Dl'STRIBUTION OF SPECIAL CLASSES OF COMPOUNDS IN THE F AMIL Y COMPO SIT AE*

William G. Padolina "' ...

An excellent review of the chemotaxonomy of the Family Compositae (=Asteraceae) was made by Herout (1970). In that review, it was noted that the Compositae are a phylogenetically relatively recently-evolved family and rich in compounds of secondary metabolism.

While many secondary metabolites abound in Compositae - volatile oils, flavonoids , alkaloids, phenolic acids, other terpenoids, and polyacetylenic com­pounds - it has been felt that the distribution of a special group of terpenoids, the sesquiterpene lactones, and the polyacetylenes provide an interesting picture of the relationships of the tribes within the family.

Sesquiterpene Lactones

Sesquiterpene lactones are highly oxidized sesquiterpenes characterized by the presence of the 'Y-Iactone. The lactone moiety is believed to have been derived from the isopropyl groups of the original famesene-type precursor. Besides the presence of this lactone, which has introduced at least two oxygen-atoms to the carbon skeleton, various other oxygenated functionalities have been found in the sesquiterpene skeletal system. Hydroxyl groups, esters, epoxides, transannular ethers, and even another lactone group are present in many sesquiterpene lactones.

While these compounds have been found mainly in Compositae, other plant families like Umbelliferae and Magnoliaceae have also indicated the presence of sesquiterpene lactones (Herout, 1970). Herz (1970) notes that while these com­pounds are not unique to Compositae, they appear to be characteristic secondary metabolites of the family or certain subgroups thereof.

A schematic representation of the proposed biogenetic scheme for sesqui­terpene lac tones is given in Fig. 1. The scheme represents the relationships of the basic types of carbon skeletons of the lactones. The detailed biogenetic path­ways for these are, no doubt, under enzymic control but published reports in this regard are very scanty.

*Discussion paper on Chemical Plant Taxonomy . .. Associate ProfessoI of Chemistry, Institute of Chemistry, University of the Philippines

Los Banos, College, Laguna, Philippines.

29

30 State-of-the-Art Papers

I ~ I .. ;

--------- ---1---- -------

~

i 0

~H -------/-~~-\--------- - - - - - - --

r=P / 0

--- -------/-~l- -------------!-----

mE > ~ 3 ~ ~ . ; ! & i [ a / d : n

o n-

O _0 1

____ 0 __ _ 0 - ----L-~-i---- - ----- ----- -----o-n 7--- /'

o

Fig. 1. Schematic representation of the biogenesis of different classes of sesquiterpene Jactones.

Chemical Plant Taxonomy 31

The distribution of sesquiterpene lactones in the individual tribes of Com­positae is given in Table 1 as summarized by Herout (1970). The distribution of sesquiterpene lac tones by species is also presented by Yoshioka et al. (1973).

Generally, the sesquiterpene lactones in Compositae are derived from a bio­genetic series which are typical of the tribes. The simplest lactone is the mono­cyclic germacrane skeleton and the more elaborate skeletal systems are derived from the germacranes.

Some of the tribes are characterized by very specialized skeletal systems. In the tribe Vernonieae, the germacranolides predominate. In tht< case of the tribe Cynareae (Cardueae) most of the species studied do not show the presence of germacranolides, but in several genera, guianolides are produced but no santa­nolides are observed. Anthemideae produce germacranolides but no pseudo­guaianolides have been found. This kind of analysis could be extended to other tribes in Compositae (Her out, 1970; Yoshioka et al., 1973). Suffice it to say that on the basis of a similar evaluation of the tribes of Compositae, the Senecioneae remains separated for it is the only tribe containing the eremophilanolide lactones. Herout (1970) presented a scheme of evolutionary relationships of the tribe of Compositae based upon the biogenetic relationship of sesquiterpene lactones in correlation with the botanical characters.

Polyacetylenes

Polyacetylenes are compounds which contain the carbon-carbon triple bond in an unbranched aliphatic moiety attached to a great variety of functional groups. A few examples are given below:

CH 3 CH = C - C '" C - CH =

Matricaria lactone

CH 3-C '" C - C '" C - C '" C - CH = CH - COOH

Oehydromatricaria acid

Polyacetylenes have been found in fungi and a number of higher plants. Biogenesis of polyacetylenes proceeds in most cases via oleic acid and other

polyunsaturated acids (Luckner, 1972). The double bonds are converted by de­hydrogenation to triple bonds and the chains may be shortened by conversion to vinyl compounds or by a or ~ -oxidation. Other functional groups like the forma­tion of phenyl rings, thioethers and furan derivatives have also been observed with polyacetylenes (Luckner, 1972).

The regularities in structural variation which characterize polyacetylenes and the considerable number of such compounds reported in Compositae make the

32 State-of-the-Art Papers

use of these compounds as phylogenetic markers appropriate (Gottlieb, 1982). The distribution of polyacetylenes in the different tribes is given in Table 2.

From the distribution of these compounds, Gottlieb (1982) suggests that a low relative oxidation and the C18 chain are indicative of primitive traits. There is a gradation of more highly oxidized and shorter chains for the more advanced families. Using this as a basis, Gottlieb (1982) further notes that the polyacetylene qistribution data supPort the suggestion by other systematists that the Senecioneae, Cynareae, and Heliantheae are the primitive tribes. In the case of the other tribes, the trends are not that clear yet but tentative clusters may be made.

References

Gottlieb, O. 1982. Micromolecular Evolution Systematics and Ecology. Berlin: Springer-Verlag. Herout, V. 1970. Chemotaxonomy of the family Composi:ae. In Pharmacognosy and Phyto­

chemistry, H. Wagner and L. Horhammer eds. Berlin: Springer-Verlag. Herz, W. 1970. Sesquiterpene lactones in Compositite. In Pharmacognosy and Phytochemistry,

H. Wagner and L. Horhlimmer eds. Berlin : Springer-Verlag. Luckner, M. 1972. Secondary metabolism in plants ·and animals. New York: Academic Press. Yoshioka, H., T.! . Mabry, and B.N. Timmerman. 1973. Sesquiterpene Lactones. Tokyo: Uni­

versity of Tokyo Press.

Table I , The frequency of occurrence of sesquiterpene lactones (Herout, 1970)

Number of Number of lac tones of different types per tribe Tribe plant species

investigaged GEx EL SA ER BA GU XA AM

Vernonieae 5 4 3 EupatoIieae 5 6 7 (Astereae) Inuleae 11 I 12 9 3 Heliantheae 56 2 3 5 1 10 (Heleniinae) 7 6 9 52 Ambrosieae 38 10 10 7 9 26 Anthemideae 57 13 35 19 Senecioneae 16 34 6 7 (Calenduleae) Cardueac 26 11 9 (Arctoteae) (Mutisieae) Cichorieae 9 3

x GE = Germacranolides, EL = Elemanolides, SA = Santanolides, ER = Eremophilanolides, BA = Bakkenolides, GU XA = Xanthanolides, AM = Ambrosanolides (= Pseudoguaianolides), PS = Psilostachyianolides. and VE = Vermeeranolides

PS VE

1

7 4

Guaianolides,

('") ::r '" 3 5 ' e?. "tI Ii> ;:? >-l ~ 0 ::;I 0 3 '<

w w

Table 2. Distribution of poly acetylenes in Compo sitae (Gottlieb, 1982) w -1>0

Tribe Cs C9 ClO Cll C12 Cj3 CJ4 C15 CI6 Cn CIS Total

9 1 1 11 Cynareae 2 14 6 18 74 45 23 19 27 9 237 Senecioneae 5 7 11 8 7 1 13 4 58 Muticeae 5 6 1 1 13 Astereae 2 56 3 4 1 3 1 5 22 98 Anthemideae 6 37 18 35 50 57 7 6 22 6 244 Helianthcae 3 4 4 28 118 19 9 8 25 218 Calenduleae 1 4 1 6 til ....

1 7 I>l

Eupatoricae 1 10 .... (1)

Inuleae 4 7 27 6 44 6 ';'>

Vernonicae 7 7 .... ::r Arctoteac 7 24 25 20 76

(1)

> ::! ." I>l '"0 (1) ... '"