Thursday, March 07, 2013
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TEST TUBE SPOT TEST
Culvenor
and Fitzgerald have described a simple kit that can be taken into the field for
use in testing samples of plant material for alkaloids. About 2-4 g of fresh
plant part is ground in a small mortar with sand and sufficient
chloroform/dichloromethane to make slurry. Ammoniacal
chloroform/dichloromethane is added and the mixture stirred for 1 min, prior to
filtration into a small test tube. Extraction of the alkaloids from
chloroform/dichloromethane is accomplished by shaking the solution with 0.5 mL
of 2N sulfuric acid and separation of the acid layer by means of a medicine
dropper. A few drops of this extract are the tested with Mayer’s reagents and
other reagents to ascertain the presence of alkaloids.
DETECTION OF SAFONINS
Saponins
has several characteristic properties that can be used as a basic for simple
detection test. (a) They are capable of hemolyzing red blood cells, (b) in
aqueous media they will produce a characteristic honeycomb froth which persists
for at least 30 min after vigorous shaking of the solution and, (c) they
produce characteristic color reaction is
the Liebermann-Burchard test.
The
appearance of the characteristic
honeycomb froth which persists for at least 30 min after shaking an
aqueous boiled (3-5 min) mixture containing the plant material is evidence for
the presence of saponins. If only a
small froth is produced by this treatment, which is stable for only a
few minutes, proteins, certain plant acids, or a low concentration of saponin
may be the cause. This does not distinguish between steroidal and triterpenoid
saponins.
The
Liebermann-Burchard test may be used to
detect the the presence of steroids and triterpenes. The following procedure
has been used to detect saponins and/or free triterpenes or steroids: the
finally ground sample (5-20 g) is extracted with boiling ethanol and the
filtered extract is evaporated to drynees. The material obtained is triturated
with ether. The residue (ether insoluble material) is subjected to froth and
Liebermann-Burchard tests. If the froth test is positive, the ether insoluble
material is hydrolyzed with aqueous hydrochloride acid 2N and any precipitate
noted. The formation of a precipitate confirms the presence of saponin. The
ethereal extract is evaporated to drynees and the residue is subjected to a
Liebermann-Burchard test (L.B. test).
LIEBERMANN-BURCHARD TEST
A
small amount of the material to be tested is placed on a white title and a few
drops of acetic anhydride are added and the strirred with a glass rod. A few drops
concentrated sulfuric acid are now added and the colors produced are noted.
Triterpenoids generally give red, pink, or purple colors which are more
persistent than the blues or greens usually obtained from steroids.
QUESTIONS
1. Did
a L.B. test can use for general terpenoid such as monoterpenoid, sesquiterpenoid, and
polyterpenoid, explain briefly!
2. Define
the reaction mechanism of triterpenoid and reagen L.B.!
3. How
we can examined the alkaloids in a part of plant, explain two types of reagent
that available for this test!
4. How
to make reagent for detection of alkaloids?
5. Mention
the various alkaloids that mostly present in the plants!
6. Why
presipitant is the indicator the present of alkaloids ?
7. How
we distinguish between steroidal and terpenoid with L.B. reagent and define the
mechanism reaction involved!
8. How
to detect saponins in the part of plant?
Posted in: Semester 4
1 komentar:
11(α)-methoxysaikosaponin F, is a triterpenoid extracted from the root of Bupleurum chinense DC. It is a Saikosaponins standard to help analyse and resolve the activities of herbal medicines such as Sho-saiko-to. Sho-saiko-to is a herbal medicine with effects as an anti-tumor drug and as a biological response modulator in vivo and in vitro. 11(α)-methoxysaikosaponin F
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