Separation and determination of cardiac glycosides in digitalis purpurea leaves by micro high-performance liquid chromatography

Identification of (antioxidative) plants in herbal pharmaceutical preparations and dietary supplements

The standard procedures for the identification, authentication, and quality control of medicinal plants and herbs are nowadays limited to pure herbal products. No guidelines or procedures, describing the detection or identification of a targeted plant or herb in pharmaceutical preparations or dietary supplements, can be found. In these products the targeted plant is often present together with other components of herbal or synthetic origin. This chapter describes a strategy for the fast development of a chromatographic fingerprint approach that allows the identification of a targeted plant in herbal preparations and dietary supplements. The strategy consists of a standard chromatographic gradient that is tested for the targeted plant with different extraction solvents and different mobile phases. From the results obtained, the optimal fingerprint is selected. Subsequently the samples are analyzed according to the selected methodological parameters, and the obtained fingerprints can be compared with the one obtained for the pure herbal product or a standard preparation. Calculation of the dissimilarity between these fingerprints will result in a probability of presence of the targeted plant. Optionally mass spectrometry can be used to improve specificity, to confirm identification, or to identify molecules with a potential medicinal or antioxidant activity.

Cardenolides content in wild Sardinian Digitalis purpurea L. populations

In order to quantify the amounts of digitoxigenin and gitoxigenin in wild Sardinian Digitalis purpurea L. an easy extraction method and an high performance liquid chromatography (HPLC) analytical technique have been set up. The analyzed samples, stemming from six different locations, showed a great variability in glycoside content. The HPLC analyses carried out on 2-year-old plants of D. purpurea showed that the amounts of digitoxigenin and gitoxigenin ranged between 11.34 and 240.59 mg kg(-1) and 4.05 and 178.07 mg kg(-1), respectively, calculated on fresh material. Chemometric analyses, carried out considering different morphological characters, showed that correlations between morphological variations and glycoside content are poor.

Multiresidue screen for cardiotoxins by two-dimensional thin-layer chromatography

A two-dimensional thin-layer chromatographic method was developed for the qualitative determination of the cardiotoxins oleandrin, gitoxin, digitoxin, gitoxigenin, and grayanotoxins I, II, and III in gastrointestinal contents (stomach, rumen, colon, and cecum contents), feces, and plant material. The cardiotoxins were extracted with dichloromethane. The extract was cleaned up by charcoal and reverse phase solid-phase extraction columns. Analysis was performed by two-dimensional thin-layer chromatography on silica gel plates and visualized by aluminum chloride followed by chloramine T spray. The method detection limits were 0.05 microg/g for oleandrin, 0.1 microg/g for gitoxin, and 0.2 microg/g for the other toxicants in gastrointestinal contents and feces and were 5 times higher in plant material. Four replicate fortifications of bovine rumen contents, bovine feces, and alfalfa at these levels were all well recovered. The diagnostic utility of the method was tested by analyzing samples submitted to the veterinary toxicology laboratory.

High-performance liquid chromatographic determination of secondary cardiac glycosides in Digitalis purpurea leaves

An analytical method for the determination of secondary cardiac glycosides in Digitalis purpurea leaves by high-performance liquid chromatography (HPLC) is described. The procedure consisted of extraction of dry leaf powder with ethanol-chloroform (2:1) and clean-up by Sep-Pak cartridges prior to HPLC analysis. HPLC was performed on an octylsilyl bonded silica column, using acetonitrile-methanol-water (4:4:5) for trisdigitoxosides and acetonitrile-methanol-water (8:30:43) for strospeside; the effluent was monitored by ultraviolet detection (at 220 nm). Quantitation of these cardiac glycosides was carried out by the internal standard method. The amounts of digitoxin, gitoxin, gitaloxin and strospeside per 100 mg of dry leaf powder were estimated to be 22.6, 14.0, 54.7 and 1.9 micrograms, respectively. The method is sufficiently sensitive and reproducible to assay secondary glycosides in Digitalis purpurea leaves.

Micro high-performance liquid chromatographic determination of cardiac glycosides in beta-methyldigoxin and digoxin tablets

A micro high-performance liquid chromatographic (micro-HPLC) method has been developed for the assay of beta-methyldigoxin and digoxin tablets. Quantitation of cardiac glycosides in tablets was carried out by the incorporation of dexamethasone as an internal standard. The procedure consisted of disintegration of tablets, extraction with acetone-ethanol (9:1) and injection for micro-HPLC on an ODS micro column, using acetonitrile-water (28:72) for beta-methyldigoxin tablets and methanol-water (1:1) for digoxin tablets; the effluent was monitored by UV detection at 220 nm. The average values of the contents in beta-methyldigoxin and digoxin tablets were 99.6 and 100.2% of the labelled amounts, respectively. The proposed method is sufficiently precise and sensitive to examine the content uniformity of tablets.

Are immunoassays for digoxin reliable?

The specificity of radioimmunoassay and fluorescence polarization immunoassay procedures for the measurement of digoxin has been assessed. Many steroids and lipids have been found to interfere and give false positive results for digoxin under the conditions of the study. Caution is recommended in the interpretation of digoxin measurements made by immunoassay procedures.