Phenolics Flashcards
Phenolics evolution
UV light can damage biomolecules directly (bond cleavage) or indirectly (Via the generation of reactive oyxgen includign singlet oxygen, hydroxyl)
Phenolics Evolutionary Chemistry
organic compounds in primordial organisms were viable only water, protected by UV absorbing oxygen by H2O.
Shikimate pathway is influencal on the evolution of these plants
Shikimate pathway with phenolics
initates a pathway calle the phenylpropanoid pathway
what is the enzyme that deaminates phenylalanine
Phenylalanine ammonia lyase (PAL)
what is a key product of the phenylpropanoid pathway
p-Coumaryl-CoA, this helped solve the UV problem
Polyketides
formed by the condensatin of acetyl-Coa and malony Coa for chain extension.
how were flavonoids formed by evolution
the starting unit of acetly-CoA was replaced by Coumaryl-Coa in bryophytes. combinbes polyketides from the mavlonate pathway and the shikimate pathway
how do flavonoids protect plants from damage caused by UV light
by exploting chemistry of phenol, acts as a sunscreen
functions of phenolics in plants
Proteins
Protection
Competition
Pigments
Structural
how are they classified
the number of benzene rings and carbon atom.
examples of classification
C6
C6-C1
C6-C2
C-6-C3
C6-C4
C6-C1-C6
C6-C2-C6 etc
(C6)n
examples of C6-C1
C6-C3
C6-C1-C6 (xanthones)
vanillin
cinnamic acid
alpha-Mangostin
simple phenolics
also the classification
resorcinol
originaly obtaine by distillation of plant resins
used to treat skin conditions
C6
C6-C1 are ?
gallic acid
substrate for the hydrolysable tannin pathway
incoorectly called a polyphenolic
strong antioxidant
C6-C2
Phenylacetic acids
4-hydroxyphenylacetic acid (HPA) occurs naturally in various plants
there is syntehtically-derived HPA (Atenolol)
used to treate hypertension
C6-C3
Cinnamic Acids,coumarins
also known as phenylpropanoids
example is p-coumaric acid
present in edible plants
well-establised as a dietary antioxidant
Coumarins
C6-C3
Gives the odour of new mown hay, common in plants in free state and as glycosides
Useto treat HIV
plant was mostly wiped out by fund existing in Singapore botanic garden
Derivative of benzo-pyropes
C6-C4
Napthaquiones
produced by higher plants, fungi and actinomycetes
Exhibit a broad range of fungicidal activities. In plants they commonly occur in the reduced and glycosidic forms
C6-C1-C6
these are xanthones
Derivived from shikimate/phenylpropanoid and acetate/malonate pathways
Magnosteen example
found in pericarp, whole fruit
used to treat skin infections, wounds
currently the alpha-mangostin is the example for this one- used for breast cancer
C6-C2-C6
anthraquinones
isolation of the purgative compounds reveled this compound
emodin from rhubard is an example
what are the flavonoids
C6-C3-C6
they are the largest group of phenols
Their carbon skeleton can be modified by different additions.
what causes the flavonoids to increase hydrophilicity
glycosylation and additin of hydroxyl groups
what causes the flavonoids to increase hydrophobicity
methylation and prenylation
what is the subgroup flavonoids with starting with A
anthocyanadins: C6-C3-C6
Anthocyanin: anthocyanidin + glycoside
they have a basic structure
glycoside is often, glucose
characterisd by a postive charge on the C ring and two double bonds in the C ring
tends to be pink purple blue and red
the other subgroup of flavanoids
flavanols are similar to anthocyanidins but don’t have the positive charge on the oxygen atom in the C ring and no double bonds in the C ring.
Example is Catechins and tannins
what is Catechin
a common flavanol that occurs in many plants
found in green tea, cocoa poweder and red wine
well knwon for its antioxidant properties
Tannins
compounds present in plant extracts that were able to combine with protein in animal hides, prevent their putrefaction and convert them into leather
Molecular weight of 1000-5000
Treat as a polyphenols with phenolic acid chemistry
tannins (hydrolysable)
hydrolysed by acids or enzymes such as tannase
these are formed from several molecules of phenolic acids united by ester linkages to a central glucose molecule.
Two main types are Gallicanism and ellagitannins, composed of Gallic acid and hexahydroxy-diphenic units.
what are the two main types of hydrolysable tannins
these are gallintanis and ellagitannis
these are composed of gallic acid and hexahydroxy-diphenic units
the galloyl groups in ellagitannins are linked by c-c bonds
In gallotannins it is depside bonds
Tannins (condensed)
condensed, also are not readily hydrolysed to simple molecules and do not contain sugar moiety
a intermediate of the synthesis of the condensed tannins are catechins
When reacted with acids or enzymes they are converted to red insoluble compounds called phlobanes
