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.

The hypouricemic actions of Biota orientalis (BO) extract and its flavonoid constituents quercetin and rutin, were in vivo examined using oxonate-induced hyperuricemic mice. Quercetin and rutin, when administered three times orally to the oxonate-induced hyperuricemic mice, were able to elicit dose-dependent hypouricemic effects. The effects of quercetin and rutin were more potent than that of Biota orientalis extract at the same dose of 100mg/kg. At doses of 50mg/kg of quercetin or above, or at doses of 100mg/kg of rutin or above, the serum urate levels of the oxonate-pretreated mice were not different from normal mice. In addition, Biota orientalis extract, quercetin and rutin, when tested in vivo on mouse liver homogenates, elicited significant inhibitory actions on the xanthine dehydrogenase/xanthine oxidase (XDH/XO) activities. The effects of quercetin and rutin resulted less potent than that of allopurinol. However, intraperitoneal administration at the same scheme did not produce any observable hypouricemic effect. These hypouricemic effects are partly due to the inhibition of XDH/XO activities in mouse liver. The pharmacological profile of the flavonoids is partly different from that of allopurinol. Such hypouricemic action and inhibition of the enzyme activity of quercetin and rutin may be responsible for a part of the beneficial effects of Biota orientalis extract on hyperuricemia and gout. The effects of quercetin and rutin on serum urate levels in hyperuricemic mice induced by oxonate and the inhibition of enzyme activities in mouse liver are discussed in relation to their absorption and metabolism, and their potential application to treat gout and hyperuricemia.

Curcuma longa (turmeric) is a well-known indigenous herbal medicine. The aqueous extracts, when administered orally to the mice from 140 to 560mg/kg for 14 days, were able to elicit dose-dependent relation of immobility reduction in the tail suspension test and the forced swimming test in mice. The effects of the extracts at the dose of 560mg/kg were more potent than that of reference antidepressant fluoxetine. The extracts, at the dose of 140mg/kg or above for 14 days, significantly inhibited the monoamine oxidize A (MAO) activity in mouse whole brain at a dose-dependent manner, however, oral administration of the extract only at a dose of 560mg/kg produced observable MAO B inhibitory activity in animal brain. Fluoxetine showed only a tendency to inhibit MAO A and B activity in animal brain in the study. Neither the extracts of C. longa nor fluoxetine, at the doses tested, produced significant effects on locomotor activity. These results demonstrated that C. longa had specifically antidepressant effects in vivo. The activity of C. longa in antidepression may mediated in part through MAO A inhibition in mouse brain.

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.

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.