PHENOLICS Flashcards
Plant bioactive secondary metabolites can be divided into three chemically basic group of compounds:
Phenolics
Alkaloids
Terpenoids
4 important precursors from the primary metabolism
erythrose-4-phosphate
phosphoenolpyruvate
acetyl CoA
3-phospho-glycerate
phenolic compounds can be synthesized to what pathways
shikimate pathway - more essential
malonic acid pathway - less essential
Also known as the chorismate pathway, involves seven enzymatic steps to convert simple carbohydrate precursors derived from glycolysis and the pentose phosphate pathway to the aromatic acids.
shikimic acid pathway
phosphoenolpyruvate + D-erythrose-4-phosphate = ___________ and the enzyme used is __________
3-deoxy-D-arabino-heptulosonate-7-phosphate; 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS)
heptulose to _____________ and the enzyme used is ____________
3-dehydroquinate
3-dehydroquinate synthase (DHQS)
3-dehydroquinate to _______________
and the enzyme used is ___________
3-dehydroshikimate
3-dehydroquinate dehydratase (DHQD)
3-dehydroshikimate (3-dehydroquinate) to __________________ and the enzyme used is _________________
shikimate; shikimate dehydrogenase
shikimate was first isolated in 1895 from the japanese star anise
shikimi flower
what enzyme used to convert shikimate to shikimic acid?
shikimate kinase (SK)
phosphorylation of shikimic acid to ________________ and the enzyme used is ______________
5-enolpyruvylshikimate-3-phosphate
5-enolpyruvylshikimate-3-phosphate synthase (EPSPS)
5-enolpyruvylshikimate-3-phosphate to _____________________ and the enzyme used is _________________
chorismic acid; chorismate synthase (CS)
chorismic acid to __________________
and the enzyme used ____________
the type of reaction______________
prephenic acid
chorismate mutase
claisen rearrangement
Is the branch point to a group of benzoic acid derivatives and tryptophan.
Chorismic acid
leads to the formation of phenylpropanoids, and some phenolics, the flavonoids, and the amino acids phenylalanine and tyrosine.
Prephenic acid
decarboxylation of prephenate to _________________ and then undergo transamination (pyridoxamine transaminase) to yield __________________
phenylpyruvate;
phenylalanine
oxidative decarboxylation of prephenate to ____________________ then by pyridoxamine transaminase yields ______________
4-hydroxyphenylpyruvate;
tyrosine
is the precursor of a variety of important secondary metabolites, including flavonoids, coumarins, and lignans.
This pathway is found in microorganisms and plants, but not in animals.
an essential amino acid
is the end product of the shikimic acid pathway
phenylalanine
The shikimate metabolites can be grouped according to the number of carbons atoms in the side chain
C6: _____________ and __________
C6-C1: _____________, including ____________
C6-C2: _____________
C6-C3: _____________
C6-C3-C6: ___________
C6: phenols and quinones
C6-C1: benzoic acid derivatives, including tannins
C6-C2: phenyl ethyl compounds
C6-C3: cinnamic acids
C6-C3-C6: flavonoids
sometimes called phenolics, are a class of organic compounds consisting of one or more hydroxyl groups (−OH) bonded directly to an aromatic hydrocarbon group.
Phenols
are oxidized derivatives of aromatic compounds (often from phenols) resulting in a fully conjugated cyclic dione structure.
Quinones
major classes of phenolic compounds
polyphenols (flavonoids tannins)
simple phenols (phenolic acid)
other phenols (lignins, coumarins, etc.)
functions of phenols
Antioxidant agents
Electron transporters
Pigment molecules
Signaling agents
Defense mechanism
_____________is a compound that have a benzene ring with a carboxylic acid functional group (-COOH) attached to it. Its common derivatives include p-hydroxybenzoic acid, salicylic acid, gallic acid, and ellagic acid.
C6-C1 metabolites
Benzoic acid
Two important benzoic acid derivatives are the ________and________ – reported to induce anti-inflammatory, gastroprotective, and anticarcinogenic activities
gallic acid and ellagic acid
lactonization of hexahydroxydyphenic acid
ellagic acid
colorimetric assays that measure the antioxidant properties of compounds
- 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) Radical Scavenging Assay
- 3-Ethylbenzothiazoline-6-Sulphonic Acid (ABTS) Assay ……….EBTSA
- Oxygen Radical Absorbance Capacity (ORAC) Assay
- Ferric Reducing Antioxidant Power (FRAP) Assay
(commonly referred to as tannic acid) are typically large molecules composed of repeating units of phenolic compounds, such as gallic acid, catechin, and ellagic acid, which are linked together through ester or ether bonds.
Tannins
Two main categories of tannins:
✓hydrolysable tannins (gallotannin and ellagitannin)
✓condensed tannins (proanthocyanidins)
(flavan-3-ol monomer, polymer formation)
contains a benzene and an unsaturated carboxylic acid group forming 3-phenyl-2-propenoic acid. Its common derivatives include p-coumaric acid, caffeic acid, and ferulic acid, sinapic acid, chlorogenic acid
Cinnamic acid
___________is a naturally-occurring anti-histamine compound from tsaang gubat plant.
Rosmarinic acid
- The largest class of secondary
metabolites having polyphenolic
structure. - Play a key role to provide
pigments in plant as dark blue and
red color of berries, yellow and
orange color of citrus fruits. - Composed of 15 carbon atoms,
which are arranged in C6-C3-C6
backbone skeleton rings, in which
ring A and ring B are linked by
three carbon ring C.
Polyphenol: Flavonoids
types of flavanoids
flavonols (addition of OH)
flavanols (dissapearance of =O)
flavones (original)
isoflavones (mirror image of flavones)
flavanones (absence of unsaturation)
anthocyanidins (absence of =O, appearance of OH, anthocyanins)
____________is a cyanogenic glycosides found in cassava
linamarin
__________is composed of the sugar part, known as the glycone, and the non-sugar part called the aglycone (with a cyanide
group).
Cyanogenic glycoside
linamarin upon the action of linamarase
glucose + acetone cyanohydrin ——— acetone, hydrogen cyanide
—has far-reaching impacts on agriculture, industry and the environment, making its metabolism a globally important part of plant biochemistry
—second most abundant polymer on
earth, next to cellulose (made of glucose units)
—made of phenolics
lignins
__________are the sugar- derivatives of the anthocyanidins (the aglycone). They are water-soluble pigments in flowers, leaves and fruits. They also impart many of the colors of fruit juices and wines.
Anthocyanins
Leaf color is due to several
compounds:
____________ which is green, gives leaves its predominant color. It is responsible for photosynthesis.
__________ are responsible for the yellow, orange and gold hues.
________give rise to the reds, purple and magenta hues. They actively formed in the leaves during autumn.
Chlorophyll
Carotenoids
Anthocyanins
