P5 Analisis Kualitatif Dan Analisis Kuantitatif Alkaloid

(1)

ANALISIS KUALITATIF DAN

KUANTITATIF ALKALOID

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UJI KUALITATIF ALKALOID :

•

Pereaksi

Pereaksi pengendap

pengendap alkaloi

alkaloid:

d:

digunakan untuk:

1-1- Melih

Melihat a

at ada tid

da tidakn

aknya

ya alk

alkaloid

aloid

2-2- Meliha

Melihat proses ek

t proses ekstr

straksi alk

aksi alkaloid sdh tunt

aloid sdh tuntas.

as.

Kekurangan:

senyawa non alkaloid dpt berinteraksi :

Pr

Prot

otein, lakt

ein, lakton,

on, ku

kumar

marin.

in.

POSITIF PALSU.

(3)

•

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

(4)

•

Reaksi Warna:

1- Pereaksi Froehd: Asam fosfomolibdat

2- Pereaksi Marqui:

Formaldehid/ H

₂

SO

₄

pekat

3- Pereaksi Mandalin: Asam

Sulfovanidat

4- Pereaksi Erdmann:

HNO

₃

/ H

₂

SO

₄

pekat

5- pereaksi

Mecke:

Asam Selenat / H

₂

SO

₄

pekat

6- Pereaksi

Shaer:

Hidrogen peroksida / H

₂

SO

₄

pekat

7- pereaksi

Rosenthaler:

Kalium arsenat / H

₂

SO

₄

pekat

8-

HNO

_{3 pekat}

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Identifikasi Alkaloid:

•

Titik lebur

•

Pereaksi warna

•

Rotasi optik

•

Uji Mikrokristal

•

Analisis HPLC, GC, GC-MS

•

Analisis UV, IR, NMR, MS.

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Analisis Kuantitatif Alkaloid:

•

Metode volumetri:

•

Dasar : Reaksi asam basa. Basa alkaloid dititrasi dg asam.

•

Titrasi dg media air:

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:

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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.

(8)

•

Colourimetric Method:

e.g. Morphine + NaNO₂/HCl

Ergot + p-dimethylaminobenzaldehyde

•

Spectrophotometric Methods.

•

Polarimetric Method.

•

Fluorimetric Method.

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

Classification of Alkaloids

•

Biogenetic.

Based on the biogenetic pathway that form the alkaloids.

•

Botanical Source.

According to the plant source of alkaloids.

•

Type of Amines.

Primary, Secondary, Tertiary alkaloids.

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•

Phenylalkylamines:

e.g. Ephedrine

•

Pyridine and piperidine

e.g. lobeline, nicotine

•

Tropane

e.g. Atropine. CH₂ CH CH₃ NH₂ N N H NCH₃ OH

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•

Quinoline

e.g.quinine and quinidine

•

Isoquinoline

e.g. papaverine •

Phenantheren

e.g. Morphine N

N

(12)

•

Indole

e.g.ergometrine •

Imidazole

e.g. pilocarpine •

Purine

e.g. caffeine N H N N N N N N H Purine 1 2 3 4 5 6 ₇ 8 9

(13)

•

Steroidal

e.g. Solanum and Veratrum

alkaloids

•

Terpenoid

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Alkaloid Quinolin

Alkaloid Kina

• Kulit batang kina mengandung alkaloid:

1- kinin dan kinidin.

2- sinkonin dan sinkonidin.

• Alkaloid kina dpt

sbg garam asam kuinat dan asam sinkotanat.

• They are diacidic bases form two types of salts:

1- Neutral salts (Monoacidic) (less water soluble). 2- Acidic salts (Diacidic) water soluble.

OH HO

OH

HO COOH

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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. N N H₃CO HO H H N N H₃CO HO H H 8 9 Quinine Quinidine

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

Properties:

•

Quinine

is very slightly soluble in H

₂

O, 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

H

₂

O insoluble

).

–

Quinine bisulfate (

acidic

and

H

₂

O soluble

).

•

Quinine

(

l

-isomer) gives

quinidine

(

d

-isomer) among other

products when warmed with KOH in amyl alcohol.

(18)

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Separation of the 4 Alkaloids

Powdered Bark

- Alk . CaO + NaOH + H₂O - 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 _quinidine,

cinchonine & cinchonidine

Hot water , Na2CO3

Quinine NaOH, ether

Aqueous layer Ether layer

Cinchonine Quinidine & Cinchonidine

-HCl PH=7, Na, K Tart. salt - filter

Precipitate Filtrate

Aqueous solution (Monosulphates) (monosulphate)

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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 

(21)



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

(

anti-arrhythmic

), particularly to inhibit auricular fibrillation

in a dose of 0.6-1.6 g of quinidine sulfate daily.

•

Cinchonine

and

cinchonidine

are used as

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Isoquinoline Alkaloids

1-

Ipecacuanha

Alkaloids

•

Occurrence:

Ipecac is the dried roots and rhizomes ofCephalis 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.

N MeO RO N OMe OMe H H R = Me Emetine R = H Cephaline N MeO HO N OMe OMe H Psychotrine

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•

Emetine:

It is non phenolic and levorotatory. It contains 2 basic nitrogens.

•

Cephaline:

It is phenolic and levorotatory.

It gives emetine on methylation with (CH₃)₂ SO₄.

•

Psychotrine:

Occurs as yellow prisms.

It is phenolic and gives cephaline on reduction.

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

Isolation of Ipeca alkaloids:

Powdered root and rhizome

- Ext. alcohol,Conc., lead acetate. - Filtration

Filtrate _Residue

Non-alkaloidal sub.

- Evap., dil. HCl & Filtration

Alkaloidal bases and salts

Filtrate (Alkaloidal HCl salts)

- Alk. with NaOH & Ext. with ether

Ether layer

Emetine (Phenolic alkaloids)

- HCl (Alkaloidal salts) - Alk. NH4OH Ext. ether

Aqueous layer Ether layer

(Psychotrine) (Cephaline)

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

Tests for identification of Ipeca alkaloids:

• 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.

• Psychotrine + conc. H₂SO₄ + HNO₃  cherry red color.

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

Uses:

• Emetine and cephaeline have antitumour and antiviral activity, but

are too toxic for therapeutic use.

• Emetine and psychotrine are mainly used as emetic drugs.

• The crude drug is used as expectorant (due to its saponin content) .

• 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

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2- Curare Alkaloids

•

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.

N OH M e O N H H M e OM e O OH O M e + M 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.

•

Tests:

 Saturated aqueous solution + FeCl3  faint green color  green color.

 Solution of the alkaloidal HC1 + Na2CO 3 yellow brown precipitate.

•

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.