Primary constituents of blue cohosh: quantification in dietary supplements and potential for toxicity.

Dietary supplements containing dried roots or extracts of the roots and/or rhizomes of blue cohosh (Caulophyllum thalictroides) are widely available. This botanical has a long history of use by Native Americans and its use continues to the present day. The primary constituents of blue cohosh are its alkaloids and saponins. The structures of the alkaloids magnoflorine, baptifoline, anagyrine, and N-methylcytisine have been known for many years. The last 10 years have seen a great increase in isolation and identification of the large number of saponins present in blue cohosh. Important developments in nuclear magnetic resonance techniques have contributed substantially to the increase in elucidation of the structures of the complex saponins. Several authors have described quantitative methods for both the alkaloids and saponins in blue cohosh. Such methods have made it possible to quantify these constituents in dietary supplements containing this botanical ingredient. Concentrations of both alkaloids and saponins vary substantially in dietary supplements of blue cohosh. The nicotinic alkaloid, N-methylcytisine, a potent toxicant, has been found in all dietary supplements of blue cohosh analyzed. The teratogenic alkaloid anagyrine has been found in some but not all dietary supplements.

Comparison of metabolism-mediated effects of pyrrolizidine alkaloids in a HepG2/C3A cell-S9 co-incubation system and quantification of their glutathione conjugates.

1. Toxicity of pyrrolizidine alkaloids (PAs) largely depends on their metabolic activation by hepatic enzymes, including cytochrome P450s, to become chemically reactive pyrrolic derivatives. These then spontaneously release the esterifying acids to generate carbonium ions that form covalent adducts with cellular nucleophiles to exhibit toxicity. 2. In our investigation, metabolism-mediated toxicity of monocrotaline, retrorsine, lycopsamine, echimidine (retronecine-type PAs), heliotrine (a heliotridine-type PA) and senkirkine (an otonecine-type PA) was studied using an in vitro co-incubation assay. 3. Human hepatocarcinoma (HepG2/C3A) cells were incubated with PAs in the presence and absence of rat liver S9 fraction and the toxicity was assessed as lowered mitochondrial activity. 4. Bioactivation potential was measured by incubating PAs with rat liver S9 fraction, NADPH and GSH in a cell free system. Pyrrolic metabolites generated were entrapped as glutathione conjugates (7-GSH-DHP and 7,9-di-GSHDHP) which were quantified using LC-MS-MS analysis. 5. Our results indicated that PAs were metabolized by rat liver S9 fraction into reactive pyrrolic derivatives which were toxic to HepG2/C3A cells. This approach can be used to determine and compare bioactivation potential and metabolism-mediated toxicity of various PAs.

In vitro metabolic stability and intestinal transport of P57AS3 (P57) from Hoodia gordonii and its interaction with drug metabolizing enzymes.

Hoodia gordonii, a succulent cactus-like plant growing in South Africa, has been used in traditional medicine for its appetite suppressant properties. Its use as a dietary supplement to promote weight loss has recently gained popularity. An oxypregnane steroidal glycoside P57AS3 (P57) is reported to be the active constituent of the sap extract responsible for anorexigenic activity. No information is available about its metabolic stability, intestinal transport and interaction with drug metabolizing enzymes. In the present investigation, the metabolic stability of P57 in human liver microsomes and its interaction with drug metabolizing enzymes (CYP1A2, 2C9, 3A4 and 2D6) were determined. Intestinal transport of P57 was studied in the Caco-2 cell model of intestinal transport and absorption. P57 was metabolically stable in the presence of human liver microsomes. The compound inhibited CYP3A4 activity with an IC50 value of 45 microM, whereas the activity of CYP 1A2, 2C9 and 2D6 was not inhibited. In the Caco-2 model, P57 exhibited a higher transport in the secretory direction than in the absorptive direction with efflux ratios of 3.1 and 3.8 at 100 and 200 microM, respectively. The efflux was inhibited by selective inhibitors of multidrug resistance associated proteins MRP1/MRP2 (MK-571) and P-gp (verapamil). In conclusion, intestinal transport of P57 was mediated by P-gp and MRP transporters. The compound was metabolically stable and showed weak inhibition of CYP 3A4.

Antileishmanial, antiplasmodial and cytotoxic activities of 12,16-dideoxy aegyptinone B from Zhumeria majdae Rech.f. & Wendelbo.

The ethanol extract of Zhumeria majdae showed potent antileishmanial and antiplasmodial activity in vitro. Bioactivity guided fractionation of the extract led to the isolation of 12,16-dideoxy aegyptinone B. This compound exhibited potent in vitro antileishmanial activity with an IC(50) of 0.75 microg/mL and a strong antiplasmodial activity with IC(50) values of 1.3 and 1.4 microg/mL against chloroquine sensitive and resistant strains, respectively. This compound was further found to have mild cytotoxicity towards cancer cell lines.

New oxypregnane glycosides from appetite suppressant herbal supplement Hoodia gordonii.

Hoodigosides A-K (1-11), eleven new oxypregnane glycosides and a previously reported oxypregnane glycoside P57AS3 were isolated from the aerial parts of Hoodia gordonii. The structures of these 12-O-beta-tigloyl isoramanone glycosides were determined on the basis of chemical evidence and extensive spectroscopic methods that include one-dimensional and two-dimensional NMR. Cytotoxicity and antioxidant activities of these compounds were tested in cell based assays where they were found to be inactive.

Glycosides of 20-deoxy derivatives of jujubogenin and pseudojujubogenin from Bacopa monniera.

A detailed phytochemical investigation of an extract of Bacopa monniera resulted in the isolation of two new dammarane glycosides along with eight known compounds. They have been identified as glycosides of the 20-deoxy derivatives of jujubogenin and pseudojujubogenin. The structures were established by different spectroscopic methods that included 1D and 2D NMR experiments. The compounds were tested for their cytotoxicity, antileishmanial, antimalarial, antioxidant, and anti-inflammatory activities. Only few compounds exhibited mild to moderate cytotoxicity towards non-cancerous kidney cell lines.