The Components of Flemingia macrophylla Attenuate Amyloid ß-Protein Accumulation by Regulating Amyloid ß-Protein Metabolic Pathway.

Flemingia macrophylla (Leguminosae) is a popular traditional remedy used in Taiwan as anti-inflammatory, promoting blood circulation and antidiabetes agent. Recent study also suggested its neuroprotective activity against Alzheimer's disease. Therefore, the effects of F. macrophylla on Aß production and degradation were studied. The effect of F. macrophylla on Aß metabolism was detected using the cultured mouse neuroblastoma cells N2a transfected with human Swedish mutant APP (swAPP-N2a cells). The effects on Aß degradation were evaluated on a cell-free system. An ELISA assay was applied to detect the level of Aß1-40 and Aß1-42. Western blots assay was employed to measure the levels of soluble amyloid precursor protein and insulin degrading enzyme (IDE). Three fractions of F. macrophylla modified Aß accumulation by both inhibiting ß-secretase and activating IDE. Three flavonoids modified Aß accumulation by activating IDE. The activated IDE pool by the flavonoids was distinctly regulated by bacitracin (an IDE inhibitor). Furthermore, flavonoid 94-18-13 also modulates Aß accumulation by enhancing IDE expression. In conclusion, the components of F. macrophylla possess the potential for developing new therapeutic drugs for Alzheimer's disease.

In vitro protective effects of salvianolic acid B on primary hepatocytes and hepatic stellate cells.

The production of reactive oxygen species (ROS) is believed to be involved in liver injury and hepatic fibrosis. Activation of hepatic stellate cells (HSCs) is a key feature of liver fibrosis. Salvia miltiorrhiza is a traditional Chinese herb used in the treatment of cardiovascular and liver diseases to resolve stasis. The effects of salvianolic acid B (Sal B), a major component of Salvia miltiorrhiza, on oxidative damage include free radical DPPH scavenging, malondialdehyde (MDA) formation and ROS generation in primary rat hepatocytes and HSCs, and on alpha-SMA, and collagen expression in transforming growth factor-beta1 (TGF-beta1)-stimulated HSCs were examined. Results indicated that Sal B scavenged DPPH potently with an IC50 2.2+/-0.2 microg/ml (3.06+/-0.3 microM), inhibited lipid peroxidation and eliminated ROS accumulation in a concentration-dependent manner on primary rat hepatocytes and HSCs. Sal B also reduced alpha-SMA and collagen synthesis and deposition in HSCs, and had no direct cytotoxicity on both hepatocytes and HSCs. Our results suggest that Sal B ameliorated oxidative damage and eliminated ROS accumulation in hepatocytes, and attenuated HSC activation, potentially conferring hepatoprotective and anti-fibrogenic effects.

Neuroprotective flavonoids from Flemingia macrophylla.

Using an Abeta-induced neurotoxicity blocking assay to direct fractionation, three new flavonoids, fleminginin (1), flemingichromone (2), and flemingichalcone (3), and twenty known compounds were isolated from the active fractions of the aerial parts of Flemingia macrophylla. The structures of 1 - 3 were elucidated on the basis of spectroscopic data. When tested for neuroprotective activity, compound 2, osajin ( 4), 5,7,4'-trihydroxy-6,8-diprenylisoflavone (5), 5,7,4'-trihydroxy-6,3'-diprenylisoflavone (6), and aureole (7) protected neuronal cells from Abeta-induced damage with EC50 values of 31.43 +/- 3.16, 5.01 +/- 1.28, 11.25 +/-1.51, 4.47 +/- 0.65, 12.09 +/- 2.55 microM, respectively.

Tournefolic acid B methyl ester attenuates glutamate-induced toxicity by blockade of ROS accumulation and abrogating the activation of caspases and JNK in rat cortical neurons.

The effects of nine polyphenolic compounds on glutamate-mediated toxicity were investigated. The underlying mechanisms by which a polyphenolic compound confers its effect were also elucidated. Treatment of cortical neurons with 50 microm glutamate for 24 h decreased cell viability by 45.8 +/- 7.9%, and 50 microm of tournefolic acid B methyl ester attenuated glutamate-induced cell death by 46.8 +/- 17.8%. Glutamate increased the activity of caspase 35.2-fold, and to a similar extent for caspase 2, 6, 8 and 9. Tournefolic acid B methyl ester abrogated glutamate-induced activation of caspase 2, 3, 6 and 9 by about 70%, and to a lesser extent for caspase 8. Treatment with glutamate for 1 h elevated reactive oxygen species (ROS) by 208.3 +/- 21.3%. Tournefolic acid B methyl ester eliminated the glutamate-induced accumulation of ROS. Glutamate increased the phosphorylation of p54-c-jun N-terminal kinase (JNK) concomitantly with activation of the endogenous antioxidant defense system. Tournefolic acid B methyl ester at 50 microm diminished the activity of p54-JNK in control and glutamate-treated cells, coinciding with the abolishment of the glutamate-triggered antioxidant defense system. Therefore, tournefolic acid B methyl ester blocked the activation of the caspase cascade, eliminated ROS accumulation and abrogated the activation of JNK, thereby conferring a neuroprotective effect on glutamate-mediated neurotoxicity.