9. Primary and secondary plant metabolites II.
Universal and specific plant metabolism
1
Azotoids
2
AZOTOIDS
Universal
azotoids
Simple specific
azotoids
Cyanogenic
compounds
Glucosinolates
Alkaloids
PHENOLOIDS
Aromatic amino acids= Compoundsderived fromthe nitrogenmetabolism
3
• Universal proteinogenic amino acids and non-proteinogenic
amino acids (metabolic intermediates) (e.g. ornithine)
• Universal amino acid derivates – chlorophyll, auxines
• Proteins: polypeptides and glycoproteins
Universal
azotoids
Amino acids
and derivates
4
• Protein + oligosaccharide chain
• Bounds with the cell membrane
• Ricine and abrin toxalbumins – a disulfide bond connects
two polypeptide chains
• Fazin in bean species
• Viscumine in mistletoe
Lectins
Ricinus communis – castor bean
Abrus precatorius
– rosary pea
Viscum album – mistletoe
5
• Universal purine and pyrimidine nucleotides (ATP, GTP, CTP, UTP,
TTP) and derivates (NAD, FAD, CoA) – some molecules are important
coenzymes
• Nucleic acids
Universal
azotoids
NAD
Nucleic acids
and derivates
6
Universal azotoids
Amino acids
and derivatesNucleic acids
and derivates
Simple specific
azotoids
Synthesized from universal compounds with a few methabolic steps (decarboxylation,
methylation), but taxonspecific occurence
• Specific amino acids
• Biogenic amines and amides
• „Protoalkaloids”
• Purine alkaloids
• Pyrimidine derivates
7
• About 200-400 biogenic amino
acids
• Never found in the genetic
code of any organism, but
perform several biological
functions
• Derived from universal amino
acids with N, S, and C, or
stereoisomer molecules
• Natural occurence mainly in
Fabaceae family
• e.g. lathyrogenes or
canavanine (in Robinia)
Simple specific
azotoidsSpecific (non-proteinogenic)
amino acids
8
• Nitrogenous compoundes derived fromamino acids by decarboxylation
• With various biological effects
• Tryptamine, phenethylamine - psychoactive
and stimulant effect, increased heart functions
• Histamine – local immune and inflammatory
response (e.g. nettle)
• Alliin – in the garlic
Simple specific
azotoids
Biogenic amines and amides
alliin
9
• Nitrogen atom derived from an amino
acid but it’s not a part of the heterocyclic
• Ephedrine: a bronchodilator with
psychohstimulant effect act as
adrenaline
• Mescaline: strong hallucinogenic effect
• Cathinone: amphetamine-like effect,
psychostimulant
• Capsaicin: active component of chili peppers
Catha edulis – khat
Echinocactus
willamsii – peyote
Ephedra distachya
– joint pine
Simple specific
azotoidsProtoalkaloids
10
• Synthesized from purine nucleotides
• Their role in plants in currently undetermined
(chemical defense or allelopathic effect)
• Stimulate the CNS
Purine alkaloidsCola nitida – kola
Coffea arabica –
arabica coffee
Theobroma cacao –
cacao tree
Chamellia sinensis –
tea plant
Simple specific
azotoids
11
Pyrimidine derivates
• Synthesized from pyrimidine nucleotids
• Natural occure mainly in glycosidic form
• During degradation oxidizing agents (H2O2) produced
Vicia faba – field bean
Simple specific
azotoids
12
• Biosynthesized from aliphatic or
aromatic amino acids
• In glycosidic from
• Widely distributed in the plant
kingdom, as a defense mechanism
against herbivores and pests
• Upon plant injury, specific enzymesremove the sugar parts
aglycones are activated and HCN is often produced spontaneously
poisoning (see seminar 4)
• e.g. amygdalin, lotaustralin,
linamarin, dhurrin, taxiphyllin,
prunasin
Cyanogenic
compounds
13
• Biosynthesized from amino acids glucose
bounds with S-glycosidic bond (thioglycoside)
with another sulphate group
• Natural occurence only in a few families,
mainly Brassicaceae
• Hydrolysis results isothiocyanates (mustardoil) goitrogen effect
• e.g. sinigrin, sinalbin
Glucosinolates
Brassica napus – oilseed rapeSinapis alba –
White mustard14
• Specific, mainly alkaline plant metabolites with a nitrogencontent
• Alkaloids are products of the nitrogen metabolism
• There are approximately 21 000 different alkaloids described
already from 4000 plant taxa
• Stored in vacuoles
• Even a small dose can lead strong biological effects
• Plant families with characteristic alkaloids: Papaveraceae,
Ranunculaceae,Fabaceae, Apocynaceae, Asclepiadaceae,
Solanaceae, Liliaceae, Amaryllidaceae
• Plants are able to decompose stored alkaloids and re-use them
again
Alkaloids
15
Protoalkaloids
True
alkaloids
Not derived from amino
acids = pseudoalkaloidsDerived from
amino acids
Terpenoid
derivates
nitrogen in heterocycle
nitrogen in side chains
Purine and
pyrimidine
derivates
Alkaloids
16
„Polyketide
alkaloids”
Major effects
• Stimulate the CNS (central nervous system) – caffeine
• Paralyse the CNS – scopolamine
• Stimulate the PNS (periferial nervous system) – efedrin
• Paralyse the PNS – hyosciamine
• Vasoconstrictor effect – ergot alkaloids
• Vasodilator effect – theophylline
• Increase blood pressure – vincamine
Scopolia carniolica
Ephedra distachya
Hyoscyamus niger
Claviceps purpurea
Camellia sinensis
Vinca minorCoffea
arabica
Alkaloids
17
True alkaloids
Amino
acid
Alkaloid unit Typical alkaloids Plant genera
ornitine tropane
pyrrolizidine
pyrrolidin
atropine, hyosciamine,
scopolamine
senecionine, jakobein
Datura, Atropa,
Senecio
lysine quinolizidine
piperidine
lupinine, lupanine, sparteine,
cytisine
pseudopelletierine, coniine
Lupinus, Laburnum,
Lobelia, Conium
nicotinic
acid
pyridine nicotine, anabasine, arecoline Nicotiana tabacum
tyrosine isoquinolin
benzylisoquinoline
pheniethylisoquinoline
chelidonine, sanguinarine
morphine
colchicine
Chelidonium majus
Papaver somnifera
Amaryllis
Colchicum autumnale
triptophan quinoline
indole
quinoline
vincamine
ergochristine, ergotamine, LSD
Cinchona pubescens
Vinca, Catharanthus
Claviceps purpurea18
Alkaloids derived from ornithine, lysine and nicotinic acid
pyrrolizidinebackbone
ornithine
nicotinic acid
lysine
lupinine
piperidinebackbone
tropanebackbone
pyridinebackbonequinolizidine
backbone
non-lysine derived pseudoalkaloids
19
Natural occurence in species of
Solanaceae, Erythroxylaceae,
Convolvulaceae
Major alkaloids are: S and R hyoscyamine
(one of its enantiomers is atropine),
scopolamine, cocaine
Inhibition of muscarinic cholinergic
receptors (competitive antagonists of
acetylcholine) anticholinergic effects
Ecgonine alkaloids (tropane derivates)
cocaine (Erythroxylum coca) block the
ion channels in neurones local
analgesic, and strong (psycho)stimulant
effect
Tropane alkalods
20
Natural occurence: Heliotropium
spp., Cynoglossum spp.,
Symphytum spp. Boraginaceae
family and Senecio spp.,
Eupatorium spp. Asteraceae
family
At least 560 types described, the
most important molecules are
jacobine and senecionine
Hepatotoxic effect (pyrrole
derivates can form irreversible DNA
adducts) thus secondary
photosensitization
Accumulation in organs
Pyrrolizidine alkaloids (PA)
Symphytum officinale –
common comfrey
Senecio jacobea –
europaean
ragwort21
Natural occurence mainly in Fabaceaefamily, especially species of Lupinus, Cytisus, Laburnum genera
Teratogenic, antibacterial, antifungalactivity
No accumulation in the organs
Binding mainly to nicotinic receptors as AChagonists
Major alkaloids: sparteine, cytisine, lupinine, lupanine, anagyrin
Quinolizidine alkaloids
Lupinus
polyphyllus –
large-leaved
lupine
Laburnum anaryroides
– golden chain
22
Lysine derived piperidine alkaloids
Lobelia alkaloids (lobeline):
nicotine-like but weaker effects
Piperine alkaloids – an amide of
piperidine, responsible of pungency
of black pepper, CNS depressant
and anticonvulsant effect
Piperidine alkaloids 1.
Lobelia inflata –
indian tobacco
Piper nigrum –
black pepper 23
Non-lysine derivedpiperidine alkaloids
pseudoalkaloids
Conium alkaloids
Absorbed through the skin,
mucous membranes and it
can cross the placenta
In the peripheral nervous
system coniine blocks thenicotine receptors on the
post-synaptic membrane of neuromuscular junctions
blocking movements
Piperidine alkaloids 2.
Conium maculatum – hemlock24
Synthesized from nicotinic acid
the heterocyclic ring is unsaturated
Widely distributed in nature provide
aroma of foodstuff
Natural insecticides synthesis
increase after insect attack
Major alkaloids: nicotine,
anabasine, arecholine
Respiratory stimulant, but larger
dose causes respiratorydepression
Nicotine acts as an agonist at
nicotinic acetylcholine receptors
Pyridine alkaloidsAreca catechu
– betel palm
Nicotiana
tabacum –
tobacco25
phenylalanine isoquinolinebackbone
phenylalanine
tyrosine
tyrosine
Alkaloids derived fromphenylalanine and tyrosine
benzylisoquinolinebackbone
phyenylethylisoquinolinebackbone
colchicine
morphine
ephedrine
26
Two six membered aromatic ringswith a heterocycle
Major alkaloids are chelidonine,
chelerythrine, sanguinarine,
With various effects:
antispasmodic, antibilious but alsocytotoxic effect anti-tumor drugs
Isoquinoline alkaloids
Chelidonium majus –
greater celadine
27
Synthesized from two units of tyrosine
Alkaloids are important as medicines
but large dose can be highly toxic
Papaverin: basic benzylisoquinolineblackbone vasodilator, smooth
muscle relaxant
Morphinan derivates – opiates
Codeine and noscapine: antitussive
effect (cough supressive)
Morphine and thebaine – painkillers,
sedative effect
Act on the opiod receptors –
suppression of transmission of painsignals
Benzylisoquinoline alkaloids
papaverine
Papaver somniferum
– opium poppy
28
• Aristolochic acids have aporphine skeleton
which is derived from bezylisoquinoline
precursors
• Forms aristolactam DNA adducts
• Mutations
• Carcinogenic effects thyrosine
aristolochic acid
29
Small group with only a few
molecules
Colchicine (a protoalkaloid): binds with tubulin dimers
inhibition of microtubuleformation inhibition of cell
division
Treatment of gout
Phenylethylisoquinoline alkaloids
Colchicum
autumnale –
meadow saffron
30
Alkaloids derived from tryptophan
tryptophan
tryptophan
amino acid backbone Cunit alkaloids
quinoline backbone
indole backbone
Synthesis includes the
terpenoid pathway
31
Nitrogene in different position than
isoquinoline alkaloids
With a monoterpenoid chain (C10)
The most important antimalariadrugs
Quinine (Cinchona officinalis)
Quinoline alkaloids
32
Simple indole derivates or isoprenoidalkaloids with a C9 or C10
monoterpenoid fragment
Vasodialator effect, increased blood
and oxygen supply to the brain
(vincamine)
Cytotoxic activity anticancer drugs
Psilocybin psychedelic compound
Indole alkaloids
Vinca minor – lesser periwinkle
Psilocybe
azurescens33
Ergot alkaloids (ergoline derivates)
Molecules are similar to serotonin, dopamine and epinephrine bind to
receptors as agonists
Vasoconstrictor, styptic and
psychedelic effects
Used to stop postnatal bleedings or in
the treatment of Parkinson’s desease
Claviceps purpurea –
ergot body34
The classification based on the precursor molecule
The backbone not derived from the nitrogen pathway
the nitrogen incorporated in a different way
Terpenoid alkaloids
• Mono and sesquiterpenoid alkaloids - rare
• Diterpenoid alkaloids
• Steroid (triterpene) alkaloids
Pseudoalkaloids
35
Various molecules due to the basic
terpenoid stucture
Nitrogen atom bounds with
amination (an amine group
incorporated into the molecule)
Affects ion channels CNS and
cardiac effects
Diterpenoid alkaloids
abietanes
tiglianes
cauranes
taxanes
Aconitum napellus –
monkshood
Taxus baccata – yew
36
Steroidal backbones are triterpene
derivates, nitrogen atom bounds with
amination
Many of them occure as glycosides
Open Na+ channels permanently –
paralysing effects
Steroidal alkaloids
Solanum spp. Veratrum spp.
Solanum nigrum –
black nightshade
Veratrum album –
white hellebore
37
Antinutritve compounds and effects
38
The adverse effect of forages
• Contamination with inorganic compounds
• Mouldy forage (fungi, bacteria)
• Narrow range of forages
• Non-optimal dosage
• Non-optimal nutirent and energy supply
• Secondary plant metabolites – antinutritives
39
• Antinutritional factors are substances that when present in
animal feed reduce the availability of one or more nutrients
• These factors interfere with the utilisation of dietarynutrients in a variety of ways
• No major role in primary metabolism (non-essential
compounds)
• Mainly secondary metabolites
• Taxonspecific compounds
Antinutritional factors (ANFs)
40
• Decrease voluntary feed intake
• Reduced digestibility
• Changes in metabolism
• Poisonous effects
decreased production (or quality)
Effects on animals species
41
Classification of antinutritional factors
Animal nutrition: based on their effects on the nutritive value
of feedstuffs and on biological responses in animals
Botany: biosynthetic pathway of plant metabolites
42
Carbohydrates with antinutritive effects
Non-starch polysaccharides (NSP)
Major structural elements in the cell wall (cellulose,
hemicellulose, pectin) – mainly in forage legumes
Cellulose has a low digestibility (only 30% of total dry matter)
Beta-glucans and arabinoxylans has high water absorptioncapacity increased viscosity sticky faeces syndrome
If the proportion of NSP is high decreased energy value and
digestibility of the forage decreased production
In cereals and pulse crops in the cells of the endosperm
Prevention: application of forage mixtures or specific enzymes
43
Non-digestable oligosaccharides
Raffinose, stachyose and verbascose are non-digestible
saccharides
Most of the species do not haveenzymes to digest them passunchanged to the colon intestinal
bacteria ferment them to gases
bloating effect
Mainly in fabaceous plants as stored
nutrients
Prevention: application of beta-
galactosidase enzyme
44
Phytic acid is a primary product of carbohydrate metabolism
Calvin-cycle glucose-6-Pfructose-6-P
myo-inositol
galactinol
oligosaccharides
phytic acid
Phytic acid and phytates
45
Phosphorus and inositol in form of phytate are not bioavailable to
non-ruminants
Phytate can form complexes with a variety of minerals reducing
the availability of the nutrients
Phytic acid and phytates
46
Phytic acid can also form complexes with
basic residues of proteins interfere with the
activity of enzymes and digestibility of other
nutrients
Natural occurence: cereals, pulse crops and
oil plants
Poultry and pig has low feed conversion of
phytates
Ruminants are tolerant as phytase enzyme is
produced by rumen microorganisms
Prevention: application of with phytase
supplementation
Hydrolyzable and condensed tannins
Natural occurence: field pea, field bean,
sainfoin
Major effects astringent taste (depresses feedintake), precipitate proteins water
insoluble complexes (decreased protein
conversion rate), bounds with iron (iron
deficiency)
Susceptible species: poultry, pig, horse
Tannin content of forage plants is generallylow, no poisonous, but mild antinutritive effect
Phenoloids with antinutritive effects
Tannins
47
Coumestrol, genistein, formononetin
Natural occurence: soybean, lucern, clovers
Similar to animal estrogen
Binds irreversible to estrogen receptors
Decreasing fertility – abnormal estrous cycle,
abortion, sterility
Susceptible species: cattle, horse
Prevention: application of forage mixtures
Isoflavanoids
48
General compound in the
Brassicaceae family
Mainly stored in the seeds
Major effects: myocardial lesions(fatty infiltration of myocardium)
Susceptible species: all livestock
species
Prevention: application of double
zero cultivars
Polyketides with antinutritive effects
Erucic acid
49
Terpenoids with antinutritive effects
Triterpenoids (saponins)
Natural occurence: species of Fabaceae family
Produce foam in the rumen
Can enter into the lipid bilayer of membranes disintegrated membranes
Decrease rumen motility
Red blood cells are affected haemolytic
effect
Generally molecules have a bitter flavour irritation of mucous membranes
Susceptible species: ruminants, poultry, pigs
Prevention: application of selected cultivars,
forage mixtures or drying50
A sesquiterpene dimer of cottonseed
Absorbed from the GT and bounds to amino acids, especially lysine, and to
dietary iron
Renders many amino acids unavailable affects enzymatic reactions
Effects on the cardiac, hepatic, renal,
reproductive systems
Green discoloration of egg yolk
Susceptible species: all animals, but
especially monogastrics, preruminants,
immature ruminants, and poultry
Prevention: high intake of protein, calcium
hydroxide, or iron and limited dietary
gossypol concentration
Gossypol
51
Natural occurence in Lathyrus species:
lathyrogenes (ODAP, BAPN, DAB)
BAPN can inhibite the collagen synthesis damage of bones and connective
tissues
Susceptible species: horse, cattle, poultry
Prevention: heat treatment or consumption
of foods containing sulphuric amino acids
Azotoids with antinutritive effects
Non-proteinogenic amino acids
52
Natural occurence: in species of Fabaceae family (lucern,
clovers)
Rapid digestion by rumen microbes slime production
frothy bloat (distension caused by foam and gases)
Suspectible species: horse, cattle
Prevention: drying, ensilage, slow adaptation to fresh
forage legumes
Water-soluble peptids of lowmolecular weight
53
Protease inhibitorsNatural occurence in legume seeds
(soybean, beans) and cereals
Mainly trypsin and chymotrypsin inhibitors these peptides form stable
inactive complexes with the pancreatic enzymes decreased protein digestion
When trypsin and chymotrypsin are reduced the pancreas stimulated to produce more
digestive enzymes hypertrophy of the
pancreas
Susceptible species: poultry, pig, carnivores
Prevention: heat treatment but trypsin
inhibitors are less susceptible to heat
Amylase inhibitors have minor importance impaired digestion of starch
54
Proteins that are generally present in the form of glycoproteins have
the ability to bind to specific sugars
Binding of lectins to epithelial cells disorders of nutrient absorption
growth depressions
Natural occurence: in beans (highly
toxic), field bean, pea, lupines (less
toxic)
Suspectible species: monogastric
species
Prevention: heat treatment (cooking,
steaming, roasting or extrusion)
Lectins (phytoheamagglutinins)
55
Sulphuric compounds from cysteine strong, hot
flavour
Natural occurence in species of Brassicaceae
Isothiocyanates produced irritation of skin and
mucous membranes, goitrogen effect disrupts the
production of thyroid hormones (interferes withiodine uptake)
Low iodine uptake losing of weight, hemorrhagic
symptoms in liver, enlarged spleen and kidneys,
abortion
If specific proteins are present carcinogenic
nitriles or thiocyanates can also be produced
It can be excreted in the milk
Susceptible species: pig, cattle, poultry
Prevention: application of double zero cultivars
Glycosinolates
56
Cyanogenic glycosides
Natural occurence: linseed, Sorghum spp., white clover
Inhibition of cell respiration
Prevention: grazing, harvesting in optimal phenological stage,
application of limited amounts in mixtures
Poisonous alkaloids
Lupinus species: quinolizidine type – lupinine, lupanine
lupine poisoning
Vicia faba: pyrimidine type - vicine, konvicine favism
Prevention: application of selected cultivars
Poisonous azotoids
57