I

The Big Heart Disease Lie

Most Effective Heart Disease Treatments

Get Instant Access

Chorismic acid

Anthranilic acid

Tryptophan

Phenylalanine tyrosine

Anthranilic acid

Tryptophan

Phenylalanine tyrosine

Cinnamic acid

Isoquinoline and benzylisoquinoline alkaloids

Cyanogenic glucosides

Betalains morphine

Indole glucosinolates

Indole phytoalexins Tryptamine

Indole and quinone alkaloids

Flavonoids and anthocyanins Lignin precursors Coumarins

Indole acetic acid Phenylethylamine

Indole acetic acid Phenylethylamine

Phytoalexins Salicylic acid

Cinnamic acid

Isoquinoline and benzylisoquinoline alkaloids

Cyanogenic glucosides

Betalains morphine

Phytoalexins Salicylic acid

Catechols Tannins Saligenin Methyl salicylate

Hydroxy benzoic acid

Tyramine hordenine

Fig. 2.4 Biosynthesis of diverse phenolic compounds from pool of amino acids formed by shikimic acid pathway cardiovascular diseases in vasoprotection and neuroprotection [61-63]. The details about the mode of action of resveratrol are discussed in reviews on resvera-trol [62-64].

The phenolic group includes metabolites derived from the condensation of acetate units (e.g. terpenoids), those produced by the modification of aromatic amino acids (e.g. phenylpropanoids, cinnamic acids, lignin precursors, hydroxybenzoic acids, catechols and coumarins), flavonoids, isoflavonoids and tannins. The phe-nolics derived from aromatic amino acids, and their precursors, are just some of the very wide range of compounds (Fig. 2.5) derived from shikimic acid [57]. A phenyl group having three carbon side chains is known as a phenylpropanoid, such as hy-droxycoumarins, phenylpropenes and lignans. The phenylpropenes are important components of many essential oils, e.g. eugenol in clove oil (Syzygium aromaticum) and anethole and myristicin in nutmeg (Myristica fragrans) [65].

Phenylalanine

Phenylalanineammonia-lyase

Cinnamate

Cinnamic acid 4-hydroxylase

p-Coumarate

4-Coumarate:CoA ligase

p-Coumarate-CoA

Chalcone synthase Chalcone reductase

Flavone ,1 synthase

Glyci tein ^-Isoli quiri tigeni n Nari n.geni n <T

wone^L.

Isoliquiritigenin

Chalcone isomerase ^

Liquiritigenin

flav< 1

Isoflavone Genistein synthase

Dihydroflavonol —► Flavonol

Daidzein Flavan-3,4-diol

Anthocyanin

I synthase * X Flavan-3,4-diol

3-Hydroxyanthocyanin \ 4 reductase

Isoflavone hydroxylase I / \

Isoflavone reductase ^ / H

, ^ Condensed tannins i Anthocyanins

Glyceollins

Fig. 2.5 Biosynthetic pathway of major flavonoids and anthocyanins

Flavonoids have two benzene rings attached by a propane unit and are derived from flavones. They are found throughout the plant kingdom, whereas isoflavonoids are more restricted in distribution, and are present in the family Fabaceae, in which they are widely distributed and function as antimicrobial, anti-insect compounds, as an inducer of nodulation genes of symbiotic Rhizobium bacteria, or as allelo-pathic agents [66]. Flavonoids are brightly coloured compounds generally present in plants as their glycosides. Different classes within this group differ by additional oxygen-containing heterocyclic rings and hydroxyl groups and include the chal-cones, flavones, flavonols, flavanones, anthocyanins and isoflavones. Anthocyanins impart red and blue pigment to flowers and fruits and can make up as much as 30% of the dry weight of some flowers. Flavanones, flavonols and anthocyanins normally exist as their glycosides. The isoflavonoids are rearranged flavonoids, in which this rearrangement is brought about by a cytochrome P-450-dependent enzyme which transforms the flavanones' liquiritigenin or naringenin into the isoflavones daidzein or genistein, respectively. Simple isoflavones such as daidzein, and coumestans such as coumestrol, have sufficient estrogenic activity to seriously affect the reproduction of grazing animals and are known as phytoestrogens [56]. Isoflavones exhibit estrogenic, antiangeogenic, antioxidant and anticancer properties [66, 67].

Major sources of isoflavones for humans are pulses, particularly soybeans and chickpeas [68]. Epidemiological studies suggest a link between consumption of soy isoflavones and reduced risks of breast and prostate cancers [66-68]. Isoflavones also possess other health-promoting activities, such as chemoprevention of osteoporosis, and prevention of postmenopausal disorders and cardiovascular diseases [69, 70]. Phenoxodiol, a synthetic analogue of diadzein, is being developed as a therapy for cervical, ovarian, prostate, renal and vaginal cancers and induces apop-tosis through inhibition of antiapoptopic proteins [71]. The other important compounds (Fig. 2.6) in this group include quercitin (flavonoid), silybin (flavonolignan) and genistein (isoflavone).

Was this article helpful?

0 0
Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook


Post a comment