Vitexin

The 2 -0-glucosylahon of vitexin and isovitexin in petals of Silene alba is catalyzed by two different enzymes. Phytochemistry 19 1935-1937. 

Fig. 2.50. Profiles of calendula (a), milk-thistle (b) and passion flower (c) tinctures (each 60 per cent v/v, ethanol) with the HPLC-MS attributions of the components detected, lc = quercetin-3-O-ruti-nosylrhamnoside 2c = rutin 3c = isorhamnetin-3-O-ruti-nosylrhamnoside 4c = isoquercitrin 5c = isorhamnetin-3-O-gluco-sylglucoside 6c = narcissin 7c = isorhamnetin-3-O-glucoside lm = taxifolin 2m = siliydianin 3m = silychristin 4m = oxy derivative of silybin/isosilybin isomers 5m and 6m = 2,3-dehydro derivatives of silybin/isosilybin isomers 7m = silybin 8m = isosilybin lp = 6,8-diC-glucosylapigenin 2p = isoschaftoside 3p = shaftoside 4p = homoorientin 5p = isovetexin-2"-0-glucoside 6p = vitexin. Reprinted with permission from A. R. Biha et al. [150].

There are three categories of constituents in passionflower flavonoids, maltol, and indole alkaloids. Among flavonoids are chrysin (5,7-dihydro flavone), vitexin, coumerin, and umbelliferone (figure 6.6). The greatest accumulation of flavonoids occurs in the leaves (Menghini and... 

Other flavones in passionflower (vitexin, coumerin, umbelliferone) have not been well characterized for their neuropharmacological action. Vitexin (derived from millet in one study) was found to have antithyroid properties. The remaining constituents, maltol and harman alkaloids, are present in small quantities and not presumed to contribute to the psychotropic effects (Meier 1995). Harman alkaloids in greater quantities are hallucinogenic and presumed to work through 5-HT receptors (Grella et al. 1998). 

Kerscher, F. and Franz, G., Biosynthesis of vitexin and isovitexin enzymatic synthesis of the C-glucosylflavones vitexin and isovitexin with an enzyme preparation from Fagopyrum esculentum M. seedlings. Z. Naturforsck, 42c, 519, 1987. 

Diets rich in millet have been associated with endemic goiter in parts of West Africa where millet is a staple. The damage has been attributed to vitexin, a C-glycosyl flavone, that in rats has antithyroid activity and that in vitro inhibits thyroid peroxidase and the free radical iodination step in thyroid hormone biosynthesis. Isoflavones have produced similar antithyroid effects in rats, but clinical studies in adults have not. " However, this remains a possible concern in infants fed soya-based milk-replacers, especially if iodine supply is compromised. 

C-(4-OH-l-ethyl benzene) isovitexin ( ) 8-C- -OH benzyl isovitexin (5,7,4 -triOH 6-Glc 8-OH-benzyl) Vitexin... 

Hydroxy-1-ethylbenzene derivatives of vitexin and isovitexin (cucumerin A and B, two regioisomers) were studied by H and C NMR analysis with DEPT, TOCSY, and COSY experiments HMBC and NOESY correlations were also used for assignment of the hydro-xyethylbenzene residue. 

Terminalia catappa, Combretaceae, commonly used in the folk medicine in Taiwan, contains several C-glycosylflavones, two of them galloyl esters of vitexin and isovitexin. The isolated compounds were tested for antioxidative activity on Cu " /02-induced low-density lipoprotein peroxidation. IC50 values were 2.1 pM for vitexin derivatives and 4.5 pM for isovitexin derivatives compared to 4.0 pM for probucol chosen as positive control. 

C-Glycosylflavones of Arum palaestinum showed antimicrobial activity against E. coli and Staphylococcus aureus, which were the most susceptible bacteria to vitexin and isoorientin. Antimicrobial activity was also described for C-glycosylflavones from Otostegia fruticosa vicenm-2. ... 

Arum palaestinum contains isoorientin and vitexin, which were studied for their antispasmodic activity on isolated organs. Isoorientin in concentrations ranging from 10 to 6 X 10 M decreased the frequency and the amplitude of the phasic contractions of uterine... 

Extracts of leaves of Combretum quadrangulare showed promising hepatoprotective effect on D-GalN or tumor necrosis factor-a (TNF-a)-induced cell death in primary cultured mouse hepatocytes. The hepatoprotective effect of C-glycosylflavones from C. quadrangulare was determined by evaluation of the serum enzyme level in comparison with the o-GalN or TNF-a treated control. At the concentration of 200 pg/ml, orientin and isoscoparin possessed an inhibitory effect on TNF-a-induced cell death of about 20%, while vitexin at 100 pg/ml produces a 95%i inhibitory effect. 

Mahlin, J.A., Jung, K.H., and Schmidt, R.R., Glycosyl imidates, synthesis of flavone C-glycosides vitexin, isovitexin and isoembigenin, Liebigs Ann. Chem., 3, 461, 1995. 

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