Different extraction processes, Pharmacognostical profile and isolation of Caffeine

1. EXTRACTION
Extraction is defined as a process that involves separation of medicinally active portions of
animal and plant tissues from the inactive components through the use of selective solvents.
TYPES OF EXTRACTION PROCESSES
The general processes used in extraction are:
1. INFUSION
Plant material is placed in a pot and wetted with cold water, boiling water is poured over it, and
left to stand, covered with lid and then poured.
2. MACERATION
Used for water soluble active constituents. It consist of macerating the plant material in cold
water for several hours.
3. DIGESTION
This method is suitable for hard barks or woods which are difficult for water to penetrate.
4. DECOCTION
It consists of boiling plant material for ten minutes or if boiling water is poured over it and
allowed to stand for thirty minutes.
5. CONTINOUS HOT EXTRACTION PROCESS
This procedure is considered as the most common method used for the extraction of organic
constituents from dried plant tissues.The powdered material is continuously extracted in a
soxhlet apparatus with a range of solvents.

2. 6. SOLVENT-SOLVENT PRECIPITATION
The extract dissolved in a suitable solvent, is mixed with a less polar but miscible solvent
causing the selective precipitation of the less soluble plant constituents.
7. LIQUID-LIQUID EXTRACTION
The solute molecules are partitioned between two immiscible solvents. The amount of solute in
each phase will depend upon their relative solubility in each solvent. which in turn is related to
their polarity.
CAFFEINE
Caffeine is chemically 1,3,7-trimethylxanthine (C8H10N4O2).It is a central nervous
system (CNS) stimulant of the methylxanthine class of psychoactive drugs. It is the world's most
widely consumed psychoactive drug, but unlike many other psychoactive substances, it is legal
and unregulated in nearly all parts of the world. It is a bitter, white crystalline purine,
a methylxanthine alkaloid, and thus closely related chemically to the
adenine and guanine contained in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is
found in the seeds, nuts, or leaves of a number of plants native to South America and East Asia.
The most well known source of caffeine is the seed (commonly incorrectly referred to as the
"bean") of COFFEA plants. Beverages containing caffeine are ingested to relieve or prevent
drowsiness and to increase one's energy level. Caffeine is extracted from the plant part
containing it for making beverages by steeping it in water, a process called infusion.
Figure 1: CHEMICAL STRUCTURE OF CAFFEINE

3. BIOLOGICAL SOURCE
It is obtained from dried ripe seeds of COFFEA ARABICA LINN or C.LIBERICA HIERN.
FAMILY: Rubiaceae
GEOGRAPHICAL SOURCE
Coffee is found mainly in Brazil, Ethiopia, Vietnam, India, Indonesia, Sri lanka and Gautemala.
USES
Caffeine is used in:
 Bronchopulmonary dysplasia in premature infants for both prevention and treatment.
 Apnea of prematurity as a primary treatment, but not prevention.
 Orthostatic hypotension treatment.
 As CNS stimulant.
EXTRACTION AND ISOLATION OF CAFFEINE
Figure 2:GENERAL PROCEDURE FOR EXTRACTION OF CAFFEINE

4. PROCEDURE
Preparation of Tea solution
Place about 20 mL of water into a 100 mL beaker. When the solution has reached a gentle boil,
remove the watch glass and place a tea bag into the gently boiling water so that it is covered as
completely as possible by the water. Note the approximate level of the liquid in the beaker at
this point. Replace the watch glass and continue gently boiling the mixture for about 15 minutes.
Add water to maintain the liquid level. Occasionally press the tea bag with the closed end of a
test tube to maintain contact of the tea in the bag with the solution. After the 15 minute boiling
period, remove the beaker from the hot plate and squeeze any excess liquid out of the tea bag
into the beaker and then add 1.1 g of sodium carbonate (Na2CO3) and stir the hot solution with a
stir rod until the sodium carbonate is dissolved. Allow the tea solution in the beaker to cool to
room temperature. While this initial tea solution is cooling, place the tea bag into a 50 mL
beaker, add 5 mL of water, cover with a watch glass, and heat this to a gentle boil for about 2
minutes. Remove this beaker from the hotplate, squeeze the excess liquid out of the tea bag into
beaker, then add the contents of this beaker to the tea solution in the original beaker.
Extraction of Caffeine
Pour the tea solution into a 60 ml separatory funnel.
Extract the tea solution with 6 ml of methylene chloride .Mix the two layers by inverting the
funnel gently several times .Vent the funnel frequently to avoid any pressure buildup. Place the
funnel in a ring and allow the layers to separate. Drain the methylene chloride extract (the lower
layer) into a dry 25 mL flask. Avoid draining any of the aqueous layer or any emulsion into the
flask. Perform a second extraction in the same manner with another 6 mL of methylene chloride.
Combine this methylene chloride extract with the first one by draining it into the same 25 ml
flask. If there are any visible water drops in the methylene chloride solution, pour the extract
back into the separatory funnel, allow the layers to separate, then drain the methylene chloride
layer into a dry 25 ml flask. Dry the methylene chloride solution by adding a small amount of
granular anhydrous sodium sulfate. Allow the methylene chloride solution to remain over the
drying agent for about 10 – 15 minutes.

5. Isolation of the Caffeine
Decant the dried methylene chloride solution into a dry, 30 ml beaker. Place the beaker on a hot
plate and evaporate the methylene chloride over a low heat setting. The evaporation can be
accelerated by directing a slow stream of air over the mouth of the beaker. As soon as solid
forming appears in the beaker, remove it from the heat .The residual heat should be enough to
complete the evaporation of the methylene chloride. Do not heat the beaker after the solvent has
evaporated to prevent sublimation of caffeine. Determine both the weight of the caffeine and its
melting point.
By: Abu Sufiyan Chhipa
B.PHARM