Phytochemistry and Systematics of the Euphorbiaceae

22 Pages·1994·8.6 MB·

by  David S Seigler

Number
Volume 81 2 Carter 379
,
Euphorbia subg. Euphorbia
1994
of form as the rest of the genus put together, from desert regions, notably in southwest Africa, and
giant forest trees, to shrubs, herbs, and even geo- especially in the northeast, in the Horn of Africa.
phytes. It is evident that vegetative characters used This proposed classification of subgenus Eu-
by previous authors can often provide some indi- phorbia based on evidence gained from exam-
is
cation of the smaller group to which a species ination of almost the species known today. Some
all
belongs, but they are not, on their own, sufficient gaps remain, especially among the groups with
to identify its relationships positively. In the scheme features at the least advanced stage of development
much
proposed here (see Fig. characters of the and fewer representative species; but these gaps
1),
more stable features of seed, capsule and inflores- are not great, and hoped that, as discoveries
it is
cence are of prime importance in determining re- of new species are made, they will be filled, and
lationships. Habit and vegetative characters of spi- the feasibility of the scheme outlined here will be
nescence and branch structure play a secondary confirmed.
role. At the same time they are used as indicators
of development within groups, as well as between Literature Cited
them, during the gradual adaptation an
to arid
Berger, A. 1907. Sukkulente Euphorbien. Ulmer,
environment.
Stuttgart.
Relationships of this very distinct and apparently BOISSIER, P. E. 1862. Euphorbiaceae, Euphorbieae.
1-188 Prodromus
Pp. in A. de Candolle (editor),
isolated group of species are not determined.
easily
Masson
Systematis Naturalis Regni Vegetalis 15(2).
Ulbert (1987) has some
suggested, with reserva-
&
Son, Paris.
tion, that it could have been derived from section Brown, 1911-1912. Euphorbiaceae. Pp. 448-
N. E.
Tirucalli Boiss. (Boissier, 1862). Species of this 608 in W. T. Thiselton-Dyer (editor), Flora of Trop-
occur Reeve, London.
in all the drier regions of Africa, the Arabian ical Africa, 6(1).
220-375 W.
1915. Euphorbiaceae. Pp. in
Peninsula, and Madagascar, .
with small leaves
T. Thiselton-Dyer (editor), Flora Capensis 5(2). Reeve,
quickly
deciduous from
succulent, cylindrical
London.
branches, leaving 409-564
prominently calloused leaf-scars Carter, 1988. Euphorbieae. Pp. in R.
S.
sometimes surrounded by glandular tissue that could M. Polhill (editor), Flora of Tropical East Africa,
Perhaps be homologous Euphorbiaceae. Balkema, Rotterdam/Brookfield.
with the spine-shield. In
Gilbert, M. G. 1987. Two new geophytic species of
personal
discussions with now seems
Gilbert, to
it Euphorbia with comments on the subgeneric group-
u
s that a more likely relationship could lie with a ing of African members. Kew Bull. 42: 231-244.
its
small group Plantarum Succulen-
of fleshy-stemmed Haworth, H. 1812. Synopsis
shrubs related to A.
euphorbia synadenium tarum. Taylor, London.
Ridley, from evergreen
JACOBSEN, H. 1954. Handbuch der Sukkulenten Pflan-
orests of India and Malaysia. These possess large
zen (Band Fischer, Jena.
1).
eaves,
with
small,
persistent stipules, that are leaf- 1960. A Handbook of Succulent Plants, Vol.
.
and
often
stiffly pointed, resembling the stipular Blandford Press, London.
1.
.
Pnckles on the 1904. Monographische Ubersicht uber die
spine-shields of tree species in "sub- Pax, F.
Diacanthium
section Euphorbia:' afrikanischen Arten aus der Sektion
This would indicate that sub-
61-
genus der Gattung Euphorbia. Engl. Bot. Jahrb. 34:
Euphorbia
(the pair-spined species) may have
85.
°ng
|"ated ln Asia and migrated to northern Africa 1921. Die Pflanzenwelt Afrikas, Euphorbi-
.
at about
the time that the continents were breaking aceae. Pp. 1-68 in Engler (editor), Die Vegetation
U
and
P Madagascar became der Erde 3(2). Engelmann, Leipzig.
separated. Develop-
& Euphorbiaceae. Pp.
Hoffmann. 1931.
and K.
ment
proliferation within Africa followed as -233 D— -i_e N_ atu*r* l1ic\hen
1 in A. Engler et al. (editors),
comi
nent became 1
The
drier. relatively few for- 19C. Englemann, Leipzig.
Pflanzenfamilien, Aufl. 2,
e
species
of today retain primitive characteristics, Rauh, W. 1967. Die Grossartige Welt der Sukkulen-
nose of the more Parey, Hamburg and Berlin.
larger, successful groups, ten.
& The
Possessing White, R. A. Dyer B. L. Sloane. 1941.
characters A.,
at the most advanced state
Abbey Gar-
Southern Africa.
a Succulent Euphorbieae,
aptation
for survival an environment,
in arid
Pasadena.
den Press,
m
3re
und
the extreme
habitat conditions of semi-
AND
PHYTOCHEMISTRY
David
Seigler
S.
THE
SYSTEMATICS OF
EUPHORBIACEAE
1
Abstract
Phytochemical data provide much useful information concerning relationships both within the Euphorbiaceae and
between that family and putative relatives. Within the Euphorbiaceae, the presence of several groups of secondary
metabolites support certain infrafamilial groupings, whereas data related to the biosynthesis and distribution of other
secondary metabolites provide information concerning the relationship of the Euphorbiaceae to other families. Simi-
larities in chemistry to both the Geraniales and Malvales are found, supporting the suggestion by Webster (1987)
that the differences between the Dilliniidae and Rosidae may not be as great as previously thought, and that the
may
Euphorbiaceae have arisen from ancestors intermediate to those two groups.
The chemistry of the Euphorbiaceae among are widespread among higher plants. Examples are
is
and and
the most diverse and interesting of flowering plant glycosides of the flavones apigenin luteolin
families (Evans, 986a, b; Hegnauer, 1966b, 1989) the flavonols kaempferol and quercetin (Seigler,
1
compounds are
and comparable to the biological diversity of the 1977, 1981b). In general, that
is
many
family (Radcliffe-Smith, 1986; Webster, 1987). formed via complicated pathways with steps
from
Because of the presence of unusual secondary me- are less likely to have evolved than those
many deliberations
tabolites, species of euphorbiaceous plants simple pathways with fewer steps. In
are poisonous and have been involved in human of this sort, one almost must consider the precur-
and livestock poisoning. Plants of this family, es- sors that may be present in a particular plant.
complex
pecially those of the genus Euphorbia, are known Although diterpenes are of relatively
all
for their ability to induce dermatitis (Evans & biosynthetic origin, many are derived from kau-
Because
Schmidt, 1980). Others have been used in folk rene, a precursor of gibberellins in plants.
and
kaurene,
medicine, as piscicides, or as arrow poisons. Several gibberellins are universal in plants,
kaurene, pre-
euphorbs are important food plants, and a number the biosynthetic pathways leading to
many apparently
are important economically as ornamental plants sumably occur in all plants. Thus,
short
and as sources of rubber, chemical precursors, complex diterpenes actually arise via relatively
pathways.
lubricants, and medicinal compounds (Radcliffe- modifications of ubiquitous biosynthetic
(-)-kaurene,
Smith, 1986; Rizk, 1987). Examples compounds such as
include
taxa.
The euphorbiaceous
principal goal of this article to evaluate a diterpene found in several
is
only
found
systematic and evolutionary relationships in the However, cocarcinogenic diterpenes,
are de-
Euphorbiaceae with information derived from ex- the Euphorbiaceae and Thymelaeaceae,
in
nu-
involving
tant phytochemical literature. These data point to rived from complicated pathways
biosynthetic
certain affinities of the Euphorbiaceae and suggest merous steps not shared with other
pathways lea 1-
alignments of subfamilial taxa of this enigmatic pathways. The probability that the
more an
family as compounds have evolved t
well. ing to these
an *
What that
types of secondary compound data are once and, hence, the probability p
slight,
is
gr
likely to be useful? Both the presence and absence that possess these compounds are related is
o
of secondary metabolites and the biosynthetic path- Understanding phylogenetic relationships
nun^
large
ways made by the
responsible for their production are useful for Euphorbiaceae difficult
is
autapc
chemical
establishing taxonomic and phylogenetic relation- ber of both morphological and
intereM^
The Many and
ships. products of relatively short pathways morphic characters. exotic
gr
or
beginning species
with readily available precursors are more compounds occur in a single
1987).
likely to have originated several times and usually species (Hegnauer, 1989; Rizk,
The
1 author thanks the National Science Foundation (NSF BSR 82-15274) support.
for
61801
_
- Department of Plant Biology, 505 S. Goodwin St., 265 Morrill Hall, University of Illinois, Urbana, Illinois
U.S.A.
Ann. Missouri Bot. Gard. 81: 380-401. 1994.
Number
2
Volume 81 Seigler 381
,
1994 Phytochemistry and Systematics of
Euphorbiaceae
Thousands of compounds from many different mosystematic purposes in the Euphorbiaceae pre-
chemical classes have been reported from members viously has been reviewed (Hegnauer, 1963, 1966a,
of the Euphorbiaceae. This article makes no at- b, 1989; Seigler, 1977).
Among
tempt to review the literature exhaustively; ref- the relatively simple and widespread
al-
erences are to recent and readily available review kaloids are the harmane types, such as L-3-car-
articles rather than to the original works. Readers boxy-l,2,3,4-tetrahydrocarboline (l), 3 found in the
should consult the references cited in these reviews seeds of Aleurites fordii Hemsl. (Crotonoideae:
A
for more detailed information. predominance of Aleuritidae: Aleuritinae) (Okuda et 1975), and
al.,
chemical work concerns the large genus Euphor- A^-methyltetrahydroharman (2) isolated from
bia, which has been studied in greater detail than Spathiostemon javensis Blume (Homonoia ripa-
most other representatives of the family. ria (Blume) Mull. Arg.) (Acalyphoideae: Acaly-
An
Although the chemistry is doubtful in some in- pheae: Lasiococcinae) (Johns et al., 1 970). ester
stances, a more usual problem involves the uncer- of vasicine (3) (a pyrroloquinazoline alkaloid) has
tain identity of the plant materials used. Voucher been reported from Croton draco Schltdl. (Cro-
specimens were not maintained in many older and tonoideae: Crotoneae), but some uncertainty exists
some
present-day studies. In other instances, the about the identity of the plant material (Hegnauer,
identification of the plant material was not verified 1966a, b; Rizk, 1987). Several piperidine alkaloids
by a specialist; this is especially important for the have been reported from members of the Euphor-
Euphorbiaceae. biaceae. Among these are astrocasine (4) [Astro-
Webster Astrocasia
casia tremula (Griseb.) (syn.
&
Major
Types of Secondary Metabolites the phyllanthoides C. B. Rob. Millsp.) Phyllan-
in
Euphorbiaceae 2,4-dime-
thoideae: Phyllantheae: Astrocasiinae],
thoxy-^^-dimethylallyl-E-cinnamoylpiperidide (5)
Of
all chemical classes, the most useful for che-
(Excoecaria agallocha L. Euphorbioideae: Hip-
motaxonomic
study of the Euphorbiaceae above
pomaneae: Hippomaninae), and julocrotine (6) (Ju-
the
level of genus appear be cyano-
to alkaloids,
genus only weakly separated
locroton spp.; this is
genic
glycosides,
diterpenes, glucosinolates, seed
Hordenine found
from Croton) (Rizk, 1987). (7) is
and
other
lipids, tannins, and triterpenes (Heg-
Securinega
Flueggea virosa (Willd.) Baill. (syn.
in
nauer,
966b,
1 1 989). These are useful for several &
Pax Hoffm.) (Phyllanthoideae:
virosa (Willd.)
reasons.
Alkaloids, diterpenes, tannins, and triter-
and
(Hegnauer, 966b). Pyrrolidine
Securineginae)
1
penes
arise from complex
pathways; the products
Mar-
have been reported from
tropane alkaloids
nave
limited
distribution within the Euphorbiaceae.
Webster Phyl-
garitaria discoideus (Baill.) (syn.
Cyanogenic
glycosides and from
glucosinolates arise
lanthus discoideus Mull. Arg.) (Phyllanthoideae:
pathways
of
intermediate complexity; although these
gabouga
and Croton S.
Flueggeinae) (phyllalbine)
compounds
and
the pathways leading to them are
1987;
Moore [4-hydroxyhygrinic acid (Rizk,
(7)]
found
in other
plant families, the distribution of
An
1977). unusual type of quinolizidine
Seigler,
ese
glycosides
Euphor-
s restricted within the
|v i Poranthera corymbosa
occurs
alkaloid (8) in
'aceae. Both
cyanogenic glycosides and glucosi-
Andrachneae: Poran-
Brongn. (Phyllanthoideae:
"oates
provide
useful characters recognition
for
biosynthetically
therinae). This series of alkaloids is
subgroups
°*
within the family. Other compounds, &
(Howard Michael,
piperidine alkaloids
related to
ammo
as
acids, coumarins,
flavonoids, lignans,
Jatropha po-
The hypotensive principle of
986).
o 1
erpenes,
and
sesquiterpenes, are widely dis-
dagrica Hook. (Crotonoideae: Jatropheae) is tetra-
ted among many
" higher plant groups and with- compound known from
. methylpyrazine a also
(9),
e Eu
Phorbiaceae.
Although
not sufficiently dis-
and Asclepiadaceae
members of the Solanaceae
in
tinctive or
restricted
in distribution to be useful at occur Cni-
1982). Purine alkaloids in
(Nahrstedt,
amily
or subfamily compounds may &
level, these Mac-
basiacanthus (Pax K. Hoffm.)
doscolus
e as use
ful characters at lower taxonomic lev- basiacantha Pax & K.
• Jatropha
bride (syn.
A report of
questionable
1987).
Hoffm.) (Rizk,
Eu-
(Hippomane mancinella
L.,
physostigmine
al
kaloids
Hippomaninae) should
Hippomaneae:
phorbioideae:
&
^ Alkaloids are widely These be confirmed (Lauter Foote, 1955).
distributed in plants.
gen° Com have been isolated from the
US
ounds range from very simple, Imidazole alkaloids
P
and°
usually
widespread,
complex
to highly entities
n
tncted
*!
distribution. Both types are found in
thf
uphorbiaceae. The use of alkaloids for che- 3 See figure at the end of the article.
382 Annals of the
Missouri Botanical Garden
genera Glochidion (Phyllanthoideae: Phyllan- and glaucine), proaporphine, dihydroproaporphine,
theae: Flueggeinae) and Alchornea (Acalyphoi- and morphinandienone types of benzylisoquinoline
&
deae: Alchornieae: Alchorneinae) (Johns Lam- alkaloids have been isolated from Croton
species
& &
berton, 1967; Maat Beyerman, 1983; Rizk, (Rizk, 1987; Rizk El-Missiry, 1986). Among
N
A a
1987). series of imidazole alkaloids including - the individual alkaloids isolated are glaucine (16),
cinnamoylhistamine (15), /V°-oxodecanoylhista- orotonsine, pronuciforine, sparsiflorine (17),
thali-
mine (10), glochidicine (11), and glochidine (12) porphine, crotsparine (18), A^O-crotsparine,
occur in Glochidion philippicum (Cav.) C. B. Rob. /V-methylcrotsparine, crotonosine (19), flavinan-
(Rizk, 1987). Alkaloids with this general structure tine, flavinine, linearisine (20), 3-methoxy-4,6-di-
are known from several other groups of plants hydroxymorphinandien-7-one, /V-norsalutaridine,
(Acanthaceae, Cactaceae, Fabaceae, Orchidaceae, norsinoacutine, salutaridine (21), and salutarine
and Rutaceae), but the structures are so diverse (Rizk, 1987). Salutaridine was first discovered in
may
that the alkaloids be of distinct biosynthetic Croton salutaris Casar. from Brazil and later found
origin (Seigler, 1977). in low concentrations in Papaver somniferum L,
The pyrimidine and guanidine alkaloids of Al- where an intermediate in the biosynthesis of
it is
chornea contain a hemiterpene unit and also rep- morphine alkaloids. Bisbenzylisoquinoline alkaloids
Among Andrachne
resent an unusual structural type. the have been reported from cordifolia
py-
rimidine alkaloids of Alchornea javanensis Mull. (Decne.) Mull. Arg. (Phyllanthoideae: Andrach-
Arg. are alchornidine (13) and alchornine (14). neae: Andrachninae) (Khan et al., 1983).
This plant also contains /V',/V2 -diisopentenylguani- The securinine alkaloids are a small group of
dine and /V1 ,/V2 ,/V3 -triisopentenylguanidine (Heg- compounds produced only by members of the sub-
Among
nauer, 1989; Rizk, 1987). family Phyllanthoideae. these, allosecuri-
Because of the widespread occurrence of the nine (22), dihydrosecurinine, norsecurinine (23),
above alkaloids among other plants (probably re- phyllantidine, phyllantine, phyllochrysine, securi-
flecting the ease with which they can arise), and/ nine (24), suffruticosine, and virosecurinine (25)
or their sporadic distribution among the Euphor- come from Securinega, Phyllanthus, and Flueg-
Securi-
biaceae, their presence does not suggest or confirm gea (Phyllantheae: Flueggeinae) species.
from
familial or subfamilial relationships. However, other nine and related alkaloids are synthesized
genera related to Glochidion and Alchornea should lysine and tyrosine via a unique pathway and rep-
be examined for the presence of imidazole, pyrim- resent a novel type of alkaloids not found in other
& Riz^
idine and guanidine alkaloids, respectively, as these plant groups (Beutler Brubaker, 1987;
compounds several
could provide useful characters at the 1987; Seigler, 1977). Their presence in
specific and generic level. members of the Phyllanthoideae reinforces the close
Fluegge"-
In contrast, the distribution of benzylisoquinoline relationship of the genera Phyllanthus,
among
alkaloids is restricted higher plants. Most and Securinega.
Acaly-
occur communis
in certain families of the Magnoliales and Ricinine (26) (Ricinus L.,
(27
h
Ranunculales, although sporadic occurrences are phoideae: Acalypheae: Ricininae), nudiflonne
known from methyl-3-carboxamide-6-pyridone
other plant groups. Benzylisoquinoline ricinidine (28),
0W
common
alkaloids are in the following (Trewia Acalyphoideae), and mallorepine
families: spp.,
Annonaceae, Rottleri-
Aristolochiaceae, Berberidaceae, (Mallotus, Acalyphoideae; Acalypheae:
pro -
Eupomatiaceae, Hernandiaceae, and are
Fumariaceae, nae) appear to be closely related
all
&
Lauraceae, Magnoliaceae, Menispermaceae, Mon- ably derived from nicotinic acid (Fodor
*
& Strunz
imiaceae, Nelumbonaceae, Papaveraceae, Ran- 1985; Sastry Waller, 1972;
santi,
e
&
unculaceae, and Winteraceae. Nowacki, 1978). I
Alkaloids of Findlay, 1985; Waller
this
similar
structural type are found commonly suggest a
less in other structures of these alkaloids ^
r0
families including the Euphorbiaceae (Croton, An- synthetic origin from nicotinic acid as is P
acalypnm
drachne), Fabaceae
(Erythrina), Rhamnaceae cyanogenic glycoside I
true for the
Acalyphea
(Rhamnus,
Phylica, Colletia, Colubrina, Disca- (Acalypha indica Acalyphoideae:
L.,
ria, Ratanilla, Talguenea, and Zizyphus), Phel- Acalyphinae) (Nahrstedt, 1987).
linaceae (Phelline), Symplocaceae (Symplocos), Maytansinoid alkaloids, such as trewiasine (
WT
genera
Rutaceae, Araliaceae (Hedera), Apiaceae (Hera- are reported often from plants of the
a^
cleum), Caprifoliaceae (Symphoricarpos), Rubi- tenus and Putterlickia of the Celastraceae
& K° *
aceae (Cephaelis), and Araceae Rhamnaceae (Reider
(Lysichiton) (Bis- Colubrina of the /
gen
the
set, 1985; Dahlgren et al., 1981). 984), but also have been encountered in
1
In the Euphorbiaceae, aporphine (thaliporphine Trewia (Powell 1981, 1983).
et al.,
Number
Volume 81 2 Selgler 383
,
1994 Phytochemlstry and Systematics of
Euphorbiaceae
Peptide alkaloids are known from Hymenocar- naultii (DC.) Baill. and B. viscosa (Labill.) Miq.
dia acida Tul. (Phyllanthoideae: Hymenocardieae) (Ricinocarpeae: Ricinocarpinae), several species of
(Paisetal., 1967; Seigler, 1977). Similar alkaloids, Cnidoscolus% (Manihoteae), Croton lobatus L., C.
such as hymenocardine (32) have been isolated punctatus Lour., C. scouleri Hook, f., Elaterios-
permum
from Panda of the Pandaceae, which Webster tapos Blume (Elatiospermeae), several
many
(1994) now merges with the Euphorbiaceae. This HeveaX species (Micrandreae: Heveinae),
merger supported by peptide alkaloid chemical species of Manihot (Manihot esculenta Crantz^)
is
data. Peptide alkaloids also have been isolated from (Manihoteae), (Adsersen et al., 1987; Hegnauer,
Weakly
the Celastraceae, Menispermaceae (Cocculus), 1989; van Valen, 1978). positive tests
some genus
Rhamnaceae, Rubiaceae, Sterculiaceae (Melochla have been observed with species of the
Most
and Waltheria), and Urticaceae (Schmidt et al., Jatropha (e.g., /. capensis Sond.). of the
1985). species examined in this subfamily contain lina-
amounts
marin (35) and usually smaller of lo-
taustralin (36) (species marked with a $). In ad-
CYANOGENIC GLYCOSIDES
careful examination of the cyanogens of
dition,
Plants from subfamilies Phyllanthoideae, Cro- Hevea brasiliensis Mull. Arg. (Crotonoideae: Mi-
tonoideae, and Acalyphoideae of the Euphorbi- crandreae: Heveinae) revealed the presence of the
aceae contain glycosides capable of releasing cy- corresponding diglycoside, linustatin (37) (Liebe-
Hevea
anide upon hydrolysis. This property also has been rei, 1986, 1988). In general, lines of brasi-
reported, but not confirmed, from plants of the liensis with large amounts of cyanogenic glycosides
Euphorbioideae. The cyanogenic glycosides and 0-glycosidases are the most susceptible to the
in-
volved are derived from several different precur- South American leaf blight (Lieberei, 1988). Cy-
appear
sors, and although one compound anogenic diglycosides, such as linustatin,
of this type,
acalyphin (30), is found only in the Euphorbiaceae, to be involved in transport of cyanogenic glycosides
others are widely within the plants and are probably more widely
distributed.
1985).
Several species of the subfamily Phyllanthoideae distributed than realized (Lieberei et al.,
are cyanogenic. Among these are Andrachne col- Several species from the Acalyphoideae also are
W. & Among Aca-
chica Fisch. E. Meyer*, A. decaisnei Benth., known to be cyanogenic. these are
A- telephioides L.*, Breynia Bridelia lypha indica L., A. ostryaefolia Riddell, Dale-
obtusiflora,
cathartica G. champia micromeria (Plukenetieae: Dale-
Bertol. *, B. exaltata F. Muell., B. Baill.
duvigneaudii J. Leonard, B. mollis Hutch., B. champiinae), Mercurialis annua L. (Acalypheae:
monoica communis (Heg-
Merr.*, and Ricinus
B. ovata Decne., B. pervilleana Mercurialinae),
Jkill., B. scleroneura Mull. Arg.*, B. tomentosa nauer, 1989; Nahrstedt, 1987; van Valen, 1978).
Blume, Phyllanthus acuminatus an- The cyanogenic glycoside acalyphin (30) has been
Vahl., P.
1987).
wstifolius (Sw.) Sw., P. gasstroemii Mull. Arg., isolated from Acalypha indica (Nahrstedt,
lacunarius F. Muell., P. speciosus Jacq., Por- A number of plants of the subfamily Euphor-
Whera
cyanogenic.
microphylla have been reported to be
Brongn.*, corymbosa, bioideae
P.
heggea
Chamaesyce abdita Burch, C.
Among
suffruticosa Secu- these are
(Pall.) Baill.* [syn.
&
Q SUtfruticosa Pa11 Render, S. ramiflora galapageia (B. L. Rob. Creenm.) Burch, C.
< -)
WML
\r\\ ma-
Arg., and (Euphorbia hirta L.), C.
S. flueggeoides Mull. Arg.] (van hirta (L.) Millsp.
en 1978). Those species marked with an * are culata (L.) Small [C. supina (Raf.) Moldenke], C.
*
L
k"nown
to contain triglochinin (33) as the cyano- recurva (Hook, f.) Burch, C. thymifolia(L.) Millsp.
viminea (Hook,
,c glycoside; other species are known to be (Euphorbia thymifolia L.), C. f.)
Euphorbia
genie, but the compounds have been Burch (Euphorbieae: Euphorbiinae),
not
ar boophthona C.
acterized. drummondii [probably E.
' Plants of Phyllanthus gasstroemii Boiss.
contain taxiphyllin (34). Plants of Bridelia monoi- A. Gardner and E. clutioides (C. Forst.) C. A.
hexagona
'« Nutt.,
contain Rendle, E.
dhurrin (an enantiomer of taxiphyllin) Gardner], E. eylesii
Euphorbi-
(Euphorbieae:
^t '"^ochinin (Hegnauer, 1989; van Valen, E. lupatensis N. E. Br.
(Hippomaneae:
h but no Gymnanthes lucida Sw.
other cyanogens have been sub- inae),
^ntiated Sapium haematospermum Mull.
from
Hippomaninae),
species of subfamily (Bride-
this
,ie*e). Roxb. (Hippomaneae: Hip-
All three cyanogens are derived from ty- Arg., S. sebiferum (L.)
&
rosine. dentata (Torr.) Britton
pomaninae), Sti/lingia
^
(Hippoma-
number Arg.
sanguinolenta Mull.
of species of the subfamily Croto- Rusby, S.
^ and doubtfully Coliiguaja
arC ^ nown Among Hippomaninae),
neae:
to cyanogenic. these
jT
arC & (Hippom.m,*e: Hip-
Aleuri Hook.
tcs trisperma Beyeria integernma Gillies
Blanco, lesche-
384 Annals of the
Missouri Botanical Garden
pomaninae) (Hegnauer, 1989). To date, the cya- known from Croton corylifolius Lam. (Schmidt,
nogenic compounds of the Euphorbioideae have 1987).
been
not characterized.
Cocarcinogenic The
diterpenes. powerful
DITERPENES
purgative properties of "croton oil," the seed
oil
A
large variety of diterpenes occur in the Eu- of Croton tiglium L. (native to Southeast Asia),
phorbiaceae (Hegnauer, 1966b, 1989). These may have long been known. The active compounds have
be grouped into compounds derived from mono- been isolated and shown to consist of the 12,13-
cyclic precursors and their derivatives (including diesters of a tetracyclic diterpene, phorbol (46)
&
cocarcinogenic diterpenes), kaurene and related (Hecker Schmidt, 1974). These compounds are
&
compounds, and labdane derivatives. potent and cocarcinogens (Evans
irritants
&
Schmidt, 1980; Evans Soper, 1978; Hecker,
Simple diterpenes from geranylgeranyl
py-
1977, 1986; Kinghorn, 1979). These compounds
rophosphate. Geranylgeraniol derivatives are
are called cocarcinogens or tumor promoters be-
found in several species of Croton, e.g., C. kerrii
cause they are not directly carcinogenic, but ap-
Shaw
Airy and C. sublyratus Kurz. (Hegnauer,
plication of a carcinogen following contact with
One
1989). simple diterpene, 18-hydroxy-6-cis-
cocarcinogenic diterpenes results in greatly en-
geranylgeraniol (38) from Croton kerrii stems,
same
hanced carcinogenic activity. At the time,
appears to serve as a prostaglandin analogue. This
these compounds have been examined for their
compound
protects the digestive tract from the
&
Heck-
antitumor properties (Evans Soper, 1978;
effects of ulceration and promotes wound healing
1986).
& er,
(Croteau Johnson, 1985; Sato et 1980).
al.,
compounds are derived
Biosynthetically, these
Cyclic diterpenes from geranylgeranyl pyro- from monocyclic diterpenoid precursors and are
phosphate. Cembrene lathyranes,
(39), duvatrienediols (such biosynthetically related to casbene, the
as 40), and a large series of compounds of the and the jatrophanes. Several major structural types
Euphorbiaceae (the lathyrols, casbene, jatro- are found. Most important among these types are
1986b),
phanes, rhamnifolanes, and crotofolanes, as well the ingenane (such as 47) (Schmidt,
(46)
as the cocarcinogenic tiglianes, daphnanes, and daphnane (48) (Schmidt, 986a), and tigliane
1
ingenanes) are derived from cyclization of a gera- (Evans, 1986a, b) series. Precursors of the tigli-
nylgeranyl pyrophosphate precursor to a large anes, ingenanes, and daphnane type cocarcino-
Eu-
monocyclic system (Schmidt, 1987). Casbene (41), genic diterpenes have been isolated from the
a bicyclic 1 4-membered ring compound, a phy- phorbiaceae as well as Thymelaeaceae.
is
toalexin Ricinus communis. compound with a al-
in This ap- Tiglianes phorbol) (tetracyclic
(e.g.,
Aqudarm.
pears to be derived from head-to-tail condensation and a seven-membered ring) occur in
as
of the diterpene pyrophosphate (Thymelaeaceae) as well
precursor, geranyl- Daphnopsis, Pimelea
Euphorbia.
geranyl pyrophosphate (GGPP)
(Schmidt, 1987). Aleurites, Croton (Crotonoideae),
A compound (Euphor-
with related structure has been Hippomane, Sapium, and Synadenium
iso-
(Bagavathi
lated from Croton nitens Sw. Euphorbiinae)
Euphorbieae:
bioideae:
&
Several unusual structural types of diterpenes 1988; Hecker, 1977; Evans Soper, 19. •
et
al.,
derived from monocyclic
precursors occur
in the Schmidt, 1986c).
twO
'#K
i' witn
Euphorbiaceae. Jatrophanes (such as 42) are known Ingenanes ingenol) (tetracyclic i
(e.g.,
(an
from Jatropha Euphorbia
gossypiifolia L., macrorhiza seven-membered occur in
/. rings)
«V
Benth., Euphorbia characias Euphorbia synonym of
L., esula Elaeophorbia, considered a
"
(Hecker.
maddenii
L., E. Boiss., E. helioscopia L., and E. bia by Webster, 1975, 1994) species
otw
kansui Liou ex H. B. Ho (Hegnauer, 1989; Man- 1977; Evans & Soper, 1978), but not
Thymelaeaceae
ners, 1987; Schmidt, 1987). Rhamnifolanes (43) taxa of the Euphorbiaceae and
known
are from Croton
rhamnifolius Kunth. were examined (Hecker, 1977).
.
(Schmidt, 1987). Lathynmes (such as 44) are Daphnane compounds (e.g., daphnetoxin) 1
[JW£
known
from Bertya cupressoidea Shaw Euphorbiaceae
Airy
(Cro- cyclic) occur in both the
Cunuria^^
tonoideae: Ricinocarpeae: Bertyinae), Euphorbia permum Codiaeae),
(Crotonoideae:
tup °
helioscopia Euphorbia
L. characias, E. ingens tonoideae: Micrandreae: Micrandrinae),
m*
E. Meyer, E. jolkini Boiss., E. lathyris L., and Excoecaria, Hippomane, Hura (Euphorbioi
^J^T^
Macaranga
tanarius Mull. Arg. (Acalyphoideae: Hureae), and Stillingia] and the
^
Acalypheae: Macaranginae) Dirca.
(Hegnauer, 1989; (Daphne, Daphnopsis, Diarthron, '
Wf**
Schmidt, '
1987). Crotifolanes (such as 45) are Lasiosiphon, Pimelea, Synaptolepi*,
Number
2
Volume Seigler 385
81
,
1994 Phytochemistry and Systematics of
Euphorbiaceae
and Wikstroemia) (Adolf et al., 1988; Hecker, found in the Asteraceae, Lamiaceae, Euphorbi-
1977; Powell et al., 1985; Schmidt, 1986c). aceae, and the genus Jungermannia (a bryophyte)
&
Daphnanes are probably derived from tiglianes by (Croteau Johnson, 1985). These compounds oc-
&
opening of the cyclopropane ring (Evans Soper, cur in the leaf-surface resins of members of the
&
1978). tribe Ricinocarpoideae (Croteau Johnson, 1985;
&
Within the genus Euphorbia, subgenera Cham- Dell McComb, 1974).
aesyce and Poinsettia lack cocarcinogenic
diter-
A
Oxygenated num-
diterpene derivatives.
common
penes. Both tiglianes and ingenanes are
ber of highly oxygenated diterpenes based on the
subgenera Euphorbia and Tithymalus (Evans
in
labdane skeleton are found the families Aster-
in
&
&
Kinghorn, 1977; Evans Soper, 1978).
aceae, Euphorbiaceae, Lamiaceae, and Verbena-
Determination of active diterpenes by means of
&
ceae (Croteau Johnson, 1985; Seigler, 1981a).
3H-PDBU
a (tritiated phorbol receptor binding as-
These compounds are complex and restricted in
say) suggested their presence in several previously
distribution. In the Euphorbiaceae, they are pri-
untested samples of euphorbiaceous plants. Activ-
marily found in the genus Croton (Seigler, 1981a).
ity was observed in the Phyllanthoideae \_Antides-
Furan formation between C-15 and C-16 com-
is
ma
(Antidesmeae: Antidesminae), Drypetes (Dry-
mon. Such compounds are cordylifoline (Burke et
peteae), Glochidion, and Uapaca (Uapaceae)],
1976) and isocrotocaudin (51). At least two
al.,
although only that observed Antidesma was
in
diterpenes of this type are found in Croton setige-
strongly
positive (Beutler et 1989). Cleistan-
al.,
Hook. [Eremocarpus setigerus (Hook.) Benth.]
rus
thol, a cocarcinogenic
diterpene, found in Cleis-
is
and another
(Bajaj et al., 1986; Jolad et al., 1982),
tanthus
schlechteri Hutch.
(Phyllanthoideae: Bri-
from Mallotus
compound, mallotucin A, isolated
delieae)(McGarry
et al., 1971). Only weak activity
repandus Mull. Arg. has been shown iden-
(Willd.)
was
observed
in the Acalyphoideae (Alchornea and
from Teu-
tical to teucrin (52) [originally isolated
Trewia) and none from Among
the Oldfieldioideae.
(Kawashima 1976).
crium (Lamiaceae)] et al.,
the
Crotonoideae,
activity was found Cnidosco-
in
lus, Jatropha,
Ricinodendron
(Aleuritidae: Rici-
GLUCOSINOLATES
nodendrinae), Codiaeum, Dimorphocalyx, Fah-
renheitia Euphorbiaceae are con-
(Codiaeae), Aleurites, Crotonogyne Glucosinolates in the
(Neoboutonieae: number Most important
Crotonogyninae), Cyrtogonone fined to a small of taxa.
Moore
(Neoboutonieae: among Drypetes gossweileri S.
Crotonogyninae), Croton these are
(includ-
•ng Eremocarpus) (Crotoneae) (Beutler et al., and Putranjiva roxburghii Wall. (Phyllanthoi-
merged Dry-
89). Similar activity was observed Aleurites deae: Drypeteae). Putranjiva is with
in
fordii Glucoputranjivin
(Aleuritidae: Aleuritinae) (Schmidt, 1987). petes by some (Hurusawa, 1954).
In the and glucojaputin have
Euphorbioideae, activity was found in Pla- (53), glucocochlearin (54),
giostyles (Stomatocalyceae: Stomatocalycinae), been isolated from Putranjiva roxburghii (Rizk,
lomalanthus from
are derived
(Hippomaneae: Carumbiinae), Du- 1987). Although glucosinolates
ngneaudia
(Hippomaneae: same pathways as cyanogenic glycosides, glu-
Hippomaninae), Ex- the
coecana,
on
Hippomane, Maprounea (Hippoma- cosinolates of the Euphorbiaceae are based al-
neae: Hippomaninae), Sapium, and Stillingia iphatic aglycones and do not resemble the cya-
Sutler
Benzyl
subfamily.
et al., 1989). A large number of other nogenic glycosides of this
genera were examined and found to lack this ac- isothiocyanate has been reported from the latex of
&
tivity. 1986).
El-Missiry,
Jatropha multifida L. (Rizk
of glu-
Among higher plants, the distribution
number fam-
terpeneS a small of
derived from Kaurene cosinolates restricted to
kaurene. is
(4Q\
Rodman 1993).
1 ls Pr°bably found (Rodman, 1991a, b; et al.,
' in all plants as it is a pre- ilies
Brassicaceae,
f°r gibbere,lins although usually only in One group of families includes the
' A
Zl\\
and Tovariaceae.
amounts. Resedaceae,
Structurally compounds are Capparidaceae,
related
^cumulated m glucosinolate-containing
a number of euphorbiaceous taxa number of other enigmatic
those families.
Xarnple, appear to be related to
™'-30-hydroxybeyer- 6)-ene families
2°12 ! 1 5( 1
may
families
lone glucosinolate-containing
- *-- (50) known from Androstachys Several other
is
glucosinolate-
SOnil Prain each other, but the
l" be related to
(Oldfieldioideae: Picrodendreae:
wostachydeae) members of the Euphorbiaceae do not
' (Pegel et 1971), Beyeria containing
al.,
any other glucosi-
JTTjMtti (DC.) and calycina Airy appear to be closely related to
Baill., B.
1966b; Rod-
(Hegnauer,
ereta1 nolate-containing plants
972;Ghisalbertietal., 1978).
1
^ '
n Rodman 1993).
pimarane man, 1991a, et al.,
y and abietane derivatives are b;
^
386 Annals of the
Garden
Missouri Botanical
SEED AND OTHER LIPIDS biosynthetically from epoxy fatty acids. 9,14-dihy-
droxyoctadecadien-10,12-oic acid (67) and
eryth-
A
number of unusual fatty acids occur primarily
ro-9, 0-dihydroxy- -octadecanyl acetate (66) are
members 1 1
as components of seed lipids of of the
found in the seeds of Aleurites fordii and 11,13-
Euphorbiaceae but are occasionally found in the
dihydroxy-9-/raAis-tetracosenoic acid in Balios-
associated with other plant parts (Smith,
lipids
permum axillare Blume (Hegnauer, 1989).
Many
1970). of these involve unusual sites of un-
E
saturation and double bonds. For example, Sapi- TANNINS
um
sebiferum (L.) Roxb. contains decanoic acid Polyphenols compounds known as tannins are
with 2-E-4-Z unsaturation (55) and Sebastiana especially widespread among woody plants, but also
ligustrina (Michx.) Mull. Arg. contains dodeca- are found herbaceous species. Both hydrolyzable
in
A
2,4-dienoic acid (56) (Smith, 1970). decanoic and condensed tannins are found in plants from
&
acid with a cyclopropane ring (57) has been iso- the Euphorbiaceae (Rizk El-Missiry, 1986). Hy-
lated from Croton species (Hegnauer, 1989). drolyzable tannins that yield ellagic acid (68) on
a-Eleostearic acid (58) is found in tung oil (Aleu- hydrolysis have been reported from several species,
montana &
rites fordii, A. (Lour.) E. H. Wilson, A. primarily from the genus Euphorbia (Rizk El-
remyi Sherff., and A. trisperma, but only ques- One geraniin
Missiry, 1986). specific ellagitannin,
tionably from the seed of A. moluccana Willd.). and has been
oil widespread the family
(69), in
is
This rapidly polymerizing acid is also found in the isolated from members of the Acalyphoideae, Cro-
oil of Garcia nutans Rohr., Ricinodendron viti- tonoideae, Euphorbioideae, and Phyllanthoideae
coides Mildbr., and R. rautanenii Schinz. (Cro- (Hegnauer, 1989; Okuda 1980). In the first
et al.,
tonoideae: Aleuritidae: Ricinodendrinae), (Heg- accompanied by the
three of these subfamilies,
it is
nauer, 1989; Jacobsonet al., 1981; Smith, 1970). encountered compound mallotusic acid (70).
rarely
An
unusual glyceride containing an allenic link- common the Geraniaceae,
Geraniin especially in
is
age and a short chain hydroxy acid (59) is found but absent from the Myrtaceae, Fagaceae, and
Saplum
in the seed lipids of sebiferum, Stillingia Fabaceae. Tannins with quite distinctive structures
sylvatica L., Stillingia texana I. M. Johnst., and have been isolated from euphorbiaceous plants,
Sebastiana ligustrina (Michx.) Mull. Arg. (Heg- Euphorbia (Okuda et
from genus
especially the
&
Heimermann
nauer, 1989; Holman, 1972).
1980).
al.,
Various hydroxy acids also occur. Although found Because tannins have complex structures and
in other plants and microorganisms (for example, some appear have restricted distribution,
in cases to
in fungi of the genus Claviceps), ricinoleic acid these compounds should be useful for systematic
complex
(60) is the major fatty acid of the triglycerides of Unfortunately, tannins occur in
studies.
Ricinus communis. Securinega analysis
suffruticosa seed complexity has precluded
mixtures;
this
usetu
oil contains 12-hydroxyheptadecanoic (61) and 12- many Tannin content alone is not
in cases.
hydroxyeicosanoic acids (Hegnauer, 1989). The for taxonomic purposes. Future work may clan >
an
main compounds
constituent of the seed oil of Mallotus phi- the structures of many of these
or
lippensis (Lam.) Mull. Arg. and Trewia nudiflora chemosystematic markers
provide additional
L. is 18-hydroxyoctadec-Z-9-£-l l-£-13-trienoic
analysis of plant groups.
&
(a-kamolenic) acid (62) (Calderwood Gunstone,
TRITERPENES
1953; Hegnauer,
1989).
latex
possess
Epoxy fatty acids are found in Alchornea cor- Many plants of the Euphorbiaceae
redo
+ are
difolia Miill. Arg. [a rich source of )-Z-14,15- that rich in terpenes. Triterpenes P "''
( i<=
most
specie-
epoxy-Z-1 1-eicosenoic acid (63)] (Kleiman et al., nant in these terpenoid fractions in
& Heg-
1983;
Mahato,
1977), Cephalocroton cordofanus Hochst. (Aca- Reviews of triterpenes (Das
&*»
& Pant
1979;
lyphoideae: Epiprineae: Epiprinineae) (Bharucha nauer, 1989; Ourisson et al.,
bei
& 1986; g'^
Gunstone, 1956), and Euphorbia lagascae Spreng. 1979; Rizk El-Missiry,
togi,
K*
Lup
the
(vernolic or cts-12,13-epoxyoleic acid) (64) (Klei- 1981a) include many references to
genus
man from the
et al., 1965; Smith, 1970). The furanoid biaceae. Species of triterpenes ^
cm*
compound, of
0, 3-epoxy- -methyloctadeca- phorbia outnumber those all
1 1 1 1 easily ^" ^
S ^
10,12-dienoic acid (65), occurs in the latex of phorbiaceous taxa (Hegnauer, 1989; w
&
Hevea Ponsinet
brasiliensis (A. Juss.) Mull. Arg. (Hasma 1979; Ponsinet et al., 1968;
al.,
&
Subramaniam,
1978).
son, 1965).
Dihydroxy fatty acids are found commonly Most of the triterpenes that have been veV°rt ,
in
<*
0-sitosterol,
the Euphorbiaceae as well as in several other fam- fro>mm the Euphorbiaceae (e.g.,
lupeo
These compounds
ilies. are thought to be derived 0-amyrin (71), friedelan, taraxerol,
Number 2
Volume 81 Seigler 387
,
1994 Phytochemistry and Systematics of
Euphorbiaceae
8
cycloartenol (73), taraxerone, /3-amyrin acetate, Cucurbitacins (such as have been reported
1 )
pseudotaraxasterol, betulin, taraxerone, 24-meth- from the Phyllanthoideae [Antidesma rupicola
Wedd.,
ylenecycloartenol, taraxasterol, friedilin, oleanolic Cleistanthus rupicola Leonard, Dry-
J.
and ursolic acid, and butyrospermol) are wide- petes gossweileri, Spondianthus preussii Engl.
spread among higher plants and are of value (Antidesmeae: Spondianthinae)], the Acalyphoi-
little
for establishing taxonomic relationships at higher deae \Discoglypremna coloneura Prain. (Cary-
levels. Their presence may, however, be useful odendreae), Mareya micrantha (Benth.) Mull. Arg.
taxonomically at the species or subgeneric level (Acalypheae: Claoxylinae), Trewia nudiflora\ and
(Mahlberg et 1988). Because triterpenes are the Euphorbioideae (Maprounea africana Mull.
al.,
difficult to isolate, purify, and characterize, many Arg., Sapium cornutum Pax) (Hegnauer, 1989).
older reports (for example, those for lanosterol) These extremely bitter compounds also occur in
should be re-examined. the Cucurbitaceae, Brassicaceae (Iberis), Liliaceae
Euphol (74), tirucallol (75), and euphorbol (76) (Phormium), Begoniaceae (Begonia), Rosaceae
often are found in the latex of members of the (Purshia), Datiscaceae, Sterculiaceae (Helicteres),
&
genus Euphorbia Scrophulariaceae (Gratiola), Polemoniaceae
(Rizk El-Missiry, 1986). In
addition, euphol is found in the Burseraceae, Ru- (Ipomopsis), and Primulaceae (Anagallis).
taceae, Simaroubaceae, Cneoraceae, and Melia-
COMPOUNDS
ceae, and tirucallol in the Anacardiaceae; either MISCELLANEOUS
(or both) serve as precursors for a series of met-
Amino 3,4-Dihydroxy-L-phenylalanine
acids.
abolically altered triterpenes in the Cneoraceae,
amino used
(L-dopa) (82), a nonprotein acid, is
Meliaceae, Rutaceae, and Simaroubaceae.
com-
for treatment of Parkinson's disease. This
Hundreds
of Euphorbia species have been ex-
pound found in several plants, primarily legumes,
is
amined
for triterpene content. The major
triter-
but also occurs in Euphorbia lathyrus L. (Heg-
penes
present are compounds related to cycloar-
nauer, 1966b).
tenol,
tetracyclic triterpenes, and pentacyclic
Many
Coumarins. coumarins are essentially
triterpenes (Hegnauer, 1989; Ourisson 1979).
et
al.,
Compounds such as
Bauerenol (77), germanicol (78), and phyllanthol ubiquitous in higher plants.
scopo-
(79) are many umbelliferone, esculin, esculetin, scopolin,
pentacyclic triterpenes found
in
many
plants from & and coumarin occur in plant families.
the genus Euphorbia letin,
(Rizk El-Mis-
The bicoumarins euphorbetin and isoeuphorbetin
Slry, 1986). In general, herbaceous species accu-
mulate cycloartenol, accumulate are found in Euphorbia lathyrus (Euphorbioideae)
cactuslike species
found
euphol and 1987). Bergenin (83) derivatives are
euphorbol, whereas "coral-like species" (Rizk,
Mallotus japonicus Mull. Arg.,
accumulate the bark of
euphol and in
(Ponsinet
tirucallol et al.,
1968; Mallotus repandus, and Macaranga peltata Mull.
Ourisson
et 1979; Ramaiah 1979;
al., et al.,
& and Flueggea microcarpa
«'zk Arg. (Acalyphoideae) in
El-Missiry, Members Amer-
1986). of the
ican subgenus Blume (Ramaiah et al., 1979; Rizk, 1987). Ber-
Poinsettia usually contain fatty acid
eu-
accompanies ellagitannins in
esters of genin frequently
pentacyclic triterpenes (Hegnauer, 989;
1
Benzocou-
(Hegnauer, 1989).
Ourisson phorbiaceous plants
et al., 1979). Although cholesterol nor-
is
ma Euphorbia royleana
from
Ily a minor marins have been isolated
plant Euphorbia pulcher-
sterol, in
nma
1987).
Willd. compound Boiss. (Rizk,
this comprises almost half
the &
sterol mixture
(Rizk El-Missiry, 1 986). Flavonoids. Flavonoids are ubiquitous compo-
here have
been
too few other investigations to Several types, such as the glyco-
nents of plants.
a
Pply the data
effectively, but probably plants of and and the
apigenin luteolin,
of the flavones
sides
other
euphorbiaceous genera do not accu- and quercetin are found in a
kaempferol
flavonols
mulate
triterpenes to the same extent as do species examined. Other types
percentage of plants
large
of
Euphorbia.
widely
such as biflavonoids, are less
of flavonoids,
number
of new and compounds
distinctive
distributed.
(primarily
pentacyclic triterpenes related to lupeol) Numerous flavonoids have been isolated and
av
e been
reported from the genus GLochidion from members of the Euphorbiaceae
characterized
hegnauer,
& &
Both C-
1989; Rizk El-Missiry, 1986). 1987; Rizk El-Missiry, 1986).
(Rizk,
Cardiac Many compounds, such
glycosides (such as 80), another group and 0-glycosides are found.
"terpenoid derived compounds and quercetin glycosides (e.g., iso-
sporadically dis- as quercetin
"ted among isovitexin,
l mem- vitexin (85),
plants, are found several quercitrin (84)), rutin,
in
kaempferol and
rs of
the isoorientin,
genus Mallotus 1987; Roberts isorhamnetin, orientin,
(Rizk,
et rhamnetin, naringen gly-
«*U 1966). kaempferol glycosides,
388 Annals of the
Garden
Missouri Botanical
cosides, apigenin and apigenin glycosides, quercit- they are involved in attraction of pollinators
in
rin, isoquercitrin, and saponarin, as well as the several taxa (e.g., Dalechampia).
anthocyanidins cyanidin, delphinidin, and pelar-
and The
Proteins peptides. seeds of several
gonidin are widespread within the Euphorbiaceae
members
of the Euphorbiaceae contain toxic pro-
many
and also are found in other plant families.
teins. For example, the castor bean, Ricinus com-
Although the distribution of these glycosides might
munis, contains antigenic proteins that agglutinate
be useful for study of problems at lower hierarchical
defibrinated blood and red blood As
cells in vitro.
levels, most flavonoids are not particularly useful
few as two to four seeds of this plant can be lethal,
for study of relationships at higher taxonomic lev-
and eight are almost always lethal (Kingsbury,
els.
964). Ricin a dimeric protein with two different
1 is
The presence of other, more unusual types of (MW
The
peptide chains 63,000). seeds of Aleu-
flavonoids has more promise in this regard. For
Jatropha curcas and
rites fordii, L., /. multifida
example, 8-methoxyflavonoids gossypetin
[e.g.,
L. also produce toxic proteins that have not been
(86)] are found in several taxa of the tribe Ricino-
studied extensively.
carpeae (subfamily Crotonoideae), including Be-
Among
Rubber. the Euphorbiaceae, latex
is
yeria brevifolia Baill., B. leschenaultii, Ricino-
found primarily in members of the subfamilies Cro-
carpos muricatus Mull. Arg., and R. stylosus Diels
tonoideae and Euphorbioideae but generally lack-
& is
(Rizk El-Missiry, 1986).
and
ing in the Phyllanthoideae, Oldfieldioideae,
Biflavonoids (e.g., heveaflavone (87)) are found
Acalyphoideae (Hegnauer, 1966b, 1989). Al-
number
in a of families, including the Pinaceae,
though complex mixture of diterpenes,
latex a
is
Anacardiaceae, Casuarinaceae, Clusiaceae, Och-
triterpenes, enzymes, amino acids, and other com-
naceae, Rhamnaceae, Caprifoliaceae, and Eu-
compounds are im-
ponents, polymeric isoprenoid
&
phorbiaceae (Geiger Quinn, 1982). These com-
Euphorbi-
portant most. Several plants of the
in
pounds are also found in certain mosses, cycads,
rubber).
aceae produce cts-polyisoprene (natural
all
and in Ginkgo biloba L.
Best known among these Hevea brasiliensis, but
is
Hydrocarbons and waxy Hevea
materials. Because produced by other
similar materials are
many
euphorbiaceous plants occur in deserts and species, Manihot glaziovii Miill. Arg. (ceara or
dry areas, they have thick cuticles and a relatively manicobe rubber), Micrandra species (Crotono-
amount waxy
large of material (Gnecco et al., ideae: Micrandreae: Micrandrinae) (caura rubber),
&
1989; Rizk El-Missiry, 1986). Most of the long and Cnidoscolus species (chilte rubber) (Rizk<
many
chain hydrocarbons, alcohols, aldehydes, acids, and 1987). Rubber has also been isolated from
wax
esters of the Euphorbiaceae are similar to those Euphorbia species (Rizk, 1987).
of other plant groups.
have been re-
Sesquiterpenes. Although several
wax
Candelilla of Euphorbia antisyphilitica compounds
ported from the family, this class of
Zucc, and waxes
the of E. cerifera Alcocer, Pedi- (Ramaiah et
does not seem to be well represented
lanthus cymbiferus
Schltdl. (syn. Pedilanthus
1979; Rizk, 1987).
al.,
aphyllus Boiss.), and Pedilanthus bracteatus
sesquiterpene,
complex type of
Picrotoxins, a
(Jacq.) Boiss. (syn. Pedilanthus pavonis Bois.)(Eu- (Menispermum,
Menispermaceae
are found in the
phorbioideae: Euphorbieae:
Euphorbiinae) are 0r-
Coriariaceae,
Anamirta, and Cocculus), the
commonly
used in cosmetics and as an extender Euphorbiaceae
chidaceae (Dendrobium), and the
wax
in other products (Rizk, 1987; Schery, 1972). Hyaenancheae)
(Hyaenanche,
Oldfieldioideae:
wax
Candelilla comprised of both hydrocarbon 1969)-
is
1981; Coscia,
[e.g., pretoxin (88)] (Cane,
and wax
fractions
esters. Hyaenanche g o-
known occur
Mellitoxin to in
is
Monoterpenes. Monoterpenes bosa Lamb. (Coscia, 1969).
are ubiquitous
among Few compounds in-
plants. of the structures are so char- Other compounds. A series of
acteristic as to be useful in a chemosystematic sense cluding crotepoxide (89) thought to be derive.^
is
fou"
with problems above the species level. Accumu- from iso-chorismic acid. This compound is
«g u
A of
lation of monoterpenes as a class is common in the in Croton macrostachys Hochst. series
^
a-homonojininycin
genus Croton, Croton setigera (Eremocarpus
se- cosidase inhibitors, including
n
diani
tigerus), and Joannesia princeps from Omphalea
Veil. (Crotono- (90), has been described
resem
compounds
ideae: Joannesieae) (Farnsworth 1969; Heg- These
et al., L. (Euphorbioideae). ^
an
Moraceae,
nauer, 966b, Few
1 1 989). other taxa in the family compounds found in legumes, the
u ^
accumulate significant quantities of these com- the Polygonaceae and have promise as anti
pounds 1988).
in vegetative portions of the plant, although and drugs (Kite et al.,
antidiabetic