Fractionation of the xanthine oxidase inhibitory methanol extract of Conyza bonariensis afforded three glycosides, in addition to nine known compounds including amyrin, b-sitostero1 daucosterol, syringic acid 3-hydroxy-5-methoxybenzoic acid, eugenol 4-Oglucopyranoside, and luteolin, apigenin and takakin 8-O-glucuronide. The structures of the glycosides were established by a combination of spectroscopic methods (IR, MS, 1Hand 13C NMR, DEPT, COSY, HMQC and HMBC) as 4-hydroxypyridin-3-carboxylic acid 4-O-glucopyranoside, 8-hydroxy-6,7-dihydrolinalool 8-O-glucopyranoside and bonaroside [viz. 1,3,4,12-tetrahydroxy-2-(9-hexadecenoylamino) octadecane 1-O-glucopyranoside]. The in vitro enzyme assay showed that syringic acid and takakin 8-O-glucuronide displayed weak inhibitory activity against xanthine oxidase with IC50 values of 500±41μM and 170±12μM, respectively.

Psoralen and isopsoralen, furocoumarins isolated from the plant Psoralea corylifolia L., were demonstrated to exhibit in vitro inhibitory actions on monoamine oxidase (MAO) activities in rat brain mitochondria, preferentially inhibiting MAO-A activity over MAO-B activity. This inhibition of enzyme activities was found to be dose-dependent and reversible. For MAO-A, the IC50 values are 15.2±1.3μM psoralen and 9.0±0.6μM isopsoralen. For MAO-B, the IC50 values are 61.8±4.3μM psoralen and 12.8±0.5μM isopsoralen. Lineweaver-Burk transformation of the inhibition data indicates that inhibition by both psoralen and isopsoralen is non-competitive for MAO-A. The Ki values were calculated to be 14.0μM for psoralen and 6.5μM for isopsoralen. On the other hand, inhibition by both psoralen and isopsoralen is competitive for MAO-B. The Ki values were calculated to be 58.1μM for psoralen and 10.8μM for isopsoralen. These inhibitory actions of psoralen and isopsoralen on rat brain mitochondrial MAO activities are discussed in relation to their toxicities and their potential applications to treat affective disorders.

Banxia-houpu decoction, a traditional Chinese medicine has been used in the treatment of depression. The present study confirmed that oral administration of polysaccharides from Banxia-houpu decoction, exhibited a reduction in the immobility time in the tail suspension and in the forced swimming tests in mice in a timedependent manner. This effect at a dose of 320mg/kg was more potent than that at a dose of 640mg/kg. The polysaccharides from Banxia-houpu decoction were active in animal models of depression with comparable effects to known antidepressants. The oral administration of the polysaccharides at a low dose for 4 weeks resulted in a significant increase in the monoamine neurotransmitter 5-hydroxytryptamine (5-HT) and dopamine (DA) levels in whole mouse brain, but produced no significant increase in 5-hydroxyindoleacetic acid (5-HIAA) and norepinephrine (NE) concentrations. The effect of polysaccharides on the brain neurotransmitter levels appeared to be quite different from the effect of fluoxetine, a serotonin specific reuptake inhibitor. The results indicate that the mode of action of polysaccharides from Banxia-houpu decoction in depression might be related to both 5-HT and DA systems. Copyright.

A total of seventeen phytochemicals including seven alkaloids (piperine, strychnine, brucine, stachydrine, tetrandrine, frangchinoline and sinomenine), four phenols (paeonol, honokiol, magnolol and eugenol) and six anthraquinones (emodin, rhein, chrysorphanol, aloe-emodin, physcion and 1,8-dihydroxyanthraquinone) was examined for inhibitory activity of monoamine oxidase (MAO) A and B from rat brain mitochondrial. Among these compounds, piperine and paeonol were found to be inhibitory against MAO A in a dose-dependent manner with IC50 values of 49.3 and 54.6μM, respectively. Piperine, paeonol and emodin were shown to inhibit MAO B in a dose-dependent manner with the IC50 data of 91.3, 42.5 and 35.4μM, respectively. Lineweaver-Burk transformation of the inhibition data indicated that the inhibitory action of piperine onMAO A was of mixed type, and that of paeonol on the same type of the enzyme was of non-competitive type. For piperine, the Ki and KI were determined to be 35.8 and 25.7μM, respectively. For paeonol, the Ki was estimated to be 51.1μM. The inhibition of piperine and paeonol on MAO B was of competitive type with Ki values of 79.9 and 38.2μM, respectively. The inhibition of emodin on MAO B was of mixed type with the Ki and KI data of 15.1 and 22.9μM, respectively. The present investigation showed that the phytochemicals piperine, paeonol and emodin are potent MAO inhibitors whereas other compounds were inactive against any type of MAO at 100μM in the present assay.

Ermiao wan, which is composed of phellodendri cortex and atractylodis rhizome, is described as eliminating heat, excreting dampness and anti-edema prescription in traditional Chinese medical literatures including Danxi's Experiences in Medicine and State Pharmacopoeia of People's Republic of China. So it is being used clinically in the treatment of gout and hyperuricemia in China. In the present study, the water extracts of Ermiao wan and phellodendri cortex at 840 and 480mg/kg/day orally for 7 days were demonstrated to possess in vivo potent hypouricemic effects both in hyperuricemic mice pretreated with oxonate and in normal mice, respectively. In the hyperuricemic animals, the effect of Ermiao wan was equal to that of the reference drug allopurinol (at 10mg/kg/day orally for 7 days), but in the normal mice, the former was weaker than latter. In addition, both Ermiao wan and phellodendri cortex were found to have in vivo relatively inhibitory effects on mouse liver xanthine dehydrogenase (XDH) and xanthine oxidase (XO) activities at the same dose described above. These inhibitory effects were weaker than that observed for allopurinol. Atractylodis rhizome at 340mg/kg/day orally for 7 days did not show any effects on the above experiments. These results suggested that atractylodis rhizomes assisted and enhanced the effect of phellodendri cortex on reduction of serum uric acid level in hyperuricemic mice, and hypouricemic effects of Ermiao wan and phellodendri cortex may be achieved by other mechanism partly instead of the XDH and XO inhibition.