Post on 09-Jun-2015
TassonomiaPrincipali famiglie di piante
aromatiche
Pinales (=Coniferales)
Pinales
Pinaceae
Cupressaceae
• Piante legnose, alberi o arbusti, a
profilo conico
• Presenza di canali resiniferi
• Piante comunemente sempreverdi,
con foglie nastri-, aghi- o
squamiformi, pluriennali (a parte
rare eccezioni).
• Piante quasi sempre monoiche con
f iori unisessuati , semplici ,
squamosi
• Coni staminati (produttori di
polline); la maggior parte porta
anche coni ovulati (produttori di
semi)
OE tipici
•Pinus spp
•Abies spp
•Cedrus atlantica
•Cedrus deodara
•Juniperus communis
•Juniperus virginiana
•Juniperus oxycedrus*
•Juniperus sabina*
•Cupressus sempervirens
•Thuja occidentalis*
Pinaceae
P. roxburghii
Cupressaceae
Magnoliales
AnnonaceaeUna famiglia d’arbusti, alberi
e rampicanti, con fiori molto
aromatici. E' divisa in 2050
specie e 125 generi, tipici dei
tropici.
Anche se queste piante non
sono comuni nel Nuovo
Mondo, il genere Annona L. è
ben rappresentato nelle zone
tropicali delle Americhe, in
particolare nelle foreste
pluviali.
Molte specie (generi Annona
e Artabotrys) vengono
coltivate per i frutti
commestibili. Altre, come
Cananga odorata, sono fonti
di materiale da profumeria.
L'olio di Cananga è un debole
allergenico da contatto.
Esemplari:
OE tipici• Cananga odorata var.
genuina• Cananga odorata var.
macrophylla
Laurales
LauraceaeAlberi od arbusti con foglie
tenaci, sempreverdi. Tipici
di cl imi tropicali o
s u b t r o p i c a l i , f i n o a
temperati.
• Foglie: coriacee, semplici e
c o m u n e m e n t e
sempreverdi. Punteggiate
di ghiandole, aromatiche
• Fiore: aggregati in
"infiorescenze" spesso
ombrelliformi.
• F rut t o : s o l i t a m e nt e
carnoso
OE tipici
•Cinnamomum verum
•Cinnamomum cassia
•Cinnamomum camphora
•Aniba rosaeodora*
•Litsea cubeba
•Laurus nobilis
•Ravensara aromatica
Piperales
Piperaceae
Famiglia che comprende
ca. 3615 specie in cinque
generi delle zone tropicali
•Piante ad habitus
erbaceo, ma anche
alberelli o liane.
•Fiori minuti senza
perianzio, raccolti spesso
in spighe dense
•Frutto drupe carnose a
seme singolo.
•Foglie morbide e/o
succulente, spesso cordate
alla base.
OE tipici
•Piper nigrum
•Piper cubeba (sin
Cubeba officinalis)
•Piper betel
•Piper longum
Poales
Poaceae
La famiglia delle piante
a fiore di maggior
successo, comprende
circa 10.000 specie in
620 generi. Queste
piante erbacee crescono
in tutte le regioni nelle
quali una pianta può
sopravvivere. La
maggior parte dei
cereali alimentari
provengono da questa
famiglia (riso, avena,
orzo, miglio, segale,
grano, mais, ecc.).
OE tipici
•Cymbopogon citratus
•Cymbopogon flexuosus
•Cymbopogon martinii
•Cymbopogon nardus
•Cymbopogon
winterianus
•Vetiveria zizanoides
Zingiberales
ZingiberaceaeFamiglia comprende ca.
1000-1300 spp. in 46-52
generi. Native delle regioni
tropicali e foreste pluviali,
specialmente dell'Indo-
Malesia.
•Piante erbacee perenni
aromatiche rizomatose, molte
sono di notevoli dimensioni e
aromatiche in tutte le loro
parti.
•Infiorescenza spesso
ramificata e pedunculata
•Fiori monosimmetrici
•Radici carnose o tuberose.
•Contengono feilpropanoidi e
curcumine.
OE tipici
•Alpinia galanga, A.
officinarum
•Amomum melagueta
•Curcuma longa, C. zedoaria
•Elettaria cardamomum
•Kaempfera rotunda, K.
galanga
•Zingiber officinale, Z.
cassumar
Santalales
SantalaceaeFamiglia di alberi,
arbusti e piante erbacee
parassiti di fusti di
altre piante. La
famiglia comprende 500
specie in 36 generi,
tipici delle zone
temperate e tropicali.
•Foglie da spiralare a
opposte
•Fiori piccoli tetra-
pentameri.
OE tipici
Eucarya spicata (sin
Santalum spicatum)
Santalum album
Geraniales
Geraniaceae
Famiglia comprendente
circa 750 specie divise in
cinque generi di
distribuzione cosmopolita,
di grande importanza per
la produzione di olii
essenziali e di rimedi
medicinali tanninici.
•Foglie stipulate con vene
palmate o pinnate o
pinnatocomposte.
•Le infiorescenze sono
cimose
OE tipici
•Pelargonium
graveolens
•Pelargonium
odorantissimum
•Pelargonium radens
•Pelargonium capitatum
•Pelargonium x asperum
Myrtales
Myrtaceae
Famiglia che comprende
4620 spp. in 131 generi di
a l b e r i e a r b u s t i
sempreverdi, tropicali,
sub-tropicali, e temperato
caldi
• Fiori raramente solitari,
solitamente raggruppati
in "infiorescenze"
• Foglie : aromatiche,
semplici, punteggiate di
cavità secretorie, quasi
sempre sempreverdi, con
a l c u n e s p e c i e d i
Eucalyptus decidue
• C a v i t à o d o t t i
s c h i z o l i s i g e n i n e l
mesofillo delle foglie.
OE tipici
•Eucalyptus spp.
•Melaleuca spp
•Syzygium aromaticum
•Myrtus communis
Rosales
Rosaceae
•Foglie spesso
composte, stipulate e
dentate, raramente
opposte
•Fiori con calice libero
•Frutti spesso acheni
o drupe
OE tipici
•Rosa damascena
Sapindales
Burseraceae540 specie divise in 21 generi
delle zone tropicali. La
maggioranza delle specie
produce oleo-gommo-resine a
seguito di lesioni della corteccia.
Usate medicinalmente, per
produrre incensi e profumi.
Il genere Amyris è stato fonte di
molta confusione botanica, dato
che è appartenuto sia alle
Burseraceae che alle Rutaceae.
Oggi si ritiene appartenga a
quest’ultima famiglia ma certe
specie sono state trasferite al
genere Commiphora delle
Burseraceae.
Così, la Amyris plumieri DC.
appartiene alle Rutaceae,
mentre la Amyris opobalsamum
L. appartiene alle Burseraceae,
e ha cambiato nome in
Commiphora opobalsamum
Engl.
OE tipici• Boswellia carterii, B.
sacra, B. serrata• Bursera aloexylon, B.
fagaroides• Commiphora erythrea, C.
molmol, C. myrrha
RutaceaeFamiglia di 1815 specie,
divise in 161 generi. Arbusti
e alberi, distribuiti sia in
zone temperate che tropicali• F r u t t i : v a r i ; n e l l e
Aurantiadeae (Citrus spp) è
un esperidio.
• Foglie: opposte, puntute,
lamina con cavità secretorie
contenenti OE.
• Strutture secretorie: cavità
secretorie nelle foglie e nei
fusti verdi, cavità schizogene
o l i s igene . Cel lu le
epidermiche nei petali.
• Fiori: solitari (raramente) o
aggregati in "infiorescenze"
cimose.
• la presenza di cumarine li
accumuna alle Apiaceae
OE tipici
•Citrus bergamia
•C. xparadisi
•C. limon
•C. reticulata
•C. aurantium flos, fol, fruct
Lamiales
LamiaceaeE' una delle famiglie più evolute, di
distribuzione cosmopolita (se si escludono
Artide ed Antartide), generalmente di tipo
erbaceo o suffruticoso, più raramente
piccoli alberi.
• Fusto: a sezione quadrata (presenza di
fasci collenchimatici), ad internodi solidi,
oppure spugnosi o vuoti
• Foglie: semplici, opposte e decussate
(estipolate)
• Fiori: da piccoli a medi, solitari,
aggregati in "infiorescenze". Fortemente
d o r s o v e n t r a l i , r a c c o l t i i n
"pseudoverticilli" (o in teste, o in cime o
in panicoli) alle ascelle delle foglie. .
• Semi: piccoli e con endosperma ridotto
• Strutture secretorie: la maggior parte
delle Lamiaceae accumulano le essenze
nei tricomi ghiandolari delle foglie, fiori e
fusti.
OE tipici
•Salvia spp.
•Lavandula stoechas, L. angustifolia, L.
latifolia
•Rosmarinus officinalis
•Mentha xpiperita.
•Hyssopus officinalis
•Ocimum basilicum
•Satureja montana
•Origanum marjorama
•Thymus vulgaris
•Melissa officinalis
•Pogostemon cablin
Oleaceae
Famiglia di 900 specie in
24 generi a distribuzione
cosmopolita, comuni
soprattutto in Asia
tropicale e temperata.
Comprende alberi e
arbusti, inclusi Olea e
Fraxinus, usati a scopo
alimentare o per il
legname.
Estratti tipici• Jasminum auriculatum• Jasminum grandiflorum • Jasminum officinale• Jasminum sambac•Osmanthus fragrans• Syringa vulgaris
VerbenaceaeUna famiglia di piante
erbacee, arbusti, alberi e
rampicanti legnosi; i
frutti sono solitamente
drupe o capsule.
Comprende 3000 specie
in 75 generi quasi tutte
tropicali e sub tropicali.
Molte piante sono
importanti come fonti di
legname (tek), alcune
sono coltivate per i fiori.
OE tipici:•Lippia citriodora•Lippia camara•Lippia abyssinica•Lippia fragrans•Lippia graveolens•Lippia umbellata
Asterales
Asteraceae
Rappresenta la più vasta famiglia
di piante a fiore, presenti in pratica
in ogni clima, a qualsiasi altitudine
ed in ogni continente; sono rare solo
nelle foreste pluviali tropicali.
E' una famiglia diversificata, con
arbusti sempreverdi, piante erbacee
rizomatose, perenni tuberose,
piante succulente.
La caratteristica che accomuna le
Asteraceae è la infiorescenza a
capolino
Tubuliflorae
Sono assenti i laticiferi ma sono
invece comuni i dotti schizogeni già
descritti nelle Apiaceae, anche se in
questa famiglia essi sono a volte
associati a tricomi ghiandolari (ad
esempio in Artemisia dracunculus).
L'OE contiene spesso composti
acetilenici e i sesquiterpeni noti
come azuleni (o meglio, i precursori
degli azuleni).
OE tipici
•Helychrisum italicum
•Chamamelum nobile
•Matricaria recutita
•Achillea millefolium
Apiales
Apiaceae
La maggior parte è composta da
piante erbacee aromatiche. Sono
distribuite in tutto il mondo ma
preferiscono le regioni montuose
temperate del continente europeo.
• Fusto: solcato, spesso con nodi ed
internodi cavi.
• Foglie: solitamente larghe; alterne,
o alterne ed opposte, con cavità
secretorie.
• Fiori: piccoli, solitamente aggregati
in "infiorescenze": disposti ad
ombrella semplice o composta, o
molto raramente in teste globulari.
• Frutto: cremocarpo (schizocarpo
secco), a due mericarpi,
• Dotti (canali) oleoresinosi detti
vittae, di origine schizogena nel
frutto e anche in foglie, radici e
fusti.
OE tipici
•Foeniculum vulgare
•Carum carvi
•Coriandrum sativum
•Pimpinella anisum
•Angelica archangelica
•Cuminum cyminum
•Apium graveolens
•Petroselinum crispum
•Anethum graveolens
Chimica degli olii
essenziali
Fotosintesi e molecole di
partenzaLa chimica unificata della vita
Fotosintesi e molecole di partenza
•Fotosintesi
•Glicolisi e ciclo di Krebs (2C)
•Piruvato (3C)
•Acido shikimico (5C ciclici)
•Acido mevalonico (5C non ciclizzati)Ciclo
dell'acido citrico
Radiazioni solari + acqua = Energia e zuccheri
Percorso shikimato (fenilpropanoidi)
Percorso mevalonato/deossixilulosio
Percorso acetato/polichetidi
Bacino degli zuccheri pentosi
Fosfoenolpiruvato
(PEP)
Piruvato
Acetil-CoA
Glicolisi
aa: cisteina, glicina, serina
Glutatione
Ac. nucleici(ATP) alcaloidi
purineallantoina, alcaloidi
amido e cellulosapolisaccaridiglicosidi
aa: triptofano
aa: fenilalanina e tirosina
flavonoidi e fenoliligninalignanistilbenipolifenolicumarineantocianinealcaloidi
amminoacidi, alcaloidi
terpeni, fitosteroli, fitoecdisteroni, alcaloidi
aa: glutammato
alcaloidi, amminoacidi non proteici
amminoacidi
amminoacidi
aa: aspartato
clorofilla
alcaloidi alcaloidi non proteici
alcaloidi
serotonina
Eritrosio 4 fosfato
Metabolismo secondario delle
piante
La chimica della sopravvivenza e della riproduzione
•OE = Prodotto
•Essenza = pool di metaboliti secondari sintetizzati e
stoccati in strutture cellulari e tessuti specifici, ben
segregati, a scopo funzionale e protettivo
Composizione:
•terpeni: mono-, sesqui- e pochi diterpeni
•composti ossigenati derivati: alcoli, aldeidi, chetoni
•fenilpropanoidi: eteri fenolici, aldeidi aromatiche
•fenoli derivati da differenti percorsi (timolo)
•composti minori: contenenti zolfo (isotiocianati,
sulfidi, ecc.) e composti azotati.
I composti ossigenati sono più importanti
dei terpeni per la caratterizzazione odorosa,
ma ci sono anche:
tioli (pompelmo), composti terpenici
contenenti zolfo (buchu), alchil sulfidi
(aglio), isotiocianati (rafano, senape),
sesquiterpeni (la nota curry dell’elicriso),
composti azotati (pirazine in coriandolo e
galbano, ecc.)
Biosintesi dei metaboliti secondari
Origine biosintetica terpenoidi
•unità isopreniche, spesso con ciclizzazione usando
l’energia dei doppi legami
Esempi:
•Monoterpeni: menta e mentolo, pino e pinene
•Sesquiterpeni: Artemisia e artemisinina
•Origine biosintetica fenoli
•dal piruvato allo shikimato, alla tirosina e
fenilalanina fino all’acido cumarico
• They protect plants against being eaten by herbivores(herbivory) and against being infected by microbialpathogens.
• They serve as attractants for pollinators and seed-dispersing animals and as agents of plant–plantcompetition.
In the remainder of this chapter we will discuss the majortypes of plant secondary metabolites, their biosynthesis,and what is known about their functions in the plant, par-ticularly their roles in defense.
Plant Defenses Are a Product of EvolutionWe can begin by asking how plants came to have defenses.According to evolutionary biologists, plant defenses musthave arisen through heritable mutations, natural selection,and evolutionary change. Random mutations in basicmetabolic pathways led to the appearance of new com-pounds that happened to be toxic or deterrent to herbi-vores and pathogenic microbes.
As long as these compounds were not unduly toxic tothe plants themselves and the metabolic cost of producingthem was not excessive, they gave the plants that pos-sessed them greater reproductive fitness than undefendedplants had. Thus the defended plants left more descen-dants than undefended plants, and they passed their defen-sive traits on to the next generation.
Interestingly, the very defense compounds that increasethe reproductive fitness of plants by warding off fungi, bac-teria, and herbivores may also make them undesirable asfood for humans. Many important crop plants have beenartificially selected for producing relatively low levels ofthese compounds, which of course can make them moresusceptible to insects and disease.
Secondary Metabolites Are Divided into Three Major GroupsPlant secondary metabolites can be divided into threechemically distinct groups: terpenes, phenolics, and nitro-gen-containing compounds. Figure 13.4 shows in simpli-
286 Chapter 13
Erythrose-4-phosphate 3-Phosphoglycerate(3-PGA)Phosphoenolpyruvate Pyruvate
Acetyl CoATricarboxylicacid cycle
Aliphaticamino acids
Aromaticamino acids
Shikimic acidpathway
Terpenes
Nitrogen-containingsecondary products
Phenoliccompounds
Malonicacid pathway
MEP pathwayMevalonicacid pathway
SECONDARY CARBON METABOLISM
CO2
Photosynthesis
PRIMARY CARBON METABOLISM
FIGURE 13.4 A simplified view of the major pathways of secondary-metabolitebiosynthesis and their interrelationships with primary metabolism.
Isoprenoidi
• Il gruppo di metaboliti secondari più ampio (+40.000), più
antiche (2.5 miliardi adi anni fà) e con funzioni più diverse:
•Chinoni respiratori (MP)
•Membrana cellulare (MP)
•Pigmenti fotosintetici (MP)
•Comunicazione cellulare (prenilazione) (MP)
•Ormoni (MP)
•Composti di difesa e comunicazione (MS)
Definizione e struttura
• Metaboliti secondari caratterizzati dalla presenza di
più unità a 5 atomi di carbonio correlate all’isoprene
(metilbutadiene), ovvero:
• Composti multipli interi di unità C-5: terpeni e
terpenoidi
• Sostanze che in genere non sono multipli interi
dell’isoprene, come gli steroidi, che sono però
strettamente legate dal punto di vista biogenetico a
terpeni e terpenoidi
Definizione e struttura
OPP OPP
DMAPP IPP
Definizione e struttura
• Terpeni e terpenoidi
–Mono, sesqui, di e triterpeni
• Steroidi
–Steroli
–Progestinici
–Saponine (glicosidi)
–Glicosidi cardiotonici
Classificazione
serve as large-volume feedstocks for the production of asuite of industrial materials. Because of their many differentstructures, plant terpenoids as a group include compoundswith many different physical and chemical properties. Theymay be lipophilic or hydrophilic, volatile or non-volatile,cyclic or acyclic, chiral or achiral. The chemical diversity ofplant terpenoids originates from often complex terpenoidbiosynthetic pathways.
Much research in the last two decades has concentratedon the molecular biochemistry and genomics of terpenoidbiosynthesis, and, to some extent, on their biologicalfunctions in nature. There is also long-standing recognitionthat the diverse pathways for specialized plant terpenoidsprovide a resource for commercial production of high-value or large-volume chemicals. This resource can beutilized both in their naturally occurring or metabolicallyengineered forms in crop plants in agriculture, forestry orhorticulture, as well as through their biochemical engi-neering into microbial fermentation systems. A broaderawareness of the value of plant terpenoids has created aninnovative climate for interdisciplinary research thatincludes chemistry, biology, chemical engineering andhealth research, and may lead to new means for theexploitation of terpenoids for human use. Research intoplant terpenoid chemicals and terpenoid-producing plantsmay also provide new leads towards hydrocarbon biofuels,as a complement to the more advanced development ofbiodiesel or ethanol biofuels.
After a general overview of terpenoid biosynthesis inplants, this paper will focus on examples of a few hemi- (C5),mono- (C10), sesqui- (C15) and diterpenoids (C20) in thecontext of terpenoids as a biomaterials resource. Examplesare selected to highlight recent research relevant to variousaspects of traditional and modern human exploitation ofplant terpenoids: (i) menthol (Figure 1), a monoterpenoidthat is produced and harvested in large amounts frompeppermint (Mentha · piperita) as an agricultural farm crop;(ii) artemisinin (Figure 1), an anti-malarial sesquiterpenoidpharmaceutical from annual wormwood (Artemisia annua)that is being explored for production in metabolicallyengineered microbial fermentation systems and transgenicplants; (iii) abietic acid and related diterpene resin acids(Figure 1) as a biological feedstock from conifers (Pinaceae)for a large chemical industry that relies to a substantialextent on century-old means of rosin collection; and (iv)Taxol (Figure 1), a high-value diterpenoid-derived anti-can-cer drug of limited supply from its initial natural source, thebark of the Pacific yew tree (Taxus brevifolia). In addition, inthe context of exploring the use of plants such as poplartrees (Populus spp.) as a source for cellulose-based biofuels(Doran-Peterson et al., 2008; Li et al., 2008; Pauly andKeegstra, 2008), this paper will briefly address the apparentloss of carbon from plants due to emission of volatileterpenoid hydrocarbons, using the hemiterpene isoprene(Figure 1) as an example. As terpenoids often occur inmixtures with other plant chemicals, the section on conifer
n-heptaneisoprene
OH
2-methylbut-3-en-2-olmethylbutane
CO2H
dehydroabietic acid
CO2H
isopimaric acid
CO2H
abietic acid
O
O
H
H
O
H
OO
artemisinin
AcO O OH
OAc
OH
OHO
OBz
O
OH
NH
O
Taxol
(–)!-pinene (–)"-pinene (–)-menthol
OH
myrcene (–)-limonene
Figure 1. Chemical structures of the hemiterp-enoids (C5) isoprene and methylbutenol; themonoterpenes (C10) myrcene, ())-limonene, ())-a-pinene, ())-b-pinene and ())-menthol; the ses-quiterpenoid (C15) artemisinin; the diterpeneresin acids (C20) abietic acid, dehydroabietic acidand isopimaric acid; the diterpenoid (C20) Taxol;and the short-chain alkanes n-heptane andmeth-ylbutane.
Terpenoid biomaterials 657
ª 2008 The AuthorsJournal compilation ª 2008 Blackwell Publishing Ltd, The Plant Journal, (2008), 54, 656–669
•Il percorso di biosintesi degli
isoprenoidi può essere suddiviso in 4
fasi:
•Sintesi di IPP e DMAPP
•Sintesi precursori delle classi
terpeniche
•Sintesi dei terpeni
•Funzionalizzione dei terpeni
Terpenoidi/Isoprenopidi
diterpene resin acids also refers to the short-chain alkanes(e.g. n-heptane; Figure 1) that are present in some coniferoleoresin secretions. Other plant terpenoids used for plant-derived materials, such as tetraterpenoids (C40) in the formof carotenoids (Tanaka et al., 2008), flavour and aromacompounds derived from mono-, sesqui-, di- and tetra-terpenoids (Schwab et al., 2008), as well as the topic ofnatural rubber, a polyterpene (van Beilen and Poirier, 2008),are covered elsewhere in this issue. The present paper isbased, in part, on a recent technical article on plantterpenoids in the Wiley Encyclopaedia of Chemical Biology(Keeling and Bohlmann, 2008) and on some excellent recentreviews on plant terpenoids, including reviews on menthol(Croteau et al., 2005) and Taxol (Croteau et al., 2006).
Overview of the biosynthesis of hemi-, mono-, sesqui and
diterpenoids in plants
The diverse metabolic pathways of plant terpenoids are allrooted in the formation of only two isomeric five-carbon (C5)precursors, dimethylallyl diphosphate (DMADP) and iso-pentenyl diphosphate (IDP) (Cane, 1999). DMADP and IDPare formed in the mevalonic acid (MEV) pathway and in the2C-methyl-D-erythritol-4-phosphate (MEP) pathway (Langeet al., 2000a; Lichtenthaler, 1999; Figure 2). The smallestplant terpenoids, the hemiterpenoids (C5), can be formeddirectly from DMADP by terpenoid synthase (TPS) activity(Miller et al., 2001). Alternatively, assembly of two, three orfour C5 units by prenyl transferases (PT) yields geranyldiphosphate (GDP; C10), farnesyl diphosphate (FDP; C15) andgeranylgeranyl diphosphate (GGDP; C20) (Takahashi and
Koyama, 2006). PT enzymes exist in plants as both homo-meric or modular heteromeric enzymes. GDP, FDP andGGDP are the substrates for families of TPS enzymes(Bohlmann et al., 1998; Christianson, 2006; Tholl, 2006; Wiseand Croteau, 1999), and serve as the immediate precursorsfor the diverse groups of all monoterpenoids (C10), sesqui-terpenoids (C15) and diterpenoids (C20), respectively. Inaddition, pairwise condensation of FDP and GGDP gives riseto the classes of triterpenoids (C30) and tetraterpenoids (C40),respectively, and assembly of an undefined number of C5
precursors yields polyterpenoids. In addition to the regularterpenoids (Cn · 5), a large number of irregular terpenoidsand terpenoid derivatives (e.g. homoterpenes) as well asterpenoid conjugates (e.g. monoterpene indole alkaloids;Facchini and DeLuca, 2008) are formed in plants.
Following formation of themanybasic structures of hemi-,mono-, sesqui- and diterpenes in the form of olefins orsimple oxygenated terpenoids by TPS, thesemetabolites canbe further functionalized by various cytochrome P450-dependent mono-oxygenases (P450), reductases, dehydro-genases or various classes of transferases. In general, thediversity of thousands of plant terpenoid structures origi-nates from many pathway combinations of TPS and terpe-noid-modifying enzymes. TPS and terpenoid-modifyingP450 enzymes exist as large and diverse gene families inplants, and the same may be true for other terpenoid-modifying enzymes. As there are only a few biologicallyrelevant isoprenyl diphosphate substrates for TPS, basiccharacterization of these enzymes is relatively straightfor-ward. In contrast, terpenoid-modifying enzymes, includingthe P450s (e.g. Kaspera and Croteau, 2006; Mau and Croteau,
OPP OPP
OPP
OPP
OPP
MEV pathway(cytosol)
MEP pathway(plastids)
1x
2x
3x(C10) monoterpenes
(C15) sesquiterpenes
(C30) triterpenes
(C20) diterpenes
(C40) tetraterpenes
(C5) hemiterpenesDMADP IDP
GDP
FDP
GGDP
1x
1x
1x
1x
2x
2x
Figure 2. General scheme of plant terpenoidbiosynthesis.DMADP, dimethylallyl diphosphate; FDP, farn-esyl diphosphate; GDP, geranyl diphosphate;GGDP, geranylgeranyl diphosphate; IDP, isopent-enyl diphosphate; MEP, methylerythritol phos-phate; MEV, mevalonate.
658 Jorg Bohlmann and Christopher I. Keeling
ª 2008 The AuthorsJournal compilation ª 2008 Blackwell Publishing Ltd, The Plant Journal, (2008), 54, 656–669
Alcoli, aldeidi, chetoni,
ossidi, esteri, ecc.
Sintesi degli isopreni presente in
archeobatteri, eubatteri ed eucarioti, a
parrtire dal mattone iniziale isoprenico,
ovvero gli “isoprenoidi attivi” IPP e DMAPP
Ma i percorsi per produrre IPP sono due:
•MVA, originale di archeobatteri
•DXP, originale degli eubatteri
•Mammiferi e lieviti usano solo PAM, mentre
alghe e piante superiori tutti e due
La prima fase
Via del mevalonato (citosol): 3 unità
di acetato > MVA > IPP (C5) +
DMAPP (C5) testa-coda > GPP (C10)
> FPP (C15) > GGPP(C20) > squalene
(C30) + fitoene (C40) > triterpeni e
steroidi + carotenoidi
Via alternativa (plastidi): piruvato e
1-deossixilulosio-5-P --> IPP +
DMAPP
La prima fase
ers of Chrysanthemum species show very striking insecti-cidal activity. Both natural and synthetic pyrethroids arepopular ingredients in commercial insecticides because oftheir low persistence in the environment and their negligi-ble toxicity to mammals.
In conifers such as pine and fir, monoterpenes accumu-late in resin ducts found in the needles, twigs, and trunk.
These compounds are toxic to numerous insects, includingbark beetles, which are serious pests of conifer speciesthroughout the world. Many conifers respond to bark bee-tle infestation by producing additional quantities ofmonoterpenes (Trapp and Croteau 2001).
Many plants contain mixtures of volatile monoterpenesand sesquiterpenes, called essential oils, that lend a char-
288 Chapter 13
CH OH
CH2OP
OC
H
CH3
OO
OH
C CCH3 C
O
S CoA
HO
CH3 C
COOH
CH2
CH2 CH2 OH
CH2 O P PCH2 O P PCH2 O P P
CH2 O P P
CH2 O P P
CH2 O P P
OHH3C
CH2 CH
OC CH2
OH OH
P
2!
2!
Glyceraldehyde 3-phosphate (C3)
Pyruvate (C3)
3! Acetyl-CoA (C2)
Mevalonic acid
Isopentenyl diphosphate (IPP, C5) Dimethyallyl diphosphate (DMAPP, C5)
Geranyl diphosphate (GPP, C10)
Farnesyl diphosphate (FPP, C15)
Geranylgeranyl diphosphate (GGPP, C20 )
Methylerythritol phosphate (MEP)
Methylerythritolphosphate pathway
Mevalonatepathway
Isoprene (C5)
Sesquiterpenes (C15)
Triterpenes (C30)
Polyterpenoids
Monoterpenes (C10)
Diterpenes (C20)
Tetraterpenes (C40)
FIGURE 13.5 Outline of terpene biosynthesis. The basic 5-carbon units of terpenesare synthesized by two different pathways. The phosphorylated intermediates, IPPand DMAPP, are combined to make 10-carbon, 15-carbon and larger terpenes.
MeC SCoA
-CH2C OSCOA
H+
CH2COSCoAMeC
OO
-CH2COSCOA
H+
OCOSCoA
O Me OH
O
O Me OH
SCoA
H
OH
O
O Me OH
OH
O Me OH
O OPP
Me
HH OPP
H rHs
H+
Me
Me
OPP
H
acetoacetil-CoA tiolasi
HMG-CoA
sintasi
NADPH
2ATP
ATP
- CO2
isomerase - Hr
acetoacetil-SCoA
3-idrossi--metil-glutaril-SCoAHMG-CoA riduttasiNADPH
emitioacetalemevalonato (MVA)
MVA-5-pirofosfatoisopentenilpirofosfato (IPP)
dimetilallil pirofosfato (DMAPP)
•Nella seconda fase si passa dai mattoni
elementari (IPP e DMAPP) alle molecole
stabili: emiterpeni, monoterpeni,
sesquiterpeni, diterpeni, triterpeni,
tetraterpeni, politerpeni.
•DMAPP è il substrato a cui si attaccano 1 o
più molecole di IPP grazie alla
preniltrasfereasi (PT), oppure che viene
direttamente trasformato in emiterpene
dalla terpene-sintasi o ciclasi (TPS)
La seconda fase
GGPP
FPP
GPP
DMAPP
... politerpeni
IPP + PT
2 IPP + PT
3 IPP + PT
n IPP + PT
La seconda fase
•A partire da GPP, FPP e GGPP si
crea il pool di mono-, sesqui-, di-, tri-,
e tetraterpeni tramite TPS e
condensazioni.
•I percorsi sono compartimentalizzati:
C5, C10 e C20 sono sintetizzati nei
plastidi, C15 nel citosol/RE
La terza fase
Percorso MVA Percorso DPX
PT + TPS
C15
PT + TPS
C5, C10, C20
Citosol/REPlastidi
Alcoli, aldeidi, chetoni,
ecc.
FunzionalizzazioneFuzionalizzazione
La terza fase
C15C10
GFPPGGPPFPPGPP
C20 C25
C30 C40 Cn
Cond. 2x
Triterpeni
steroidi Carotenoidi
TPS TPS TPS TPS
Cond. 2x Cond. 2x
La terza fase
C5
C5
PPO
OPPOPP
OPP
+
(DMAPP)
(IPP)
geranil pirofosfato (GPP)
monoterpeni
nerilI PP (NPP)
isomerasi (?)
Genesi dei monoterpeni
OPP -
OH
OH
O
O
H
H
linalil PP
alfa-terpineolo
canfora
canfene
tuione
terpinen-4-olo
alfa-pinene
beta-pinene
fencone
isobornilene
Percorsi sintetici a partire dai monoterpeni ciclici: ciclizzazione e
funzionalizzazione
ular, cellular and genomic levels (Croteau et al., 2005). Thebiochemistry of menthol biosynthesis has been elucidatedby in vivo substrate feeding using isolated glandulartrichomes, cell-free assays using native enzymes, detailedkinetic characterization of cloned and recombinantly ex-pressed enzymes, and enzyme structure–function analyses(Croteau et al., 2005). In brief, the biosynthesis of ())-menthol (Figure 3) from GDP passes through a series ofseven enzymatic reactions starting with formation of thecyclic monoterpene ())-limonene, followed by a number ofredox modifications. Limonene synthase is a typical multi-product plant monoterpene synthase that stereospecificallygenerates ())-limonene together with minor amounts ofacyclic myrcene and bicyclic ())-a-pinene and ())-b-pinene(Colby et al., 1993; Hyatt et al., 2007). Subsequenttransformations of ())-limonene to ())-menthol involvehydroxylation to ())-trans-isopiperitenol by the P450 limo-nene-3-hydroxylase, oxidation of ())-trans-isopiperitenolto ())-isopiperitenone by NAD-dependent isopiperitenoldehydrogenase, formation of (+)-cis-isopulegone byNADPH-dependent ())-isopiperitenone reductase, isomeri-zation of (+)-cis-isopulegone to (+)-pulegone by isopulegoneisomerise, formation of ())-menthone by NADPH-dependent(+)-pulegone reductase, and finally formation of ())-menthol
by ())-menthone reductase. Other metabolites of the samepathway are (+)-menthofuran, (+)-neomenthol, (+)-isomen-thol and (+)-neoisomenthol. (+)-Menthofuran is producedfrom (+)-pulegone by the P450 menthofuran synthase.(+)-Neomenthol is formed from ())-menthone by an alter-native ())-menthone reductase. (+)-Isomenthone is formedfrom (+)-pulegone by (+)-pulegone reductase, and convertedto (+)-isomenthol and (+)-neoisomenthol by ())-menthonereductases.
The corresponding genes, in the form of cDNAs, for thecomplete pathway from GDP to ())-menthol and its off-products, have been cloned and the corresponding enzymesfunctionally characterized (Croteau et al., 2005). The currentunderstanding of this pathway provides a starting point forquantitative and kinetic metabolic flux analyses of ())-menthol biosynthesis (conceptually discussed by Lange,2006). It has also become possible to strategically alter themonoterpene composition and quality of the essential oil ofMentha through metabolic engineering (Mahmoud andCroteau, 2001, 2003; Wildung and Croteau, 2005). By com-bining metabolic engineering of Menthawith existing large-scale agricultural production systems and processing plants,it should also be feasible to utilize the biochemical andagro-industrial production capacities of Mentha for future
O
(+)-pulegone
O
(+)-cis-isopulegone
OPP
geranyl diphosphate
OH
(+)-neomenthol
OH
(+)-isomenthol
OH
(+)-neoisomenthol
O
(+)-menthofuran
O
(+)-isomenthone
MR
(–)-limonene
OH
(–)-trans-isopiperitenol
O
(–)-isopiperitenone
O
OH
iPIMFS
LS L3OH
iPR
iPD
PR
MR
(–)-menthone
(–)-menthol
Figure 3. Biosynthesis of ())-menthol and re-lated monoterpenoids in Mentha.LS, ())-limonene synthase; L3OH, ())-limonene-3-hydroxylase; iPD, ())-trans-isopiperitenoldehydrogenase; iPR, ())-isopiperitenone reduct-ase; iPI, (+)-cis-isopulegone isomerase; PR, (+)-pulegone reductase; MR, ())-menthone reduct-ase; MFS, (+)-menthofuran synthase.
660 Jorg Bohlmann and Christopher I. Keeling
ª 2008 The AuthorsJournal compilation ª 2008 Blackwell Publishing Ltd, The Plant Journal, (2008), 54, 656–669
C10
C5
OPP
OPP OPP
+
(GPP)(IPP)
(E, E)-farnesil PP (FPP)
sesquiterpeni (C15)
Genesi dei sesquiterpeni
OE a monoterpeni
•alfa- e beta-pinene, alfa-
fellandrene, gamma-terpinene,
limonene
•Pinus spp., Abies spp., Juniperus
spp., Cupressus spp., Melaleuca
spp., Citrus spp. flavedo,
OE a sesquiterpeni
•alfa-, beta- e gamma-
bisabolene; beta-cariofillene,
cadinene
•Cedrus atlantica, Matricaria
recutita, ecc.
OE ad alcoli
•Citronellolo, geraniolo, linalolo, mentolo,
alfa-terpineolo, terpinen-4-olo.
•Citrus petitgrain, Coriandrum sativum,
Ocimum basilicum, Aniba rosaeodora,
Lavandula spp., Cymbopogon spp.,
Pelargonium spp., Melaleuca alternifolia,
Ravensara aromatica, Salvia sclarea,
ecc.
OE a aldeidi
•Aldeidi grasse, citrali, citronellale,
cinnamaldeide.
•Cymbopogon spp., Eucalyptus
citriodora, Lippia citriodora.Melissa
officinalis, Cinnamomum spp.,
OE a chetoni
•Mentone, piperitone, carvone, tujone,
verbenone, canfora, ecc.
•Anethum graveolens, Carum carvi,
Hyssopus officinalis, Lavandula
spica, Rosmarinus officinalis, Mentha
xpiperita, Salvia officinalis
OE ad esteri
•Linalil, geranil e bornil acetato,
citronellil formiato, benzil benzoato
•Anthemis nobilis, Cananga
odorata, Petitgrain, Elettaria
cardamomum, Helycrhisum
italicum, Pelargonium spp., Rosa
spp.
OE ad ossidi
•1,8-cineolo, 1,4-cineolo, alfa-
bisabololo ossido
•Eucalyptus spp., Myrtus
communis, Thymus
mastichina
Resine
•Materiali compositi essudati dalle piante a scopo
di difesa e protezione, sia preformate che indotte.
•Miscele liposolubili di composti volatili e non
volatili di natura terpenoidici e/o fenolica.
•Frazione terpenoidica non volatile formata da
diterpeni e/o triterpeni, quella volatile da mono e
sesquiterpeni. I composti fenolici includono
fenilpropanoidi e fenoli liposolubili (THC, NDGA).
Resine
Conifere: Cupressaceae, Pinaceae,
Podocarpaceae, Taxaceae, ecc.
Angiosperme: Dracaena, Daemonorops,
Liquidambar, Guaiacum, Larrea,
Garcinia, Croton, Euphorbia, Populus,
Copaifera, Myroxylon, Cistus, Boswellia,
Bursera, Commiphora, Pistacia, Styrax,
Ipomoea, Ferula, Opopanax, Grindelia.
Resine: piante
Composti fenolici
Definizione
Gamma molto vasta di composti accomunati dal
possedere almeno un anello aromatico con uno o
più sostituenti idrossilici e dal fatto d’essere
presenti nella maggioranza delle spermatofite.
Il prodotto di partenza per la biosintesi della
maggior parte dei fenoli è l’acido shichimico,
spesso insieme al malonato (flavonoidi), a volte
direttamente dall’acetato (fenoli semplici,
chinoni).
Composti fenolici
Via biogenetica
Dalla condensazione di fosfoenolpiruvato (PEP) e D-eritrosio-4-P, si
forma l'acido 3-deossi-D-arabinoeptulosonico -7-fosfato (DAHP), il
quale ciclizza ad acido 3-deidrochinico e poi a acido 3-deidroshimico,
per dare poi acido shichimico.
Percorso sempre più raro nelle piante più evolute (ma vedi Rutaceae
e Apiaceae) perché i metaboliti sono + pericolosi e reattivi e il
percorso meno plastico di quello dell’isoprene.
Timolo e carvacrolo si originano da un diverso percorso: para-cimene
attraverso il !-terpinene
Composti fenolici
elimination of an ammonia molecule to form cinnamic acid(Figure 13.10). This reaction is catalyzed by phenylalanineammonia lyase (PAL), perhaps the most studied enzymein plant secondary metabolism. PAL is situated at a branchpoint between primary and secondary metabolism, so thereaction that it catalyzes is an important regulatory step inthe formation of many phenolic compounds.
The activity of PAL is increased by environmental fac-tors, such as low nutrient levels, light (through its effect onphytochrome), and fungal infection. The point of controlappears to be the initiation of transcription. Fungal inva-sion, for example, triggers the transcription of messengerRNA that codes for PAL, thus increasing the amount ofPAL in the plant, which then stimulates the synthesis ofphenolic compounds.
The regulation of PAL activity in plants is made morecomplex by the existence in many species of multiple PAL-encoding genes, some of which are expressed only in spe-cific tissues or only under certain environmental conditions(Logemann et al. 1995).
Reactions subsequent to that catalyzed by PAL lead tothe addition of more hydroxyl groups and other sub-stituents. Trans-cinnamic acid, p-coumaric acid, and theirderivatives are simple phenolic compounds called phenyl-propanoids because they contain a benzene ring:
and a three-carbon side chain. Phenylpropanoids areimportant building blocks of the more complex phenoliccompounds discussed later in this chapter.
Now that the biosynthetic pathways leading to mostwidespread phenolic compounds have been determined,researchers have turned their attention to studying how thesepathways are regulated. In some cases, specific enzymes,
such as PAL, are important in controlling flux through thepathway. Several transcription factors have been shown toregulate phenolic metabolism by binding to the promoterregions of certain biosynthetic genes and activating tran-scription. Some of these factors activate the transcription oflarge groups of genes (Jin and Martin 1999).
Some Simple Phenolics Are Activated byUltraviolet LightSimple phenolic compounds are widespread in vascularplants and appear to function in different capacities. Theirstructures include the following:
• Simple phenylpropanoids, such as trans-cinnamicacid, p-coumaric acid, and their derivatives, such ascaffeic acid, which have a basic phenylpropanoid car-bon skeleton (Figure 13.11A):
• Phenylpropanoid lactones (cyclic esters) calledcoumarins, also with a phenylpropanoid skeleton (seeFigure 13.11B)
• Benzoic acid derivatives, which have a skeleton: which is formed from phenylpropanoids bycleavage of a two-carbon fragment from the sidechain (see Figure 13.11C) (see also Figure 13.10)
As with many other secondary products, plants can elabo-rate on the basic carbon skeleton of simple phenolic com-pounds to make more complex products.
Many simple phenolic compounds have important rolesin plants as defenses against insect herbivores and fungi.Of special interest is the phototoxicity of certain coumarinscalled furanocoumarins, which have an attached furanring (see Figure 13.11B).
C1C6
C6 C3
C6
Secondary Metabolites and Plant Defense 291
Shikimic acidpathway
Erythrose-4phosphate(from pentosephosphate pathway)
Phosphoenolpyruvicacid (from glycolysis)
Acetyl-CoA
Miscellaneousphenolics
Malonic acidpathwayPhenylalanine
Cinnamic acid
Simple phenolics Flavonoids
Lignin
Hydrolyzabletannins
Gallicacid
C3C6[ ]
C3C6[ ]n
C3C6[ ]
C3C6[ ] C1
C6[ ] C3C6 C6[ ]
Condensed tanninsnC3
C6 C6[ ]
FIGURE 13.9 Plant phenolics arebiosynthesized in several differ-ent ways. In higher plants, mostphenolics are derived at least inpart from phenylalanine, a prod-uct of the shikimic acid pathway.Formulas in brackets indicate thebasic arrangement of carbonskeletons:
indicates a benzene ring, and C3 is a three-carbon chain. More detail on the pathway from phenylalanine onward isgiven in Figure 13.10.
C6
O OH
CO2-OH
OH
H
H*
O
CO2-
OH
OH
H*
OH
OH
OH
CO2H
Hb
HaO
HO2C
P
H
H
OHOH
OP
O
POO
CO2H
OH
OH
H
Hb
OH
H a POO
CO2H
OH OH
O
C O2-O
OH
OHOH
H
fosfoenolpiruvato
D-eritrosio-4-fosfato
ac deidrichinicoac deidroscichimico
ac scichimico
- 2H
- Pi+ 2 H
-H2O
NADPH
Via biogenetica
Il metabolismo dell’acido shichimico dà origine ad un
grande numero di composti aromatici legati agli
amminoacidi aromatici fenilalanina e tirosina,
polifenoli con uno schema di sostituzione
caratteristico: p-idrossi-, o-diidrossi, o 1,2,3-triidrossi.
Questo li differenzia dai polifenoli che si originano
dall’acetato che hanno uno schema di sostituzione
meta-.
Composti fenolici
OH
OH
OH
COOH CH2 CH COOH
NH2
CHOH CHCO 2H
Ac. shikimicoFenilalanina
Ac. p-idrossibenzoico
Ac. idrossibenzoici
Alcuni chinoni
Flavonoidi e isoflavonoidi
Xantoni ed idrossistilbeni
Fenoli
- C2
-CO2riduzione
idrossiacetofenoni
idrossicumarine
OH CH CH CH 2OH
FenilpropeniLignani
Lignine
Alcool p-idrossicinnamilico
riduzionepolimerizzazione
dimerizzazione
• Composti caratterizzati da un anello
aromatico a cui è legato un gruppo
propionico. Derivazione biosintetica è
l'aminoacido aromatico fenilalanina.
• Di questa classe di composti ci
interessano soprattutto le cumarine, i
fenilpropeni (C6-C3) e i lignani ((C6-C3)2)
Fenilpropanoidi
Fenilpropeni (C6-C3)
Essi fanno di solito parte dell'olio essenziale
delle piante aromatiche. A differenza della
maggior parte degli altri composti fenolici,
sono liposolubili. Alcuni sono abbastanza
comuni, come l'eugenolo altri sono più rari (ad
esempio anetolo e miristicina).
Fenilpropanoidi
NH2
COOH
COOH
MeO
OH
MeO
O
O OMe
MeO
fenilalanina
acido cinnamico
cavicolo
anetolo
estragolo apiolo
Biosintesi nel
percorso
dell’acido
shichimico
Acido cinnamico
NH2
COOH
COOH
MeO
OH
MeO
O
O OMe
MeO
fenilalanina
acido cinnamico
cavicolo
anetolo
estragolo apiolo
Fenilpropeni
Unità C6Unità C3
Cumarine (C6-C3)
• Il nucleo benzo-2-pirene delle cumarine semplici deriva
dallo scheletro fenilacrilico degli acidi cinnamici
attraverso idrossilazione, isomerizzazione del doppio
legame della catena laterale, e lattonizzazione
• Un caso particolare è dato dalle cumarine con un
anello furanico fuso con l’anello benzenico: le
furanocumarine, ristretti alle Rutaceae e Apiaceae, di
derivazione biogenetica mista, una unità shichimica e
una unità isoprenoidica.
Fenilpropanoidi
In spite of results such as these, the importance ofallelopathy in natural ecosystems is still controversial.Many scientists doubt that allelopathy is a significant fac-tor in plant–plant interactions because good evidence forthis phenomenon has been hard to obtain. It is easy toshow that extracts or purified compounds from one plantcan inhibit the growth of other plants in laboratory exper-iments, but it has been very difficult to demonstrate thatthese compounds are present in the soil in sufficient con-centration to inhibit growth. Furthermore, organic sub-stances in the soil are often bound to soil particles and maybe rapidly degraded by microbes.
In spite of the lack of supporting evidence, allelopathyis currently of great interest because of its potential agri-cultural applications. Reductions in crop yields caused by
weeds or residues from the previous crop may in somecases be a result of allelopathy. An exciting future prospectis the development of crop plants genetically engineered tobe allelopathic to weeds.
Lignin Is a Highly Complex PhenolicMacromoleculeAfter cellulose, the most abundant organic substance inplants is lignin, a highly branched polymer of phenyl-propanoid groups
that plays both primary and secondary roles. The precisestructure of lignin is not known because it is difficult toextract lignin from plants, where it is covalently bound tocellulose and other polysaccharides of the cell wall.
Lignin is generally formed from three different phenyl-propanoid alcohols: coniferyl, coumaryl, and sinapyl, alco-hols which are synthesized from phenylalanine via variouscinnamic acid derivatives. The phenylpropanoid alcohols arejoined into a polymer through the action of enzymes thatgenerate free-radical intermediates. The proportions of thethree monomeric units in lignin vary among species, plantorgans, and even layers of a single cell wall. In the polymer,there are often multiple C—C and C—O—C bonds in eachphenylpropanoid alcohol unit, resulting in a complex struc-ture that branches in three dimensions. Unlike polymerssuch as starch, rubber, or cellulose, the units of lignin do notappear to be linked in a simple, repeating way. However,recent research suggests that a guiding protein may bind theindividual phenylpropanoid units during lignin biosynthe-sis, giving rise to a scaffold that then directs the formation ofa large, repeating unit (Davin and Lewis 2000; Hatfield andVermerris 2001). (See Web Topic 13.3 for the partial structureof a hypothetical lignin molecule.)
Lignin is found in the cell walls of various types of sup-porting and conducting tissue, notably the tracheids andvessel elements of the xylem. It is deposited chiefly in thethickened secondary wall but can also occur in the primarywall and middle lamella in close contact with the cellulosesand hemicelluloses already present. The mechanical rigid-ity of lignin strengthens stems and vascular tissue, allow-ing upward growth and permitting water and minerals tobe conducted through the xylem under negative pressurewithout collapse of the tissue. Because lignin is such a keycomponent of water transport tissue, the ability to makelignin must have been one of the most important adapta-tions permitting primitive plants to colonize dry land.
Besides providing mechanical support, lignin has signif-icant protective functions in plants. Its physical toughnessdeters feeding by animals, and its chemical durability makesit relatively indigestible to herbivores. By bonding to cellu-lose and protein, lignin also reduces the digestibility of thesesubstances. Lignification blocks the growth of pathogensand is a frequent response to infection or wounding.
C6 C3
Secondary Metabolites and Plant Defense 293
H
OH
HO
C CCOOH
H
OCH3
HO
C CCOOHH
H
HO O O O OO
OCH3
CH
O
HO OH
COOH
Caffeic acid
C3C6[ ]
Ferulic acid
Furan ring
Umbelliferone,a simple coumarin
C3C6[ ]
Vanillin Salicylic acid
C1C6[ ]
Psoralen,a furanocoumarin
(A)
(B)
(C)
Simple phenylpropanoids
Coumarins
Benzoic acid derivatives
FIGURE 13.11 Simple phenolic compounds play a greatdiversity of roles in plants. (A) Caffeic acid and ferulic acidmay be released into the soil and inhibit the growth ofneighboring plants. (B) Psoralen is a furanocoumarin thatexhibits phototoxicity to insect herbivores. (C) Salicylic acidis a plant growth regulator that is involved in systemicresistance to plant pathogens.
Cumarine
OH
(OH)
CH CH
O
S CoA
O O
O
O
OH
OH
O
O
OH
OH
OH
O
O
OH
OH
OH
OH
OH
O
O
OH
OH
O
O
OH
OH
OH
OH
O+
OH
OH
OH
OH
cumaril-S-CoAcumarina
Flavanone Flavone
Diidroflavonolo Isoflavone
FlavonoloAntocianidina
Unità C6Unità C3
OE a fenilpropanoidi
•Cinnamomum zeylanicus
•Artemisia dracunculus
•Foeniculum vulgare
•Pimpinella anisum
•OE da scorze di agrumi (% bassa ma rischio)