08-16-2017, 10:43 PM
Studies on phytochemical constituents of six Malaysian medicinal plants
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INTRODUCTION
The world is rich with natural and unique medicinal plants.
Medicinal plants are now getting more attention than ever
because they have potential of myriad benefits to society
or indeed to all mankind, especially in the line of medicine
and pharmacological. The medicinal value of these plants
lies in bioactive phytochemical constituents that produce
definite physiological action on the human body (Akinmoladun
et al., 2007).
MATERIALS AND METHODS
Collection of plant samples
The plant materials are brought from local markets or collected from
local area. The plants are processed and analyzed.
Processing of plant samples
The leaves of the plants are properly washed in tap water and then
rinsed in distilled water. The rinsed leaves are dried in an oven at a
temperature of 35-40 C for 3 days. The dried leaves of each plant
are pulverized, using a sterile electric blender, to obtain a powered
form. The powdered form of these plants is stored in airtight glass
068 J. Med. Plant. Res.
containers, protected from sunlight until required for analysis.
Preparation of aqueous extract of plant samples
The aqueous extract of each plant sample is prepared by soaking
10 g of powdered samples in 200 ml of distilled water for 12 h. The
extracts are then filtered using filter paper or Whatman filter paper.
Phytochemical analysis
Chemical tests are conducted on the aqueous extract of each plant
sample and also of the powdered form of the plant samples using
standard methods Edeoga et al. (2005).
Qualitative analysis on phytochemical constituents
Test for tannins
0.5 g of powdered sample of each plant is boiled in 20 ml of distilled
water in a test tube and then filtered. The filtration method used
here is the normal method, which includes a conical flask and filter
paper. 0.1% FeCl3 is added to the filtered samples and observed for
brownish green or a blue black colouration, which shows the presence
of tannins.
Test for phlobatannins
10 ml of aqueous extract of each plant sample is boiled with 1%
HCl acid in a test tube or conical flask. If the sample of plant carries
phlobatannins, a deposition of a red precipitate will occur and
indicates the presence of phlobatannins.
Test for saponins
2 g of powdered samples of each plant is boiled together with 20 ml
of distilled water in a water bath and filtered.10 ml of the filtered
sample is mixed with 5 ml of distilled water in a test tube and shaken
vigorously to obtain a stable persistent froth. The frothing is
then mixed with 3 drops of olive oil and observed for the formation
of emulsion, which indicates the presence of saponins.
Test for flavonoids
A few drops of 1% NH3 solution is added to the aqueous extract of
each plant sample in a test tube. A yellow coloration is observed if
flavonoid compounds are present.
Test for terpenoids
5 ml of aqueous extract of each plant sample is mixed with 2 ml of
CHCl3 in a test tube. 3 ml of concentrated H2SO4 is carefully added
to the mixture to form a layer. An interface with a reddish brown
coloration is formed if terpenoids constituent is present.
Test for cardiac glycosides
1 ml of concentrated H2SO4 is prepared in a test tube. 5 ml of
aqueous extract from each plant sample is mixed with 2 ml of glacial
CH3CO2H containing 1 drop of FeCl3.The above mixture is
carefully added to the 1 ml of concentrated H2SO4 so that the concentratedH2SO4 is underneath the mixture. If cardiac glycoside is
present in the sample, a brown ring will appear, indicating the
presence of the cardiac glycoside constituent.