Phenolics

Question 1

Phenolics evolution

Answer 1

UV light can damage biomolecules directly (bond cleavage) or indirectly (Via the generation of reactive oyxgen includign singlet oxygen, hydroxyl)

Question 2

Phenolics Evolutionary Chemistry

Answer 2

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

Question 3

Shikimate pathway with phenolics

Answer 3

initates a pathway calle the phenylpropanoid pathway

Question 4

what is the enzyme that deaminates phenylalanine

Answer 4

Phenylalanine ammonia lyase (PAL)

Question 5

what is a key product of the phenylpropanoid pathway

Answer 5

p-Coumaryl-CoA, this helped solve the UV problem

Question 6

Polyketides

Answer 6

formed by the condensatin of acetyl-Coa and malony Coa for chain extension.

Question 7

how were flavonoids formed by evolution

Answer 7

the starting unit of acetly-CoA was replaced by Coumaryl-Coa in bryophytes. combinbes polyketides from the mavlonate pathway and the shikimate pathway

Question 8

how do flavonoids protect plants from damage caused by UV light

Answer 8

by exploting chemistry of phenol, acts as a sunscreen

Question 9

functions of phenolics in plants

Answer 9

Proteins
Protection
Competition
Pigments
Structural

Question 10

how are they classified

Answer 10

the number of benzene rings and carbon atom.

Question 11

examples of classification

Answer 11

C6
C6-C1
C6-C2
C-6-C3
C6-C4
C6-C1-C6
C6-C2-C6 etc
(C6)n

Question 12

examples of C6-C1
C6-C3
C6-C1-C6 (xanthones)

Answer 12

vanillin
cinnamic acid
alpha-Mangostin

Question 13

simple phenolics
also the classification

Answer 13

resorcinol
originaly obtaine by distillation of plant resins
used to treat skin conditions
C6

Question 14

C6-C1 are ?

Answer 14

gallic acid
substrate for the hydrolysable tannin pathway
incoorectly called a polyphenolic
strong antioxidant

Question 15

C6-C2

Answer 15

Phenylacetic acids
4-hydroxyphenylacetic acid (HPA) occurs naturally in various plants

there is syntehtically-derived HPA (Atenolol)
used to treate hypertension

Question 16

C6-C3

Answer 16

Cinnamic Acids,coumarins
also known as phenylpropanoids
example is p-coumaric acid
present in edible plants
well-establised as a dietary antioxidant

Question 17

Coumarins

Answer 17

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

Question 18

C6-C4

Answer 18

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

Question 19

C6-C1-C6

Answer 19

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

Question 20

C6-C2-C6

Answer 20

anthraquinones
isolation of the purgative compounds reveled this compound
emodin from rhubard is an example

Question 21

what are the flavonoids

Answer 21

C6-C3-C6
they are the largest group of phenols
Their carbon skeleton can be modified by different additions.

Question 22

what causes the flavonoids to increase hydrophilicity

Answer 22

glycosylation and additin of hydroxyl groups

Question 23

what causes the flavonoids to increase hydrophobicity

Answer 23

methylation and prenylation

Question 24

what is the subgroup flavonoids with starting with A

Answer 24

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

Question 24

the other subgroup of flavanoids

Answer 24

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

Question 25

what is Catechin

Answer 25

a common flavanol that occurs in many plants
found in green tea, cocoa poweder and red wine
well knwon for its antioxidant properties

Question 26

Tannins

Answer 26

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

Question 27

tannins (hydrolysable)

Answer 27

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.

Question 28

what are the two main types of hydrolysable tannins

Answer 28

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

Question 29

Tannins (condensed)

Answer 29

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