Isoflavonoids

8 Isoflavonoids.- FxiU details of the pathways leading to, and the interconversion of, pterocarpan and isoflavan phytoalexins in lucerne (Medicagg sativa) seedlings have now been published. Experiments with double-labelled medicarpin 

CuCl -treated pea (Pisum sativum) pods. Analysis of C- 

This fits with the involvement of dalpanol as an intermediate, 

From limited tracer experiments, such as with the 

A soluble UDP-glucose isof1aVone 7-0-glucosyltransferase from roots of chick pea (Cicer arietinu ro) catalysed the 7-0-glucosylation of 4 -methoxyisoflavones formononetin and biochanin A. The corresponding 4 - 

The biosynthesis of isoflavonoids has recently been reviewed by Dixon (1999). Isoflavones may be either constitutively synthesized under the control of developmental programs or induced in response to environmental stress such as pathogen 

FIGURE 1.2 Structure and ultraviolet (UV) scan of phytoestrogens. (Reprinted with permission from Franke, A.A., et ah, Proc. Soc. Exp. Biol Med., 208, 18-26, 1995.) 

FIGURE 1.3 Isoflavonoid biosynthesis via the phenylpropanoid pathway. (Reprinted with permission from Jung, W., Yu, O., Lau, S.-M.C., O Keefe, D.P., Odell, J., Fader, G and 

There are reports on the presence of isoflavonoids in numerous families of the plant kingdom inclusive 49 angiosperm families (Mackova et al. 2006). The most famous example is their occurrence in the Fabaceae. Isoflavones are formed by structural 

Isoflavonoids show fungicidal and bactericidal effects. They play an important role as constitutive constituents and also as phytoalexins. From the pharmacological point of view estrogenic activity of isoflavones such as genistein and daidzein is of increasing relevance (Harbome and Williams 2000). Rotenoids, especially rotenone, are potent insecticides. 

Biosynthesis of HydroxyphaseoUin.—The biosynthesis of a newly discovered pterocarpan (48) has been investigated in disease-resistant soya bean hypo-cotyls. [U- C]Phenylalanine and [9- C]isoliquiritigenin were readily incorporated into (48). Label also appeared in daidzein, coumestrol, and spjagol (49). The biosynthetic pathway followed the generally expected route 

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Phytoalexins are low molecular weight compounds produced in plants as a defense mechanism against microorganisms. They do, however, exhibit toxicity to humans and other animals in addition to microbes (30). Coumarins, glycoalkaloids, isocoumarins, isoflavonoids, linear furanocoumarins, stilbenes, and terpenes aU. fall into the category of phytoalexins (31). Because phytoalexins are natural components of plants, and because their concentration may increase as a response to production and management stimuli, it is useful to recogni2e the possible effects of phytoalexins in the human diet. 

ADLERCREUTZ H, BANNWART C, WAHALA K, MAKELA T, BRUNOW G, BASE T, AROSEMENA P J, KELLIS J T J R, VICKERY L E (1993) Inhibition of human aromatase by mammalian lignans and isoflavonoid phytoestrogens. J Steroid Biochem Mol Biol. 44 147-53. 

HARPER, A, KERR, D J, GESCHER, A and CHIPMAN K J (1999) Antioxidant effects of isoflavonoids and lignans, and protection against DNA oxidation. Free Rad Res. 31149-60. 

LOUKOVAARA M, CARSON M, PALOTIE A, ADLERCREUTZ H (1995) Regulation of sex hormone-binding globulin production by isoflavonoids and patterns of isoflavonoid conjugation in HepG2 cell cultures. Steroids. 60 656-61. 

Deglycosylation of flavonoid and isoflavonoid glycosides by human small intestine and liver beta-glucosidase activity. FEES Lett 436, 71-5. 

HUTCHINS A M, SLAVIN J L and LAMPE I w (1995) Urinary isoflavonoid phytoestrogen and lignan excretion after consumption of fermented and imfermented soy products. JAm Diet Assoc 95, 545-51. 

SLAVIN J L, KARR s c, HUTCHINS A M and LAMPE J w (1998) Influence of soybean processing, habitual diet, and soy dose on urinary isoflavonoid excretion. Am J Clin Nutr 68, 1492S-5S. 

VEDAVANAM K, SRIJAYANTA s, o reilly j, RAMAN A, WISEMAN H. (1999) Antioxidant action and potential antidiabetic properties of an isoflavonoid-containing soyabean phytochemical extract (SPE). Phytother Res. 13 601-8. 

Recently, some of the specific faecal bacteria involved in the metabolism of dietary isoflavonoids were isolated (Hur et al., 2000). They have been shown to selectively convert genistin and daidzin to their respective aglycones. One of the isolated bacteria, under anoxic conditions, was further shown to metabolise genistein and daidzein to their respective dihydroxy-genistein and dihydroxy-daidzein. In the case of lignans, enterodiol and enterolactone were shown to be excreted in vivo only in rats harbouring a gut microflora (Rowland et al, 1999). 

However, the estrogenic and anti-estrogenic activity of isoflavonoids could... 

ADLERCREUTZ H, HONJO H, HIGASHI A, FOTSIS T, HAMALAINEN E, HASEGAWA T and OKADA H (1991) Urinary excretion of lignans and isoflavonoid phyto-oestrogens in Japanese men and women consuming traditional Japanese diet. Am J Clin Nutr. 54 (6) 1093-100. 

CHEN z, ZHENG w, CUSTER L J, DAI Q, SHU X o, JIN F and FRANKE A A (1999) Usual dietary consumption of soy foods and its correlation with the excretion rate of isoflavonoids in overnight urine samples among Chinese women in Shanghai. Nutr Cancer. 33 (1) 82-7. 

DAY A J, DUPONT M S, RIDLEY S, RHODES M, RHODES M J, MORGAN M R and WILLIAMSON G (1998) Deglycosylation of flavonoid and isoflavonoid glycosides by human small intestine and liver and beta-glucosidase activity. FEES Lett. 436 (1) 71-5. 

JoussEN A M, ROHRSCHNEIDER K, REICHLING J, KiRCHHOF B and KRUSE F E (2000) Treatment of comeal neovascularization with dietary isoflavonoids and flavonoids. Exp Eye Res. 71 (5) 483-7. 

KiMiRA M, ARAI Y, SHIMOI K and WATANABE s (1998) Japanese intake of flavonoids and isoflavonoids from foois. J Epidemiol. 8 (3) 168-75. 

MAZUR W, FOTSIS T, WAHALA K, OJALA S, SALAKKA A and ADLERCREUTZ H (1996) Isotope dilution gas chromatographic-mass spectrometric method for the determination of isoflavonoids, coumestrol and lignans in food samples. Biochem. 233 (2) 169-80. 

MORTON M S, MATOS-FERREIRA A, ABRANCHES-MONTEIRO L, CORREIA R, BLACKLOCK N, CHAN P S, CHENG 0, LLOYD s, CHIEH-PING w and GRIFFITHS K (1997) Measurement and metabolism of isoflavonoids and lignans in the human male. Cancer Lett. 114 (1-2) 145-51. 

NAKAMURA Y, TSUJi s and TONOGAi Y (2000) Determination of the levels of isoflavonoids in soybeans and soy-derived foods and estimation of isoflavonoids in the Japanese daily intake. JAOAC Int. 83 (3) 635-50. 

SEOW A, SHI c Y, FRANKE A A, HANKIN J H, LEE H P and YU M c (1998) Isoflavonoid levels in spot urine are associated with frequency of dietary soy intake in a population-based sample of middle-aged and older Chinese in Singapore. Cancer Epidem Biomarkers Prev. 1 (2) 135-40. 

WHITTEN P L, PATISAUL H B and YOUNG L J (2002) NeuTobehavioral actions of coumestrol and related isoflavonoids in rodents. Neurotoxicol Teratol. 24 (1) 47-54. 

The colors of muscadine grape juice and wine were enhanced by copigmentation with formonetin, biochanin A, and prunetin, the major isoflavonoids extracted from red clove leaves, at ratios of 1 2, 1 4, and 1 8. The 1 8 ratio representing the maximum amount of isoflavonoids used due to its limiting solubility yielded the maximum color enhancement when compared to standard solutions of anthocyanins, at 23 and 60°C. ... 

Talcott, S.T., Pelle, J.E., and Brenes, C.H., Red cloves isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice. Food Res. Int., 38, 1205, 2005. 

Isoflavonoids Pueraria mirifica SiOj CHCI3 + MeOH UV 254 nm Estrogenic activity 90... 

Miscellaneous phenolics Flavonols, flavones, flavanones, anihocyanins, isoflavonoids... 

H. Gagnon, 3. Seguin, E. Bleichert, S. Tahara, and R. K. Ibrahim, Biosynthesis of white lupin isoflavonoids from (U- C]L-phenylalanine and their release into the culture medium. Plant Physiol. 100 16 (1992). 

P. Wojtaszek, M. Stobiecki, and K. Gulewicz, Role of nitrogen and plant growth regulators in the exudation and accumulation of isoflavonoids by roots of intact white lupin (Lupinus aihus L.) plants. J. Plant Phy.siol. 742 689 (1993). 

II. FLAVONOIDS AND ISOFLAVONOIDS AS SIGNAL MOLECULES FROM HOST PLANTS... 

In marked contrasts to the flavonoids, the isoflavonoids have a very limited distribution in the plant kingdom and are almost entirely restricted to the subfamily Papilionoidae. Their estrogenic effect was discovered following the observation of a decline in birth rate for sheep fed on Trifolium sublerraneum. Changes in... 

R. M. Zacharius and E. B. Ralan, Isoflavonoid changes in soybean cell suspensions when challenged with intact bacteria of fungal elicitors. J. Plant Physiol 135 122... 

M. Pamiske, B. Ahiborn, and D. Werner, Isoflavonoid-inducible resistance to the phytoalexin glyceollin in. soybean rhizobia. J. Bacterial 173 2222 (1991). 

D. Morandi, J. A. Bailey, and V. Gianinazzi-Pearson, Isoflavonoid accumulation in soybean root infected with vesicular-arbuscular mycorrhizal fungi. Physiol. Plant Pathol. 24 357 (1984). 

M. J. Harrison and R. A. Dixon, Isoflavonoids accumulation and expression of defense gene transcripts during the establi.shment of vesicular-arbuscular mycorrhizal associations in roots of Medicago truncatula. Mol. Plant-Microbe Interact. 6 ... 

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