Flora Of Subclass Ranunculidae

Flavonoids (Table 2 a, b, c). Evolutionary advance of dicotyledons is accompanied by increase in the relative importance of flavones over flavonols (BateSmith 1962), by decrease in the incidence of proanthocyanidins and, according to postulates of more general validity, by increase in mean oxidation level of the compounds pertaining to a biosynthetic class and by decrease in lignification (Gottlieb 1982,1989, 1990). In respect to all these concepts, the flavonoid data registered in Table 2a, b, and c require the three subclasses of block 1 to keep the evolutionary sequence Magnoliidae-Ranunculidae-Caryophylli-dae.

Table 1. General chemical markers for blocks of dicotyledons

Block 1 Block 2

Block 3

Magnoliidae Hamamelidae Asteridae Ranunculidae Dilleniidae Caryophyllidae Rosidae

Myricetin Gallic acid Proanthocyanidins

Rare Common Very rare Common Common Ubiquitous

Very rare Absent Very rare

The same concepts are also helpful for the placement of the families of each subclass in a putative evolutionary sequence. One of the best clues in this task concerns the proanthocyanidins, very common in all larger groups of the Magnoliidae with the exception only of the more herbaceous orders Piperales and Aristolochiales. Presence/absence of proanthocyanidins, interpreted in the same spirit, also allows ordering of the families of the two additional subclasses Ranunculidae and Caryophyllidae, and again this corresponds roughly to the listing of the families in order of diminishing woodiness.

Thus the six core families of the orders Magno-liales, Annonales, and Laurales must be listed at the top of Table 2 a. Clearly flavonols predominate over flavones and additional oxy-functions exist on the Arings of flavones and flavonols of the hence most advanced family Lauraceae. The next 12 entries refer to considerably smaller, peripheral families. Neglecting the fact that absence of registries here may be due to lack of an adequate number of analyses, an identical trend concerning the flavone/flavonol ratio commands the indicated sequence from top to bottom. Among the remaining orders, the less woody Aristolochiales possess the most strongly oxygenated flavo-noidal A-rings.

In relation to the flavonoids of the Magnoliidae, the flavonoids of the Ranunculidae, with their frequent additional oxygenation at carbons 6 or 8 of ring A, confirm the derived position of the latter subclass as a whole. The herbaceous Papaveraceae and Fuma-riaceae are placed at the extreme position in the list, due to their flavonoids, which show considerable expansion of the number of substitution patterns.

Flavonoid metabolism in Caryophyllidae shows comparable trends. Here also flavonols predominate over flavones and often include additional oxy-groups at position 6 (much more rarely at position 8) of the A-rings, whereas tri-oxygenated B-rings continue to be extremely rare. Again, the accentuation of substitutional variation of flavones and flavonols is used to arrange the families in the direction towards the presumably more highly evolved ones. Dihydro-flavones and dihydroflavonols, evidence for relative advance of flavonoid evolution in plants, are more widespread in the Caryophyllidae than in the Ranunculidae.

Table2a. Flavonoid types of Magnoliidae

Flavones

Flavonols

Flavanones

Flava-

Flavans

Flavans

Antho-

Other

nonols

-3-OH

3,4-

cyani-

(incl. G =

di-OH

dins

gallic acid)

MYRI AL

KQ

P

+

+ C

+

Dhc Isf Dap

MAGN

K Q og om

c

+ PC

ANNO A L C6 om

K Q ogomoa

PP6P8P68N6 ART

c

CD

+

Dhc

E om cm cb

MONI

K Q og om

+

HERN

KQ om

ETcp

+

LAUR L L68 T8 cg om cm

K Q M K68 068 om

P N cp

P AR T om + C om

+

Dhccp

AUST

Q

HIMA

Q om

+

Dhc

TRIM 68 om

Q og om

+

+

+

EUPO A Lomcm

KQog

+

CAÑE AL

Q

+

+

Dhc Isf

WINT A L A6 cg om

KQ

T

+

CALY ALog

KQog

Eog

Tom

CGCC-G

C

G

DEGE

Q og om

+

GOMO

KQom

LACT

K Q og om

AMBO

Kogom

+

CHLO

K Q cg og

T

PC

PIPE C A cg om

Q

P omcm

Dhc

SAUR

KQ

ARIS

KQK68 Q68 og om

PC

NELU ALog

KQog

CGC

CD

+

ILLI

Q og

Cop

+

G

SCHI

QM

+ P C om G

CABO

Q

CERA

Q

+ D

NYMP Lcg

QMQ6

+ CD

G

RAFF

+

G

HYDN

+

Table 2b.' Flavonoid types of Ranunculidae

Flavones

Flavonols

Flavanones

Flava-

Flavans

Flavans

Anthocya- Other

nonols

-3-OH

3,4-di-OH

nidins

LARD ALT om cp

K Q K8 Q8 og om oa

+

+ C

BERB AL

K Q M og om cp

AM

+

RANU A L og eg cm oa

K Q Q8 og om oa

N om

+ D

Dhc Isf

MENI ALAÓomoal

KQog

+

CIRC

PAPA C2'6' A L og

K Q K8 Q8 Q68 og om E

FUMA

KQog

Table 2c. Flavonoid types of Caryophyllidae

Flavones

Flavonols

Flavanones

Flava-

Flavans

Flavans

Anthocya- Other

nonols

-3-OH

3,4-

nidins

di-OH

PORT A Leg

K Q og cg

+

Rch

BASE A cg

Q

AIZO

K Q M K6 og om

+

PHYT

K Q og om

NY CT Lcmom

KQom

+

Rot

CACT ALC6

K Q M K6 og om

N om

ART AM

DIDI A T6 cg

K Q M M6 og om cm

Tom cm

og

+ D

MOLL A L og cg om oa

ENog

AM cm

PC

Aur

CARY A L C6 og cg om o;

a K Q og om oa

+ PC

AMAR C L C6 L6 cg og om G K Q G6 og om o2m 5N og

C

Isf

CHEN CALTC6A6L6

K Q M K6 Q6 og om

P P2'6 om

P6o2m

Isf

T6 cgom o2m

o2m oa os

o2m

Further conspicuous features of flavonoids in block 1 concern deoxygenation of the B-rings (chiefly in Magnoliidae) and the relative scarcity of free hy-droxyls. Indeed O-methylation and O.O-methylen-ation are frequent. Prenylation is a relatively rare phenomenon in contrast to C-benzylation, which, however, is restricted to flavonoids of the Annon-aceae. Although without connection to flavonoid chemistry, this topic can be expanded with a comment on the widespread occurrence of benzyl benzoate derivatives as an indication of a close common ancestry for Annonaceae, Lauraceae, and Piperaceae.

Myricetin (and the often co-occurring equally vicinal trihydroxybenzenoid derivative gallic acid) has been reported only sporadically in families of block 1 (Table 1). Examples are Illiciaceae (gallates), Schi-sandraceae (gallates, myricetin), Nymphaeaceae (gallates), and Calycanthaceae (catechin gallates) (Table 2). These families are exceptional also because they do not produce phenylalanine-derived alkaloids. Indeed, while in Illiciales (Illiciaceae, Schisandraceae) no alkaloids have yet been located, Nymphaeaceae and Calycanthaceae are characterized by exclusive alkaloid types, respectively fu-ranosesquiterpenoid quinolines and bis-tryptamines.

Benzylisoquinoline Alkaloids (Table 3). Within the angiosperms, few groups are chemically as homogeneous and as easily circumscribed as the Magno-liidae-Ranunculidae-Caryophyllidae. Among several biosynthetic classes of secondary metabolites, none provides more convincing evidence than the phenylalanine-derived benzylisoquinoline alkaloids and betalains. True, the former appear sporadically also in some additional unrelated families such as, in order of approximate diminishing importance, Fabaceae, Rutaceae, Rhamnaceae, Euphorbiaceae, Moraceae, Araceae, Liliaceae, Apiaceae, Loganiaceae, Celas-traceae, Buxaceae, Thymelaeaceae, Sapindaceae, Juglandaceae, Symplocaceae, Dipsacaceae, Capri-foliaceae, and Convolvulaceae; and the latter were located also in a few species of the Basidiomycetes. However, by far the most ample distribution and biosynthetic diversity for benzylisoquinoline alkaloids occurs in the Magnoliidae- Ranunculidae complex, and for betalains occurs exclusively in the Caryophyllidae. With respect to distribution, benzylisoquinoline alkaloids have been encountered in all major (gallate-free) families of the complex and, including the minor families in the count, have been located so far already in ten out of 29 families of the Magno-

Addenda to Tables 2 and 8

1. Glossary of symbols (initials of trivial names of compounds belonging to the types indicating in the column headings) for 5,7-di-hydroxy-flavonoids (additional hydroxylation given in the first column):

Flavones

Flavonols

Flavanones

Flavanonols

Chrysin Apigenin Luteolin Tricetin

Galangin Kaempferol Ouercetin Myricetin

Pinocembrin Naringenin Eriodictyol Tri-OH-pinoc.

Pinobanksin ARomadendrin Taxifolin AMpelopsin

5,7-OH Flavan-3-ols Flavan-3,4-diols Proanthocyanidins Anthocyanidins

4' Afzelechins leucoPelargonidins ] largonidins

3',4' . Catechins leucoCyanidins > + Cyanidins

3',4',5' GalloCatechins leucoDelphinidins J Delphinidins

  1. Other flavonoid types: isoflavones Isf, dihydrochalcones Dhc, 1,3-diarylpropanes Dap, rotenoids Rot, aurones Aur, dibenzoyl-methanes Dbm, retrochalcones Rch.
  2. Additional structural features og O-glycosylation eg C-glycosylation om O-methylation cm C-methylation o2m 0,0-methylenation oa O-acylation ca C-acylation cb C-benzylation os O-sulphatation op O-prenylation cp C-prenylation oal O-allylation
  3. Numbers 6, 8, 2' and 6' following the symbols of flavonoids refer to positions of the flavonoid substituted by additional oxy-groups, e.g., A6 ... 6-oxyapigenin ( = 5,6,7,4'-tetraoxyflavone); numbers 5 and 7 preceding the symbols of flavonoids refer to positions of the flavonoid exempt of substitution by oxy-groups, e.g., 5A ... 5-deoxyapigenin ( = 7,4'- dioxyflavone).
  4. The coupling mode of dimers is indicated by the bridge positions of the two monomers.
  5. The presence of chalcones is not explicited, but indicated by the structure of the corresponding flavanones.
  6. Esterification by gallic acid (G) of catechins is indicated as follows: C-G

Table 3. Benzylisoquinoline alkaloid types of Magnoliidae and Ranunculidae

Aporphines and other simple derivatives Berberines Morphines and other complex derivatives

ABCDEFGHI JKLMNOPQRS TUV ABCDE FGH I JKLMNOP ABCDEFGH I

Table 3. Benzylisoquinoline alkaloid types of Magnoliidae and Ranunculidae

Aporphines and other simple derivatives Berberines Morphines and other complex derivatives

ABCDEFGHI JKLMNOPQRS TUV ABCDE FGH I JKLMNOP ABCDEFGH I

MAGN

+

+

+

+

+

+

+

+

+

ANNO

+

+

+

+

+

+

+

+

MONI

+

+

+

+

+

+

+

+

HERN

+

+

+

+

+

+

LAUR

+

+

+

+

+

+

+ +

+

EUPO

+

+

+

PIPE

+

+

ARIS

+

+

+

+

NELU

+

+

+

+

+

BERB

+

+ +

+

+

+

+ +

+ +

+

+ +

+

+

+

RANU

+

+

* +

+

+

+

+

+ + + +

+

+

+

+

+

MENI

+

*

+

+

+

+

+

+

+

+

+ +

+

+ + + +

PAPA

+

+

+

+

+

+ +

+

*

* + + *

+ *

+

FUMA

+

+

+

+ +

+

+

+ * +

★ * * * * *

Addenda to Table 3

Aporphines and other simple derivatives: benzyltetrahydroisoquinolines A, A.A-dimere B, A.G-dimers C, A.H-dimers D, H.O-dimers E, A.J-dimers F, proaporphines G, aporphines H, oxoaporphines I, aristolactams, aristolochic acids J, phenanthrenes K, tas-pines L, benzylisoquinolines M, oxoisoaporphines N, pavines O, isopavines P, cularines Q, quettamines R, tropoione-isoquinolines S, azafluoranthenes T, N-benzyltetrahydroisoquinolines U, dibenzopyrrocolines V.

Berberines: tetrahydroprotoberberines A, protoberberines B, isoindolobenzazepines C, corydamines D, B.B-dimers H, benzophe-nanthridines F, F.F-dimers G, protopines H, rhoeadines I, spirobenzylisoquinolines J, indenobenzazepines K, phtalidoisoquinolines L, narceines M, retroprotoberberines N, hypercorines O, peshawarines P.

Morphines and other complex derivatives: protostephanines A, erythrinans B, cocculolidines C, morphines D, Q (see Aporphines etc.).D-dimers E, D.D-dimers F, hasubanonines G, G.G-dimers H, acutumines I.

Present +, relatively abundant *.

liidae and in five out of seven families of the Ranunculidae. With respect to diversity, while the Magnoliidae produce chiefly aporphines and other types of close biosynthetic association with the benzyltetrahy-droisoquinoline precursors, the Ranunculidae produce additionally a host of alkaloidal types pertaining to the morphine and the berberine types that are bio-synthetically farther removed from the precursors. The strongest accumulation of morphines occurs in Menispermaceae, while most of the alkaloids of the Papaveraceae and Fumariaceae are berberins. With respect to the diversification of such alkaloids, the Berberidaceae and Ranunculaceae occupy an intermediate position between the Magnoliidae and the mentioned families of the Ranunculidae; one of the reasons for the order in which they were placed in Table 3 and in the other tables.

Betalains (Table 4). Biotransformation of phenylalanine into benzylisoquinoline alkaloids not only continues, but is even greatly enhanced, leading to additional structural types and representatives on the transition from the Magnoliidae to the Ranunculidae. Thus the benzylisoquinoline-free Caryophyllidae seem to lack a close relationship to this complex of subclasses. However, closer scrutiny demonstrates the continued reliance on phenylalanine as starting material for the synthesis of nitrogen-containing derivatives also in the Caryophyllidae. Pertinent examples constitute the mesembrine alkaloids in Aizoaceae, the beta-phenylethylamines in Cactaceae and Chenopodiaceae, and chiefly the betalain pigments in most families except the Molluginaceae and Caryophyllaceae. The relationship of benzylisoquinolines and betalains as chemical markers becomes even more plausible if it is remembered that the formation of both classes of metabolites involve oxidations, the former oxidative transamination and the latter oxidative ring opening of the amino acid.

Finally, among other alkaloidal classes, the presence of tryptophan-derived indoles in the Caryophyllaceae, Amaranthaceae, and Chenopodiaceae and Krebs cycle-derived quinolizidines in the Chenopodiaceae are highly advanced characters of these families (Table 4).

Neolignans (Table 5). Only in the Myristicaceae, one of the eight relatively large families of the Magno-

Table 4. Alkaloid types (except benzylisoquinolines) of Magnoiiidae, Ranunculidae, and Caryophyllidae

Biosynthetic precursors

Table 5. Neolignan and lignan types of Magnoiiidae, Ranunculidae, and Caryophyllidae

Table 4. Alkaloid types (except benzylisoquinolines) of Magnoiiidae, Ranunculidae, and Caryophyllidae

Biosynthetic precursors

Phenylalanine

Anthra-nilate

Tryptophane

Other

MYRI

Tra Car

MAGN

Pha

ANNO

Nfe

Tra Ind cp

Aza Azf Azh

LAUR

Pha Nfe Cry

CALY

Cal

BERB

Lup

RANU

Lup

PAPA

Nfe

PORT

Bee Bex

BASE

Bee

AIZO

Mes Bee Bex

Tra

Qui

PHYT

Bee Bex

Glu

NYCT

Pha Bee Bex

Qui

CACT

Pha Bee Bex Isq

Tra

His

DIDI

Bee

CARY

Can

Tïa Car

AMAR

Pha Bee Bex

Can

Tra

CHEN

Pha Bee Bex Isq

TVa Car

Lignans JKLMNOA B

Addenda to Table 4

Derivatives of phenylalanine: amines Pha, 1,2-nitrophenyl-ethane Nfe, cryptopleurine (also based on on lysine) Cry, me-sembrine alkaloids Mes, isoquinolines Isq, betalains: beta-cyanins Bee, betaxanthins Bex.

Derivatives of anthranilic acid: canthinones Can.

Derivatives of tryptophan: amines Tra, carbolines Car, Calycan-thus alkaloids Cal.

Other: azaanthracenes Aza, azafluorenones Azf, azahomoa-porphines Azh, histaminamides His, lupine alkaloids Lup, pipe-ridines Pip, quinolizidines Qui, glucosinolates Glu.

liidae, have benzylisoquinoline alkaloids not yet been isolated. Other complex alkaloidal classes also seem to be absent from this family which is, in contrast, well known for its accumulation of many types of neolignans. Precisely as indicated above for benzylisoquinoline alkaloids, neolignans also appear sporadically in some additional unrelated taxa (e.g., Krameria-ceae, Rutaceae, Zygophyllaceae, Verbenaceae, Visca-ceae, Combretaceae, Araceae, Loranthaceae, Thea-ceae, Resedaceae, and Cucurbitaceae). However, even more conspicuously than is the case for alkaloids, nowhere do neolignans possess such ample distribution and biosynthetic diversity as in the Magnoiiidae. It may be of significance that the Myristicaceae are an entirely woody family. This is also true of the Himan-tandraceae, Austrobaileyaceae, Trimeniaceae, and Schisandraceae, endowed only with neolignans. In the central Magnoliaceae and Lauraceae, benzylisoquinolines and neolignans occur together, but from the

Table 5. Neolignan and lignan types of Magnoiiidae, Ranunculidae, and Caryophyllidae

Lignans JKLMNOA B

MYRI

+

+

+

+

+

+

MAGN

+

+

+

+ +

+ +

+

+

ANNO

+

MONI

+

HERN

+

+

LAUR

+

+

+

+

+ + + +

+

+

+

AUST

+

+

+

HIMA

+

+

TRIM

+

+

EUPO

+

+

+

CANE

+

WINT

+

PIPE

+

+

+ +

+ + +

+

+

SAUR

+

+

+

ARIS

+

+

+

+

+ +

+

ILLI

+

+

SCHI

+

+

+

+

+

LARD

+

+

+

BERB

+

MENI

+

PHYT

+

CHEN

+ d

Addenda to Table5 on neolignans (e.g., D) and lignans (e.g., B). The digits represent bridge positions connecting two phe-nylpropane units.

Oxygen bridges are not specified, d = Degradation product.

8.8' A; 8.8',2.7' B; 8.3' C; 8.1T); 8.1',7.9' E; 7.1' F ; 8.1',7.3' G; 8.3',7.5' H; 8.8',2.2' I; ^¿.l' J; 3.3' K; S.SJ.T L; 8.2',7.1',8.3' M; 1,5',2.2' and 1.5',2.2',2.6', 3.1' and 8.5', 9.2' N; only oxygen-linked dimera O.

more highly evolved Monimiaceae and Hernandia-ceae only the alkaloids have so far been isolated.

Clearly then, the two classes of metabolites, benzylisoquinoline alkaloids and neolignans, are replacement characters of a dynamic nature. In the major magnolialean lineage benzylisoquinolines gain and neolignans lose in diversity. Thus the more highly derived Ranunculidae should demonstrate enhanced biosynthetic versatility for alkaloids and reduced biosynthetic versatility for neolignans. Both these postu-

Table 6. Terpenoid types of Magnoliidae, Ranunculidae, and Caryophyllidae

Pentacyclic Tetracyclic Special steroids Diterpenes Sesqui- Mono-

Triterpenes Triterpenes terpenes terpenes

Table 6. Terpenoid types of Magnoliidae, Ranunculidae, and Caryophyllidae

Pentacyclic Tetracyclic Special steroids Diterpenes Sesqui- Mono-

Triterpenes Triterpenes terpenes terpenes

MYRI

OH Url

Cy2Cy4

KaLa

MAGN

SI

ANNO

Lai Cyl

Ka La Pi CI At

LAUR

OH Tr Frl Fr3

Cyl Cul Cu2 Cy3

La Cl Cc Cz SI Sf

CANE

Dr

WINT

Dr

CHLO

SISf

ARIS

KaLa Cl SISf

ILLI

An

SCHI

Lai La5 La6 Cyl Cy4

NYMP

FpFg

LARD

Oil 012 Lui og

BERB

OH og

Ec

RANU

Oil Lui Lu2 og om oa

Lai Cyl om oa

Ec Ca Pr Br Bu Sg

At AtA, AcA, KaA

MENI

Oil Frl Gl

Ec

CI

PAPA

Oil

Cyl Cy2

PORT

Oil

CI Cldl Cld2

BASE

Oil 012 Url

AIZO

Oil

Ec

PHYT

OH Url Frl Tr

NYCT

Oil Url

Ec

CACT

OU Url Lui

Cyl Cy5

EcCy

MOLL

OH Hoi Ho2 Sp

CARY

OH Url Ur3 Lui

Ec

AMAR

OU Url Lui Pf

Ec

CHEN

OU Url Frl Lui

Ec

+

Addenda to Tables 6 and 10

  1. Pentacyclic triterpenoid types: arborane Ar, friedelane Frl, 16-methyl-28-norfriedelane Fr2, secofriedelane Fr3, glutinane Gl, hopane Hoi, 21 H-hopanc Ho2,17,21-secohopane Ho3, E,B-friedohopane Ho4, lupane Lui, 19 H-lupane Lu2, 30-norlupane Lu3, 24-norlupane Lu4, oleanane OH, 30-noroleanane 012,28-noroleanane OB, pfaffic acid Pf, taraxastane "IS, taraxerane Tr, spergulagenane Sp, ursane Url, 2,3-secoursane Ur2, isoursane Ur3.
  2. Tetracyclic triterpenoid types: cucurbitane Cul, hexanorcucurbitane Cu2, cycloartane Cyl, 24-methylcycloartane Cy2,24,24-di-methylcycloartane Cy3, secocycloartane Cy4, 4-norcycloartane Cy5, dammarane Dal, 24-methyldammarane Da2, 3,4-secodam-marane Da3, euphane Eu, lanostane Lai, 24,24-dimethyllanostane La2, 24,25-diraethyllanostane La3, 24-methyl-29-norlanos-tane La4, secolanostane La5, abeolanostane L6,24-methyllophane Loi, 24-ethyllophane Lo2, tircullane Ti.
  3. Special steroid types: brassinolides Br, cardenolides Ca, ecdysones Ec, pregnanes Pr, bufodienolides Bf, sapogenins Sg, cyclos-tanes Cy.
  4. Diterpenoid types: aconanes Ac, atisanes At, cinncassiols Ce, cinnzeylanols Cz, clerodanes CI, clerodane derivatives based on bicyclo(5.4.0) undecane Cldl, clerodane derivatives based on bicyclo(5.3.0)decane Cld2, kauranes Ka, labdanes La, pimaranes Pi, aconane alkaloids AcA, atisane alkaloids AtA, kaurane alkaloids KaA.
  5. Special sesquiterpenoid types: drimanes Dr, furanoids Sf, lactones SI, anisatins An, furylpiperidines Fp, furylquinolines Fg.
  6. Special monoterpenoid type: iridoids Ir.

lates are observed, the high alkaloidal diversification mentioned above contrasting with the paucity of neo-lignans, which in the Ranunculidae are restricted to the Lardizabalaceae and are absent from the Caryophyllidae.

However, not all neolignan-containing families lie on the major magnolialean lineage. Indeed, the relationship of Schisandraceae with other neolignan-pro-ducing families should be a rather distant one. Their dibenzocyclooctane neolignans constitute an exclusive type. Furthermore the Schisandraceae, Illicia-ceae, and Trimeniaceae (in analogy with the Solana-ceae), in contrast with all other magnolialean families, utilize angelic and tiglic acid for the synthesis of esters. In the Illiciaceae, besides a magnolol-type neolignan, highly prenylated allylphenols have been located. In the Aristolochiaceae, the sole other family with exclusive neolignans, such compounds do not arise by the common process which seems to involve simple oxidative coupling of allylphenols (and propenylphenols), but by an unusual reaction mechanism: oxidative methoxylation of allylphenols.

Terpenoids (Table 6). Among the most conspicuous chemical characteristics differentiating the Magnoliidae from the rest of the angiosperms is the general dearth of triterpenoids and steroids. Whenever present, they belong only to the most unexceptional types. A secofriedelan derivative and a hexahydro-cucurbitacin in the Lauraceae and the lanostanoid polycarpol from the Annonaceae hardly provide sufficient evidence to change this impression. In the Magnoliidae the sole unusual triterpenoids worth mentioning, acids of the lanostane, secolanostane, abeolanostane, cycloartane, and secocycloartane type, occur in the Schisandraceae, a family observed to be relatively isolated also on account of other characteristics. Although the triterpenoids of Ranunculidae and Caryophyllidae continue to belong to the common pentacyclic (oleanane, lupane, and friede-lane) and tetracyclic (cycloartane and lanostane) series, they assume a progressively more conspicuous place among the secondary metabolites of these subclasses. This fact is underlined by steroids. Ecdysons have been isolated from three out of seven families of the Ranunculidae and from five out of the 11 families of the Caryophyllidae. The variability of the steroidal theme, undoubtedly again indicating considerable oxidation to accompany biosynthesis of metabolites in more highly advanced taxa, is thus an important marker for these subclasses, where chiefly Ranuncu-laceae excel, producing additionally cardenolides, pregnans, and bufodienolides.

The modest expression of triterpenoids in the Magnoliidae is, up to a certain point, compensated by a greater variability of diterpenoids, most of them, excepting the pentacyclic cinnzeylanols and cinn-cassiols from the Lauraceae, belonging to rather common types. For the Ranunculidae, apart from the fabulous number of diterpene alkaloids of the ent-kaurane, ent-atisane, and ent-aconane types in Ranunculaceae, practically only the clerodanes of the Menispermaceae are worth mentioning. In the Caryophyllidae the diterpenes continue to be represented by clerodanes (in Portulacaceae, accompanied by structural derivatives), an important clue of affinity, given the relative rarity of this diterpenoid type in dicotyledons. While sesquiterpenoid types are widely distributed in the Magnoliidae and elsewhere (cf. drimanes in Winteraceae and Canellaceae, but also in the Polygonaceae; lactone and furano derivatives in the Magnoliaceae, Lauraceae, Chloran-thaceae, and Aristolochiaceae, but also in the Aster-aceae) and thus do not constitute secure chemo systematic markers of relationships within the Magnoliidae, anisatin types again attest the isolated position of the Illiciaceae, and furylpiperidines and fu-rylquinolines are characteristic of the Nymphaea-ceae. Mono- and sesquiterpene-containing essential oils are widespread in families of block 1.

Lignans (Table 5). Structurally comparable types of lignans are widespread in the magnolialean families and extend as far as the more primitive Ranunculidae, most conspicuously the Berberidaceae (Podophyllum). However, from here on and through the Caryophyllidae, they become much scarcer, in parallel with increasing herbacity of the families.

Polyketides (Table 7). Some additional chemical characters underline the affinity of families belonging to the central core of the Magnoliidae. One of the more interesting ones refers to the utilization of pyruvate for the synthesis of predominantly polyketide-derived lactones in the Myristicaceae, Annonaceae, Magnoliaceae, and Lauraceae, as well as galbulimima alkaloids in the Himantandraceae. The Piperaceae are unmistakably related with the core families, sharing chiefly with the Lauraceae not only benzylisoqui-noline alkaloids and neolignans, but also alpha-pyrones and cinnamoyl amides.

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