Medical drugs, derivatives of aliphatic cyclic compounds. Derivatives of adamantane: influence of the functional groups on the pharmacological action. Terpenoids: general characteristic, sources of obtaining, methods of analysis, storage and usage.
Derivatives of alicyclic compounds include polymethylene hydrocarbones, which have cyclic structure and their chemical properties similar to alkanes.
From the many derivatives of cycloalkanes only cyclopropane and adamantane derivatives are used in the medicine.
Cyclopropane (Cyclopropanum)
Cyclopropane (in the mixture with oxygen) now rarely used as a means for inhalation anesthesia.
Adamantane derivatives
Adamantane by the chemical structure is tricyclo[3,3,1,13,7]decane, that containes three condensed cyclohexane rings with two general Carbon atoms.
• For the first time adamantane derived from petroleum. It si the crystalline compound with a slight odor of camphor and melting temperature 269 °С.
• The first data about the antiviral activity of 1-aminoadamantane derivatives were published in 1964 year. Then it was found that adamantane derivatives are biologically active compounds with a wide spectrum of action. Among them are found compounds that exhibit not only antiviral but also antibacterial, anticonvulsant, antisecretory and vasodilator action.
• In the medical practice midantane, gludantane and remantadine are used.
Midantane (Midantanum)
Amantadine hydrochloride*
1-aminoadamantane hydrochloride
Characters. White crystalline powder with a faint odor and a bitter taste. Soluble in water and chloroform, readily soluble in alcohol, practically insoluble in ether.
Identification of midantane
1. Reaction on chloride ions (by the conjugated HCl): with AgNO3 solution in the presence of nitrate acid; a white amorphous precipitate AgCl will form, which is insoluble iitric acid, but readily soluble in dilute solution of ammonia NH4OH:
Cl– + Ag+ ® AgCl↓
AgCl + 2NH4OH = [Ag(NH3)2]Cl + 2H2O
2. Boiling of the substance with the solution of alkali; medicine decomposes with the evaporation of ammonia NH3, which can be detected by the blue color of the moist red litmus paper.
R–NH2×HCl + NaOH ® R + NH3 + NaCl + H2O
3. Reaction with 2-nitroindanedione-1,3 solution; yellowish precipitate will form (reaction on midantane-base – 1-aminoadamantane).
TEST ON PURITY
Checks the loss in weight on drying, sulfate ash, heavy metals content (up to 0,001%), acidity and alkalinity of the solutions.
Assay
Acidimetry, nonaqueous titration by the standard solution of perchloric acid in the media of concentrated acetic acid, at the presence of mercury acetate and crystal violet indicator (from violet to blue-green colorу). Еm = M. m.
Storage
Potent drug list. In the airtight container, in a dark place.
Aplication
Antiparkinsonian agent. Initially, the drug was proposed as an antiviral agent, and later was discovered its effectiveness in parkinsonism different etiologies
Medical drug with quick action. Take orally after meals in the form of 0.1 g tablets coated by yellow surface. The duration of treatment – 2-4 months. You can take alone or in combination with other medical drugs.
Gludantane (Gludantanum)
glucurenide 1-aminoadamantane (midantan)
Characters. White or white with a faint yellowish tinge crystalline powder. Not soluble in water and alcohol.
Application. Antiparkinsonian and antiviral agent. As an antiviral agent used at ocular viral infections as 0.5% aqueous solution. Method of issuance: pills of 0.2 g, 0.5% solution in 10 ml vials.
Gludantane (Gludantanum)
glucurenide 1-aminoadamantane (midantan)
Characters. White or white with a faint yellowish tinge crystalline powder. Not soluble in water and alcohol.
Application. Antiparkinsonian and antiviral agent. As an antiviral agent used at ocular viral infections as 0.5% aqueous solution. Method of issuance: pills of 0.2 g, 0.5% solution in 10 ml vials.
Gludantane identification
1. Reaction with Felling reagent (reducing properties of glucuronic acid); red color precipitate Cu2O will form.
Сu2+ + 2OH– → Сu(OH)2↓;
2KNa[Cu(C4H4O6)2] + RCHO + 3NaOH + 2KOH → 2СuOH↓ + RCOONa + + 4KNaС4H4O6 + 2H2O;
2CuOH → Cu2O↓ + H2O.
2. Reaction with sodium nitroprusside Na2[Fe(CN)5NO] in the presence of acetone and sodium carbonate ; green color will form.
Assay
Acidimetry, nonaqueous titration (see midantane). Еm = M.m.
Storage
Potent drug list. In an airtight container, in a dark place.
Remantadine (Remantadinum)
Remantadine hydrochloride*
1-adamantyl-1-aminoethane hydrochloride
Characters. White crystalline powder, odorless with bitter taste. Slightly soluble in water, soluble in alcohol and chloroform.
Appliation. Antiviral agent. Used for prevention and early treatment of influenza in a pill form (after eating) of 0.05 g.
Remantadine receiving
Reductive amination of adamantylmethylketone using formamide HCONH2 by the following scheme:
Assay
Acidimetry, nonaqueous titration (see midantane).
Еm = M. m.
Storage
Potent drug list. In the airtight container, in a dark place.
Remantadine identification
1. Reaction on chloride ions (by the conjugated HCl): with solution of AgNO3 in the presence of nitrate acid; white amorphous precipitate of AgCl will form, which is not soluble in nitrate acid, but easy soluble in dilute solution of ammonia NH4OH:
Cl– + Ag+ ® AgCl↓
AgCl + 2NH4OH = [Ag(NH3)2]Cl + 2H2O
2. Reaction with sodium nitroprusside Na2[Fe(CN)5NO] in the presence of CH3COCH3 and Na2CO3; violet color will form.
Test on purity
During the control of goodquality transparency, color and pH of solution are checked, content of ammonium chloride impurity (not more then 0.1%) and others.
Medical substances – derivatives of terpenes
Terpenes are hydrocarbons and their oxygen containing derivatives, that are a part of the essential oils and resins of conifers and other plants. Chemical structure of different terpenes have much in common. These molecules consist of various amounts connected with each other remnants of isoprene – 2-methylbutadiene-1,3.
Therefore, the general formula of terpenes are multiples to С5Н8, ie (С5Н8)n. Terpenes can have alicyclic and cyclic structure. Among of the terpenes distinguish monoterpenes (С10Н16), sesquiterpenes (С15Н24), diterpenes (С20Н32), triterpenes (С30Н48) and polyterpenes ((С5Н8)n). Cyclic terpenes can have mono- and bicyclical structure.
The first research of the synthesis and study of the chemical structure of terpenes belong to the early nineteenth century. In 1803 y. pharmacist Kind got bornylchloride (“synthetic camphor”) from turpentine. D. I. Mendeleev studied essential oils and resins. In the early twentieth century E. E. Wegner was established structure of pinene, camphene, linomene and others terpenes, which belong to the pine turpentines. Extensive research in the field of terpenes russian scientists made: L. S. Ruzichko, A. M. Zaitsev, F. M. Flavitskyy, N. D. Zelinskyy, S. S. Nametkina, A. E. Favorskyy, V. E. Tishchenko, B. A. Arbuzov.
Medical substances from terpene group by the chemical structure can be classified on mono- and bicyclical terpenes. Their derivatives – terpenoids – according to the character of functional group divided on alcohols, aldehydes, ketones, esters, acids and etc.
Medical drugs – derivatives of monocyclic terpenes
Three medical drugs from the monocyclic terpenes: menthol, “Validol”, terpin hydrite by the chemical structure are derivatives of hydroaromatic hydrocarbon – menthane (1-methyl-4-(methylethyl) cyclohexane).
In the medical practice l–menthol is used (levorotatory isomer of menthol) and racemic menthol, which contains sum of stereoisomers, including not less than 70 % of d,l–menthol.
Menthol racemic
(Mentholum racemicum) (SPhU)
A mixture of equal parts of (1RS,2SR,5RS)-5-methyl-2-(1-methylethyl)cyclohexanol
Menthol molecule includes 3 asymmetric Carbon atoms; it means that can exist 23 = 8 optical active isomers and 4 racemates.
Menthol is found in the essential oil of peppermint in a free state and partly in the form of ether of acetic acid.
The content of menthol in the essential oil depends on a variety of mint, place and conditions of cultivation.
Menthol receiving
1. From peppermint essential oils:
а) freezing method used for essential oil containing menthol to 80 %. In the fractional distillation of peppermint oil isolated fraction which boils at 208-212 °С, after the cooling of this fraction to -20 °С menthol crystals allocated;
b) borate method – for varieties of mint oils containing menthol to 50-60 %. Essential oil is heated with boric acid under the reduced pressure:
Menthol ester of boric acidhas a high boiling point, allowing it to separate from other components of peppermint oil. Then after the distillation of the ether with water vapor as a result of hydrolysis menthol is obtained.
2. Menthol (racemate) can be synthesized by the reducing of menthone, which contained in the peppermint oil:
3. In the industry menthol (racemate) is obtained by the interaction of m-cresol with isopropylchloride followed by hydrogenation of thymol under the pressure and in the presence of catalysts:
Characters of the racemic menthol
Crystalline powder, granular or as agglomerates or prismatic or needle colorless shiny crystals with a strong peppermint smell and taste that cold. Volatile at ordinary temperatures (melting temperature about 34 °C), distilled with steam. Practically insoluble in water, easily soluble in 96% alcohol, ether and petroleum ether, easily soluble in fatty oils and liquid paraffin, slitly soluble in glycerol. With camphor, thymol, phenol, resorcinol, chloral hydrate forms the eutectic mixtures.
Test on purity
In the purity determination spend definition of transparency and color of solution S, кислотності acidity or alkalinity, optical rotation (+0,2º – -0,2º), accompanying impurities (method of GCh), mass of the dry residue.
Identification of menthol
1. By the physico-chemical constants: specific optical rotation, methods of thin-layer and gas chromatography.
2. By the reaction of the formation of ester with dinitrobenzoyl chloride in the presence of anhydrous pyridine, which identified by melting point determination:
3. Non-pharmacopoeial reaction.
а) IR-spectroscopy .
b) Color reaction with o-phthalic anhydride – in the presence of H2SO4 conc. orange-red color appears.
с) An alcoholic solution of furfural after the mixing with menthol and H2SO4 conc. becomes purple.
d) In the presence of menthol gray-green color of vanadium oxyquinolinate benzene solution when heated in a water heater goes into the red .
е) At the action of vanillin solution in concentrated sulfuric acid observed yellow color, which when added water becomes crimson.
The reaction is based on the oxidation and the interaction of the activated methylene group of menthol with aromatic aldehydes:
Assay of menthol
1. SPhU does not require a quantitative definition of the substance.
2. Gas-liquid chromatography.
3. Photocolorimetry based on the color reactions with aldehydes .
4. Acetylation method, the reverse titration .
Medical substance acetylated with acetic anhydride in the medium of anhydrous pyridine (at the heating with Libich refrigerator). An excess of acetic anhydride decomposed with water to the acetic acid and titrated it with sodium hydroxide solution, indicator – phenolphthalein. In parallel control experiment sould be conducted. Еm= М.m.
Storage and usage of menthol
In the airtight container, in a cold, dark place, at the temperature <15ºС.
Externally as a sedative, analgesic and weak antiseptic mean to treat inflammatory diseases of the upper respiratory tract in the form of 0,5-5% alcohol and oil solutions. Internally (1-2 drops of 5% alcoholic solution on sugar for sublingual receiving) at stenocardia as antispasmodic mean.
Levomenthol (Levomentholum) (SPhU)
(1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexanol
l–menthol (levorotatory isomer of menthol)
Characters. Prismatic or needle, colorless, shiny crystals. It melts at a temperature about 43 °С. Practically insoluble in water, very easily soluble in 96 % alcohol, ether and petroleum ether, easily soluble in the fatty oils and Vaseline oil, very slightly soluble in glycerin.
Identification and test on purity are similar to racemic menthol except optical rotation value (-48º – -51º).
Validol (Validolum)
25-30 % solution of menthol in menthyl ester of isovaleric acid
Extraction. By the reaction of menthol etherification by isovaleric acid menthyl ester of isovaleric acid obtained, in which menthol dissolved.
Characters. Transparent oily liquid with a smell of menthol. Practically insoluble in water, easily soluble in alcohol.
Validol identification
1. Reaction on menthol with vanillin in concentrated sulphatic acid (equations of reactions, see menthol).
2. Density 0,894-0,907 g/sm3.
3. By GLCh revealed, that validol is a more complex mixture according to the composition, which contains besides 22,2-25,7 % of menthol and 52,7-55,7 % of isovaleric acid menthyl ester also 17,4-18,9 % of 2-methylbutyric acid menthyl ester and 2,2-5,9 % of menthene series hydrocarbones (menthene-1, menthene-2, menthene-3).
Usage
Mean, that has a sedative effect on the central nervous system, has a moderate reflex vasodilator effect. Assign to treat stenocardia, nervousness, sea and air diseases.
Release forms: bottle–droppers of 25 % solution; tabl. by 0,06 g № 6 and 10.
Assay of validol
1. Alkalimetry, reverse titration.
Define content of isovaleric acid menthyl ester by the its hydrolysis with alcohol solution of КОН, an excess of which titrated with HCl solution, indicator – phenolphthalein. In parallel control experiment conducted. Еm= М.m.
2. GLCh.
Storage
In a cold place, in the airtight container.
Terpin hydrate (Terpinum hydratum)
п-Mentanediol-1,8-hydrate
Characters. Colorless transparent crystals or white crystalline powder, odorless, with slightly bitter taste. Not soluble in water, chloroform, ether, soluble in alcohol. Sublimes at a slow heating to 100 °С, forming the cooling needle crystals. In a dry warm air slowly evaporates.
Receiving of terpin hydrate
Hydratation of pinene that contained in the pinene fraction of turpentine. For this turpentine mixed with sawdust and add 25 % sulfuric acid, leave in the cold place for 10-14 days. Terpin hydrate falls in the form of precipitate.
Identification of terpinehydrate
1. When added concentrated H2SO4 to the hot solution of terpinehydrate liquid becomes turbid and acquires fragrant smell of terpineol and cineol (eucalyptol):
2. At the evaporation of terpinehydrate to the dry state with an alcoholic solution of FeCl3 in a porcelain cup dark red, purple, green colorу appear simultaneously in the different places, and when added to the cooled residue benzene – blue.
3. Temperature of melting 115-117 °С.
4. Does not give the reaction with vanillin.
Assay of terpin hydrate
For the substance AND does not provide quantitative determination.
Terpin hydrate content can be detected by colorimetric method, which based on the reducing of phosphor wolfram acid.
Quantitative content of terpin hydrate in tablets determined by gravimetric method with its extraction by ethanol. Ethanol is distilled off, the residue weighed.
Storage and usage
In the TCC (tightly closed conteiners).
Internally. In the treatment of chronic bronchitis as an expectorant.
Codterpin IC tabl. – codeine phosphate, terpin hydrate, sodium hydrocarbonate.
Alex Plus lozenges – terpin hydrate, dextromethorphan hydrobromide, levomenthol.
Medical drugs – derivatives of bicyclic terpenes
Bicyclic terpenes – a compounds consisting of two fused non-aromatic cycles.
As a medicinal substance use natural bicyclic terpene – camphor and its derivatives – bromcamphor and sulfocamphoric acid. These substances are derivatives of hydrocarbon camphene (bornylane) (1,7,7-trimethylbicyclo[2,2,1]heptane). Camphor is a ketoderivatives of camphane.
Due to the presence in its molecule two asymmetric Carbon atoms are d–camphor (dextrorotatory isomer), l–camphor (levorotatory isomer) and racemic camphor.
Camphor racemic
(Camphora racemica) (SPhU)
Characters. Crystal. powder or friable crystal. mass of white color, easily volatile even at room temperature, with a strong characteristic odor and spicy bitter then cooled taste. At the carefully heating evaporates without charring. Slightly soluble in water, very easily soluble in alcohol, ether and petroleum ether. Easily soluble in the fatty oils, very slightly soluble in glycerin. With thymol, menthol, phenol and і chloralhydrate forms dense liquids (eutectic mixtures).
Can be found in the essential oils of camphor containing plants – laurel, basil, some species of wormwood, sage, and rosemary.
Camphor receiving
1. Natural d-camphor obtained by the steam distillation of crushed wood of camphor tree. Then camphor purified by sublimation and squeeze on the presses.
2. l–Camphor obtained by the N. V. Vershinin method. The initial product is a fir oil, which is distilled with aquatic steam from “fir quotes”. It consists of bornylacetate (30-40 %), camphene (10-20 %), pinene (10 %) and other compounds. At the temperature higher then 180 °С isolated fraction of the fir oil, which contains bornylacetate, hydrolysed it with sodium hydroxide solution and then oxidized it to the camphor by chromic mixture or nitrate acid.
3. Synthetic racemic camphor obtained by the method of V. E. Tishchenko from pinene, which contained in turpentine. Pinene fraction isomerizes in camphene by using a catalyst – titanium (IV) oxide, and then after the interaction with formic acid bornylformiate obtained, which hydrolyzed to borneol and oxidized to camphor:
Identification of the racemic camphor
1. Melting temperature – 172-180 °С.
2. IR–spectroscopy.
3. Specific rotation of 10 % solution in ethanol – from -0,15° to +0,15°.
4. By the reaction with hydroxylamine hydrochloride in the presence of anhydrous sodium acetate with oxime formation, which are identified by melting temperature 118-121 °С:
5. Non-pharmacopoeial reaction. Colour reaction with aldehydes:
a) With furfural – blue–violet color;
b) With vanillin in Н2SO4 – red-violet color;
c) with p–dimethylaminobenzaldehyde Н2SO4 – pink color:
6. Reactions on keto-group: formation of oxime, phenylhydrazone, 2,4-dinitrophenylhydrazone, semicarbazone.
For example, with 2,4-dinitrophenylhydrazine solution in hydrochloric acid at the heating to the boiling camphor gives yellow color and yellow recipitate, melting point of which is measured:
7. UV–spectrophotometry.
8. d–camphor, l–camphor and racemic camphor differ from each other by some constants: freezing point, specific rotation (10% ethanol solution), melting temperature of 2,4-dinitrophenylhydrazone.
Assay of the racemic camphor
1. For the substance SPhU does not provide quantitative determination.
2. Oxime method. Based on the camphor interaction with hydroxylamine hydrochloride. Insoluble in the water oxime can be detected by gravimetric method or by the titration of the equivalent amount of HCl, which separated, by the sodium hydroxide solution, indiator – bromthymol blue. Em = М. m.
3. Camphor can be quantitatively defined also with colorimetric method by the products of reactions with aldehydes.
4. GLCh.
Storage and usage of camphor
In TCC, in a cold place.
Camphor is used as a stimulant of the central nervous system and cardiotonic agent for the treatment of acute and chronic heart failure, collapse, respiratory depression, poisoning by hypnotics and narcotics means.
Assign orally or subcutaneously as a 20% oil solution. For exterior usage camphor shows local irritant and antiseptic action.
Specific analeptic action of camphor is due to the carbonyl group of the molecule and its nearest activated methylene group. Any changes in the structure of camphor caused by the introduction of substituents, weaken its analeptic and cardiotonic activity. Bromine which introduced into the molecule, causes the appearance of sedative effect in bromcamphor.
Issue: 20 % solution f/in. amp. by 2,0 and 5,0 ml; 10 % oil solution (camphor oil) vial. by 30 ml; 2 and 10 % alcohol solution (camphor alcohol) vial. by 40 ml.
Complex preparations, which contain menthol and camphor:
Camphomen spray 30 g – nitrofural, menthol, eucalyptus oil, castor and camphor oil.
Cameton spray 30 g – chlorbutanolhydrate, camphor, menthol, eucalyptus and vaseline oil.
Pectusin tabl. – menthol, eucalyptus oil.
Boromenthol ointment – boric acid, menthol, vaseline.
Hevcamen ointment – menthol, camphor, eucalyptus oil, clove and peppermint oil.
Menthoclar gel – mixture of essential oils of eucalyptus, peppermint, thyme, cedar, menthol, camphor.
Menovazine solution – anaestesine, Novocain, menthol, ethanol.
Bom–benge ointment – menthol, methylsalicylate.
Efcamon ointment – camphor, clove oil, mustard, eucalyptus, menthol, methyl salicylate, tincture of cayenne pepper, cinnamon alcohol, chloral hydrate.
Capsicame ointment – dimethylsulfoxide, benzylnicotinate, racemic camphor, purified turpentine.
Bromcamphor racemic
(Bromcamphora racemata)
Characters. Colorless crystals or a white crystalline powder with a camphor smell and taste. Very sligtly soluble in water, easily – in alcohol, ether, chloroform and fatty oils.
Extraction. The action of bromine on camphor. Reaction is carried out in an environment of chloroform or chloral hydrate, the solvent is distilled off and bromcamphor recrystallized.
Identification of bromcamphor
1. After the heating of bromcamphor with sodium hydroxide and zinc sawdust bromides detected in the filtrate by the reaction with chloramine:
2. Melting temperature 74-76 °С.
3. At the heating with H2SO4 conc. – red-brown color.
4. UV–spectrophotometry.
Assay of bromcamphor
1. Argentometry by the modified Folgard method after the boiling with 30 % solution of КОН and zinc sawdust. To the reaction mixture add 0,1 ml of the titrated solution NH4SCN, (NH4)2Fe(SO4)2 and titrate with AgNO3 solution to the disappearance of the red color, Em = M.m.
FeNH4(SO4)2 + 3NH4SCN → Fe(SCN)3 + 2(NH4)2SO4
Fe(SCN)3 + 3AgNO3 → 3AgSCN↓ + Fe(NO3)3
From the volume of AgNO3 solution, that was left on the titration district 0,1 ml of NH4SCN solution.
2. The method of combustion in Oxygen. Absorbent solution is hydrogen peroxide. Bromide–ion, that formed is detected by mercurimetric method.
3. In the medical forms bromcamphor is detected by refractomeric and spectrophotometric method at 306-308 nm (solvent ethanol).
Storage and usage of bromcamphor
In TCC from dark glass, in the dark place at a temperature not exceeding 25ºС.
Applied internally in the form of tablets of 0,1- 0,5 g as a sedative mean.
Sulfocamphoric acid
(Acidum sulfocamphoratum)
Characters. White with a yellowish then crystalline powder. Very easily soluble in water and alcohol, almost insoluble in ether.
Identification of the sulfocamphoric acid
1. Presence of sulfo-group detected after the mineralization of the drug with a mixture of sodium carbonate and sodium nitrate. Sulfates, that formed, can be detected with a solution of barium chloride.
2. Presence of keto-group confirmed confirmed by the formation of yellow-orange precipitate of hydrazones after the interaction with solution of 2,4-dinitrophenylhydrazine:
3. Melting temperature 192-195 °С, specific rotation from -20 °С to -24 °С.
Assay
Alkalimetry, direct titration, indicator – phenolphthalein, Еm = M.m.
Sulfocamphoric acid is a part of sulfocamphocain solution (Solutio Sulfocamphocainum 10 % pro injectionibus).
Ingredients: Sulfocamphoric acid 49,6 g
Novocain base 50,4 g
water for injections to 1 l
The resulting colorless or slightly yellow transparent liquid having a pH 4,2-5,8 and gives a positive reaction to the sulfonic acid and keto-group of sulfocamphoric acid. Under the action of sodium hydroxide released butter precipitate of novocain base, which after the extraction with chloroform gives the reaction on primary aromatic amino–group.
At the quantitative determination by alkalimetry method determine content of sulfocamphoric acid and by nitritometric method determine novocain base.
Storage and usage
In TCC, in a dark place.
Pharmacological action of sulfocamphocain is similar to camphor, but according to a good solubility in water, it is rapidly absorbed. Displayed in acute cardiac and respiratory failure, in cardiogenic shock and others.
Issue – 10 % solution f/in. Amp. by 2,0 №10.
References:
1. British Pharmacopoeia, 2009. – 10952 p.
2. European Pharmacopoeia, 2008. – 7895 p.
3. David G. Watson. Pharmaceutical analysis. – New York: Churchill Livingstone, 2000. – 400 p.
