Phenylpropanoids:Definition: Phenylpropanoids represent a large group of natural products containing a phenyl ring attached to a three-carbon propane side chain(C6-C3) in their structure. Biosynthesis: Derived from the aromatic amino acids phenylalanine and tyrosine or the intermediates of the shikimic acid biosynthetic pathway.Categories: Simple Phenylpropanoids (phenylpropenes, phenylpropyl alcohols, phenylpropionaldehydes, phenylpropionic acids)

Simple phenylpropanoidsPhenylpropenesphenylpropyl alcoholsPhenylpropionaldehydes

Simple phenylpropanoidsphenylpropionic acids

Phenylpropanoid synthesisShikimic Acid Pathway

Shikimic Acid Pathway

Shikimic Acid Pathway

Shikimic Acid Pathway

Shikimic Acid Pathway

Shikimic Acid Natural Products

Phenylpropanoids:

Flavonoids water soluble plant pigmentsAnthocyanidins improve microcirculation & nightvisionCoumarins - AnticoagulantsLignans Anti-cancer drugsTannins in green tea, red raspberry & witch hazel

Structure and Classification: Coumarins are lactones which are derived from p-hydroxycinnamic acids which undergo ortho hydroxylation then ring closure between the ortho hydroxyl group and the carboxylic group of the side chain, after a trans to cis isomerization of the side chain double bond.

Coumarins are widely distributed in higher plants, and commonly found in families such as the Umbelliferae (Apiaceae) and Rutaceae, both in the free form and as glycosides.

Coumarins:

Lignans: Structure and Classification Lignans are typically found as dimeric phenylpropanoids derivatives and are found in woody tissues and resin of plants. Most of lignans are free form, seldom as glycoside. They have antitumor, antiviral, liver protective, etc. activities. The two phenylpropanoid units mostly linked through the -C atom of the C3 side chains.

www.1ppt.comLOGOProperties: Colourless crystal, no volatility, insoluble in water, soluble in organic solvents. Optical Activity: one or more chiral center. The optical activity is related to biological activities. The optical activity is easily changed by acid.

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Structure and Classification Classification:

LignansSimple LignansMonoepoxylignansLignanolidesCyclolignansCyclolignolidesBisepoxylignansDibenzocyclooctene lignansBiphenylene lignansOther lignans

Shikimic Acid LigninsA synthetic Lignan

Lignin a complex phenolicPrimary metabolite - secondary cell wall component occurs in all vascular plantsStructural functionAlso protective because deters herbivores due to its toughnessBlocks growth of many pathogens because only small group of fungi can degrade

Lignin monomersPolymer of three phenolic alocholsDifferent species have different ratios of these monomersLignin in beech has 100:70:7 of coniferyl: sinapyl: para-coumaryl

FlavinoidsOne of the largest classes of phenolicsCarbon skeleton has 15 carbons with two benzene rings connected by a 3-C bridge-C3-

FlavonoidsMany have antimicrobial activityanti-bacterial, anti-fungal, and anti-viralFlavonoids in red wine responsible for the French Paradox - lower risk of heart attacks by inhibiting platelet aggregation and blood clots

FlavinoidsFlavinoids classified into different groups based on the degree of oxidation of the 3-C bridgeAnthocyaninsFlavonesFlavonolsIsoflavonesMajority of flavinoids exist as glycosides

Shikimic Acid Flavones

AnthocyaninsColored flavinoids - red, pink, blue, purple pigmentsAttract animal pollinators and seed dispersers

Flavones and FlavonolsAlso flower pigmentsAbsorb UV not visible light - not visible to human eye but visible to many insects - maybe be attractants, nectar guidesAlso present in leaves where they protect against UV-B damageAppeared to be involved in legume roots in attracting N-fixing bacteria

IsoflavonoidsSome have strong insecticidal activity - rotenoidsSome have estrogenic/anti-estrogenic activity and cause infertility in mammalsMany are phytoalexins - antimicrobial cmpds produced in response to bacteria and fungi

Soy isoflavonesIsoflavones in soybean are thought responsible for a host of beneficial effectslower cholesterol, especially LDL - thereby lower risk of cardiovascular diseaselower blood pressureestrogenic effects reduce symptoms of menopause and reduce risks of osteoporosisinhibit growth of tumors and thought to be responsible for low rates of breast and prostate cancer among cultures eating soy products

TanninsTannin a general name for a large group of complex phenolic substances that are capable of tanning animal hides into leather by binding collagenFound in almost every plant part - abundant in unripe fruitDeter herbivores due to astringent properties - bind saliva and other digestive proteinsAntimicrobial - tannins in heart wood prevent decay

Tanins