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)