ANALISIS KUALITATIF DAN KUANTITATIF ALKALOID
UJI KUALITATIF ALKALOID : •
Pereaksi pengendap alkaloid: alkaloi d:
digunakan untuk: 1- Melihat Melihat ada ada tidakn tidaknya ya alkaloid alkaloid 2- Melihat Melihat proses ekstr ekstraksi aksi alkaloid alkaloid sdh tuntas. tuntas. Kekurangan: senyawa non alkaloid dpt berinteraksi : Prot Protein, ein, lakton, lakton, kumar kumarin. in.
POSITIF PALSU.
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Klasifikasi pereaksi pengendap Alkaloid:
1- Pereaksi yg membentuk garam dobel: a- Mayer’s Reagent:
Potassium Mercuric Iodide.
b- Dragendorff’s Reagents: Potassium Iodobismethate. c- Gold Chloride.
2- Pereaksi Halogen: a- Wagner’s Reagent: Iodine/ Potassium Iodide.
3-Asam Organik: a- Hager’s Reagent: asam pikrat b- asam tanat.
4- Asam teroksigenasi dg BM tinggi: a- Asam fosfomolibdat b- Asam fosfotungstat c- Asam silikotungstat
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Reaksi Warna:
1- Pereaksi Froehd: Asam fosfomolibdat 2- Pereaksi Marqui: Formaldehid/ H2SO4 pekat 3- Pereaksi Mandalin: Asam Sulfovanidat 4- Pereaksi Erdmann: HNO3 / H2SO4 pekat
5- pereaksi Mecke: Asam Selenat / H2SO4 pekat 6- Pereaksi Shaer: Hidrogen peroksida / H2SO4 pekat 7- pereaksi Rosenthaler: Kalium arsenat / H2SO4 pekat 8- HNO3 pekat
Identifikasi Alkaloid: •
Titik lebur
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Pereaksi warna
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Rotasi optik
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Uji Mikrokristal
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Analisis HPLC, GC, GC-MS
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Analisis UV, IR, NMR, MS.
Analisis Kuantitatif Alkaloid: •
Metode volumetri:
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Dasar : Reaksi asam basa. Basa alkaloid dititrasi dg asam.
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Titrasi dg media air:
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1- Titrasi langsung alkaloid dlm pelarut alkohol dg standar asam. 2- Titrasi kembali : melarutkan alkaloid dalam sejumlah standar asam dan kelebihan asam dititrasi dengan larutan standard alkali. Titrasi bebas air: penetapan kadar alkaloid basa lemah: kafeina.
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Gravimetric methods:
These methods are recommended for determination of: 1- Very weak bases which can not be determined by volumetric methods e.g. caffeine and colchicine. 2- Mixtures of alkaloids that are obtained from the same plant but differ greatly in their molecular weight e.g. Cinchona and Rawolfia alkaloids. They can be performed by either: 1- Direct Weighing of the alkaloidal mixtures 2- Precipitation of the total alkaloids and determination of the weight of the precipitate obtained. The major drawbacks of the gravimetric methods are: 1- They are insensitive to microamounts of alkaloids. 2- They could not be applied in case of thermolabile and volatile alkaloids. 3- Lipophilic impurities in the residue are calculated as alkaloids.
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Colourimetric Method: e.g. Morphine + NaNO2/HCl Ergot + p-dimethylaminobenzaldehyde
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Spectrophotometric Methods.
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Polarimetric Method.
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Fluorimetric Method.
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Chromatographic Methods
Classification of •
Alkaloids
Biogenetic. Based on the biogenetic pathway that form the alkaloids.
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Botanical Source. According to the plant source of alkaloids.
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Type of Amines. Primary, Secondary, Tertiary alkaloids.
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Basic Chemical Skeleton
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Phenylalkylamines: e.g. Ephedrine
CH2
CH
CH3
NH2
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Pyridine and piperidine e.g. lobeline, nicotine N
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N H
Tropane e.g. Atropine.
NCH 3
OH
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Quinoline e.g.quinine and quinidine N
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Isoquinoline e.g. papaverine
N
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Phenantheren e.g. Morphine
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Indole e.g.ergometrine N H
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Imidazole
N
e.g. pilocarpine N •
Purine e.g. caffeine
6 1
7 5
N
H
N 8
2
N
4
3
Purine
N 9
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Steroidal e.g. Solanum alkaloids
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and Veratrum
Terpenoid e.g. Taxol
Alkaloid Quinolin Alkaloid Kina •
Kulit batang kina mengandung alkaloid: 1- kinin dan kinidin.
HO
COOH
2- sinkonin dan sinkonidin. •
Alkaloid kina dpt sbg garam asam kuinat dan asam sinkotanat.
HO
OH OH
Quinic acid
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They are diacidic bases form two types of salts: 1- Neutral salts (Monoacidic) (less water soluble). 2- Acidic salts (Diacidic) water soluble.
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Both Quinine and Quinidine, Cinchonine and Cinchonidine are Diastereoisomers. Each pair differs in the stereochemistry at C-8 and C-9.
HO
HO
9
H3CO
8
N
N
H
H
H3CO
N
Quinine
H
H
N
Quinidine
Properties: •
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Quinine is very slightly soluble in H2O, soluble in ethanol, chloroform, ether, benzene and other organic solvents. Quinine is a diacidic base. It forms 2 types of sulfates: –
Quinine monosulfate (neutral and H2O insoluble).
–
Quinine bisulfate (acidic and H2O soluble).
Quinine (l - isomer) gives quinidine (d -isomer) among other products when warmed with KOH in amyl alcohol. Quinine is levorotatory, while quinidine is dextrorotatory.
Separation of the 4 Alkaloids Powdered Bark - Alk . CaO + NaOH + H 2O - Reflux with benzene & - Filtration while hot
Benzene filtrate (Alkaloidal bases) dilute H2SO4
Acidic aqueous layer (Alkaloidal bisulphates) pH to 6.5 with Na2CO3
Precipitate Quinine
(monosulphate)
Hot water , Na2CO3
Aqueous solution (Monosulphates) quinidine, cinchonine & cinchonidine NaOH, ether
Quinine
Ether layer Quinidine & Cinchonidine
Aqueous layer
-HCl PH=7, Na, K Tart. salt - filter
Precipitate
Filtrate
Cinchonine
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Identifikasi
1- Uji Fluoresensi: Solution of the alkaloid in oxygenated acids (e.g H2SO4, HNO3 or phosphoric acid) blue fluorescence (+ ve with quinine and quinidine).
2- Thalleoquine test: Aqueous solution of the alkaloidal salt + Br2 /H2O (few drops till the appearance of yellow color) + NH4OH emerald green color (+ ve with quinine and quinidine).
3- Rosequin test (Erythroquinine test): Aqueous solution of the alkaloidal salt + dil HCl + Br2 /H2O (few drops till the appearance of yellow color) + CHCl3 + pot. Ferrocyanide + NH4OH red color in the CHCl3 layer (+ ve with quinine and quinidine).
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Uses:
Quinine is used mainly as anti-malarial in a dose of 2g of quinine sulfate or other salt for 14 days. Quinidine is used as a cardiac depressant (antiarrhythmic), particularly to inhibit auricular fibrillation in a dose of 0.6-1.6 g of quinidine sulfate daily. Cinchonine and cinchonidine are used as antiinflammatory.
Isoquinoline Alkaloids 1- Ipecacuanha Alkaloids •
Occurrence: Ipecac is the dried roots and rhizomes of Cephalis ipecacuanha (Brazilian ipecacuanha) or Cephalis acuminata (Cartagena or Panama ipecacuanha) Fam. Rubiaceae.
It contains several alkaloids (2 –2.5 %), mainly emetine (50- 70 % of total alkaloids), with cephaline and psychotrine . MeO
MeO
OMe N
RO
H
OMe H N
R = Me R=H
Emetine Cephaline
HO
OMe OMe
N H N Psychotrine
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Emetine:
It is non phenolic and levorotatory. It contains 2 basic nitrogens.
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Cephaline:
It is phenolic and levorotatory. It gives emetine on methylation with (CH3)2 SO4.
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Psychotrine:
Occurs as yellow prisms. It is phenolic and gives cephaline on reduction. It gives emetine on reduction followed by methylation.
Isolation of Ipeca alkaloids: Powdered root and rhizome - Ext. alcohol,Conc., lead acetate. - Filtration
Filtrate Alkaloidal bases and salts
Residue Non-alkaloidal sub.
- Evap., dil. HCl & Filtration
Filtrate (Alkaloidal HCl salts) - Alk. with NaOH & Ext. with ether
Ether layer Emetine
Aq.alk. solution(Phenolic alkaloids) - HCl (Alkaloidal salts) - Alk. NH4OH Ext. ether
Aqueous layer (Psychotrine)
Ether layer (Cephaline)
Tests for identification of Ipeca alkaloids: •
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Alkaloidal solution in HCl + Ca hypochlorite orange color. Emetine and cephaline + Froehd's reagent: dirty green color (the color with emetine fades by addition of HCl). Psychotrine + Froehd's reagent: pale green color. Cephaline and psychotrine + p-nitrodiazobenzene dye soluble in NaOH purple color.
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Psychotrine + conc. H2SO4 + HNO3 cherry red color.
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Emetine + Liebermann's reagent black color.
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Uses:
Emetine and cephaeline have antitumour and antiviral activity, but are too toxic for therapeutic use.
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Emetine and psychotrine are mainly used as emetic drugs.
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The crude drug is used as expectorant (due to its saponin content) .
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Emetine HCl and Dehydroemetine (DHE) have an antiamoebic effect, and are used for the treatment of amoebic dysentry and Fasciola.
Ipeca alkaloids are diaphoretic, alone or in combination with opium (e.g. Dover's powder).
2- Curare Alkaloids •
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Occurrence: Curare or South American arrow poison is the dried crude extract, obtained mainly from Chondrodendron tomentosum (Menispermaceae) and certain Strychnos species, (Loganiaceae). Curare contains several alkaloids (4-7%), the most important is d -tubocurarine. MeO N Me O
OH
H
O H
Me Me
N+
OH
OM e
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Properties: d -tubocurarine (4ary alkaloid) is freely soluble in H2O. It is a phenolic dextrorotatory alkaloid. It is a bis-benzyltetrahydroisoquinoline alkaloid.
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Tests:
Saturated aqueous solution + FeCl3 faint green color green color.
Solution of the alkaloidal HC1 + Na2CO 3 yellow brown precipitate.
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Uses:
Tubocurarine chloride is mainly used by i.m. or i.v. routes as skeletal muscle relaxant.
It is used to control and reduce convulsions of strychnine poisoning and of tetanus.
It is used as a diagnostic aid in myasthenia gravis.
