MP and MPM containing cardiac glycosides

Cardiac glycosides are a big group of substances, derivatives of cyclopenthaneperhydropenantrene which have in the С-17 position unsaturated lactone cycle and selectively affect the heart muscle Cyclopentaneperhydrophenanthrene

Its formation may be considered as a general mechanism of steroid biosynthesis. The familiar is acetate → mevalonate →isopentenyl pyrophosphate → squalene → cholesterol pathway. To obtain the optimum cardiac activity, the aglycone should possess an α/β unsaturated lactone ring that is attached at the l7-position of the steroid nucleus and the A/B and C/D ring junctions should have the cis-configuration.

CardenolideBufadienolide Two types of cardiac glycoside may be distinguished according to whether there is a five-or six-membered lactone ring. These types are known respectively as cardenolides (e.g. digitoxigenin) and bufanolides or bufadienolides (e.g. sciliarenin). The bufadienolides derive their name from the generic name for the toad, Bufo (the prototype compound bufalin was isolated from the skin of toads)

Cardiosteroids Cardenolides Bufadienolides Digitalis groupStrophantus group

Characteristic Features are: l. An unsaturated lactone ring attached to steroid nucleus at C 17 with β- configuration. 2. A tertiary p-hydroxy group at C An axially oriented hydroxy group at C 3 to which the sugar residueis attached. 4. The cis fusion of the ring C/D and in most cases of the rings A/B as well. 5. Methyl groups at C 10 and C The methyl group at C 19 may be replaced by a CHO or CH 2 OH group (e.g. Strophanthus). 7. Additional hydroxy groups may be present at C 1, C 5, C 11, C 12, and C 16.

The sugars when combined with the aglycones increase both the potency and toxicity of the active principle. In addition, the sugars afect certain physical properties of this chemical combination, such as solubility in water and difusion through semipermeable membranes and consequently the rate of absorption and transportation of the compounds. The genin may be attached to one, two, three, or four monosaccharide molecules, which have the chain structure of di-, tri- or tetrasaccharides. Thus, from a single genin one may have a series of tetra-, tri-, di-, or mono-glycosides. Some of the sugar units found in cardiac glycosides are normal ones such as the hexose, glucose and the methyl pentose rhamnose; others are desoxy sugars containing less than the normal amount of oxygen, they have so far not been found in nature except in cardiac glycosides. Among these sugars, which are sometimes referred to as the 'rare’ sugars, antiarose (deoryglucose); digitalose (a methyl ether of antiarose) may be mentioned.

D-digitoxose D-Cymarose L-Oleandrose The presence of acetyl groups generally tends towards diminishing the cardiac activity It may be also noted that digitoxose and cymarose are 2-deoxy sugars, which give certain reactions on deoxysugar ( e.g. Keller- Killiani test).

Physicochemical properties Cardiac glycosides are colourless or white crystals, or amorphous substances, without odour, taste is bitter, they have melting temperature ( ºC), optically active, many of them have fluorescence in UV-light. Many of them are bad soluble in water, good soluble in water solutions of methyl and ethyl alcohols. Glycosides with long carbon chain are better soluble in water and water-alcohol solutions, aglycones- in organic solvents. Cardiac glycosides are colourless or white crystals, or amorphous substances, without odour, taste is bitter, they have melting temperature ( ºC), optically active, many of them have fluorescence in UV-light. Many of them are bad soluble in water, good soluble in water solutions of methyl and ethyl alcohols. Glycosides with long carbon chain are better soluble in water and water-alcohol solutions, aglycones- in organic solvents. They can hydrolyse under acids, mild bases and ensymes They can hydrolyse under acids, mild bases (removes O-acetyl group) and ensymes

Methods of obtaining The main method of obtaining of cardiac glycosides is extraction. Extragents is alcohol or alcohol-water mixture. The fatty matter is removed from the plant material by extraction with petroleum ether. The defatted material is digested with water at 0-4 degree to remove the polysaccharides. The water extract is discarded and the marc is extracted with several portions of water–ethanol mixtures increasing the alcohol content progressively. The hydroalcoholic extract is concentrated to a smaller volume by distilling it in vacuum at 50 degree. Tannins are precipitated from the concentrate with lead hydroxide, and filtered. The filtrate is treated according to the rate of solubility of the glycosides in water as follows.

Test for Sterols Liebermann test for sterols: This test is characteristic of aglycones of the scillarenin type (the squill glycosides) and is due to the steroid part of the molecule. The test is carried by adding one drop of concentrated sulphuric acid to a solution of the glycoside in glacial acetic acid. A change in colour occurs from red, through violet and blue to green. Test with antimony trichloride: Both the cardenolides and the bufadienolides( scilladienolides) give this colour reaction. When most of these cardioactive glycosides are heated with antimony trichloride and trichloracetic acid, a blue or violet colour is obtained. Test for Aglycone Moiety Legal test: This is a test for unsaturated lactones. The test may be carried out as follows: A small quantity (a few mg) of the glycoside (except scillaren) is dissolved in a few drops of pyridine. A drop of 2% sodium nitroprusside and a drop of 20 % sodium hydroxide solution are then added. Production of a deep red colour gives a positive test

Raymond test: A positive Raymond test depends on the presence of an activated methylene group (C 31, in the lactone ring of the cardenolides). A small quantity of glycosidei s dissolvedi n 1 ml of 50 % ethanol, and this is followed by the addition of 0,1 ml of 1 % solution of dinitrobenzene in ethanol (or methanol). To this solution two or three drops of 20 % sodium hydroxide solution are then added. Appearance of a violet colour (which then changes to blue) gives a positive test. Kedde reagent: This is widely used for spraying developed chromatograms of the cardenolides( or glycosides containing cardenolide aglycones). This reagent is essentially a modified form of the reagents used for the Raymond test. The Kedde reagent may be prepared by mixing equal volumes of 2% solution of 3,5-dinitrobenzoic acid in methanol and 5-7 % aqueous solution of potassium hydroxide. The cardenolides react with this reagent to give a blue or violet colour which fades in one or two hours. Tollens test: A small quantity of glycoside is dissolved in a few drops of pyridine. Ammonia silver nitrate solution is then added. Liberation of silver gives a positive test

Test for Sugars Keller-Kiliani test: The 2-deoxy sugars. This test may not be reliable if the sugar is acetylated. Glycoside is dissolved in glacial acetic acid containing a trace of ferric chloride; concentrated suphuric acid containing the same amount of ferric chloride is placed at the bottom of the test tube with a pipette. An intense blue colour develops at the surface between the two reagents in 2-5 minutes spreading gradually into the acetic acid layer. Xanthydrol test: This test is given by 2-deoxy sugars. When these are heated in the solution of xanthydrol in glacial acetic acid containing 1 % HCl, a red colour is developed

Quantitatirre Determination 1. colourirnetric method; 2. fluorimetric melhod; 3. gravimetric method; 4. biological method (deternination of LD 50 ); 5. immunoassay(radioimmunoassay); 6. RP-HPLCw ith UV or fluorometric detector.

Biological action The overall action of the digitalis glycosides is complicated by the number of different effects produced, and their exact mode of action on myocardial muscle in relation to current views on cardiac muscle physiology is still an area of investigation. Digitalis is probably acts in competition with K+ions for specific receptor enzyme (ATPase) sites in the cell membranes of cardiac muscle and is particularly successful during the depolarization phase of the muscle when there is an influx of Na+ ions.

The clinical effect in cases of congestive heart failure is to increase the force of myocardial contraction (the positive inotropic effect) resulting in a complete emptying of the ventricles. CG are also used to control supraventricular (atrial) cardiac arrhythmias. The diuretic action of digitalis, important in the treatment of dropsy, arises from the improved circulatory effect. The differ in the pharmacokinetics of CG according to their lipophilicities: - absorption after oral administration; - plasma protein binding; - rate of elimination; - onset of action; - duration of action; - mode of excretion.

Administration Glycosides with a long duration of action. Digitoxigenin derived glycosides are characterized by a long duration of action, e.g. digitoxin (Lanatoxin, Digilong, Digimerck). Glycosides with a medium duration of action. Digoxin (Lanoxin, Digacin, Lanicor’ and its derivatives have intermediate pharmacokinetic properties between digitoxin and the short acting Strophanthus glycosides. Acetyldigoxin (Dioxanin, Lanatilin) is prepared from lanatoside C by removal of the terminal glucose unit by enzyme hydrolysis. Glycosides- with a short duration of action. Strophanthus glycosides are characterised by a rapid onset and a very short duration of action, used only for intravenous therapy. Ouabain (Purostrophan, Strodival') and Proscillaridin (Sandoscill, Talusin) are used when the rapid action is required, especially in acute congestive heart failure.

Distribution in nature In plants cardiac glycosides appear to be confined to the Angiosperms. Cardenolides are the most common and are particularly abundant in the Apocyanaceae and Asclepidiaceae, but are also found in some Liliaceae, Ranunculaceae, Moraceae, Cruciferae, Euphorbiaceae, Tiliaceae, Leguminosae and Scrophulariaceae. In plants cardiac glycosides appear to be confined to the Angiosperms. Cardenolides are the most common and are particularly abundant in the Apocyanaceae and Asclepidiaceae, but are also found in some Liliaceae, Ranunculaceae, Moraceae, Cruciferae, Euphorbiaceae, Tiliaceae, Leguminosae and Scrophulariaceae.

Collection Either first- or second-year digitalis leaves are permitted by pharmacopoeias. There has been a long-standing general belief that the pharmacological activity of leaves increases during the course of a day to reach a maximum in the early afternoon. After collection the leaves should be dried as rapidly as possible at a temperature of degree and subsequently stored in airtight containers protected from the light. Their moisture content should not be more than about 60 %

Raw materials are storaged on the list B (potent substances) ; Strophantus seed – list А (poisonous substances).

MP and MPM containing cardiac glycosides

Digitalis leaves (Purple foxglove leaves) - Digitalis Folia, EuPh Digitalis purpurea- Purple Foxglove, Digitalis Scrophulariaceae Content : minimum 0.3 per cent of cardenolic glycosides, expressed as digitoxin (Mr 765) (dried drug). IDENTIFICATION A. The leaf is brittle and often occurs broken. The upper surface is green and the lower surface is greyish- green. The apex is subacute and the margin is irregularly crenate, dentate or serrate. The base is decurrent. The venation is pinnate, the lateral veins being prominent especially on the lower surface, leaving the midrib at about 45° and anastomosing near the margin ; a veinlet terminates in each tooth of the margin and the lower veins run down the winged petiole. The upper surface is rugose and pubescent; the lower surface shows a network of raised veinlets and is densely pubescent.

B. Reduce to a powder (355) (2.9.12). Examine under a microscope. The powder shows the following diagnostic characters : epidermal cells with anticlinal walls which are straight or slightly sinuous on the upper surface and markedly sinuous on the lower surface; the cuticle is smooth. Trichomes are of 2 types: uniseriate, non-glandular, usually of 3-5 cells, often with 1 or more collapsed cells, walls mostly finely warty or faintly striated; glandular trichomes usually with a unicellular, sometimes a multicellular uniseriate stalk and a unicellular or bicellular or exceptionally tetracellular head. Anomocytic stomata are absent or very rare on the upper surface, numerous on the lower surface. Calcium oxalate crystals and sclerenchyma are absent.

C. Thin-layer chromatography Reference solution. Dissolve 5 mg of purpureaglycoside A CRS, 2 mg of purpureaglycoside B CRS TESTS Foreign matter (2.8.2). There are no leaves with few or no trichomes and epidermal cells showing, in surface view, beaded anticlinal walls (Digitalis lanata). Loss on drying (2.2.32) : maximum 6.0 per cent, determined on g of the powdered drug (355) (2.9.12) by drying in an oven at 105 °C. Total ash (2.4.16) : maximum 12.0 per cent. Ash insoluble in hydrochloric acid (2.8.1) : maximum 5.0 per cent. ASSAY From the absorbances at 540 nm measured and the concentrations of the solutions, calculate the contant of cardenolic glycosides, expressed as digitoxin.

Constituents. Constituents. Cardioactive steroid glycosides: - A-sequence (aglycone digitoxigenin): purpurea glycoside A (primary glycoside), digitoxin (secondary glycoside); - B-sequence (aglycone gitoxigenin): purpurea glycoside B (primary glycoside), gitoxin (secondary glycoside); - E-sequence (aglycone gitaloxigenin): gitaloxin, glucoverodoxin. Steroidal saponins digitonine, desgalactotigonin, purpureagitoside. Anthracene derivatives: anthraquinones.

Digitalis is extensively used as a cardiac stimulant and tonic and as a diuretic. Digitoxin, gitoxin and cordigit are used in treatment of chronic (or less often acute) heart failure of II and III levels. The action of these medicines begins in min, and lasts from 8 to 24 hours. The medicines from Digitalis can accumulate in the body and thus they must be combined with other medicines, which do not accumulate.

Digitalis lanata leaf - Digitalis lanatae folia Digitalis lanata- Grecian Foxglove, Wooly foxglove Scrophulariaceae Constituents. The leaves contain the crystalline glycosides digitoxin, gitoxin and digoxin each occurring free as well as combined with an acetyl group and a molecule of dextrose. In the combined form, these substances are known respectively as lanatosides A, B and C. Constituents. The leaves contain the crystalline glycosides digitoxin, gitoxin and digoxin each occurring free as well as combined with an acetyl group and a molecule of dextrose. In the combined form, these substances are known respectively as lanatosides A, B and C. Uses. Medicines from Digitalis lanata have more benefits than medicines from Digitalis purpurea: they less accumulate in body, have faster action on heart, more compatible. Uses. Medicines from Digitalis lanata have more benefits than medicines from Digitalis purpurea: they less accumulate in body, have faster action on heart, more compatible. In medicine. In medicine digoxin, celanid, isolanid, lanicor, lanatosid and lanatosid C are widely used.

Applying: chronic heart failure, heart rhythm disturbances The action of the drug begins after hours, the maximum effect starts after 2-6 hours.

Strophantus seed – Strophanthi semina Strophanthus species - Strophantus Kombe Oliv. Strophantus hispidus DC, Strophanthus gratus (Hook.) Apocynaceae Constituents. Cardenolides, 3-8 %, chief glycoside strophanthin-G (ouabain, over 80 %), strophanthin-K, about 30% of fixed oil, kombic acid, strophantic acid, the alkaloids trigonelline and choline, saponins (0,2 %) etc. Constituents. Cardenolides, 3-8 %, chief glycoside strophanthin-G (ouabain, over 80 %), strophanthin-K, about 30% of fixed oil, kombic acid, strophantic acid, the alkaloids trigonelline and choline, saponins (0,2 %) etc. Uses. Cardiac stimulant (of strophant group) and diuretic. For treatment Strophantin-K (in ampoules) is widely used. Strophantin-G is used as a standard in biological assessment of medicines. Uses. Cardiac stimulant (of strophant group) and diuretic. For treatment Strophantin-K (in ampoules) is widely used. Strophantin-G is used as a standard in biological assessment of medicines.

S t rophanthin-G is used as a standard when evaluating the biological activity of MPM and remedies that contain cardio glycosides Indications. Acute heart failure and congestive chronic heart failure in the decompensation stage. Acute cardiovascular failure, decompensated form of chronic circulatory blood failure of II and III stages

Adonidis vernalis herba Adonis vernalis- Pheasant’s Eye, False Hellebore, Spring Adonis Ranunculaceae Constituents. Cardenolids: adonitoxin, cymarin, K- strophanthin-β; flavonoids, including vitexin and luteolin; saponins, tannins, carotines, ascorbic acid.

Uses. Together with cardiotonic action, which is lower than strophantus and foxglove have, medicines from Adonis have sedative action on CNS. Infusion is part of Behterev’s mixture, which also contains sodium bromide and codein. Dry extract of adonis (1:1 or 2:1) is used for the production of tablets and infusions. Tablets adonis-brom are used as sedative agent. Adonisid is part of cardiovalen, cardiofit, dry adonisid. Hypnotic and sedative. The drug has sedative and cardiotonic activities. The nature of Spring Adonis glycosides occupy the intermediate position between strophanthus and digitalis. They manifest on heart positive inotropic (increase the force of myocardial contraction), negative chronotropic (decrease the rate of heart contraction) and negative bathmotropic effect (reduced excitability of the heart muscle). Comparing with other glycosides Adonis drugs are characterized by a more expressed sedative and diuretic action

Used at the rheumatic heart disease, Infarction with disorders of blood circulation, stenocardia (angina), vegetative neurosis used in the treatment of neuro dystonia neuroses of the heart, coronary heart disease, hypertension (I-II stage)

Convallariae herba Convallariae folia Convallariae flores Convallaria majalis- Lily-of-the-Valley Convallariaceae Constituents. The cardiac tonic glycoside convallatoxin occurring in needle-like crystals only slightly soluble in water; the glycoside convallamarin, soluble in water, to which is ascribed cardiac stimulant properties; another glycoside convallarin (insoluble in water) which is emetic and cathartic; starch; calcium oxalate, etc. Constituents. The cardiac tonic glycoside convallatoxin occurring in needle-like crystals only slightly soluble in water; the glycoside convallamarin, soluble in water, to which is ascribed cardiac stimulant properties; another glycoside convallarin (insoluble in water) which is emetic and cathartic; starch; calcium oxalate, etc. Uses. Tincture (1:10), corglicon, Zelenin drops, convaflavin is used as cholagogue medicine and part of marelin. Uses. Tincture (1:10), corglicon, Zelenin drops, convaflavin is used as cholagogue medicine and part of marelin.

Corglycon – (the sum of GC from Convallaria majalis) has a cardiotonic activity. Apply at acute and chronic blood circulation failure of the 2-nd and 3-th stages Zelenin drops have a sadative and spasmolitic activity. Prescribe at : dystonia spasms digestive tract of renal And hepatic colic, hyperacidic gastritis, chronic Gastritis increased excitation

Pharmacotherapeutic group. Hypnotics and sedatives. Prescribe at : c ardiovascular neurosis accompanied by bradycardia. Valocarmid has sedative and spasmolitic activity. The specific effect of the drug is due to the presence of the substances that are part of it. Valeric acid causes a calming effect on the central nervous system. The tincture of belladonna blocks the M-cholinergic receptors of smooth muscles of internal organs, so that makes spasmolitic action. Tincture of lily of the valley increases the myocardial contraction property, stroke and minute volume of blood. Sodium bromide enhances the processes of inhibition in the cortex, restores the balance between the processes of excitation and inhibition in hyperexcitability. Menthol, irritates the mucous of the mouth, reflexively dilates coronary vessels.

Erysimi canescentis recens herba Erysimum canescens- Erysimum Brassicaceae Constituents. The cardiac tonic glycoside (up to 6% in seeds and 1 to 1.5% in leaves). The main glycosides are erysimin and erysimoside. Constituents. The cardiac tonic glycoside (up to 6% in seeds and 1 to 1.5% in leaves). The main glycosides are erysimin and erysimoside. Uses. Employed as cardiac stimulant. Pharmacological action is similar to Strophantus preparations. Erysimin has cardiotonic, sedative and diuretic action. Juice is part of. Uses. Employed as cardiac stimulant. Pharmacological action is similar to Strophantus preparations. Erysimin has cardiotonic, sedative and diuretic action. Juice is part of cardiovalen.