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Biosynthesis & Biomimetic Total Synthesis -
Primary Metabolism, Enzyme Cofactor Chemistry & Shikimate Metabolites
Alan C. [email protected]
Format & Scope of Lecture• What is biosynthesis?
– some definitions – phototrophs, chemotrophs; metabolism (catabolism/anabolism), 1° & 2° metabolites• Overview of primary metabolism → secondary metabolites
– photosynthesis & glycolysis → shikimate formation → shikimate metabolites– acetylCoA & the citric acid cycle → α-amino acids → penicillins, cephalosporins, alkaloids– acetylCoA → malonylCoA → fatty acids, prostaglandins, polyketides, macrolide antibiotics– acetylCoA → mevalonate → isoprenoids, terpenoids, steroids, carotenoids
• Biological/biosynthetic reactions – enzyme & cofactor chemistry– free energy source – ATP– C-C & C-O bond formation – CoASH, SAM, DMAP, biotin– oxidation – NAD+, FAD, haem iron oxo monooxygenases– reduction – NADPH– C-N bond formation – pyridoxal
• The shikimate biosynthetic pathway– aromatic amino acids: Phe, Tyr & Trp– ArC3 metabolites – coumarins, lignans & lignins
• mixed shikimate/malonylCoA (polyketide): flavonoids– ArC2, ArC1 & ArC0 metabolites
• mixed shikimate/mevalonate (isoprenoid): ubiquinones, menaquinones & tocopherols
Me MeMe
O
camphor
N
O
O
OH
H CO2H
H
clavulanic acid
N
N
Me
nicotine
O
O
O
OHpatulin
N
MeO
N
H
H
HHO
quinine
NMe
NH
HO2C
H H
lysergic acid
N
N N
N
O
Ocaffeine
O
O
Me
Me
androstenedione
CO2 H2O Pi N2hv
Metabolism & Natural Product Diversity
Phototrophs & Chemotrophs• Living organisms are not at equilibrium. They require a continuous influx of free energy to perform
mechanical work & for cellular growth/repair:
– Phototrophs (e.g. green plants, algae & photosynthetic bacteria): derive free energy from the sun viaphotosynthesis (‘CO2 fixation’):
• 35 × 1015 kg/year by green plants, which constitute 99% of Earths biomass (i.e. 1.7 × 1012 tons of dry matter)• 1g of carbon processed = >6250 litres of air
– Chemotrophs (e.g. animals, fungi): derive free energy by oxidising nutrients (carbohydrates, lipids, proteins) obtained from other organisms, ultimately phototrophs
• some bacteria & fungi require just D-glucose• mammals require sugars, essential amino acids (~half total used) & certain vitamins (enzyme co-factors or precursors)
• Degradation of the nutrients is coupled to the stoichiometric production of ‘high energy’ phosphate compounds, particularly adenosine triphosphate (ATP, see later). All metabolic function is underpinned by ATP energetic coupling.
• By analogy with a money-based economy, the metabolic cost of production of a given metabolite from another can be quantified in terms of ‘ATP equivalents’ defined as the # of moles of ATP consumed/produced per mole of substrate converted in the reaction or sequence
CO2 + H2Ohv
(CHO) + O 2 PHOTOSYNTHESIS
complex metabolites
CatabolismAnabolism
ATP
ADP + P i
NAD(P)H
NAD(P) + H
Nutrients
Energy &Building blocks
Cell components & Growth
simple products
Building Blocks
reductivebiosynthesis
energyrelease
oxidativedegredation
energystorage
CO2 + H2O
hv'CO2 fixation'(photosynthesis)
respiration
N2
'nitrogen fixation'(by diazatrophs, lightening,the Haber process)
CO2 + H2O
Natural product secondary metabolites
O2
Metabolism• Metabolism is the term used for in vivo processes by which compounds are degraded,
interconverted and synthesised:– Catabolic or degradative: primarily to release energy and provide building blocks
• generally oxidative processes/sequences (glycolysis, Krebs cycle)– Anabolic or biosynthetic: primarily to create new cellular materials (1° & 2° metabolites)
• generally reductive processes/sequences
• These two types of process are coupled – one provides the driving force for the other:
Types of Metabolite & Biosynthesis• Biosynthesis is the term for the in vivo synthesis of metabolites/natural products:
– These are divided into two camps:• Primary metabolites: These are the universal and essential components for the survival of living organisms. e.g. sugars,
amino acids, nucleotides, ‘common’ fats and polymers such as proteins, DNA, RNA, lipids and polysaccharides• Secondary metabolites: Compounds produced by organisms which are not required for survival, many of which have no
apparent utility to the host organism. Frequently a given metabolite will only be produced in a single organism or in a set of closely related organisms. Provide a rich source of pharmacologically active compounds. e.g. shikimate derivatives, alkaloids, fatty acids, polyketides, isoprenoids
– Although the boundary is imprecise the term biosynthesis is most commonly applied, by organic chemists, to the in vivo synthesis of secondary metabolites:
“Now ever since Perkin, failing to make quinine, founded the dyestuffs industry, organic chemists have found the study of ‘natural products’ an inexhaustable source of exercises, which can be performed out of pure curiosity even when paid for in the hope of a more commercial reward. As a result the organic chemist’s view of nature is unbalanced, even lunatic but still in some ways more exciting than that of the biochemist. While the enzymologist’s garden is a dream of uniformity, a green meadow where the cycles of Calvin and Krebs tick round in disciplined order, the organic chemist walks in an untidy jungle of uncouthly named extractives, rainbow displays of pigments, where in every bush there lurks the mangled shapes of some alkaloid, the exotic perfume of some new terpene, or some shocking and explosive polyacetylene. To such a visionary both the diatetrynes* are equal prizes, to be set together as ‘natural products’. We shall do the same, but since to a more sober eye both are in a sense less ‘natural’ than, say, glycine or ATP, we may prefer the term ‘secondary metabolite’.”
Bu’Lock Adv. Appl. Microbiol. 1961, 3, 293
Primary Metabolism - Overview
CO2 + H2O
1) 'light reactions': hv -> ATP and NADH 2) 'dark reactions': CO2 -> sugars (Calvin cycle)
OHOHOHOOH
HO
glucose & other 4,5,6 & 7 carbon sugars
Primary metabolism Secondary metabolites
oligosaccharidespolysaccharidesnucleic acids (RNA, DNA)
phosphoenol pyruvate
glycolysis
CO2
HOOH
OHOOH
HO
POCO2
PO
erythrose-4-phosphate
SHIKIMATE METABOLITEScinnamic acid derivativesaromatic compoundslignans, flavinoids
+
shikimate
aromatic amino acids
aliphatic amino acids
peptidesproteinsCO2
Opyruvate
SCoA
Oacetyl coenzyme A
Citric acidcycle
(Krebs cycle)
ALKALOIDSpenicillinscephalosporinscyclic peptides
tetrapyrroles (porphyrins)
PHOTOSYNTHESIS
saturated fatty acidsunsaturated fatty acidslipids
FATTY ACIDS & POLYKETIDESprostaglandinspolyacetylenesaromatic compounds, polyphenolsmacrolides
ISOPRENOIDSterpenoidssteroidscarotenoids
SCoA
OCO2
malonyl coenzyme A
CoAS
O
O
HO
HOCO2
mevalonateacetoacetyl coenzyme A
Primary metabolites
Biological/Biosynthetic Reactions –Enzyme Catalysis & Cofactors
• Most biosynthetic steps are catalysed by specific, individual enzymes. They generally perform familiar processes such as oxidation, reduction, alkylation, hydrolysis, acylation, hydroxylation, elimination etc.
• Different enzymes carrying out related reactions often employ common co-factors: small organic functional fragments and/or metal ions. e.g.
– FREE ENERGY RELEASING COUPLE: Adenosine triphosphate (ATP)
– C-C & C-O BOND FORMATION: Coenzyme A (CoASH); S-adenosyl methionine (SAM); dimethylallylpyrophosphate (DMAP); biotin
– OXIDATION: NAD(P)+; FAD; Haem iron oxo species (e.g. P450)
– REDUCTION: NAD(P)H; (FADH2)
– C-N BOND FORMATION: Pyridoxal
Free Energy Releasing Couple - ATP• Adenosine triphosphate (ATP)
– phosphorylation of an alcohol by adenosine diphosphate (ADP) is highly exothermic (i.e. liberates energy):
– The phosphorylated alcohol (ROP) is then activated towards nucleophilic displacement:
– So, overall the endothermic process ROH + Y- → RY + OH- has been achieved by ‘coupling’ the process to the ‘hydrolysis of ATP’
– The situation is analogous to the use of tosylate activation to achieve nucleophilic displacement of an alcohol
– In general, the exothermicity associated with phosphorylation shifts the equilibria of ‘coupled’ process by a factor of ~108
N
NN
N
O
NH2
OHOH
OPOPOPOOOOOO
HO
PPPO-
N
NN
N
O
NH2
OHOH
OPOPHO
OOOO
PPO-
+ ROH PRO
OO
OH+ ∆G° = -31 kJmol-1
enzyme
Mg2+ or Mn2+
adenosine triphosphate (ATP) ADP
-OP
Nu + ROP R-Nu + OP OP = Pi = orthophosphate = P OHO
OO
Acylation & C-C Bond Formation α to C=O – CoASH• Coenzyme A (CoASH)
– Coenzyme A acts as an acyl transfer/α-carbon activation reagent by forming reactive acyl thioesters:
– Acyl CoA derivatives can act as nucleophiles or electrophiles depending on the circumstances– These modes of reactivity inherent properties of alkyl thioesters:
• The good leaving group ability of RS- (cf. RO-) reflects: pKa (RSH) ~10 cf. pKa (ROH) ~16• The enhanced acidity of protons α to the carbonyl of thioesters cf. normal esters reflects the poor orbital overlap
between the lone pairs on sulfur (nS) [cf. nO] and the carbonyl anti bonding molecular orbital π*C=O
N
NN
N
O
NH2
OHO
OPOPO
OOOO
coenzyme A (CoASH)
H
O
NH
O
NH
HS
PHO
OO
HO
pantothenate
X
OR
SCoA
OR
Y
Y
OR
SCoA
OR
ACYL TRANSFER
R'-LG
R'
α-CARBON ALKYLATION
SCoA
OR
ALDOL REACTIONS
SCoA
OR CLAISEN-type C-ACYLATION
O
OH
SCoAO
O
C O
XR'
nOp
π*C=O
OX
R'
nX-π*C=O resonance makes carbonyl less susceptible to enolisationSulfur is in the 2nd period
so its lone pair has poor size/energy match with the π*C=O orbitalHence: pKa(RCH2COSR’) ~20 cf. RCH2COOR’ ~25
i.e. α to a thioester is similar to α to a ketone
RR
H
H
H
H
B:
OHX
R'
RH
+ BH
Methylation/Dimethylallylation – SAM & DMAP• S-Adenosyl methionine (SAM)
– SAM acts as a versatile O-, C-, N- & S- methylating reagent in vivo
– Equivalent to performing an SN2 methylation using MeI in the laboratory
• Dimethylallyl pyrophosphate (DMAP)– DMAP acts a dimethylallylating reagent – the pyrophosphate (+ Mg2+/Mn2+) is an excellent leaving group
– Equivalent to performing an SN2 allylation using allyl bromide in the laboratory
N
NN
N
O
NH2
OHOH
SO2C
S-adenosyl methionine (SAM)
Me
NH3
Nu
Nu-Me
methionine
e.g.
R2N
O
O
Me SR2
OMe
Me SR2
Me SR2
O
Me
OH
Me
R2NMe
Nu
OPOPO
OOOO
dimethylallyl pyrophosphate (DMAP)
Nu
Carboxylation – Biotin
• Biotin– Biotin in the presence of bicarbonate, ATP and Mg2+ enables nucleophile carboxylation in vivo:
– a very similar reaction can be carried out in the laboratory• H. Sakurai et al. ‘α-Carboxylation reaction of carbonyl compounds with bromomagnesium ureide-carbon dioxide
adducts’ Tetrahedron Lett. 1980, 21,1967
biotin (R = carrier protein)
Nu
NHHN
S
O
HH
O
NHR
NHN
S
O
HH
O
NHR
HCO3ATPMg2+
O
OMg
Nu O
O
HN NH
O 1) MeMgBr (2 eq)2) CO2
N N
OMgBr
BrMg N N
O
O
O
O
OBrMg MgBr
white powder
O
DMF110C
O O
O
CH2N2
[74%]
MgBrO O
OMe
Oxidation – NAD+
• Nicotinamide-adenine dinucleotide (NAD+) [and its phosphorylated analogue (NADP+)] are mediators of biological oxidation (e.g. alcohol to ketone oxidation)
– In general, the couple NAD+/NADH is used by enzymes in catabolic oxidation (degradation)– The reagent is a stereospecific hydride acceptor:
– Different enzymes show different absolute specificities but are generally specific for the pro-R or pro-S hydrogens both for removal and delivery
– The Oppenauer oxidation is a similar (non-stereoselective) laboratory reaction:• for asymmetric variants see: K. Nishide et al. Chirality 2002, 14, 759
N
NN
NO
NH2
OROH
OPOPO
OOOO
nicotinamide-adenine dinucleotide (NAD+) R = HNB. NADP+: R = PO3H-
O OHOH
N
O
NH2+ H
- H N
O
NH2
HRHS
NB. H = H + 2e
R OH
H H
R O
H
stereospecific:
N
ONH2
N
ONH2
HH
HR O
H+ H
NADH
NAD+ NADH
R OH
H H
R O
HAl(OtBu)3
H
OAl
O
RH OtBu
OtBuO
HO H
++ Al(OtBu)3
Oxidation – FAD• Flavin adenine dinucleotide (FAD) is also a mediator of biological oxidation (e.g. alcohol to
ketone oxidation, alkane dehydrogenation to alkene)– Unlike NAD+, which readily diffuse from enzyme to enzyme, FAD is usually tightly bound to a given enzyme
– Re-oxidation of the FADH2 back to FAD is generally by molecular oxygen via single electron transfers(SETs). The intermediate superoxide radical anion and peroxyflavin can also mediate hydroxylationand epoxidation reactions:
N
NN
NO
NH2
OHOH
OPOPO
OOOO
flavine-adenine dinucleotide (FAD)
+ H2
- H2
R OH
H H
R O
H
FADH2
OH
OH
OHN
NN
HN OO
NHN
NH
HN OO
NN N
HN OO
FAD FADH2
NHN NH
HN OO
isoalloxazine
FADH2
NN
N
HN OO
NHN
NH
HN OO
- H
NHN
N
HN OO
O O
O ON
HNN
HN OO
NHN
N
HN OO
OO - H
NN
N
HN OO
OO
O O+
FADsuperoxideradical anion
peroxyflavin
peroxidedianion
Biomimetic Oxidation using FAD Models• FAD model system
– S. Shinkai Chem. Lett. 1982, 812 & Bull. Soc. Chim. Fr. 1983, 56, 1694
• Peroxyflavin model systems– J. E. Bäckvall Chem. Eur. J. 2001, 7, 297
OH
ZrCl4
O
N NN N
N OO
~100%
M4+
(1 eq)
N NHN NH
N OO
H H(1 eq)
intermolecular oxidation
NPh
NB. simple N-alkylated nicotinamide salts (cf. NAD+) perform poorlye.g.
CONMe2
X
NHEtN
N
N OO
FFN N
O(2.8 mol%)
H2O2 (2.6 eq), MeOH, 50 min
NHEtN
N
N OO
FF
via
OOH
>90%
Oxidation – Haem Iron oxo Species (P450)• Haem iron oxo species e.g. in cytochrome P450 (a ubiquitous heam monooxygenase) are also
mediators of biological oxidation (e.g. phenolic coupling, epoxidation, hydroxylation):
– The porphyrin ring acts as a tetradentate ligand for the octahedral iron. The two axial positions are occupied by an enzyme amino acid ligand (typically a histidine nitrogen) and hydroxy/hydroperoxy residue respectively
– Ferricyanide effects similar oxidative processes in the laboratory (e.g. phenolic coupling)• D.H.R. Barton & G.W. Kirby Proc. Chem. Soc. 1960, 392
N N
N N
CO2HHO2C
FeV
L
haem Fe(V) oxo species
N N
N N
CO2HHO2C
FeIII
L
haem Fe(III) species
N N
N N
CO2HHO2C
FeIV
L
OHH
O2
OHH
HHO+
O
O
MeO
NMeK3Fe(CN)6
OH
MeO
NMe0.92% (!)HO
O
MeO
NMeHO
narwedinedesmethyl belladine
Reduction - NADPH• Dihydro-nicotinamide-adenine dinucleotide phosphate (NADPH) [and its de-phosphorylated
analogue (NADH)] are mediators of biological reduction (e.g. ketone to alcohol reduction) – In general, the couple NAPH/NADP+ is used by enzymes in anabolic reduction (biosynthesis)– The reagent is a stereospecific hydride donor:
– As for the reverse process, different enzymes show different absolute specificities but are generally specific for the pro-R or pro-S hydrogens both for removal and delivery
– NADPH acts like a biochemical equivalent of ‘laboratory’ metal hydride reductants (e.g. LiAlH4, NaBH4) or their chiral equivalents (e.g. CBS-borane):
N
NN
NO
NH2
OROH
OPOPO
OOOO
Hydro-nicotinamide-adenine dinucleotide (NADPH) R = PO3H-
NB. NADH: R = H
O OHOH
N
O
NH2
+ H
- H
N
O
NH2
NB. H = H + 2e
R O
H H
stereospecific:
N
ONH2
N
ONH2
HH
R O
H
HRHS
R OH
H HH
NADP+
NADPH NADP+
O B-Me CBS·BH3(10 mol%)0.6 eq BH3·DMS
CH2Cl2, rt, 45 minN
O
H PhPh
BMeBH3
H
B-Me CBS·BH3
HO
100% yield, 95% ee
Biomimetic Reduction using NADH Models• J.G. deVries, R.M. Kellog J. Am. Chem. Soc. 1979, 101, 2759
• M. Seki et al. J. Am. Chem. Soc. 1981, 103, 4613
N
O
NH
H2NOC
N
O
H
CONH2O
O
OEt
O
OEtOHH
67% yield, 98% ee
Mg(ClO4)2, MeCN:CH3Cl (3:1), rt, 1h
H HH H
O
O
OEtO
OEtHHO
61% yield, 86% ee
Mg(ClO4)2, MeCN, rt, 72h
NH
OO
O
HN
OO
OO
N
RHR HHH
Transamination - PLP• Pyridoxine (vitamin B6) → pyridoxal-5’-phosphate (PLP)
– PLP forms imines (Schiffs bases) with primary amines. This forms the basis of in vivo transamination of α-ketoacids to give α-amino acids (& also racemisation/decarboxylation processes, see ‘alkaloids’)
– The α-carbon protonation is stereospecific and gives the (S) configured chiral centre – Jørgensen has developed a catalytic enantioselective laboratory equivalent of this process:
• K.A. Jørgensen et al. Chem. Comm. 2003, 2602
HO
Pyridoxine (vitamin B6)N
OH
OH
pyridoxaminephosphate
Enz-NH2
NH
O
NH3OP
R CO2
R CO2
O
NH
O
NOP
R CO2
NH
O
NOP
R CO2
H
NH
O
NOP
R CO2H
NH3
HNH
O
NOPH H
Enz-NH3 Enz-NH2
H
Enz
H2Opyridoxal phosphate
bound as imine
H
transaminase
imineexchange
imineformation
N
NH2
NH
O
O
OMe
+N
ZnN
OO
TfO OTf
1) Zn-cat (20 mol%) MeNO2, 40h, rt
2) Boc2O, Et3N, MeOH 50°C
Zn-catNH
O
OMe
N
O
+
15% yield, 37%ee
NHBocH
Primary Metabolism - Overview
CO2 + H2O
1) 'light reactions': hv -> ATP and NADH 2) 'dark reactions': CO2 -> sugars (Calvin cycle)
OHOHOHOOH
HO
glucose & other 4,5,6 & 7 carbon sugars
Primary metabolism Secondary metabolites
oligosaccharidespolysaccharidesnucleic acids (RNA, DNA)
phosphoenol pyruvate
glycolysis
CO2
HOOH
OHOOH
HO
POCO2
PO
erythrose-4-phosphate
SHIKIMATE METABOLITEScinnamic acid derivativesaromatic compoundslignans
+
shikimate
aromatic amino acids
aliphatic amino acids
peptidesproteinsCO2
Opyruvate
SCoA
Oacetyl coenzyme A
Citric acidcycle
(Krebs cycle)
ALKALOIDSpenicillinscephalosporinscyclic peptides
tetrapyrroles (porphyrins)
PHOTOSYNTHESIS
saturated fatty acidsunsaturated fatty acidslipids
FATTY ACIDS & POLYKETIDESprostaglandinspolyacetylenesaromatic compounds, polyphenolsmacrolides
ISOPRENOIDSterpenoidssteroidscarotenoids
SCoA
OCO2
malonyl coenzyme A
CoAS
O
O
HO
HOCO2
mevalonateacetoacetyl coenzyme A
Primary metabolites
Shikimate Metabolites
SHIKIMATE METABOLITES
NHNH3
O2C
(S)-tryptophan
CO2
OH
NH3H
CO2
NH3H
(S)-tyrosine (S)-phenylalanine
MeOOMe
OMe
OO
O
OH
H
H
H
O
O
O
MeOOH
scopoletin
OH
OH
3
Me
α-tocopherol (vitamin E)
Me
podophyllotoxin
menaquinone (vitamin K2)
O
OMe
Hn
OH
O
HO OH
epigallocatechin (EGC)
OHHO
HOH
Biosynthesis of Shikimate
• Phosphoenol pyruvate & erythrose-4-phosphate are converted to shikimate and its phosphatederivative:
– The detailed mechanisms of these steps have been studied intensively. Most are chemically complex and interesting. For more details see:
• J. Mann Chemical Aspects of Biosynthesis Oxford Chemistry Primer No. 20, 1994 (key details)• E. Haslam Shikimic Acid – Metabolism and Metabolites Wiley, 1993 (full details and primary Lit. citations)
phosphoenol pyruvate(PEP)
OOH
HO
PO
CO2
PO
erythrose-4-phosphate+
PO
CO2
HOOH
OH
O PO
CO2
HOO
OH
O
CO2
HO OH
O
OH
CO2
OOH
OH
HOCO2
OOH
OH
dehydroshikimate 5-dehydroquinate
CO2
HOOH
OH
shikimate
NADPH
NAD
NADH
NADP
Pi
DAHP
non-concertedsyn-elimination
CO2
POOH
OH
shikimate phosphate
ATP
ADP H2O
Pi
H
Shikimate → Tryptophan, Tyrosine & Phenylalanine• Shikimate phosphate → chorismate → anthranilate → tryptophan
• Chorismate → prephenate → tyrosine & phenylalanine– NB. The enzyme chorismate mutase which mediates the conversion of chorismate to prephenate is the only
known ‘Claisen rearrangementase (!)’
PiCO2
POOH
OH
shikimate phosphate
CO2
PO
PEP
+
CO2
POOH
O CO2
HPi CO2
OHO CO2
chorismate
CO2
anthranilate
NH2 NHNH3
O2C
(S)-tryptophan[78 ATP equivs]5-EPS-3-P
non-concerted1,4-anti-elimination
'NH3'
ArC0
ribose derived
glyphosate(Roundup)
PO NH2
CO2
NAD
NADH
CO2
OHO CO2
chorismate
Claisenrearangement
O2C
OHprephenate
O
CO2
CO2
H2O CO2
CO2
OH
NH3H
CO2
NH3H
(S)-tyrosine[62 ATP equivs]
(S)-phenylalanine[65 ATP equivs]
O2C
OH(S)-arogenate
CO2
'NH3'
H3N H
ArC3
ArC3
Tyrosine/Phenylalanine → ArC3 Metabolites• Tyrosine & phenylalanine → cinnamate derivatives → ArC3 metabolites
– coumarins, lignans (stereoselective enzymatic dimerisation) & lignins (stereorandom radical polymerisation)
CO2
X
NH3H
X
H
X = OHX = H
CO2
O
O
MeOOH
scopoletin (a coumarin)germination stimulant
MeOOMe
OMe
OO
O
OH
H
H
H
podophyllotoxin (a lignan)natural product used to treat worts
Oand
OH
CO2
MeO
ferulate
O
O
OH
OMe
HO
MeO
pinoresinol (a lignan)
PAL
phenylalanineammonia lyase
fragment of lignin polymer'woody' component of cell walls
OOMe
OHMeO
O
O
OMeOH
O
OMeO
HOHO
OH
n x ArC3
2 x ArC3
ArC3
HH
H
H
Biomimetic Lignan Synthesis• Oxidative dimerisation of cinnamyl alcohols gives symmetric furanofuran lignans
– review: R,C.D. Brown, N.A. Swain Synthesis 2004, 811
O
O
OH
OMe
HO
MeOsyringaresinol
IN VIVO: oxidasesee: N.G. Lewis et al. Science 1997, 275, 362
IN VITRO: CuSO4 (cat.), O2(g), acetone-H2O [90%]see: B. Vermes et al. Phytochem. 1991, 30, 3087
HO
MeO
OH
2 x coniferyl alcohol
O
OMe
O
MeO
OH
HO
O
OMe
O
MeO
OH
HO
OMe
OMe
OMe
HH
H
H
OMe
OMe OMe
OMe
Tyrosine/Phenylalanine → Flavonoids• 4-Hydroxycinnamic acid → flavonoids: flavanones, flavanonols, flavones & anthocyanins
– Glycosides of these ArC3 metabolites (esp. anthocyanins) constitute coloured pigments in flowers and insects. They also confer bitter and astringent flavours (e.g. tannins in tea are polymerised flavonoids)
– NB. ‘Mixed’ biosynthetic origin: shikimate/malonylCoA (polyketide)
OH
CO2
OH
O CoA
OH
O
OO
O
CoA
SCoAO CO2
malonyl coenzyme A
3 x
OH
O
OH
HO OH
chalconesynthase
H
OH
O
O
HO OH
flavanones
ORRO
OH
O
O
HO OH
flavones
ORRO
OH
O
O
HO OH
flavanonols
ORRO
ArC3OH
ArC3
ArC3
OH
O
HO OH
anthocyanins
ORRO
OH
ArC3
Chorismate → Coenzymes Q & Vitamins E & K• Chorismate → p- & o-hydroxybenzoic acids → coenzymes Q & vitamins E & K
– NB. ‘Mixed’ biosynthetic origin: shikimate/mevalonate (isoprenoid)
CO2
OHO CO2
chorismateCO2
O
pyruvate
H
CO2
OH
CO2
OHR
OHRMeO
O
O
Me
MeO
MeO
Hn
ubiquinones (coenzymes Q)lipid-soluble electron transport
O2C
OH
prephenate
O
CO2CO2
OH
O
H
CO2
OH
OO
CO2
OH
CO2 OH
CO2
homogentisateOH
OHH
3
R
OH
OH
3
R1
tocopherols (vitamins E)electron transport, antioxidant
CO2
O CO2
isochorismate
OH
OH2
menaquinones (vitamins K)cofactors for plasma proteins
essential for blood clottingCO2
O
O SCoA
HO
OHCO2
O
OR
O
OMe
Hn
R2 R1, R2 = H or Me
R
isoprenoid
isoprenoid
isoprenoid
ArC1
ArC0
ArC1
H
O2CO
CO2 CO2
α-ketoglutarate (αKG)
CO2
O
CO2
αKG
Primary Metabolism - Overview
CO2 + H2O
1) 'light reactions': hv -> ATP and NADH 2) 'dark reactions': CO2 -> sugars (Calvin cycle)
OHOHOHOOH
HO
glucose & other 4,5,6 & 7 carbon sugars
Primary metabolism Secondary metabolites
oligosaccharidespolysaccharidesnucleic acids (RNA, DNA)
phosphoenol pyruvate
glycolysis
CO2
HOOH
OHOOH
HO
POCO2
PO
erythrose-4-phosphate
SHIKIMATE METABOLITEScinnamic acid derivativesaromatic compoundslignans
+
shikimate
aromatic amino acids
aliphatic amino acids
peptidesproteinsCO2
Opyruvate
SCoA
Oacetyl coenzyme A
Citric acidcycle
(Krebs cycle)
ALKALOIDSpenicillinscephalosporinscyclic peptides
tetrapyrroles (porphyrins)
PHOTOSYNTHESIS
saturated fatty acidsunsaturated fatty acidslipids
FATTY ACIDS & POLYKETIDESprostaglandinspolyacetylenesaromatic compounds, polyphenolsmacrolides
ISOPRENOIDSterpenoidssteroidscarotenoids
SCoA
OCO2
malonyl coenzyme A
CoAS
O
O
HO
HOCO2
mevalonateacetoacetyl coenzyme A
Primary metabolites