*Corresponding author. Tel.:#44-1224-262547; fax:#44-1224-262555.
E-mail address:[email protected] (S.D. Sarker).
Biochemical Systematics and Ecology 29 (2001) 105}107
6-Oxygenated
#
avones from
Baccharis triner
v
is
(Asteraceae)
Hazel Sharp
!
, Barbara Bartholomew
!
, Colin Bright
!
, Zahid Latif
!
,
Satyajit D. Sarker"
,
*
, Robert J. Nash#
!Molecular Nature Limited, IGER, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK
"Pharmaceutical Sciences Section, School of Pharmacy, The Robert Gordon University, Schoolhill,
Aberdeen AB10 1FR, UK
#Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK
Received 9 December 1999; accepted 14 February 2000
Keywords: Baccharis trinervis; Asteraceae; 5,7-Dihydroxy-6,4@-dimethoxy#avone; 5-Hydroxy-6,7,4@ -trimethoxy#avone; 5,4@-Dihydroxy-3,6,7-trimethoxy#avone; Chemotaxonomy
1. Subject and source
Baccharis trinervis(Lam.) Pers. (Family: Asteraceae alt. Compositae), used in South
American folk medicine as an antiseptic, digestive and to treat snake-bites (Duke, 1999), is widely distributed from Mexico to Argentina (USDA-ARS-GRIN database, 1999). Plant material was collected from Costa Rica and supplied by Biotics Limited, University of Sussex, Brighton, UK. A voucher specimen (MNL10118) has been maintained at the herbarium of the Institute of Grassland and Environmental Re-search (IGER), Aberystwyth, UK.
2. Previous work
Previous phytochemical studies onB. trinervisestablished the presence of#avones
(Herrera et al., 1996; Arriaga-Giner et al., 1982) and neoclerodane type diterpenes
(Kuroyanagi et al., 1993; Jakupovic et al., 1986). Antiviral activity (Abad et al., 1999), anti-in#ammatory and antioxidant properties (de las Heras et al., 1998) of this plant have also been reported.
3. Present study
The CH2Cl2 extract of branches of B. trinervis (0.78 kg) was fractionated by
BiotageTM75#ash chromatography on silica gel using a step gradient of increasing polarity: n-hexane}EtOAc}MeOH with nine fractions of 1000 ml. Reversed phase preparative HPLC (C18 preparative column, eluted with a gradient
*water : acetonitrile : 0.1% TFA in acetonitrile"60 : 30 : 10}0 : 90 : 10 in 25 min,
55 ml/min, detection at 210 nm) of the#ash fraction 5 (40% EtOAc inn-hexane) has yielded 5,7-dihydroxy-6,4@-dimethoxy#avone, (pectolinarigenin,1, 6.8 mg) (Hase et al., 1995), 5-Hydroxy-6,7,4@-trimethoxy#avone (salvigenin,2, 35.0 mg) (Hertz and Gibaja, 1972; Talpatra et al., 1974; Xaasan et al., 1980) and 5,4@ -dihydroxy-3,6,7-trimethoxyf-lavone (penduletin,3, 1.1 mg) (Wang et al., 1989). Compounds1and3were further puri"ed by reversed phase semi-preparative HPLC (C18 semi-preparative column, eluted isocratically with the solvent mixture water: 0.1% TFA in MeOH"30 : 70,
25 mL/min., detection at 210 nm). Structures of all these compounds have been determined on the basis of UV,1H NMR,13C NMR, HMBC, HMQC and LC-MS data, and direct comparison with the respective literature data. Unambiguous assign-ment of13C NMR data for salvigenin (2) has been presented for the"rst time.
Salvigenin(2).13C NMR (125 MHz, CDCl
3):d182.9 (C-4), 164.2 (C-2), 162.9 (C-4@),
159.0 (C-7), 153.4 (C-9), 153.3 (C-5), 133.0 (C-6), 128.2 (C-2@, C-4@), 123.8 (C-1@), 114.7 (C-3@, C-5@), 106.4 (C-10), 104.3 (C-3), 90.8 (C-8), 61.0 (6-OMe), 56.5 (7-OMe), 55.7 (4@-OMe).
4. Chemotaxonomic signi5cance
The genusBaccharisis well-known for producing#avones (Kuroyanagi et al., 1985; Kupchan and Bauerschmidt, 1971; Dictionary of Natural Products, 1999). While
several other #avones have been reported from B. trinervis (Herrera et al., 1996;
Arriaga-Giner et al., 1982), none of the compounds (1}3) has previously been isolated from this species. However, compounds1}3have been reported from other genera within the Asteraceae (alt. Compositae) and also from other plant families (Dictionary of Natural Products, 1999). As#avonoids are an important class of compounds for plant systematic and evolutionary studies, the chemotaxonomic importance of the
#avonoids (1}3) reported here deserves consideration.
Acknowledgements
We thank David Thomas for his assistance with LC-MS data. BBSRC is thanked for partial"nancial support for purchasing BRUKER DRX500 NMR spectrometer.
References
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Kuroyanagi, M., Fujita, K., Kazaoka, M., Matsumoto, S., Ueno, A., Fukushima, S., Katsuoka, M., 1985. Chem. Pharm. Bull. 33, 5075.
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