1.Anti-inflammatory flavonoids and pterocarpanoid from Crotalaria pallida and C. assamica.
Ko HH1, Weng JR, Tsao LT, Yen MH, Wang JP, Lin CN. Bioorg Med Chem Lett. 2004 Feb 23;14(4):1011-4.
One new isoflavone, 5,7,4'-trihydroxy-2'-methoxyisoflavone (3) and seven, and four known compounds were isolated from the barks of Crotalaria pallida and the seeds of C. assamica, respectively. The known compounds, apigenin (1) and 2'-hydroxygenistein (2), isolated from C. pallida, showed significant concentration-dependent inhibitory effects on the release of beta-glucuronidase and lysozyme from rat neutrophils in response to formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB) with IC(50) values of 2.8+/-0.1 and 17.7+/-1.9, and 5.9+/-1.4 and 9.7+/-3.5 microM, respectively. The known compounds, daidzein (4) and 2'-hydroxydaidzein (6), isolated from C. pallida, inhibited of the release of lysozyme and beta-glucuronidase from rat neutrophils in response to fMLP/CB with IC(50) values of 26.3+/-5.5 and 13.7+/-2.6 microM, respectively. Compounds 1 and 4 also showed significant concentration-dependent inhibitory effects on superoxide anion generation in rat neutrophils stimulated with fMLP/CB with IC(50) values of 3.
2.CYP81E1, a cytochrome P450 cDNA of licorice (Glycyrrhiza echinata L.), encodes isoflavone 2'-hydroxylase.
Akashi T1, Aoki T, Ayabe S. Biochem Biophys Res Commun. 1998 Oct 9;251(1):67-70.
The microsome of yeast cells overexpressing CYP81E1, a cytochrome P450 cDNA recently cloned from licorice (Glycyrrhiza echinata L., Fabaceae), catalyzed the hydroxylation of isoflavones, daidzein and formononetin, to yield 2'-hydroxyisoflavones, 2'-hydroxydaidzein, and 2'-hydroxyformononetin, respectively. The chemical structures of the reaction products were confirmed by mass spectrometric analysis. Genistein also yielded a putative 2'-hydroxylated product, but flavanones and cinnamic acid derivatives were not used as substrates for the reaction with the recombinant yeast microsome. CYP81E1 protein was thus demonstrated for the first time to be isoflavone 2'-hydroxylase involved in the biosynthesis of isoflavonoid-derived antimicrobial compounds of legumes.
3.Phytoalexin synthesis in soybean: purification and characterization of NADPH:2'-hydroxydaidzein oxidoreductase from elicitor-challenged soybean cell cultures.
Fischer D1, Ebenau-Jehle C, Grisebach H. Arch Biochem Biophys. 1990 Feb 1;276(2):390-5.
An NADPH:2'-hydroxydaidzein oxidoreductase (HDR) from elicitor-challenged soybean cell cultures was purified to apparent homogeneity by a five-step procedure. The purification procedure included affinity adsorption on Blue Sepharose and elution of the enzyme with NADP+. It was shown by gel filtration and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis that HDR consists of only one polypeptide, which has a Mr about 34,700. The pH optimum of the reaction was 7.0. Apparent Michaelis constants determined for 2'-hydroxydaidzein, 2'-hydroxyformononetin, and NADPH were, respectively, 50, 60, and 56 microM. A low conversion of 2'-hydroxygenistein to the corresponding isoflavanone was also observed but isoflavones lacking a 2'-hydroxyl group and various other flavonoids did not serve as substrates. Enzymatically derived 2'-hydroxydihydrodaidzein gave a positive CD spectrum at 328 nm, which shows its 3R stereochemistry. Antibodies against HDR were raised in rats.