Protective effect of jakyak-gamcho-tang extract and its constituents against t-BHP-induced oxidative damage in HT22 cells.

The present study investigated whether Jakyak-Gamcho-Tang (JGT, Shaoyao-Gancao-tang) and its constituents have the protective effect against tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity on hippocampal HT22 cell line. JGT consists of two medicinal herbs, Paeoniae Radix (PR) and Glycyrrhizae Radix (GR). In contrast to treating with t-BHP alone, pre-treatment of HT22 cells with JGT, PR and GR (50-400 microg/ml) for 3 hours significantly increased the cell viability in a concentration-dependent manner. In addition, JGT, PR and GR exhibited the scavenging activity in both 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion assays. Among the tested extracts, PR showed the most potent protective and antioxidative activities. These results suggest that PR acts as an antioxidant and this property may contribute to the neuroprotective activity of JGT extract.

Rhynchophylline and isorhynchophylline inhibit NMDA receptors expressed in Xenopus oocytes.

Rhynchophylline and isorhynchophylline are major tetracyclic oxindole alkaloid components of Uncaira species, which have been long used as medicinal plants. In this study, the effects of rhynchophylline and isorhynchophylline on the ionotropic and metabotropic glutamate receptor-mediated current responses were examined using Xenopus oocytes injected with total RNA prepared from rat cortices or cerebelli. Rhynchophylline and isorhynchophylline (1-100 microM) per se failed to induce membrane current, but these alkaloids reversibly reduced N-methyl-D-aspartate (NMDA)-induced current in a concentration-dependent but voltage-independent manner. The IC(50) values of rhynchophylline and isorhynchophylline were 43.2 and 48.3 microM, respectively. Substitution of Ba(2+) for Ca(2+) in the recording medium did not alter the extent of rhynchophylline- and isorhynchophylline-induced suppression of NMDA currents. In contrast, neither alkaloid had an effect on the currents mediated by ionotropic kainic acid-type and (+/-)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors or by the metabotropic glutamate receptor(1 and 5) (mGlu(1/5)). Rhynchophylline and isorhynchophylline (30 microM) significantly reduced the maximal current responses evoked by NMDA and glycine (a co-agonist of NMDA receptor), but had no effect on the EC(50) values and Hill coefficients of NMDA and glycine for inducing currents. These alkaloids showed no interaction with the polyamine binding site, the Zn(2+) site, proton site or redox modulatory site on the NMDA receptor. These results suggest that rhynchophylline and isorhynchophylline act as noncompetitive antagonists of the NMDA receptor and that this property may contribute to the neuroprotective and anticonvulsant activity of the Uncaira species plant extracts.

Pteropodine and isopteropodine positively modulate the function of rat muscarinic M(1) and 5-HT(2) receptors expressed in Xenopus oocyte.

Pteropodine and isopteropodine are heteroyohimbine-type oxindole alkaloid components of Uncaria tomentosa (Willd.) DC, a Peruvian medicinal plant known as cat's claw. In this study, the effects of these alkaloids on the function of Ca(2+)-activated Cl(-) currents evoked by stimulation of G protein-coupled muscarinic M(1) acetylcholine and 5-HT(2) receptors were studied in Xenopus oocytes in which rat cortex total RNA was translated. Pteropodine and isopteropodine (1-30 microM) failed to induce membrane current by themselves. However, these alkaloids markedly enhanced the current responses evoked by both acetylcholine and 5-hydroxyhyptamine (5-HT) in a concentration-dependent and reversible manner with the maximal effects at 30 microM. Pteropodine and isopteropodine produced 2.7- and 3.3-fold increases in the acetylcholine response with EC(50) values of 9.52 and 9.92 microM, respectively, and 2.4- and 2.5-fold increases in the 5-HT response with EC(50) values of 13.5 and 14.5 microM, respectively. In contrast, in oocytes injected with total RNA from the rat cerebellum or spinal cord, neither alkaloid had an effect on the metabotropic current responses mediated by glutamate receptor(1 and 5) (mGlu(1/5)) receptors or ionotropic responses mediated by N-methyl-D-aspartate, kainic acid or glycine. Pteropodine and isopteropodine (10 microM) significantly reduced the EC(50) values of acetylcholine and 5-HT that elicited current responses, but had no effect on the maximal current responses elicited by acetylcholine and 5-HT. On the other hand, mitraphylline, a stereoisomer of pteropodine, failed to modulate acetylcholine- and 5-HT-induced responses. These results suggest that pteropodine and isopteropodine act as positive modulators of muscarinic M(1) and 5-HT(2) receptors.

Protective effect of rhynchophylline and isorhynchophylline on in vitro ischemia-induced neuronal damage in the hippocampus: putative neurotransmitter receptors involved in their action.

Rhynchophylline and isorhynchophylline are major tetracyclic oxindole alkaloid components of Uncaira species, which have been long used as medicinal plants. In this study we examined the protective effects of rhynchophylline and isorhynchophylline on in vitro ischemia-induced neuronal damage in the hippocampus and interaction of these alkaloids with neurotransmitter receptors in a receptor expression model of Xenopus oocytes. In vitro ischemia was induced by exposing the hippocampal slices to oxygen- and D-glucose-deprived medium over 8 min. The resultant neuronal damage was elucidated as deterioration of population spike (PS) amplitudes evoked trans-synaptically by electrical stimulation of Schaffer collaterals and recorded in the CA1 area. Rhynchophylline and isorhynchophylline, as well as the N-methyl-D-aspartate (NMDA) antagonist (+/-)-2-amino-5-phosphono-valeric acid (APV), the muscarinic M1 receptor antagonist pirenzepine, and the 5-HT2 receptor antagonist ketanserin, attenuated the in vitro ischemia-induced neuronal damage in a concentration-dependent manner. There was no difference in the extent of protection against the neuronal damage between rhynchophylline and isorhynchophylline treatment. In Xenopus oocytes expressing the rat brain receptors encoded by total RNA, both rhynchophylline and isorhynchophylline reduced muscarinic receptor- and 5-HT2 receptor-mediated current responses in a competitive manner. Together with our previous findings that rhynchophylline and isorhynchophylline have a non-competitive antagonistic effect on the NMDA-type ionotropic glutamate receptors, the present results suggest that these alkaloids exert their protective action against ischemia-induced neuronal damage by preventing NMDA, muscarinic M1, and 5-HT2 receptors-mediated neurotoxicity during ischemia.

An isocoumarin with hepatoprotective activity in Hep G2 and primary hepatocytes from Agrimonia pilosa.

Phytochemical investigation of the aqueous extract of the roots of Agrimonia pilosa Ledeb. (Rosaceae), as guided by hepatoprotective activity in vitro, furnished two isocoumarins, agrimonolide (1) and agrimonolide 6-O-beta-D-glucoside (3), and (+)-catechin (2). Compound 1 showed hepatoprotective effects on both tacrine-induced cytotoxicity in human liver-derived Hep G2 cells and tert-butyl hydroperoxide-induced cytotoxicity in rat primary hepatocytes with EC50 values of 88.2 +/- 2.8 and 37.7 +/- 1.6 microM, respectively.

Scopoletin suppresses pro-inflammatory cytokines and PGE2 from LPS-stimulated cell line, RAW 264.7 cells.

Scopoletin (1-50 microg/ml) inhibited the release of PGE2, TNF-alpha, IL-1beta and IL-6 and suppressed the expression of COX-2 in a concentration-dependent manner. These results suggest that scopoletin might suppress the production of such pro-inflammatory cytokines and exert inhibitory activity on LPS-induced PGE2 production through the depression of COX-2 expression.

Effects of aqueous extract of Sophora flavescens on the expression of cell cycle regulatory proteins in human oral mucosal fibroblasts.

Sophorae Radix, the dried roots of Sophora flavescens AITON (Leguminosae), has been used in Oriental traditional medicine for treatment of skin and mucosal ulcers, sores, gastrointestinal hemorrhage, diarrhea, inflammation and arrhythmia. In the present study, we examine the effect of the aqueous extract of Sophorae Radix (AESR) on cell proliferation and cell cycle regulation in human oral mucosal fibroblasts (HOMFs). To study the molecular mechanisms of cell cycle regulation by AESR, we also measured the intracellular levels of cell cycle regulatory proteins such as cyclin D, cyclin-dependent kinases (CDK)-4, CDK-6, cyclin E, CDK-2, p53, p21WAF1/CIP1 and p16INK4A. Cell proliferation was increased in the presence of 10 approximately 500 microg/ml of AESR. Maximal growth stimulation was observed in those cells exposed to 100 microg/ml of AESR. Exposure of HOMFs to 100 microg/ml of AESR resulted in an increase of cell cycle progression. The levels of cyclin E and CDK-2 were increased in HOMFs after 100 microg/ml of AESR treatment, but the levels of cyclin D, CDK-4, and CDK-6 were unchanged. After exposure to 100 microg/ml of AESR, the protein levels of p16INK4A and p53 were decreased as compared to that of the control group, but the level of p21WAF1/CIP1 was similar in the cells treated with 100 microg/ml of AESR and untreated cells. The results suggest that AESR may increase cell proliferation and cell cycle progression in HOMFs, which is linked to increased cellular levels of cyclin E and CDK-2 and decreased cellular levels of p53 and p16INK4A. Further studies are necessary to clarify the active constituents of AESR responsible for such biomolecular activities.

In vitro protein tyrosine phosphatase 1B inhibitory phenols from the seeds of Psoralea corylifolia.

Protein tyrosine phosphatase 1B plays a major role in the negative regulation of insulin signaling, and this establishes protein tyrosine phosphatase 1B as an attractive therapeutic target for diabetes. Bioassay-guided fractionation of the EtOAc-soluble extract of the seeds of Psoralea corylifolia afforded two protein tyrosine phosphatase 1B inhibitory compounds, psoralidin (1) and bakuchiol (2), along with inactive corylin. Compounds 1 and 2 inhibited PTP1B activity in a dose-dependent manner, displaying IC50 values of 9.4 +/- 0.5 microM and 20.8 +/- 1.9 microM, respectively.

The chalcone butein from Rhus verniciflua shows antifibrogenic activity.

Butein is known to be the major component of the bark of Rhus verniciflua Stokes (Anacardiaceae). The aim of this work was to investigate the effects of butein on liver fibrosis induced by carbon tetrachloride (CCl4) in rats, and to explore its antifibrogenic mechanism. Butein (10 mg/kg/day or 25 mg/kg/day) showed a significant reduction of hydroxyproline and malondialdehyde levels in rats. The expression of alpha1(I) collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNAs in liver was clearly reduced in a dose-dependent manner in rats given butein compared with control CCl4-treated rats. These data suggest the potential of butein to serve as an antifibrogenic agent by inhibition of collagen accumulation and lipid peroxidation, and by down-regulation of the expression of both alpha1(I) collagen and TIMP-1 mRNA.

Antimalarial activity of lavandulyl flavanones isolated from the roots of Sophora flavescens.

Four lavandulyl flavanones, (2S)-2'-methoxykurarinone (1), sophoraflavanone G (2), leachianone A (3), and (-)-kurarinone (4), which are isolated from the roots of Sophora flavescens have been tested for in vitro antimalarial activity against Plasmodium falciparum. Compounds 1-3 showed moderate antimalarial activities with EC(50) values of 2.4 x 10(-6), 2.6 x 10(-6), and 2.1 x 10(-6) M, respectively. These compounds did not show selective toxicity against P. falciparum in the toxicity test on mouse mammalian tumor cells, however, it is suggested that the position of methoxyl groups in flavanone skeleton plays an important role on antimalarial activity.