The present study was undertaken to investigate the antidepressant-like effects of the methylene chloride fraction of Albizzia julibrissin (MCAJ) using a tail suspension test in mice. MCAJ was orally administered at 50, 100, or 200 mg/kg to mice, 1 h before the tail suspension test. Acute treatment with MCAJ at 200 mg/kg significantly reduced the immobility time compared with the control group, and thus showed an antidepressant-like effect. This effect was comparable to that of imipramine at 10 mg/kg. This antidepressant-like effect was reversed by treatment with WAY-100635 (a 5-HT1A receptor antagonist) or pindolol (a 5-HT1A/1B receptor antagonist). However, the antidepressant effect of MCAJ was not effected by treatment with GR55562 (a 5-HT1B receptor antagonist) or ketanserin (a 5-HT2A receptor antagonist). Therefore, our findings suggest that MCAJ exerts its antidepressant-like effect via the 5-HT1A receptor system.

Traditionally, the stem bark of A. julibrissin was dried and boiled with water. Asians administered this A. julibrissin soup to patients as a folk medicine to treat insomnia, diuresis, sthenia, and confusion (Zhu, 1998 ). It has been reported that saponins (Kinjo et al., 1992; Chen et al., 1997), phenolic glycosides (Jung et al., 2004b), triterpenes (Chen and Zhang, 1997), flavonoids, and other compounds (Kang et al., 2000) have been isolated from the stem bark of A. julibrissin.

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Recently, it was reported that the aqueous extract of A. julibrissin stem bark has anxiolytic-like activity in rats in the elevated plus maze test (Kim et al., 2004).

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(for the present study) ...the dried powdered stem barks (750 g) of A. julibrissin were extracted twice (each time for 3 h followed by heating) with a mixture of EtOH and water (1:1) in a reflux apparatus. The extract was concentrated to dryness under vacuum. The yield of the 50% ethanolic mixture extract was 18% (w/w, 132 g). Part of the ethanolic extract (68 g) was suspended in 1 L of distilled water, and partitioned successively
with methylene chloride and BuOH. The yields of the methylene chloride, butanol and water soluble fractions were 13.3, 16.4 and 38.3%. The methylene chloride soluble fraction (MCAJ, 13.3 g) was used in the animal experimental model.

Both the bark and the flowers of Albizia are used as a calming sedative in Oriental traditional medicine. Categorized in the Chinese Materia Medica as a calming spirit herb, the bark is thought to 'anchor' the spirit, while the flowers lighten it. The flowers have also been used for the treatment of insomnia, amnesia, sore throat, and confusion in Oriental traditional medicine as well as depression, melancholy, and anxiety.

The flowers are in bloom here! Time to collect and extract.