Extracts from Traditional Chinese Medicinal Plants Inhibit Acetylcholinesterase, a Known Alzheimer's Disease Target.

Inhibition of acetylcholinesterase (AChE) is a common treatment for early stages of the most general form of dementia, Alzheimer's Disease (AD). In this study, methanol, dichloromethane and aqueous crude extracts from 80 Traditional Chinese Medical (TCM) plants were tested for their in vitro anti-acetylcholinesterase activity based on Ellman's colorimetric assay. All three extracts of Berberis bealei (formerly Mahonia bealei), Coptis chinensis and Phellodendron chinense, which contain numerous isoquinoline alkaloids, substantially inhibited AChE. The methanol and aqueous extracts of Coptis chinensis showed IC50 values of 0.031 µg/mL and 2.5 µg/mL, therefore having an up to 100-fold stronger AChE inhibitory activity than the already known AChE inhibitor galantamine (IC50 = 4.33 µg/mL). Combinations of individual alkaloids berberine, coptisine and palmatine resulted in a synergistic enhancement of ACh inhibition. Therefore, the mode of AChE inhibition of crude extracts of Coptis chinensis, Berberis bealei and Phellodendron chinense is probably due to of this synergism of isoquinoline alkaloids. All extracts were also tested for their cytotoxicity in COS7 cells and none of the most active extracts was cytotoxic at the concentrations which inhibit AChE. Based on these results it can be stated that some TCM plants inhibit AChE via synergistic interaction of their secondary metabolites. The possibility to isolate pure lead compounds from the crude extracts or to administer these as nutraceuticals or as cheap alternative to drugs in third world countries make TCM plants a versatile source of natural inhibitors of AChE.

Anti-infective and cytotoxic properties of Bupleurum marginatum.

BACKGROUND: Bupleurum marginatum Wall. ex DC (Apiaceae) is a perennial herb widely used in traditional Chinese and Kampo medicine for the treatment of various infectious diseases. The biological activities of B. marginatum have not been fully investigated. This study aims to investigate the antitrypanosomal, antimicrobial and antiviral activities of methanol (ME) and dichloromethane (DCM) extracts of B. marginatum aerial parts and the ability of both extracts to inhibit the growth of different cancer cell lines. METHODS: Phytochemical characterization of the extracts was performed by LC-MS profiling. The antitrypanosomal activity was evaluated using the resazurin method. The antimicrobial activity was assessed using agar diffusion and microdilution methods, and the minimum inhibitory concentration (MIC) values were determined. The antiviral activity was determined for 6.25, 12.5, and 50 µg/mL doses using a plaque reduction assay. Cytotoxicity was investigated in eight cancer cell lines (Caco-2, CCL-81, CCRF-CEM, COS-7, HL-60, MIA PaCa-2, MCF-7, and PANC-1) using the MTT assay and the caspase 3/7 activity was determined over the range of 62.5-1000 µg/mL. RESULTS: Phytochemical analyses resulted in the characterization of 15 components, mainly flavonoids and lignans. The DCM extract showed significant antitrypanosomal activity (IC50: 36.21 µg/mL) and moderate activity against Streptococcus pyogenes (MIC value: 0.25 mg/mL). At a dose of 12.5 µg/mL, the DCM extract inhibited 73.6% of the plaque production by hepatitis A virus. CCRF-CEM cells were the most sensitive to both extracts (IC50: 12.5-22.7 µg/mL). The cytotoxicity was mediated by induction of apoptosis (19-fold increase in the cellular caspase 3/7 level after treatment with the DCM extract at 1 mg/mL). CONCLUSIONS: ME and DCM extract of B. marginatum showed anti-infective and antiproliferative effects.

Secondary metabolites of ponderosa lemon (Citrus pyriformis) and their antioxidant, anti-inflammatory, and cytotoxic activities.

Column chromatography of the dichloromethane fraction from an aqueous methanolic extract of fruit peel of Citrus pyriformis Hassk. (Rutaceae) resulted in the isolation of seven compounds including one coumarin (citropten), two limonoids (limonin and deacetylnomilin), and four sterols (stigmasterol, ergosterol, sitosteryl-3-beta-D-glucoside, and sitosteryl-6'-O-acyl-3-beta-D-glucoside). From the ethyl acetate fraction naringin, hesperidin, and neohesperidin were isolated. The dichloromethane extract of the defatted seeds contained three additional compounds, nomilin, ichangin, and cholesterol. The isolated compounds were identified by MS (EI, CI, and ESI), 1H, 13C, and 2D-NMR spectral data. The limonoids were determined qualitatively by LC-ESI/MS resulting in the identification of 11 limonoid aglycones. The total methanolic extract of the peel and the petroleum ether, dichloromethane, and ethyl acetate fractions were screened for their antioxidant and anti-inflammatory activities. The ethyl acetate fraction exhibited a significant scavenging activity for DPPH free radicals (IC50 = 132.3 microg/mL). The petroleum ether fraction inhibited 5-lipoxygenase with IC50 = 30.6 microg/mL indicating potential anti-inflammatory properties. Limonin has a potent cytotoxic effect against COS7 cells [IC50 = (35.0 +/- 6.1) microM] compared with acteoside as a positive control [IC50 = (144.5 +/- 10.96) microM].

Myrtenal inhibits acetylcholinesterase, a known Alzheimer target.

OBJECTIVES: Inhibition of acetylcholinesterase (AChE) is a common treatment for early stages of the most general form of dementia, Alzheimer's disease. In this study selected components of essential oils, which carry a variety of important functional groups, were tested for their in-vitro anti-acetylcholinesterase activity. METHODS: In-vitro anti-acetylcholinesterase activity was measured by an adapted version of Ellman's colorimetric assay. KEY FINDINGS: 1,8-cineole, carvacrol, myrtenal and verbenone apparently inhibited AChE; the highest inhibitory activity was observed for myrtenal (IC50 = 0.17 mm). This is the first study showing the AChE inhibitory activity of myrtenal. CONCLUSIONS: Our investigations provided evidence for the efficacy of monoterpenes as inhibitors of AChE.

Chemical composition and biological activity of Citrus jambhiri Lush.

The fresh peel of Citrus jambhiri was extracted with aqueous methanol and the residue was fractionated using light petroleum, chloroform and ethyl acetate. The constituents of the extracts were separated by column chromatography employing solvents of different polarity. The chemical structure of the isolated compounds was then identified by MS and NMR. Column chromatography of the petroleum fraction resulted in the isolation of nobiletin, 5-O-demethylnobiletin, tangeretin, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 3,5,6,7,8,3',4'-heptamethoxyflavone, and a mixture of ß-sitosterol and stigmasterol. The chloroform fraction afforded 6-demethoxynobiletin, 5,4'-dihydroxy-6,7,8,3'-tetramethoxyflavone, limonin and nomilin. The flavonoid glycosides naringin, hesperidin and neohesperidin were isolated from the ethyl acetate fraction. The chemical structure of the isolated compounds was established by MS and NMR (APT, COSY, HSQC, HMBC, and NOESY). LC-ESI-MS analysis of the ethyl acetate fraction afforded eight flavonoid glycosides, while the dichloromethane fraction of the defatted seeds contained seven limonoid aglycones. The chloroform fraction exerted the strongest DPPH(∗) free radical scavenging activity in comparison to other fractions. The petroleum fraction showed a significant inhibition of lipoxygenase indicating an anti-inflammatory action (IC(50) 29±1µg/mL). Some of the isolated polymethoxyflavones exhibited strong cytotoxicity against COS7, HeLa and Caco-2 cell lines.