Ethnopharmacological communication
Two flavonoids from Artemisia herba-alba Asso with in vitro GABAA-benzodiazepine receptor activity

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Abstract

An ethyl acetate extract of Artemisia herba-alba was partitioned by HPLC in 10 fractions that were tested in the [3H]-flumazenil radioligand assay, for affinity to the GABAA-benzodiazepine receptor. Two fractions showed activity from which hispidulin and cirsilineol were isolated. The structures were confirmed by 1H NMR. The IC50 values were 8 μM for hispidulin and 100 μM for cirsilineol.

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Plant

Aerial parts of Artemisia herba-alba Asso (Lamiaceae) were collected from Lebanese herbal stores (dabbous stores), in Beirut, Lebanon. The plant was identified with help from K. Sleem, American University in Beirut. A voucher sample (Salah1) is stored at the Department for Medicinal Chemistry, The Danish University of Pharmaceutical Sciences.

Uses in traditional medicine

Artemisia herba-alba has a wide use in traditional medicine, for treatment of gastric disturbances, such as diarrhoea, abdominal cramps and for healing external wounds (Feuerstein et al., 1986). Uses for diabetes mellitus and other conditions as jaundice are also reported (Marrif et al., 1995). The species is recommended for neurological disorders, and an ethanolic extract has shown activity in the GABAA-benzodiazepine receptor assay (Salah and Jäger, 2005).

Previously isolated classes of constituents

Flavonoids, essential oils and eudesmanolides (Feuerstein et al., 1986, Saleh et al., 1987, Boriky et al., 1996).

Material and methods

Ten gram of Artemisia herba-alba plant material was first extracted with heptane to remove non-active lipophilic compounds. The plant material was hereafter extracted with 3× 100 ml ethyl acetate, which subsequently was partitioned against 3× 100 ml water to remove non-active polar compounds.

The separation of the ethyl acetate phase was carried out by gradient HPLC on a Phenomenex Luna 5 μ C-18 column (250 mm × 21.2 mm), using MeCN/0.05% TFA as mobile phase. The resulting 10 fractions were tested in

Results

Two fractions were active in the GABAA-benzodiazepine receptor assay. From these fractions hispidulin (1.2 mg) and cirsilineol (1.0 mg) were isolated and identified on basis of 1H NMR by comparison with data reported previously (Matsuura et al., 1973, Akkal et al., 2003).

The IC50 values for hispidulin and cirsilineol were 8 and 104 μM, respectively. The IC50 value of hispidulin in the present study is within the same range as previously published values of 1.3 μM (Shen et al., 1994, Kavvadias et

Acknowledgements

The authors thank the Danish Medical Research Council for financial support and K. Sleem, American University in Beirut, for identification of the plant material.

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