…A circular dichroism (CD) spectrum was obtained on another portion of the vestitone generated using the IFR-active clone. Although a quantitative measurement was not made, the strong positive signal (Cotton effect) in the 320 to 345 nm region is characteristic of (3R)-vestitone [20]. (Chemically synthesized racemic vestitone showed no CD effect.)…”

Section: Isolation and Identification Of An Alfalfa Ifr Cdnamentioning

confidence: 99%

Stress responses in alfalfa (Medicago sativa L.) 11. Molecular cloning and expression of alfalfa isoflavone reductase, a key enzyme of isoflavonoid phytoalexin biosynthesis

et al. 1991

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The major phytoalexin in alfalfa is the isoflavonoid (-)-medicarpin (or 6aR, 11aR)-medicarpin. Isoflavone reductase (IFR), the penultimate enzyme in medicarpin biosynthesis, is responsible for introducing one of two chiral centers in (-)-medicarpin. We have isolated a 1.18 kb alfalfa cDNA (pIFRalf1) which, when expressed in Escherichia coli, converts 2'-hydroxyformononetin stereospecifically to (3R)-vestitone, as would be predicted for IFR from alfalfa. The calculated molecular weight of the polypeptide (35,400) derived from the 954 bp open reading frame compares favorably to estimated Mrs determined for IFR proteins purified from other legumes. The transcript (1.4 kb) is highly induced in elicited alfalfa cell cultures. The kinetics of induction are consistent with the appearance of IFR activity, the accumulation of medicarpin, and the observed induction of other enzymes in the pathway. Low levels of IFR transcripts were found in healthy plant parts (roots and nodules) which accumulate low levels of a medicarpin glucoside. IFR appears to be encoded by a single gene in alfalfa. The cloning of IFR opens up the possibility of genetic manipulation of phytoalexin biosynthesis in alfalfa by altering isoflavonoid stereochemistry.

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“…2) between δ H = 6.79 (H-6′) with δ H = 2.82 (H-4) and the methoxy group at δ H = 3.74 located the other methoxy group at C-5′. The absolute configuration at C-3 was assigned to be S from its CD spectrum, which showed a positive Cotton effect at 229 nm and a negative Cotton effect at 297 nm [10,11]. From these data, compound 1 was identified as 3(S)-7,2′,4′-trihydroxy-5,5′-dime- [12].…”

Section: Resultsmentioning

confidence: 99%

Isoflavonoids from the Roots ofCampylotropis hirtella

Shou¹,

Tan²,

Shen³

2009

Planta Med

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From the dried roots of Campylotropis hirtella (Franch.) Schindl., five novel isoflavonoids, 3( S)-7,2',4'-trihydroxy-5,5'-dimethoxy-6-(3-methylbut-2-enyl)-isoflavan ( 1), 3( S)-2',4'-dihydroxy-5,5'-dimethoxy-(6'',6''-dimethylpyrano)-(2'',3'':7,6)-isoflavan ( 2), 3( R)-5,4'-dihydroxy-2'-methoxy-3'-(3-methylbut-2-enyl)-(6'',6''-dimethylpyrano)-(7,6 : 2'',3'')-isoflavanone ( 3), 3( R)-5,4'-dihydroxy-2'-methoxy-(6'',6''-dimethylpyrano)-(7,6: 2'',3'')-isoflavanone ( 4), and 3( R)-5,4'-dihydroxy-7,2'-dimethoxy-6-geranylisoflavanone ( 5) were isolated. The structures of the compounds were elucidated on the basis of spectroscopic analysis. All isolates exhibited good immunosuppressive activities on mitogen-induced splenocyte proliferation, and their cytotoxicity on splenic lymphocytes was also tested.

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Absolute configurations of isoflavans

Cited by 46 publications

References 20 publications

Antiprotozoal Isoflavan Quinones from Abrus precatorius ssp. africanus

Antiprotozoal Isoflavan Quinones from Abrus precatorius ssp. africanus

Stress responses in alfalfa (Medicago sativa L.) 11. Molecular cloning and expression of alfalfa isoflavone reductase, a key enzyme of isoflavonoid phytoalexin biosynthesis

Isoflavonoids from the Roots ofCampylotropis hirtella

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