Flavonoides en Eucryphia

Después de la nota sobre la ultima patente de Gloria Montenegro y su equipo de la PUC, me dio por mirar más sobre flavonoides y Ulmo, caía en un lindo paper del 2000, "Variation in flavonoid exudates in Eucryphia species from Australia and South America" E. Wollenweber et al. / Biochemical Systematics and Ecology 28 (2000) 111 - 118.

Bien cagónes los latinos ... mejor aplicar la patente de Gloria en las mieles de Downunder!

Abstract

Leaf and bud exudate #avonoids were analysed for all Eucryphia species, and 28 compounds

were identi"ed. Cladistic analyses of phytochemical data indicate that the two Tasmanian

species, E. lucida and E. milliganii are sister taxa, which is consistent with morphological

studies. Cluster analysis and ordination would suggest that the species E. wilkiei from north

eastern Queensland is relatively isolated from other Australian and South American

taxa. ( 2000 Elsevier Science Ltd. All rights reserved.

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The family placement of Eucryphia is uncertain. Cronquist (1981) placed it in its

own family, Eucryphiaceae, based on a number of floral characters including the 4}14

(18), multi-ovulate, carpels and large solitary flowers, with prominent petals. Several

morphological characters e.g. interpetiolar stipules and pollen, however strongly

support its inclusion in Cunoniaceae (Hu!ord and Dickison, 1992; Hideux and

Ferguson, 1976). Phytochemical characters (Jay, 1968; Bate-Smith et al., 1977) have

also been interpreted by Hu!ord and Dickison (1992) as supporting its inclusion in

Cunoniaceae.

A correlation between tissue flavonoid chemistry and plant geography among

Eucryphia species was recognised by Bate-Smith et al. (1967). The authors studied the

five species E. cordifolia, E. glutinosa, E. lucida, E. milliganii and E. moorei, as neither

E. jinksii or E. wilkiei were known at that time. They reported seven flavonol

glycosides and one dihydroflavonol glycoside, along with two flavanol methyl ethers

that were found as aglycones from these five species.

In this study the flavonoids in leaf and bud exudates were recovered from all

Eucryphia species. The two Tasmanian species, E. lucida and E. milliganii, exhibit

conspicuous sticky exudates which cover the young buds (Forster and Hyland, 1997).

Eucryphia glutinosa is named after the sticky exudate that occurs on young foliage

and buds. These exudates are probably derived from colleters, that are present in all

species, and occur on the inner surface of the stipules that protect the developing buds

(Dickison, 1978; Rutishauser and Dickison, 1989).

3. Results and discussion

Twenty-eight flavonoids were identified from the seven Eucryphia species (Table 1).

The South American species E. glutinosa exhibits two flavones, apigenin-7, 4@-

dimethyl ether and luteolin-7,3@-dimethyl ether, which it shares with two Australian

and one Tasmanian species. The other South American species, E. cordifolia, contains

only apigenin-7,4@-dimethyl ether as a trace constituent. Both South American species

lack 3-hydroxylation, i.e. flavonols are missing. The two Tasmanian species, E. lucida

and E. milliganii, with their conspicuous bud exudates, are rich in flavone and flavonol

methyl ethers. These two species share 8 flavonoids (apigenin-7-methyl ether,

luteolin-7,3@,4@-trimethyl ether, kaempferol-3-methyl ether, kaempferol-3,7,4@-

trimethyl ether, quercetin-3-methyl ether, quercetin-3,7,4@-trimethyl ether, quercetin-

3,3@,4@-trimethyl ether and quercetin-3,7,3@,4@-tetramethyl ether) which are not

recorded from any other taxon. Four flavonoids (luteolin-3@-methyl ether, kaempferol-

3,7-dimethyl ether, kaempferol-3,4@dimethyl ether and quercetin-3-methyl ether)

are only produced by Eucryphia lucida, two others (luteolin-7,4@-dimethyl ether,

quercetin-3,4@-dimethyl ether) are only produced by E. milliganii. The southern

Australian mainland species (E. jinksii and E. moorei) also have a diverse range

of flavonoids. Four flavonoids, i.e. isoscutellarein-8,4@-dimethyl ether isoscutellarein-

7,8,4@-trimethyl ether, kaempferol-4@-Methyl ether, and quercetin-3,7,4@-trimethyl

ether, were identified from E. jinksii only. We want to stress that E. jinksii is the

only species capable of hydroxylating the 8-position. Another flavone, 6-OH-luteolin-

6,7-dimethyl ether, was also found to be present in only one species, E. moorei.

The S. Australian and the Tasmanian species are able to methylate the same hydroxyls.

E. wilkiei from north eastern Queensland is the only species where flavonoid

glycosides have been found as exudate constituents. Further, Eucryphia wilkiei,

E. jinksii and E. lucida. share a flavonoid aglycone whose identity remains to be established.