INTRODUCTION
Two main source of medicine are, one is synthetic and another is naturally occurring. Synthetic drugs show rapid onset of action but having more side effects in comparison to naturally occurring drugs. The modern trend re back to choose choose natural natural medicine medicine against synthetic synthetic medicine. medicine. Natural source of drugs are plants, animals, or minerals. About 8000 plants are listed in medicinal uses. In this 1800 in Ayurveda, 1100 in Shiddha, 750 in Unani, 300 in Tibetan and 4700 plants are used as traditionally ethno medicinally. The world over the total trade of medicinal plants about 8800-lakh dollar, of which contribution of India in world trade less then 1%. Out of this majority of plants are yet to be study photochemical, estimated of such pants to the extent of 5000 to 6000. Phytochemistry is branch of Chemistry, which deals with the study of chemistry of plants. Where the term phytochemistry is comes out from phyta + chemistry (phyta⇒ plant). word pharma pharmaphy phytoc tochem hemist istry ry is derive derived d from Pharmaphytochemistry The word pharmakon⇒drugs, phyta ⇒ plants i.e. chemistry of medicinal substance inside the plants. Alkaloids Chemistry: Sertuerner in 1806 laid the foundation of Alkaloids Chemistry. It is the branch of Pharma Phyto Chemistry, which deals with the study of Alkaloids. He reported isolation of Morphine from opium . What is Alka What Alkalo loid ids: s: Alka Alkalo loid idss mean meanss Alka Alkali li like likes. s. The The Phar Pharma maci cist st W.Meissner proposed the term Alkaloids in 1819. Acc. to him "Alkaloids (alkali = base, oid=like sub) are basic nitrogenous compd. of plant origin which have complex molecular structure & many pharmacological activity."
Acc to Landenberg " Alkaloids are defined as natural plant compounds that have a basic character and contain at least one nitrogen atom in a heterocyclic ring and having biological activities." Acc to characteristic features Alkaloids are basic nitrogenous plant origin, mostly optically active & possessing nitrogen hetero cycles as there structural structural units with physiological action.
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This definition not fully correct because not follow on all alkaloids for e.g. olchic hicine ine is rega regard rded ed as an alk alkalo aloid alth althou ough gh it is not Colchicine: Colc Heterocyclic and is scarcely basic. Thiamine: It is heterocyclic nitrogenous base but not as a alkaloid because it is universally distributed in living matter. Nitrogen as side chain: Some compound is classed as in alkaloids but they do not contain nitrogen in heterocyclic ring, but contain nitrogen inside the chain e.g. e.g. ephe ephedr drin ine, e, hord horden enin ine, e, beta betani nine ne,, chol cholin ine, e, musc muscar arin ine, e, stry strych chni nine ne & tryptamine etc. Naturally occurring open chain basic compound: These compounds have physiological activity but do not class in alkaloids e.g. Cholines, amino acid, phenylethylamines etc.
neithe herr basi basicc chara charact cter er nor nor poss posses essi sing ng any any phys physio iolo logi gica call Piperine: It is neit activity but include in alkaloids. Those compound, which fully satisfy the definitions, like physiological active, heterrocyclic basic nitrogenous ring but they do not classed in alkaloids e.g.- Thiamine, caffeine, purine, theobromine, and xanthenes. Acc. To Pelletier 1983 “ an alkaloids is cyclic compounds containing nitrogen in negative of oxidation state. Which is of limited distribution in Living organisms” . "From above discussion, a conclusion can be drown quit safely that it is still difficult to define an Alkaloid"
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OCCURRENCE OF ALKALOIDS
Alkalo Alkaloids ids are chemic chemicall ally y nitrog nitrogeno enous us hetero heterocyc cyclic lic basic basic compou compound nd occur in nature, about15% of vascular plant & widely distributed in higher pla plant nt e.g. e.g... -Apo -Apocy cyna nace ce,, papa papave vera race ceae ae,, papi papila lana nace ceae ae,, rana ranane neul ulac acea eae, e, solenaceae. They are present in the form of salts of organic acid, like acetic acid, oxalic acid, malic, lactic, tartaric, tannic, aconitic acid, few are with sugar e.g. Solanum, veratrum groups. Acc. to parts of plants: Leaves: Nicotine Bark : Cinchonine, Quinine. Seeds: Strychnine, Nibidine. Roots: Rawelfinine, Glycyrrhizin, Punarnavine I & II NOMENCLATURE
There was no systematic nomenclature. But there are some methods for nomenclature are mention below. 1. According to their source: There are named according to the family in which they are found. e.g. papavarine, punarnavin, ephedrin . 2. According to their Physiological response: There are named according to
their physiological response. e.g.. Morphine means God of dreams, Emetine E metine means to vomit. 3. According to there discover: There are named according to there discover. e.g.. pelletierine group has been named its discoverer, P.J. Pelletier. 4. Prefixes: There are named by some prefixes are fix in nomenclature of alkaloids. e.g. epi, iso, neo, pseudo, nor- CH 3 group not attach to Nitrogen.
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CLASSIFICATION Alkaloids are classified as: A) Taxo Taxono nomi micc base based: d: Acco Accord rdin ing g to thei theirr fami family ly e.g. e.g. sola solana nace ceou ous, s, papilionaceous without reference their chemical type of alkaloids present & another according to genus. e.g.. ephedra, cinchona etc. B) Pharmacological based: Their pharmacological activity or response. For example: 1. Anal Analge gesi sicc alkal alkaloi oids ds 2. Cardio Cardio active active alkaloid alkaloidss etc. etc. Do not have chemica chemicall simila similarity rity in their group. C) Bio Synthetic based: According to this alkaloids are classified on the basis of the the type type prec precur urso sors rs or buil buildi ding ng bloc block k comp compou ound ndss used used by plan plants ts to synthe synthesis sisee the comple complex x struct structure ure.. e.g.. e.g.. Morphi Morphine, ne, papave papaverin rine, e, narcot narcotine ine,, tubocurarine & calchicine in phenylalanine tyrosin derived base.
This classi classific ficati ation on is univer universal sally ly adopte adopted d & D) Chemical Chemical classifi classificatio cation: n: This depend dependss on the fundam fundament ental al ring ring structu structure. re. Accord According ing to these these two main main groups. Non-heterocyclic Alkaloids: In this group of alkaloid not has any one 1. Non-heterocyclic
Heterocyclic ring in their structure. e.g.- Hordinine ( Hordeum vulgare ), Ephedrine( Ephedra Ephedra gerardiana) Genateceae. 2. Heterocyclic Alkaloids: According to heterocyclic ring the alkaloids are sub divide in following: -
This 1) Pyrrole-Pyrrolidine: Thi
type type of alk alkalo aloids ids cont contai ains ns pyro pyroll ll or pyrrolidine ring in their structure e.g.. Hygrines Coca sp.
2) Pyrrolizidine: Alkaloids containing Pyrrolizidine Heterocyclic ring in their structure e.g.. - seneciphylline Senecio sp.
Pyrrole
Pyrrolizidine
Pyridine
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3) Pyridine Pyridine & Piperidin Piperidine: e: Alkaloids Alkaloids containin containing g Pyridine Pyridine Heterocycl Heterocyclic ic ring in their structure e.g. Nicotine, Lobaline, Piperidine, Ricinine. 4) Piperi Piperidin dinee (Tr (Tropa opane) ne):: Alkalo Alkaloid id conta containi ining ng tropo tropone ne ring. ring. Hyoscyomine, Atropine Hyoscine- Solanceae Cocain- Coca sp.
Tropane
Quinoline
Iso Quinoline
Nor Lupinane
e.g..e.g..-
Indole
Alkaloids containing quinolin ring in their structure 5) Quinoline : Those Alkaloids e.g..e.g..- Quinin Quinine, e, Quinid Quinidine ine.. (Cinch (Cinchona ona bark) bark) Cincho Cinchonin nine, e, Cincho Cinchonid nidine ine & cusparin -(cusparia bark 6) Iso Quinoline: Alkaloids containing iso quinoline ring in thier chemical stru struct ctur uree e.g. e.g. Papa Papava vari rine ne,, Narce Narcein inee Emet Emetin inee & ceph cephal alin ine. e. (Cep (Cepha hali liss sp Rubiaceae). 7) Reduced Reduced isoquino isoquinoline line (Aporphi (Aporphine): ne): The alkaloid contain reduced isoq soquin uinoli oline rin ring in their eir stru struccture ture e.g e.g. Bald aldine, ine, (Peu Peumus mus Bald aldus) us) (Manioniaceae) 8) Nor Lupinane: Alkaloids present in leguminoceae plants e.g. spartine, lupanine. 9) Indole Alkaloids: Alkaloids containing indole ring. e.g. Yohimbine, Aspidospermine (Apocynaceae) Vinblasine, vincristine (catheranthus roseus).
EXTRACTION AND ISOLATION
Purification or isolation of alkaloids from a plant is always difficult process because an alkaloids bearing plant generally contains a complex mixture of several alkaloids with glycoside organic acid also complicate the process. Following steps are involved in isolation process. 1. Detection of presence of Alkaloids: First of all confirm the presence of alkaloids in raw material or crud drugs by various reagents called Alkaloids reagents e.g.
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I. Mayer (Cream Co lour) Test II. Marquis (Conc. HCHO) Test . III. Erdmann (Conc. HNO 3) Test IV. Hager's (Yellow Colour) Test V. Frohdes (Molybdic acid) Test 2. Extraction: - The plants is dried, then finally powdered and extracted with boiling methanol. The solvent is distilled off and the residue treated with inorganic acids, when the bases (alkaloids) are extracted as their soluble salts. The aqueous layer containing the salt of alkaloids and soluble plant impurities is made basic with NaOH. The insoluble alkaloids are set free precipitate out. The solid man (ppt.) so obtained is then extracted with ether when alkaloid pass into solution and impurity left behind. Flow Chart of extraction
Powdered Drug/ Macerated Plant Light Petroleum ether. Filtration.
Filtrate Plant residue Evaporate. 1. CH 3OH (72 hrs. extraction) 2. Filtration. Fat 3. Evaporate. Crude Plant extract 1. Dissolve Water. 2. Acidify to pH-2. 3. Steam distillation. 4. Filter. Filtrate Ether.
Ether soluble Evaporate.
Acid Solution Ether + NaOH
Basic Material
Aque Aqueou ouss resi residu duee
Ethe Etherr solu soluti tion on Evaporate. (Crude Alkaloids) 6
3. Separation of Alkaloids: After detection of next step is separation of a
relatively small percentage of alkaloids from large amount of crude drugs. E.g.- Opium contains 10% Morphine, Chincona contains 5-8 % Quinine, Belladona- 0.2% of Hyoscyamine. The required alkaloid is separated from the mixture from fractional, crystallization, chromatography and ion exchange method. PHYSICAL-PROPERTY
I)
They are colorless, crystalline solid. Exception - Berberin (Yellow), Nicotine Coniine (liquid).
II)
They are insoluble in water (exception liquid alkaloids soluble in water), soluble in organic solvent ( CHCl 3, Ethyl alcohol ether)
III) Taste: They are bitter in taste. IV) Optically active, Most of levo ratatory but few are -Dextro rotatory e.g. Coniine, some inactive- e.g.- papaverine.
CHEMICAL TEST OF ALKALOIDS 1. Mayer's Test: Specimen Specimen with Mayer's Mayer's reagent reagent give Cream or pale yellow ppt.
Specimen with Dragendrof Dragendrofff Reagent Reagent give 2. Dragendr Dragendroff off Reagent Reagent Test: Test: Specimen orange ppt. 3. Wagners Test: Specimen with Wagner's Reagent give brown or reddish brown ppt. 4. Hager's Test: Specimen with Hager's reagent give yellow ppt. (Special Type) 5. Amonium Rinker Test: Specimen with Ammonium Rinket solutions with
HCL give flocculent pink ppt.
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GENERAL METHODS FOR STRUCTURE DETERMINATION DETERMINATION OF ALKALOIDS
Molecular formula of majority of Alkaloids is complex so very little achievement in their elucidation of structure. During 19th Century. Now general procedures for elucidation of structure of alkaloids are adopted. 1. Molecular formula molecular weight: A pure specimen of alkaloids its empirical formula and molecular weight by elemental or combustion analysis. No. Of double bond is determined by double bond equivalent method. 2) Number of Double bond: - Number of Rings present in an alkaloids can be determine by following formula- C a Hb Nc Od
Then number of double bond present in Ring= a-b/2 + C/2 + 1 3) Functional group Analysis: a) Functional Nature of Oxygen: - Oxygen presents in alkaloids as: - OH (Phenolic/ Alcoholic), - OCH 3 Methoxy, - OCOCH 3 (Acetoxy), - OCOC 6H5 ( Benzoxyl), -COOH (Carboxylic),- COOK (carboxylate),>C=O (Carbonyl),= C-O-O (Lactones (Lactones Ring).It Ring).It can be determined determined by infra red or organic organic analysis analysis method. (1) (1) Hydrox Hydroxyl yl group: group: - Forma Formati tion on of Acet Acetat atee on trea treatme tment nt with with Acet Acetic ic anhydride /Acetyl chloride or benzoate on treatment with Benzyl chloride.
R- OH + (CH 3CO)2 O R- OH + CH 3COCl R- OH + C 6H5COCl
ROOCCH 3 + CH3COOH ROOCCH 3 + HCl ROOCC 6H5 + HCl
If Prim Primary ary amin amines es are are pres presen entt in an alka alkalo loid idss also also give give this this test test.. Then Then Hydroxyl group is can be determined by zerewitinoff method. NaOH R-OH +CH3COCl
R-OCOCH3-
R- OH +CH3COONa
Excess of Alkali is estimated by titration with standard HCl. Number of -OH group group can be calcul calculate ated d from from the the volume volume of Alkali Alkali used used for Hydrol Hydrolysi ysis. s. Grignard-method.
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- OH + MeMgI - NH + MeMgI
- OMgI + CH4 - NMgI + CH4
1- OH= 1>NH group= 22.4 liter of N2 STP
10, 20-OH -OH, 30 -OH -OH grou group. p. By oxid oxidat atio ion n or dehy dehydr drat atio ion n to unsa unsatu turat rated ed compound. If OH group is phenolic, and then Alkaloid is - Soluble in NaOH - Re precipitated by CO 2 - Giving coloration with FeCl 3
(2) Carboxylic group: - soluble in aqueous solution sodium carbonate or ammonia on treat with alcohol form ester. Number of -COOH group can be determined by volumetrically by titration against a standard. Ba(OH) 2 solution by using phenolphthalein as an indicator. treatment nt with with Hydrox Hydroxyla ylamin mine. e. Semica Semicanbe nbezid zide, e, (3) Oxo-gr Oxo-group oup:: - On treatme phenylhydrazide ,oxime ,semicarbazone phenyl Hydrazine >C=O + H2
NOH
>C=N-OH
>C=O +H2 NNHCONH NNHCONH 2
>C=NNHCONH2
The distinction between aldehyde and ketone is done by oxidation or reduction, also by NMR, IR, and UV techniques.
(4) Methoxyle group: - BY Zeisel determination method. When methoxy group present in a alkaloids treated with HI at 126 0C perform methyl iodide whic which h can can trea treate ted d furt furthe herr with with silv silver er nitri itrite tess to perf perfo orm silv silver er iodi iodide de precipitate. Which estimated gravimetrically e.g.. Papavarine.
C2OH4OO4
HI N
AgNO3 4MeI
4AgI
(estimated gravimetrically) gravimetrically)
(5) Methylenedioxy group: - On heated with concentrated with HCL or H2SO4 to form formaldehyde and further formation of dime done derivative, which estimated gravimetrically. -OCH2 O-
heat/HCl/H2SO4
HCHO
dime done derivative (Estimated gravimetrically) gravimetrically)
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b) Ester Amide Lacton & Lactum group: These groups are identified by the estimation of product. >CONH2 + NaOH
Heat
-COONa + NH3
>COOR
Heat
-COONa + ROH
+ NaOH
c) Nature of Nitrogen Majority of nitrogen presence in alkaloids are secondary and tertiary: If tertiary when treated with H 2 O2 (50%) form. =N +H2O2
=N
O +H2O
If alkaloids react with one molecule of methyl-iodide to form N-methyl derivative, it means secondary e.g. (C8H16O4) NH + CH 3I
(C8H16O4) NCH3 + HI
General reaction of alkaloids with acetic-anhydride, methyl-iodide, and nitrous acid are often showing the nature of nitrogen If reac reactt with with one one mole molecu cule le of meth methyl yl-i -iod odid idee to form form crys crysta tall llin inee quaternary salt this indicates that nitrogen is tertiary e.g. N= (C10H24)= N + 2CH3I
IH3C+ N= (C10H24)= N +CH3I-
N-methyl group: On distillation with soda lime if methylamine is produce show the presence of N-methyl group for e.g. Soda-lime (C10H14 N)=N-CH N)=N-CH3 CH3 NH NH2 Nicotine CaO
Determination of Number of CH 3-groups Attached to N-atom: By HerzigMayer ’s method when a sample is treated with hydrogen iodide at 150 0-3000C and than than treate treated d silver silver nitrat nitrate, e, which which form form silver silver iodide iodide,, which which estima estimated ted gravimetrically.
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N- methylamine + HI
1500-3000
>NH + MeI
AgNO3
AgI
Estimated gravimetrically
d) Estimation of C-Me Group by Kuhn –Roth Oxidation: When trea treate ted d with with K 2Cr 2O7 or H2SO4 an acid acid is prod produc uce, e, whic which h esti estima mate ted d gravimetrically. K 2Cr 2O7 or H2SO4 -C-Me
MeCOOH Estimated gravimetrically
e) Degradation of Alkaloids: For discovering the structural system which incorp incorpora orate te these these substi substitue tuents nts groups groups & is tackle tackled d by degrad degradati ation on of the molecules by following methods:
1) Hoffmann's exhaustive methylation: - This is a composite reaction of alkaloid (Heterocyclic amines). This involves following steps: The alka alkalo loid id is trea treate ted d with with exce excess ss of CH 3I to form form quarte quartertio rtionar narey ey a) The -ammoniumiodide.
0
b) 4 -ammonium iodide is converted to the hydroxide and heated. The -OH of
hydroxide extracts hydrogen atom from beta position and eliminate a water molecule molecule and also the ring is cleaved at the N-atom N-atom to give an open chain 3 0amine.
c) The step I st and IInd are repeated when a second cleavage at the N-atom
given an unsaturated hydrocarbon which isomerase’s to conjugated derivative.
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The exhaustive methylation of an alkaloid is an important method for the investigation of the nature of the C-skeleton in the heterocyclic system. alkalo loid idss do not not cont contai ain n beta beta 2) Emde Emde Degr Degrad adat atio ion n Meth Method od: If alka Hydrogen atom then Hoffmann exhaustive degradation method is failed. In such such case casess Emde Emde degr degrad adat atio ion n are are appl applie ied, d, in this this fina finall step step invo involv lvee the the reduct reductive ive cleava cleavage ge of quarte quarterti rtiona onarey rey ammoniu ammonium m salt salt either either by Na-Hg Na-Hg or NaNH3 or by catalytic hydrogenation e.g. Na-Hg or NaNH 3
RCH2 NR NR 3X
RCH3 + NR 3+ HX
2) Von Braun's Method: - This method is of two types: A. Tertiary amine, which contains at least one-alkyl substituents, is treated with cyanogen bromide. The results in cleavage of an alkyls nitrogen bond to give an alkyl halide and a substituted Cyanamid. R 3 N + CN - Br --
R - Br + 2 N R N - CN
This method is often applicable to such compounds that do not respond to Hofmann's method e.g. – Cocaine B. Secondary cyclic Amine is treated with Benzoyle chloride in presence of NaOH to yield the Benzoyle derivative which on treatment with phosphorus followed by distillation under reduced pressure yield di Halo compund.
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Br2
NaOH
R 2 NH+ NH+ C6H5COCl
R 2 N-COC N-COC6H5
Distillation
R 2 NCBr NCBr 2C6H5
Br-RRBr + C6H5CN
3) Reductive degradation & Zinc dust distillation : In some case ring may open by Heating up to 300 0C with Hydroiogic acid e.g. Coniine C8H17N
Zn dust /Heat
+ 6H C3H7
4) Alkali fusion: This is very drastic method, which is often employed to break down the complex of complex alkaloids molecule to simpler fragment. The nature of fragment, which will give information type of nucleus present in alkaloid molecule e.g. Adrenaline, Papaverine, Cinchonine Adrenaline
KOH Fusion
5) Oxidation: - This method gives quite information about the structure of alkaloids by varying the strength of the oxidizing agents it is possible to obtain a variety of product e.g. A. Mild oxidation- H 2O2, HI in ethanolic solution & alkaline potassium ferriccyanide. B. Moderate oxidation: KMnO 4 (Alkali) Cr2O 3 (Acetic Acid) C. Vigorous oxidation: K 2Cr 2O7, (H2SO4), Cr2O3 (H2SO4), conc. HNO 3, MnO2 (H2SO4) K 2Cr2O7 (H2SO4) C10 H14 N N2 C6H5COOH
6) Dehydrogenation: - When Alkaloid is distilled with catalyst such as sulphur, selenium or palladium dehydrogenation takes place to form relatively simple & easily recognizable product which provide the clue to gr oss skeleton.
7) Synthesis: - The structure of the alkaloids arrived at by the exclusive analytical evidence based on going method is only tentative. The final conformation of the structure must be done by the unambiguous synthesis.
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BIOSYNTHESIS OF ALKALOIDS
As more and more structure of alkaloids were elucidated, it become increasingly probable that the precursor in the biosynthesis of many alkaloids were were amin amino o acid acidss and and amin aminoo-al alde dehy hyde de or amin amines es deri derive ved d from from them them,, Woodward 1948 proposed a biosynthesis of strychnine. Because the great diversity of structure of alkaloids, it not possible to deve develo lop p only only one one hypo hypoth thes esis is of bios biosyn ynth thes esis is of alka alkalo loid ids. s. Thus Thus many many pathways have been proposed, each one accounting for the biosynthesis of a number of alkaloids of related structure. The most common aminoacids that act as precursor in biosynthesis of alkaloids are: i. Ornithine H2N (CH2) CHNH2COOH ii Lysine H2N (CH2)3 CHNH2COOH iii. Phenylalanine (R=H) RC6H5CH2CH(NH2)COOH
iv. Tyrosine (R=OH) vi. Methionine MeSCH2CH2CH(NH2)COOH vii Trytophen Some common reactions are: Decarboxylation Decarboxylation : formation of amine RCH (NH2) COOH
RCH2 NH NH2 +CO2
Oxidation: formation of aldehyde
RCH (NH2) COOH
RCOCOOH
Shiff base formation:
R 1CHO +R 2 NH NH2
R 1CH=NR 2
PHYSICAL METHOD
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RCHO
These following physical methods are applied to elucidate the structure of alkaloids: • • • • • • •
U.V. Spectroscopy IR Spectroscopy Nuclear Magnetic resonance spectroscopy Mass spectroscopy Optical rotatory dispersion & circular dichroism. Conformational Analysis X-Ray diffraction
1. ATROPINE
This is the most important alkaloid of tropane group and occurs in the root rootss of dead deadly ly nigh nights tsha hade de ( Atropa ron apple ( Datura Atropa belladonn belladonna a), thron stamonium)n and many other member of solanaceous family together with l hyoscyamine which is optically active ( [<] D = -220 ). Atropine is the racemic form of l -hyoscyamine -hyoscyamine which readily racemises to atropine when warmed in an ethanolic alkaline solution, thus atropine is ( ± )-hyoscyamine ISOLATION
Atropine is extracted either by from belladonna root or from juice of datura plant. In practice, the juice which contains hyoscyamine is heated with potassiu potassium m carbonate carbonate solution when hyoscyamin hyoscyaminee is racemised racemised to atropine. atropine. Then, this atropine is extracted with chloroform. The chloroform is recovered by evaporation and the residue is then extracted from the residue with dilute sulphuric acid. The solution is made alkaline with potassium carbonate when atropine is precipitated out. The precipitated atropine is extracted with ether and purified by converting it in to an oxalate or a sulphate.
STRUCTURAL ELUCIDATION
NO3. Molecular formula- C17H23 NO Melting point- 118oC. Structure-
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UV ( Ethanol ): λ max max 246, 251.6, 257, 263.5, 271 nm ( c 147.6, 175.1, 209.8, 143.3 and 24.6 respectively ) IR ( KBr ): Vmax 3070 (OH- Hydrogen bonded), 2930 ( CH stretch ), 2810 ( N- CH3 stretch ), 1725 ( O-C=O ), 1595, 1580 ( C=C, Ar ), 1155, 1030 ( CC-O ), 770,725 and 690 ( monosubs Ar ) cm -1. 1 H NMR ( CDCl3 ): δ 7.23 ( 5H, s, Ar-H ), 4.96 ( 1H, t, H-3 ), 3.9 ( 1H, m, H10 ), 2.93 ( 2H, bs, H-5 ), 1.66 ( 8H, m, H-2,4,6,7 ).
2. MORPHINE
Morphine was the first alkaloid to be isolated from serturner plant ( 1806 ). In opium, it is present in a quantity of 10-23 percent along with other substances like fats, resins, proteins, carbohydrates, mineral salts, meconic acid about 20 or more alkaloids. Code Codein inee and and theb thebai aine ne are are the the othe otherr clos closel ely y rela relate ted d alka alkalo loid idss to morphine. Theses three are commonly known as morphine alkaloids and from a sub-group of the opium alkaloids. In all morphine alkaloids, phenanthrene nucl nucleu euss is pres presen ent. t. Due Due to this this,, thes thesee are are also also know known n as phenanthrene alkaloids. The morphine alkaloids have been studied comparatively more due to the following reasons: (i) These are widely used as analgesic agents, and (ii) These undergo a wide variety of molecular rearrangements.
ISOLATION
Morphine is extracted from opium by involving the following steps : 16
(i) First of all, the raw opium is extracted with cold dichloromethane repeatedly. Papaverine, narcotine and gum go into the dichloromethane layer wherea whereass morphi morphine ne and other other substa substance ncess remain remain in the insoluble residue. Dichloromethane layer is separated. (ii) The dichloromethane layer obtained from step ( i) is evaporated to dryness to yield a residue which is extracted with hot dilute HCl, then treated with the charcoal and finally filtered. The filtrate is neutralized with ammonia when when papave papaverin rinee and narcot narcotine ine are precip precipita itated ted out. out. When When precip precipita itate te is shak shaken en with with hot hot alco alcoho hol, l, the the papa papave veri rine ne goes goes into into alco alcoho hol. l. From From this this,, papaverine is precipitated out as oxalate and then purified by recrystallisation. The crude narcotine present in the residue from the alcohol extraction is similarly purified. (iii) The The resi residu duee obta obtain ined ed from from the the dich dichlo loro romet metha hane ne extr extrac acti tion on is o agitated with lime water at temperature below 20 C. morphine, codeine and thebaine are present in lime water which when extracted several times with benzene remove codeine and thebaine in a benzene layer. Then, the pH is raised to 8 when the crude morphine is precipitated out. The filtrate still cont contai ains ns morph morphin ine. e. This This filtr filtrat ate, e, when when evap evapora orate ted d in vacu vacuum um and and then then extracted with amyl alcohol, yields further amount of crude morphine. the two sample of crude morphine are mixed. (iv) The crude morphine obtained from step ( iii) is dissolved in dilute HCl HCl and and filt filter ered ed thro throug ugh h alco alcoho hol. l. Then Then the the filt filtra rate te is neut neutra rali lize zed d with with ammonia followed by the addition of alcohol. This results in precipitation of morphine. The precipitated morphine is dissolved in minimum quantity of dilute HCl and the resulting solution so obtained on concentration and cooling yields crystals of morphine hydrochloride. (v) The benzene extract obtained from step ( iii) is evaporated to yield a resi residu due. e. This This is then then treat treated ed with with hot hot alco alcoho hol, l, foll follow owed ed by cool coolin ing g and and filtration. The filtrate when treated with sulphuric acid yields a precipitate of codeine sulphate which is filtered out. To the resultant filtrate, tartaric acid is added to precipitate out thebaine as thebaine acid tartrate.
STRUCTURAL ELUCIDATION
NO3. Molecular formula- C17H19 NO Melting point- 254-256oC. Structure-
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UV ( Ethanol ): λ max max 286, 250 and 298 nm ( log c 3.256, 3.275, 3.360 respectively ) IR ( KBr ): Vmax 3480, 3350 ( OH ), 3210 (OH bonded), 2940, 2920 ( CH stretch ), 2840( N- CH 3 stretch ), 1640 (C=C alkene ), 1605 ( C=C, Ar ), 1250, 1090( X-O stretch), 760 ( monosubs. Ar ) cm -1. 1 H NMR ( HCl ): δ 6.76 (d, H-1 ), 6.68 ( d, H-2 ), 5.75 ( d, H-7 ), 5.40 ( d, H8 ), 5.06 ( d,H -5, J5,6= 2Hz ), 4.37 ( m, H -9 ),4.20 (d, H -14 ), 3.0 (s, N-Me ), 2.16 (d, H-10 )
3. EPHEDRINE
It is an important drug which occurs along with five other alkaloids, name namely ly pseu pseudo doep ephe hedr drin ine, e, meth methyl ylep ephe hedr drin ine, e, meth methyl ylps pseu eudo doep ephe hedr drin ine, e, norephedrine and norpseudoephedrine in the genus Ephedra; a species which occu ccurs in tempe empera rate te and sub subtro tropica picall regi regio ons of Asia, sia, Amer Americ icaa and Mediterranean. The base ephedrine was first isolated from the Ephedra in 1887 by Nagai and much later Gulland and Virden obtained a very small amount from the Yew ( Taxus baccata L. ). The Chinese have used the herb Ma Huang. ( a Chinese drug ) which contains ephedrine and is said to have been used medicinally in china for 5000 years. Ephedrine has been used successfully in the treatment of bronchial asth asthma ma,, hey hey fever fever and and othe otherr alle allerg rgic ic cond condit itio ions ns.. It also also incr increa ease sess bloo blood d pressure. It is a much stronger stimulant than caffeine. ISOLATION
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1 kilo of powdered Ma Huang was extracted with cold benzene in the presence of dilute Na2CO3 solution, and the benzene extract was shaken up with a sufficient quantity of dilute HCl to remove the basic substances. The acid solution was made alkaline with solid K 2CO3 and the liberated base was then extracted with chloroform. The chloroform solution, when dried over anhydrous Na 2SO4 and distilled, gave 2.6 g of crude base. Preparation of Ephedrine HCl by Fractional Crystallization Crystallization
The crude base obtained as above was taken up with about twice its weight of alcohol and neutralized with concentrated HCl diluted with twice its volume of alcohol. Nearly pure ephedrine hydrochloride crystallized out on standing. After filtering it was washed with a mixture of alcohol and ether, and and then then with with pure pure ethe ether, r, and and drie dried. d. A furt furthe herr quan quanti tity ty of ephe ephedr drin inee hydrochloride may be got by concentrating the mother liquors and washings. The final mother liquor was kept for the isolation of pseudoephedrine (see below). Ephedr Ephedrine ine hydroc hydrochlo hloride ride crysta crystalli llized zed out from from alcoho alcoholl in prisma prismatic tic 22 needles, mp 216°C, [α] D -32.5° . The salts prepared by fractional crystallization show no change in the melting point when recrystallized seven times. In many of our experiments the salts were recrystallized twelve times.
STRUCTURAL ELUCIDATION Molecular formula- C10H15 NO. NO. o Melting point- 38.1 C. Structure-
UV (Methanol): λ max max 250, 256 and 262 nm (log c 170, 20, 165 respectively) IR ( KBr ): Vmax 3330 ( -OH stretching ) 2480 ( NH + 2 stretching ), 1490, 1450 (ArH ) 750 and 699 ( C-H out of plane deformation ) cm -1.
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1
H NMR ( D2O ): δ 7.53 (5H, s, Ar-H ), 5.28 ( d, OH ), 3.60 (m, CHNH 2 ) 2.9 ( s, NH-CH 3 ), and 1.20 ( d, CH- CH 3 ). 4. RESERPINE
Reserpine is the main constituent of Rauwolfia species, particularly R. Other import important ant alkalo alkaloids ids presen presents ts in these these serpentina and R. vomitoria vomitoria.. Other specie speciess are yohimb yohimbine ine,, ajmali ajmalicin cinee and ajmali ajmaline. ne. All these these alkalo alkaloids ids are hypertensive and sedative reagents. Reserpine is mainly used for the treatment of hypertension, headache, tension states, asthma and dermatological disorders.
ISOLATION
Mature root bark (264 g) was extracted with methanol in a Soxhlet for 30 hr, the extract concentrated to remove the methanol, and the residue treated with NaHCO, solution and ether. Any resinous material separating at this stage was dissolved in a little methanol and retreated in the same way, this process being repeated thrice or until no more resin formation occurred. All the aqueous aqueous solutions solutions were extracted four times with ether and the combined combined ether extracts washed with 2% acetic acid (3~100c.c.) then 2% HC1 (2 x 100 c.0.). c.0.). The combined combined acid acid extract extractss were then then Basificati Basification on with with NH, gave a resin which would not dissolve in ether. A solution of this material in a little methanol methanol gradually gradually deposited deposited a crystalline crystalline precipita precipitate te which after after several recrystalli recrystallizati zations ons from methanol methanol (Yield (Yield 0.07 g). g). A furt furthe herr quan quanti tity ty was was obtained on longer standing.
STRUCTURAL ELUCIDATION
N2O9. Molecular formula- C33H40 N o Melting point- 264-265 C.
Structure-
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UV: λ max max 296, 267, 216 nm (c 9660, 15700 and 55700 respectively ) IR: Vmax 3480 ( N-H stretching ), 2840-3030 ( C-H stretching ), 1732 and 1713 ( C=O stretching ) cm -1. 1 H-NMR (CDCl3 ): δ 7.85 ( s, NH ), 6.7-7.3 ( indole Ar-H ), 7.34 ( 2H, s, trimethoxybenzene Ar-H ), 5.05 ( H-18, m ), 4.43 ( H-3, t ), 3.92 ( 6H, s,OMe X 2 ), 3.29 ( 3H, s, CH-OMe ), 3.79 ( 3H, s, C 16- OMe ), 3.46 ( s, C 17 OMe )
5. VINCRISTINE
Vincristine is an indole alkaloid obtained along with the Vinblastine from the catharanthus roseus family. Apocynaceae . This plant was previously known as Vinca roseae L. Vincristine is one of the cytotoxic drugs and used in treatment of acute leukemias particularly in children and in other cases such as lymphosarco lymphosarcoma, ma, reticulum reticulum sarcoma, neuroblast neuroblastoma oma wilms tumor and tumors tumors of the brain, breast and lung.
ISOLATION
The mixture of dried ground plant of Vinca rosea and dilute tartaric acid is extracted with benzene. Collect benzene extract and evaporate till concen concentrat trate. e. The concen concentra trated ted extrac extractt is then then steam steam distil distillat lated ed to obtain obtain insoluble residue. Dissolve the residue by mixing it with dilute tartaric acid and hot methanol, and then distill out the methanol from it .Carryout the extraction of the bottom product using dilute solution of ammonia. Collect the extract, evaporate and dry. The dried powder of Vincristine is dissolved in benzene and chromatographic separation is carried out on alumina column using eluting solvents as benzene, benzene + Chloroform, Chloroform and Chloroform + Methanol mixture. STRUCTURAL ELUCIDATION
N4O10. Molecular formula- C46H56 N 21
Melting point- 273-281oC. Structure-
UV: λ max max 296, 290, 275, 255, 221 nm (c 15600, 14000, 11400, 15400 and 47100 respectively ). MS : m/z 824 ( M +, negligible ), 806 ( M + - 18 ).
Functions Alkaloids functions As reservoir of nitrogen • • As reservoir for protein synthesis As detoxicating agents • 22
• •
As toxicating agents As harm one for many activity of plant.
Alka Alkalo loid idss have have many many physiolog physiological ically ly biological biological and pharmacological properties
Conclusion It can be concluded that: 1. Alkaloids are naturally occurring heterocyclic complex compounds. 2. Alkaloids have indefinite definition. 3. Alkaloids have mainly nitrogen in heteroatom. 4. Alkaloids have complex molecular structure. physiologically and pharmacologically active. 5. Alkaloids are bio & physiologically
Reference: 1) Qadry Qadry J.S (Twelth (Twelth Edition) Edition),, Shah Shah and Query’s Query’s Pharmacog Pharmacognos nosy, y, B. S. Shah Parkashan. 2) Shah C.S. &. J.S Qadry, 11th edition, A Text Book of Pharmacognosy, B. S. Shah Parkashan.
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3) Handa S. S., A Text Book of Pha Pharma rmacognosy, Vallabh Parkashan, New Delhi. 4) Gupta Gupta A.K. Vol-1, Vol-1, Quality Quality Standards Standards of Indian Medicina Medicinall Plants, ICMR, New Delhi. 5) Evans W.C., W.C., (Fifteenth (Fifteenth edition edition)) Trees & Evans Pharmacog Pharmacognosy, nosy, W.B. Saunders. 6) Agar Agarwa wal. l. O. P., P., VolVol-2, 2, Chem Chemis istr try y of Natu Natura rall Prod Produc uct, t, Goel Goel Publication Meerut. Page 193-311. 7) Fina Finarr I. L., L., VolVol-II II Vth Vth edit editio ion, n, Orga Organi nicc Chem Chemis istr try y (Ste (Stere reoochemistry & Chemistry of Natural Products) ELBS. , Page 696702 8) Robe Robert rt MF, M Wink ink, Alk Alkalo aloids ids (Bio (Biocchemi hemist stry ry,, Eco Ecology ogy, Medicine application) Plenum Press, N. York. Brunto ton n Jean Jean,, 2 nd edition, edition, Pharmacogno Pharmacognosy sy Phytochem Phytochemistry istry of 9) Brun Medicinal Plants, Levoisier Paris. Page 783-799.
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