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