Exudate flavonoids from aerial parts of Mirabilis viscosa (Nyctaginaceae)

BiochemicalSystemsticsand Ecology, Vol. 24,No.J/8. p.799.1996 Copyright0 1996 ElsevierScience Ltd Printedin Great Britain.Al rights reserved 0305-1978/96 $15.00+0.00

Pergamon PII: SO305-1978(96)00081-6

Exudate Flavonoids from Aerial Parts of Mirabihs viscosa (Nyctaginaceae) ECKHARD lnstitut fur Botanik der Technischen

Key Word

Index-Mirabilis

Subject

and Source

Hochschule,

viscosa; Nyctaginaceae;

WOLLENWEBER

Schnittspahnstrasse

and MARION

3, D-64287

Darmstadt,

D6RR Germany

leaf and stem exudate; flavonoid aglycones.

Aerial parts of Mirabilis viscosa Cav. were collected from plants cultivated in the Botanical Garden Darmstadt in August 1994. A voucher is kept in the herbarium of the Botanical Garden at Darmstadt.

Previous

at

Work

To our knowledge exudate flavonoids of Mirabilis have not been studied previously. Their presence in the genus has only been mentioned once before by Wollenweber (1996). Abronia lafifoha, another member of this family, had been the first Nyctaginaceae found to excrete flavonoid aglycones; it also was the first species ever found to excrete an isoflavonoid (Wollenweber et al., 1993).

Present

Study

Freshly collected aerial parts of M. viscosa were briefly rinsed with acetone to dissolve the lipophilic exudate material. Following the usual procedure (cf. Wollenweber et al., 1996). the concentrated solution was first passed over Sephadex LH-20, eluted with MeOH, to eliminate a small portion of terpenoid material. The non-polar flavonoid portion was then subjected to CC on polyamide, while a more polar flavonoid portion was passed over acetylated polyamide. Elution was with toluene and increasing quantities of MeCOEt and MeOH in both cases. Individual flavonoids were identified by direct TLC comparisons with markers on silica and on polyamide (cf. Wollenweber er al., 1993). some were confirmed by their spectral data. The following flavonoid aglycones have been identified unambiguously. (A) Flavones: apigenin and its 7-methyl, 4’-methyl and 7,4’-dimethyl ethers; scutellarein 6,7-dimethyl ether; luteolin and its Y-methyl and 7,3’-dimethyl ethers. (B) Flavonols: kaempferol, its 3-methyl, 7-methyl, 4’-methyl, 3,7-dimethyl, 3,4’dimethyl, 7,4’-dimethyl and 3,7,4’-trimethyl ethers; 6-hydroxykaempferol6,4’-dimethyl ether; quercetin-3methyl, 3’-methyl, 3,7-dimethyl, 3,3’-dimethyl, 7,3’-dimethyl, 3,7,3’-trimethyl, 7,3’,4’-trimethyl and 3,7,3’,4’-tetramethyl ethers; quercetagetin 3,6,3’-trimethyl ether. Among the cited flavonoids, kae 3-Me, kae 3,7-diMe, kae 3,4’-diMe, kae 3,7,4-triMe, qu 3,3’-diMe and qu 3,7,3’-triMe are the major exudate constituents; they were all obtained in crystalline form. The other flavonols as well as the cited flavones are minor constituents. We want to stress that the three 6-O-substituted products found, namely scut 6,7diMe, 6-OH-kae 6,4’-diMe, and queg 3,6,3’-triMe are trace constituents that could only be identified after isolation by preparative TLC. Following our previous report on the unexpected finding of an isoflavone in the exudate of Abronia lafifofia (Wollenweber et a/, 1993). the present study revealed the leaf and stem exudate of M. viscosa to be a rich source of flavonoid aglycones. It is hoped that further Nyctaginaceae will soon be studied for the presence of externally deposited flavonoids. Acknowledgements-The here.

authors wish to thank Mr H. Groh who cultivated the plant material analyzed

References Wollenweber. E. (1996) In Flavonoids and Eioflavonoids 7995. (Proc. IN. Biofl. Symp., Vienna, 1995) (Antus. S.. Gabor, M. and Vetschera, K., eds), pp. 21 l-220. Akademiai Kiadb, Budapest; Wollenweber, E.. Papendieck. S. and Schilling, G. (1993) Nat. Prod. fetters 3, 119; Wollenweber, E., Henrich, B., Mann, K. and Roitman, J. N. (1996) Z. Naturforsch. 51~. in press. (Received 3 JuQ 1996; accepted 22 Jo/y 1996) 799