Chemodiversity of Exudate in Seven Tribes of and ()§ Karin M.Valant-Vetscheraa and Eckhard Wollenweberb,*

a Department of Systematics and Evolution Ð Comparative and Ecological Phytochemistry, University of Vienna, Rennweg 14, A-1030 Wien, Austria b Institut für Botanik der TU Darmstadt, Schnittspahnstrasse 3, D-64287 Darmstadt, Germany. E-mail: [email protected] * Author for correspondence and reprint requests Z. Naturforsch. 62c, 155Ð163 (2007); received October 26/November 24, 2006 Members of several genera of Asteraceae, belonging to the tribes , Cardueae, Lactuceae (all subfamily Cichorioideae), and of , , and Helian- theae (all subfamily Asteroideae) have been analyzed for chemodiversity of their exudate profiles. The majority of structures found were and , sometimes with 6- and/or 8-substitution, and with a varying degree of oxidation and methylation. Flava- nones were observed in exudates of some genera, and, in some cases, also flavonol- and flavone glycosides were detected. This was mostly the case when exudates were poor both in yield and chemical complexity. Structurally diverse profiles are found particularly within Astereae and . The tribes in the subfamily Cichorioideae exhibited less complex flavonoid profiles. Current results are compared to literature data, and botanical information is included on the studied taxa. Key words: Asteraceae, Exudates, Flavonoids

Introduction comparison of accumulation trends in terms of The of Asteraceae is distributed world- substitution patterns is more indicative for che- wide and comprises 17 tribes, of which Mutisieae, modiversity than single compounds. Cardueae, Lactuceae, , , and Earlier, we have shown that some accumulation Arctoteae are grouped within subfamily Cichori- tendencies apparently exist in single tribes (Wol- oideae, whereas , Plucheae, , lenweber and Valant-Vetschera, 1996). In continu- , Astereae, Anthemidae, Senecioneae, ation of such studies (Wollenweber et al., 1989; Helenieae, Heliantheae and are mem- 1997a, b; 2005), belonging to various tribes bers of subfamily Asteroideae. The subfamily Bar- have been analyzed for the first time for exudate nadesioideae consists of a few genera only, and it flavonoids, and their accumulation trends are dis- is assumed to be basal in the Asteraceae (Bremer, cussed in relation to previously published data, 1994). Alignment of genera to the existing tribes both on exudate and on tissue flavonoids, and in or subtribes is sometimes difficult, and in several relation to available botanical information. cases, still heavily discussed. Much information on the phylogeny of the family is now coming from Material and Methods molecular systematic studies. Also chemical con- stituents are seen as valuable additional charac- Collection data ters, such as flavonoids at the generic level (e.g. Eriophyllum lanatum var. lanatum, : Belenovskaya, 1996) and even at the acraeus, robusta, glutino- family level (Emerenciano et al., 2001). However, sus, Hypochaeris maculata, Hypochaeris radicata, variation may be much larger than Hypochaeris uniflora, Iva xanthifolia, Sigesbeckia variation at the molecular genetic level. Therefore, flocculosa, lyallii, Xanthium strumarium, Xeranthemum foetidus, and elegans were § Part V in the series “Exudate Flavonoids in Miscella- cultivated in the Botanic Garden of the Technical neous Asteraceae”. For Part IV see Wollenweber et al. University Darmstadt (BG-TUD) and collected in (2005), for Part III see Wollenweber et al. (1997b). the flowering stage between October 1997 and Au-

0939Ð5075/2007/0300Ð0155 $ 06.00 ” 2007 Verlag der Zeitschrift für Naturforschung, Tübingen · http://www.znaturforsch.com · D 156 K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V gust 2004. Vouchers are deposited in the Herba- laciniatum: Seeds from Tucker Prairie rium of BG-TUD and in the Herbarium in the In- Natural Area, Callaway Co., Missouri (K. M. Va- stitute of Botany, University of Vienna (WU) and lant-Vetschera, August 1999, SCHN 5962, BG- partly in Herbaria of collectors (Missouri, MO). TUD) collections from natural habitats are listed Silphium terebinthinaceum: Missouri, 1.8 km S below. of State Highway 72 junction on State Highway sagittata: Bogus Canyon, North 21, just S of Arcadia town limits (G. Yatskievych Logan, Cache County, , USA (B. Bohm, and T. E. Smith, 99Ð152, 10. 09. 1999, MO). spring 2000, UBC). Further material of B. sagittata arvensis: Field-collected at Münster, was collected from four populations in British Co- near Darmstadt (H. Groh, July 1997, BG-TUD). lumbia, Canada (Ecological Reserve, Princeton; Anarchist Mountain, Ossyos; Okanogan Falls; Extraction and identification Marble Canyon area; UBC). Aerial parts were collected either in the field : Bogus Canyon, and thoroughly air-dried, or they were freshly col- North Logan, Cache County, Utah, USA (B. Bohm, spring 2000, UBC). lected in the Botanic Garden of TU Darmstadt. Gochnatia foliolosa: San Felipe, Precordillera (P. Both kinds of material were rinsed with acetone Lo´ pez, December 2001, CONC). very briefly, to avoid extraction of tissue constitu- Gochnatia glutinosa: , 10 km W of ents. The mostly resinous residues obtained after junction routes 9 and 52, ca. 20 km N of Volcan, evaporation of acetone were “defatted” by solu- 2450 m (Stuessy 12978, 20/02/93, WU). tion in a small volume of hot MeOH, cooling to Grindelia chiloensis: Argentina, 12 km W of Ð10 ∞C, and removal of precipitated material by junction routes 3 and 26, Patagonican Steppe, S of centrifugation. The supernatants were chromato- Comodoro, 220 m (Stuessy 12913, 15/02/93, WU). graphed on a Sephadex LH-20 column (Pharma- resinosa: cia), eluted with methanol, to separate flavonoids a) , Region IV, 22.6 km N Ovalle, on road to from the predominant terpenoids. At this point, La Serena, 400 m (Stuessy 12753, 18/01/93, WU). most flavonoids were readily and unambiguously b) Chile, Region IV, ca. 2 km S of junction identified by direct comparisons with markers. gravel roads toward Andacollo and Corral Que- In some cases, however, further workup of fla- mada, 610 m (Stuessy 12764: 19/01/93 (WU). vonoid fractions by column chromatography over berberidis: (D. W. Clark, silica, polyamide SC-6 or acetylated polyamide 1595, ASU). (Macherey-Nagel; elution with toluene and in- Hazardia ferrisiae: Arizona (D. W. Clark, 1606, creasing quantities of methylethyl ketone and ASU). methanol) was required. Several flavonoids were : Arizona (D. W. Clark, 1612, further purified by preparative TLC on silica. ASU). Comparative TLC of fractions and co-chromato- intybaceum: Summit station of graphy with markers were carried out on poly- mount Rubiei, near Lecco at Lake Como, Italy (E. amide (DC 11, Macherey-Nagel) with the solvents Wollenweber, September 1999, BG-TUD). (i) PE100Ð140/toluene/MeCOEt/MeOH 12:6:1:1 Lapsana communis: Field-collected at Münster, v/v/v/v, (ii) toluene/PE100Ð140/MeCOEt/MeOH near Darmstadt (H. Groh, June 2001, BG-TUD). 12:6:2:1 v/v/v/v, (iii) toluene/dioxane/MeOH scoparium: Chile, 9.6 km N of 8:1:1 v/v/v, and (iv) toluene/MeCOEt/MeOH Hurtado on winding gravel road to Uicuna, 12:5:3 v/v/v, and on silica with the solvents (v) 1750 m (Stuessy 1268, 19/01/93, WU). toluene/MeCOEt 9:1 v/v and (vi) toluene/diox- glutinosa: Tasmania (Rozefelds 1378, ane/HOAc 18:5:1 v/v/v. Chromatograms were 1999, HO). viewed under UV light (366 nm) before and after Olearia ramulosa: Tasmania (Rozefelds 1379, spraying with “Naturstoffreagenz A” (0.2% of di- 1999, HO). phenyl-boric acid 2-aminoethyl ester in MeOH). Proustia cuneifolia: San Felipe, Precordillera (P. Authentic samples of flavonoids were available in Lo´ pez, Dec. 2001, CONC). E. W.’s laboratory. Some flavonoids were further murinus: Chile, 6.9 km NE of junction characterized by their mass spectra. gravel roads toward Andacollo and Corral Que- mada (T. Stuessy 19/01/93, WU). K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V 157

Results trends are presented according to the tribal align- The analyzed species are grouped according to ment of genera (Bremer, 1994). It should be men- their sectional alignment (Bremer, 1994). Results tioned that aglycones reported in the literature as concern genera of Mutisieae, Cardueae, Lactuceae originating from leaf material most probably occur of subfamily Cichorioideae, and Astereae, Senecio- as exudate constituents. neae, Helenieae, and Heliantheae of subfamiliy As- teroideae. Their aglycone composition is listed in Flavonoid aglycones of Mutisieae species sequence of increasing complexity of substitution From this , species of the S-hemispheric patterns and in abbreviated form (see Table I). Gochnatia and Proustia have been analyzed. Hydroxylation is indicated as OH, methoxylation Gochnatia comprises 68 South American species, as OMe, and methyl groups are abbreviated as with 2 species occurring in Southeast . They Me. Compounds listed in brackets were present are mostly or trees. Five species are sum- only in minor amounts. The various accumulation marized in Proustia, occurring in South America

Table I. Flavonoid aglycones: Flavonoid structure Trivial name Abbreviated name structural information, trivial Ј names and abbreviations used in 5,7,4 -TriOH-flavone ap the text. Genkwanin ap-7-Me Acacetin ap-4Ј-Me 5,6,7,4Ј-TetraOH-flavone Scutellarein scut Pectolinarigenin scut-6,4Ј-diMe 5,7,3Ј,4Ј-TetraOH-flavone Luteolin lut Chrysoeriol lut-3Ј-Me Diosmetin lut-4Ј-Me Velutin lut-7,3Ј-diMe 5,6,7,3Ј,4Ј-PentaOH-flavone 6-OH-Luteolin 6-OH-lut Nepetin 6-OH-lut-6-Me 6-OH-lut-6,3Ј,4Ј-triMe 3,5,7,4Ј-TetraOH-flavone kae Isokaempferide kae-3-Me Rhamnocitrin kae-7-Me kae-3,7-diMe kae-3,4Ј-diMe 3,5,6,7,4Ј-PentaOH-flavone 6-OH-Kaempferol 6-OH-kae Penduletin 6-OH-kae-3,6,7-triMe 3,5,7,3Ј,4Ј-PentaOH-flavone qu qu-7-Me qu-3Ј-Me qu-7,3Ј-diMe qu-7,4Ј-diMe qu-3,7,3Ј-triMe qu-3,7,4Ј-triMe qu-3,7,3Ј,4Ј-tetraMe 3,5,6,7,3Ј,4Ј-HexaOH-flavone queg queg-6-Me queg-3,6-diMe Tomentin queg-3,7-diMe queg-6,3Ј-diMe Chrysosplenol-D queg-3,6,7-triMe queg-3,6,3Ј-triMe queg-3,6,4Ј-triMe queg-3,6,7,3Ј-tetraMe Bonanzin queg-3,6,3Ј,4Ј-tetraMe 3,5,7,8,3Ј,4Ј-HexaOH-flavone goss 5,7,4Ј-TriOH- nar Sakuranetin nar-7-Me Isosakuranetin nar-4Ј-Me 5,7,3Ј,4Ј-TetraOH-flavanone Eriodictyol eriod 158 K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V and being more or less spiny shrubs. Gochnatia is parison of exudate flavonoids. All of them are an- claimed to be a taxon crucial for understanding nual or perennial herbs. Hieracium comprises per- the evolution of the Mutisieae (Bremer, 1994). ennial herbs with circumpolar, but European- 1.) Gochnatia foliolosa D. Don ex Hook and centred distribution. Hypochaeris, by contrast, oc- Arn.: ap/-7-Me; kae-7-Me/-3,7-diMe; qu/-3-Me/-7- curs also in the Mediterranean and in South Me/-3,7-diMe/-3,3Ј-diMe/-7,3Ј-diMe/-3,7,4Ј-triMe America, and comprises some 60 species. Lapsana (; eriod). is much smaller, with 10 species being distributed 2.) Gochnatia glutinosa D. Don ex Hook and in Europe and temperate Asia, as well as in North- Arn.: kae-3-Me/-3,7-diMe/-3,4Ј-diMe/-7,4Ј-diMe/- west Africa. Finally, Sonchus with its 60 species 3,7,4Ј-triMe; qu/-3-Me/-7-Me/-3Ј-Me/-3,7-diMe/- has a world-wide distribution (Bremer, 1994). 3,3Ј-diMe; eriod/-7-Me. 1.) Hieracium intybaceum All.: nar-7-Me/-7,4Ј- 3.) Proustia cuneifolia D. Don.: ap-7-Me/-4Ј-Me; diMe; ap/-7-Me/-7,4Ј-diMe. Earlier, ap-4Ј-Me has kae-7-Me; qu-7,3Ј-diMe; nar-7-Me. Earlier, nar-7- been described as further exudate constituent Me, nar-4Ј-Me, ap-7,4Ј-diMe have been isolated from another accession (Wollenweber, 1984). This from another accession (Bittner et al., 1989). indicates that some variation exists in this alpine Exudate flavonoids have so far not been re- plant species. A similar composition of exudate ported for both genera. Earlier studies on G. foli- flavonoids was also reported from H. amplexicaule olosa var. fascicularis yielded kae-3,7-diMe, qu-3Ј- L. (Wollenweber et al., 1997a). Mainly flavonoid Me, qu-3,7-diMe and qu-3,3Ј-diMe (Faini et al., glycosides were reported from Hieracium spp. 1984). Ybarra et al. (1994) reported on the occur- (Svehlı´kova´ et al., 2002), and simple aglycones (ap, rence of ap-7-Me, nar-7-Me, eriod-7Me, kae-3,3Ј- lut, and one unidentified flavone aglycone) were diMe and kae-3,7-diMe in aerial parts of G. gluti- found in addition in some species from Montene- nosa. Both species are the only members of Goch- gro (Petrovic et al., 1999). natia sect. Pentophorus, sharing glandular lower 2.) Hypochaeris maculata L. yielded only apige- leaf surfaces as typical morphological feature, nin and luteolin. No flavonoid aglycones could be which distinguishes them from species of other detected in the leaf washes of H. radicata L. and sections (Freire et al., 2002). Leaf extracts of H. uniflora Vill. In a recent phylogenetic study Gochnatia polymorpha (Less.) Cabr. var. polymor- (Tremetsberger et al., 2005), H. radicata was found pha, which is placed in a different section (Freire to be in a separate clade from H. maculata, which et al., 2002), were earlier found to contain ap-7-Me claded together with H. uniflora. This relationship and 6OH-lut-6,4Ј-diMe (desmethoxycentaureidin; is apparently not reflected by exudate flavonoid Sacilotto et al., 1997). Activity-guided fractiona- data. Glycosides of isoetin characterize species of tion of aerial part extracts of Proustia pyrifolia Hypochaeris such as H. radicata and H. uniflora, DC. yielded quercetin and dihydroquercetin (Del- and are mentioned also for H. maculata (Gluchoff- porte et al., 2005). Fiasson et al., 1991). Free isoetin has so far not been found in exudates of these taxa. Ј Flavonoid aglycones of Cardueae species 3.) Lapsana communis L.: ap/-7-Me/-7,4 -diMe; lut/-3Ј-Me/-7,3Ј-diMe/-7,3Ј,4Ј-triMe; kae-3,7,4Ј-tri- The small Xeranthemum with its 5 mostly Me; qu-3,7,3Ј-triMe/-3,7,3Ј,4Ј-tetraMe; lut-glyco- annual species is distributed from South Europe to side, chlorogenic acid. Caffeic acid, chlorogenic Southwest Asia and North Africa (Bremer, 1994). acid and 3 further derivates were earlier described Exudate flavonoids were so far unknown from this from aerial parts (Fontanel et al., 1998). genus. Aerial parts of X. annuum were earlier 4.) The exudate of Sonchus arvensis L. con- found to accumulate luteolin and quercetin tained only lut and traces of qu-3Ј-Me. Flavonoid (Zemtsova and Molchanova, 1979). Xeranthemum aglycones (ap-4Ј-Me, kae, lut/-3Ј-Me, qu-3Ј-Me) foetidus analyzed now yielded only quercetin, api- have been reported from the ethyl acetate extract genin and scut-6-Me, along with traces of kaemp- of a Chinese accession (Qu et al., 1996). ferol. Flavonoid aglycones of Astereae species Flavonoid aglycones of Lactuceae species Species of Grindelia, Gutierrezia, Hazardia, Species of the genera Hieracium, Hypochaeris, Nardophyllum, and Olearia have been analyzed Lapsana and Sonchus were included in our com- from this large tribe. Grindelia species are known K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V 159 for their resinous nature. The 55 known species, Greene contained only ap-4-Me, qu/-3,3Ј-diMe being annual or perennial herbs, occur in North and kae-3,7-diMe (Hoffmann et al., 1984). Thus, and South America. A similar geographic distribu- flavonoid diversification could be of some system- tion characterizes the 27 herbal or shrubby species atic significance in this genus. of Gutierrezia. Hazardia comprises 13 shrubby 3.) Gutierrezia resinosa (Hook et Arn.) S. F. species of Southwest and North Blake: Two different accessions from Chile exhib- (Bremer, 1994). Tonestus is a segregate ited infraspecific differentiation as indicated be- from the South American genus Haplopappus, low: with 8 recognized species occurring in North Accession a: qu-3-Me/-3,7-diMe; queg-3,6,7- America (Nesom and Morgan, 1990), whereas triMe; goss-3,8-diMe/-3,7,8-triMe; 5,3Ј,4Ј-triOH- Haplopappus s. str. is a South American genus 3,6,7,8-tetraOMe-flavone; 5,4Ј-diOH-3,6,7,8,3Ј- consisting of 70 species (Bremer, 1994). Nardo- pentaOMe. phyllum is a rather small genus of 10 South Ameri- Accession b: qu-3-Me; queg-3,6-diMe/-3,7-diMe; can species, being shrubs, sometimes spiny (Ne- goss-3,7,8-tri-OMe; 5,3Ј,4Ј-triOH-3,6,7,8-tetraO- som, 1993). Olearia contains some 130 species, Me; 5,4Ј-diOH-3,6,7,8,3Ј-pentaOMe-flavone. shrubs and trees, with a distribution centred in Earlier, literature data revealed the presence of Australia and New Zealand (Bremer, 1994). This 5,3Ј,4Ј-triOH-3,6,7,8-tetraOMe and of 5,4Ј-diOH- genus apparently is of polyphyletic origin, accord- 3,6,7,8,3Ј-pentaOMe (Bittner et al., 1983; Hoen- ing to molecular systematic studies (Cross et al., eisen and Silva, 1986). Exudate flavonoids have 2002). been reported from G. sarothrae (Pursh) Britt. 1.) Grindelia chiloensis (Cornell.) Cabr. yielded (Hradetzky et al., 1987); in the same paper, the only kae-3-Me and kae-3,4Ј-diMe. The presence of occurrence of flavonoid aglycones in extracts of kae-3-Me is in accordance with earlier reports on G. grandis and of G. is commented. flavonoids from aerial parts (Ruiz et al., 1981). Similar substitution trends have been observed in This shrubby species contains large amounts of all species studied so far, as is also evident from resins, and it is currently under investigation as a results on G. wrightii (Fang et al., 1986). possible resin crop (Wassner and Ravetta, 2005). 4.) Haplopappus glutinosus Cass. ex DC.: ap; The majority of resin components are of terpenoid scut-6-Me/-6,4Ј-diMe; (kae-3-Me/-3,4Ј-diMe); 6- nature, with some unidentified flavonoids men- OH-kae-3,6-diMe/-3,6,4Ј-triMe; queg-3,6,3Ј-triMe. tioned (Zavala and Ravetta, 2002). In contrast to other Haplopappus spp. (Valant- 2.) Grindelia robusta Nutt.: Previous studies on Vetschera and Wollenweber, 2004), there is a cultivated material showed the presence of kae- strong tendency towards formation of 6-methoxy- 3-Me/-3,4Ј-diMe; 6-OH-kae-3,6-diMe/-3,6,7-triMe; lated flavones and flavonols. So far, only flavonoid qu-3,3Ј-diMe/-3,7,3Ј-triMe/-3,3Ј,4Ј-triMe; queg-3,6, glycosides have been reported from this taxon 4Ј-triMe/-3,6,7,3Ј-tetraMe (Timmermann et al., (Marambio and Silva, 1996). A relatively poor 1994). A new accession from cultivation in the Bo- profile (kae-3-Me; qu-3-Me/-3,3Ј-diMe; eriod-7- tanic Garden (BG-TUD) yielded a somewhat dif- Me) characterizes H. pectinatus Phil., a species ferent profile, consisting of kae-3,7-diMe/-3,4Ј- that is postulated to hybridize with Grindelia chi- diMe/-3,7,4Ј-triMe; 6-OH-kae-3,6,7-triMe/-3,6,4Ј- loensis (Bartoli and Tortosa, 1998), with a similarly triMe; qu-3,4Ј-diMe/-3,7,3Ј-triMe/-3,7,4Ј-triMe/ incomplex flavonoid aglycone profile. It would be -3,7,3Ј,4-tetraMe. Similar trends have been ob- interesting to check further possible hybrids for served for Grindelia glutinosa (Cav.) Dunal., yield- their exudate flavonoid composition. ing complex 6-OMe derivatives of kaempferol as 5.) Hazardia berberidis Greene: (kae-3,7- exudate constituents (Timmermann et al., 1994). It diMe)/-3,4Ј-diMe/-7,4Ј-diMe/-3,7,4ЈtriMe; qu/-3- appears that both species are closely related, as Me/-7-Me/-3Ј-Me/-3,7-diMe/-3,3Ј-diMe/-3,4Ј-diMe/- some authors assign only subspecies status to them 7,3Ј-diMe/-3,7,4Ј-triMe/-3,3Ј,4Ј-triMe/-7,3Ј,4Ј-tri- (Timmermann et al., 1994). Further species studied Me/-3,7,3Ј,4Ј-tetraMe. for exudate flavonoids include G. tenella and G. 6.) Hazardia ferrisiae (S. F. Blake) W. D. Clark: squarrosa (Wollenweber et al., 1989) and G. nana kae-3-Me/-7-Me/-3,4Ј-diMe. var. integrifolia Nutt. (Wollenweber et al., 1997b). 7.) Hazardia orcuttii Greene: kae-3-Me/-3,7- No 6-substituted flavonoids were found in the exu- diMe; qu/-3-Me/-3,3Ј-diMe; goss-3,8-diMe. In dates of G. tenella; similarly, resin of G. camporum these Hazardia species, flavonols are the dominat- 160 K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V ing exudate compounds, with only one species ac- of well differentiated growth forms. The genus Eu- cumulating 8-substituted flavonols, whereas 6-sub- ryops comprises some 97 species, mostly shrubs or stituted flavones and flavonols, along with subshrubs, with occurrence in South, tropical- and eriodictyol derivatives, were found in exudates of Northeast Africa, Arabia (Bremer, 1994). H. squarrosa Greene var. grindelioides (DC.) 1.) Senecio murinus Phil., a Chilean species, con- W. D. Clark (Clark and Wollenweber, 1985). tained kae-3-Me/-3,7-diMe/-3,7,4Ј-triMe; qu-3,7- Taken all species analyzed so far together, the re- diMe in its exudate. The exudate of S. viscosa L. sulting accumulation trends are quite complex contained some simple flavone and flavonol and diversified. methyl ethers (Wollenweber et al., 1997a), corre- 8.) Nardophyllum scoparium Phil.: qu-3-Me; sponding in substitution patterns to the new re- queg-3,6-diMe/-3,6,7-triMe/-3,6,4Ј-triMe; (5,7,3Ј,4Ј- sults. It is a pity that only so few species could so tetraOH-3,6,8-triOMe-flavone;) 5,7,3Ј-triOH-3,6, far be analyzed for exudate compounds. 8,4Ј-tetraOMe-flavone. This appears to be the first 2.) Euryops acraeus M. D. Hend. exhibited a report on flavonoids compounds in this genus, poor profile, consisting of kae and qu-3Ј-Me only. which so far has only been studied for diterpenes Altogether, Senecioneae are apparently not very (e.g. Zdero et al., 1990). Controversies as to the productive in terms of exudate flavonoids, and taxonomic position have been successfully re- structures appear to be quite simple in terms of solved (Nesom, 1993). substitution patterns. 9.) Benth: ap; kae-3-Me/-3,4Ј- diMe; qu-3-Me/-7-Me/-3Ј-Me/-7,4Ј-diMe/-3,4Ј-di- Me/-3,7,3Ј-triMe/-3,7,3Ј,4Ј-tetraMe; eriod-7-Me Flavonoid aglycones of Helenieae species (/-7,3Ј-diMe). Only one species of Eriophyllum was studied 10.) Olearia ramulosa Benth.: ap/-7-Me; lut/-7- from this tribe. Species of this genus are either Me/-3Ј-Me/-4Ј-Me/-7,3Ј-diMe; kae; qu/-3Ј-Me. The subshrubs or herbs, and 11 species are distributed profiles of both species are quite different: flava- in the West USA, Northeast Mexico and South- nones occur additionally in exudates of O. glandu- west Canada (Bremer, 1994). Eriophyllum lana- losa, while flavones predominate in those of O. ra- tum (Pursh.) Forbes yielded several exudate fla- mulosa. In a recent phylogenetic study, both vonoids: ap; scut-6,4Ј-diMe; lut; 6-OH-lut-6-Me/ Olearia species were placed in different clades -6,3Ј,4Ј-triMe; queg-3,6,3Ј,4Ј-tetraMe. Earlier, queg- (Cross et al., 2002), and it would be interesting to 6-Me/-3,6-diMe/-6,3Ј-diMe/-3,6,4Ј-triMe were iso- test more species of those clades for eventual exu- lated from E. confertifolium (DC.) A. Gray, while date flavonoid diversification. Leaf extracts of E. staechadifolium Lag. yielded qu/-3-Me/-3Ј-Me/ Olearia muelleri (Sonder) Benth., coming in the -3,3Ј-diMe; queg-3,6-diMe/-3,6,3Ј-triMe (Wollen- same clade as O. ramulosa (Cross et al., 2002), con- weber et al., 1997b). Apart from these results, no tained queg-3,6,4Ј-triMe and queg-3,6-diMe (Jef- further flavonoid data are available on this genus. feries et al., 1974), while those of O. paniculata (J. R. and G. Forst) Druce of the second clade con- tained the flavone scut-6,4Ј-diMe (Chivers et al., Flavonoid aglycones of Heliantheae species 1966). It is assumed that these compounds are also Species of Iva, Sigesbeckia, Silphium, Xanthium, exudate constituents, and accumulation trends Zinnia and Balsamorhiza were studied here. Iva may prove to be group-specific. consists of 15 North American species, being herbs 11.) (A. Gray) A. Nelson: (ap)/ Ј Ј or shrubs. Sigesbeckia is a small taxon with 3 an- -7-Me/-7,4 -diMe; lut/-3 -Me/-7-Me; 6-OH-lut-6- nual species from tropical Africa and Asia. Sil- Me/-6,4Ј-diMe/-6,7,3Ј-triMe; kae/-7-Me; qu/-3Ј- Ј phium comprises 23 species (perennial herbs) dis- Me/-7,3 -diMe. This aglycone profile corresponds tributed in the United States. Xanthium with its 3 to trends observed in this tribe, and it is not spe- sometimes spiny species is widespread in warm cific enough to separate this species clearly from parts of the world. The 22 species of Zinnia grow those of Haplopappus. in the South of , Mexico, Central and South America as shrubs or herbs, and Bal- Flavonoid aglycones of Senecioneae species samorhiza consists of 14 species, occurring in the Senecio is quite a large genus of about 1250 spe- West of North America and Mexico as perennial cies of world-wide distribution, and with a range herbs (Bremer, 1994). K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V 161

1.) Iva xanthifolia Nutt.: 5,7,4Ј-OH-6,8-OMe- tions (Bohm and Choy, 1987; Bohm et al., 1989), flavone (desmethoxysudachitin); 5,4Ј-OH-6,7,8- except for the report on qu-4Ј-Me (Robson and OMe-flavone (xanthomicrol); 5,7-OH-6,8,4Ј-OMe- McCormick, 1988), which was not found now in flavone (nevadensin). The generic concept of Iva the exudates. Also, 6-OH-kae-7-Me and queg-7- has been recently revised, and it was suggested to Me reported from B. deltoidea could not be found treat I. xanthifolia in the segregate genus Cycla- in any of the samples studied now. In terms of ac- chaena (Miao et al., 1995). cumulation trends, Balsamorhiza differs from the 2.) Sigesbeckia flocculosa L’Her.: qu/-3-Me/-3,7- closely related Silphium (Clevinger and Panero, diMe/-3,7,4Ј-triMe; (eriod;) qu-3-glucoside; chlo- 2000) by a more complex exudate profile. rogenic acid. This Peruvian species differs from The 7-methyl ethers of 6-OH-kae and of queg S. jorullensis Kunth, of which que-8-Me was earlier were reported earlier as flavonoid aglycones from described, and from S. orientalis, which had B. deltoidea (Bohm and Coy, 1987). Referring to yielded qu-5-Me (Wollenweber et al., 1989). Siges- this paper, 6-OH-kae-7-Me was later reported as beckia jorullensis was analyzed lately regarding “a single major flavonoid from leaf exudate of B. the morphology of glandular hairs and their essen- sagittata” (Bohm et al., 1989). However, synthesis tial oil production (Heinrich et al., 2002), but fla- revealed that both structures were not correct vonoids have not been specified in this publica- (Tominaga and Horie, 1993). As a matter of fact, tion. our thorough search for these two flavonols in all 3.) Xanthium strumarium L.: 6-OH-kae-6-Me/- our samples of B. sagittata (as well as in samples 3,6-diMe; queg-3,6-diMe/-3,6,3Ј-triMe. Earlier, only of B. deltoidea), using snythetic markers, proved small amounts of exudate were obtained from an- their absence. other accession, yielding 6-OH-kae-6-Me and queg-3,6-diMe (Wollenweber et al., 1997a). 4.) Zinnia elegans Jacq.: ap/-7-Me/-4Ј-Me/-7,4Ј- Chemodiversity at the tribal level diMe; lut/-7-Me. Earlier, Z. acerosa (DC.) A. Gray In terms of accumulation tendencies, it appears was found to accumulate a series of 8-OMe fla- that the tribes of the Cichorioideae have a less vone derivatives in its exudate (Wollenweber et complex aglycone composition, as far as oxygena- al., 1997b). tion patterns are concerned. Trends in the Muti- 5.) Silphium laciniatum L.: (kae; qu-3-Me/-3Ј- sieae include formation of mainly flavonol methyl Me;) 6-OH-kae-6-Me/-3,6-diMe; querecetagetin-6- ethers except for those with 6- or 8-methoxylation. Me/-3,6-diMe/-6,3Ј-diMe/-3,6,3Ј-triMe; kae-3-glu- Flavones are not so common, but have coside; qu-3-glucoside; and eriod-3Ј-Me-6-C5. been found occasionally. Trends in Cardueae as 6.) Silphium terebinthinaceum Jacq. yielded kae- based upon a single genus only indicate a relative 3-glucoside; qu-3-rhamnoside; qu-3-glucoside and poorness in terms of chemical diversity. Earlier, 6- qu-3-rhamnoglucoside from the leaf washes. This substituted flavones and flavonols had been found species thus affords an example of lack of agly- in Centaurea exudates, but Cirsium yielded only cones in the exudate, which is quite uncommon relatively simple flavones and flavonols (Wollen- among the Asteraceae. Limited literature exists on weber and Valant-Vetschera, 1996). Lactuceae flavonoids of this genus, mentioning mainly the oc- trends are almost identical to the Mutisieae trends. currence of flavonol glycosides in extracts (e.g. El- Genera of the Lactuceae appear to accumulate Sayed et al., 2002). rarely exudate flavonoids. In the positive cases, 7.) (Pursh.) Nutt.: Minor mostly rather simple flavone or flavonol deriva- infraspecific variability was noted between several tives were found so far. Similar results have been accessions studied. Major compounds in all acces- obtained with new species and accessions studied sions were queg-6-Me and 6-OH-kae-6-Me, ac- now. Hieracium is remarkable as it also yielded companied by queg-6,3Ј-diMe and 6-OH-kae-6,4Ј- flavanones. The poorest profile was observed in diMe and qu. Variation was noted for queg-3,6,3Ј- Sonchus arvensis. Despite the low yield, structures triMe as well as kae and kae-4Ј-Me. are sometimes quite diversified. These data are 8.) Balsamorhiza macrophylla Nutt. yielded qu; well in accordance with earlier observations on qu-3-Me; qu-3Ј-Me; (qu-3,3Ј-diMe;) qu-3,3Ј,4Ј- flavonoid aglycone diversification in genera of the triMe; queg-3,6,3Ј,4Ј-tetraMe. The accumulation Cichorioideae (Wollenweber and Valant-Vet- trends of both taxa are in line with earlier publica- schera, 1996). 162 K. M. Valant-Vetschera and E. Wollenweber · Exudate Flavonoids of Asteraceae V

Astereae and Heliantheae exhibit the largest de- group very little data are available, and that espe- gree of complexity. Within Astereae, quercetagetin cially the large genus Senecio would need more and/or gossypetin methyl ethers have been fre- investigations. Correlation of exudate flavonoid quently found in the exudates of some species of accumulation to the existence of glandular struc- Grindelia, Gutierrezia, Hazardia and Nardophyl- tures, which excrete compounds on the leaf surfa- lum. Especially some Astereae are known for their ces, and the preferences for xeric or alpine habitats high resin content (e.g. Grindelia). Both tribes is again confirmed, as had been indicated earlier were earlier observed to have quite some diversity (e.g. Wollenweber and Valant-Vetschera, 1996). in their oxygenation patterns (Wollenweber and Acknowledgements Valant-Vetschera, 1996). The presence of flavonol glycosides in leaf washes of some Heliantheae is Thanks are due to Bruce Bohm, Vancouver (Ca- remarkable. The Helenieae come close to the Heli- nada), Dennis Clark, Tempe, AZ (USA), H. Groh, antheae in the complexity of their exudates as had Münster (Germany), P. Lo´ pez, Concepcion been exemplified earlier (Wollenweber and Val- (Chile), Andrew Rozefelds, Hobart (Tasmania), ant-Vetschera, 1996). Tod Stuessy, Vienna (Austria) and George Yatski- At present, it looks as if the tribes of the Aste- evych, St. Louis, MO (USA) as well as to staff members of the Botanical Garden at Darmstadt roideae are much more complex in their exudate for plant material. E. W. is also grateful to T. flavonoid chemistry as compared to the Cichori- Horie, Tokushima (Japan) for a gift of synthetic 6- oideae. This is also true for genera of other tribes OH-kae-7-Me and queg-7-Me and to J. N. Roit- that had been studied before (Valant-Vetschera man, Albany, CA (USA) for structural identifica- and Wollenweber, 2004; Wollenweber et al., 1997a, tion of the 6-C-prenyl derivative of eriodictyol-3- b, 2005). The only exception is represented by the methyl ether. The skilful technical assistance of Senecioneae, which showed little complexity in the Marion Doerr, Darmstadt (Germany) is also exudates. It has to be mentioned that from this gratefully acknowledged.

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