THE PHARMACEUTICAL EVALUATION OF I. GABONENSIS
THE PHARMACEUTICAL EVALUATION OF I. GABONENSIS
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Date
1993-02
Authors
ABDURAHMAN, EZZELDIN MUKHTAR
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Abstract
This study deals with the pharmacognostic
aspects of the leaves, fruits and seeds of Irvingia
gabonensls (O'Rorke) Baill, with special reference
to its seed fat content.
I. gabonensls is a forest tree up to 25 meters
high and 2 meters in girth. The plant is widelydistributed
in Nigeria especially in the Eastern
and Western regions of the country, where the
kernels are an important source of food. They
are eaten in various parts of West Africa. The
plant has two varieties, namely gabonensls with
sweet edible fruits and excels a with bitter inedible
fruits. Detailed macroscopical, microscopical and
phytochemical studies were carried out on the two
varieties of the plant and pharmacognostic parameters
were established for the identification of the two
varieties. Also, some pharmacopoeial standards have
been recommended for I. gabonensls leaves and kernels.
The composition of the fatty acid in the seed
fat was determined by different chromatographic
techniques including thin layer chromatography (TLC),
gas chromatography/mass spectrometry (GC/MS) and
high resolution gas chromatography (HRGC). TLC of
the hydrolysed seed fat on silica gel plates
impregnated with AgNO3 revealed the presence of
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lauric, myristic, stearic and oleic fatty acids.
For GC/MS analysis, the seed fat was first hydrolysed
and the free fatty acids (FFE) were derivatized to
methyl esters (FAME) before injecting onto a carbowax
column. Identification was made by comparing the
retention time and mass spectra of the FAME with
computerized reference data. The fatty acids
identified were capric, lauric, myristic, palmitic,
stearic, oleic and linolic acids.
The so called "Dika Fat" was indeed found to be
a mixture of fat and wax. The "fat" was only partially
hydrolysed with aqueous KOH to afford glycerol and the
fatty acids. On the other hand, alcoholic KOH
hydrolysed the "fat" completely to afford glycerol
and an alcohol which was immiscible with water.
The percentage composition of the fatty acids in
the seed fat was determined by the HRGC of the FAME
on a GC equiped with fused silica column. It was
found that myristic acid (52.3190 and lauric acid
(36.9250 were the principal saturated acids in
I. gabonensis var. excels a seed fat. The unsaturated
acids were present In very low concentration. Similar
results were ontained for I.gabonensis var. gabonensis.
The seed fat was evaluated as a possible base
for ointment and suppository dosage forms. Wool fat
and castor oil were mixed separately with the seed
fat in different proportions to produce semisolid
preparations of such consistency and composition that
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can be applied on the skin by inunction. The seed fat
mixed with either 20% wool fat or with 30% castor oil
produced two suitable ointment bases with the desired
properties. The rate of release of drugs from these
bases was studied using the water soluble resorcinol
and the less water soluble s a l i c y l i c acid. The results
indicate that the rate of release of resorcinol was
lower than the r a t e of release of s a l i c y l i c acid while
the ointment bases formulated with the seed fat and
wool fat released more drugs than those formulated
with the seed fat and castor o i l.
A suppository base consisting of wool fat (10%)
and the seed fat (90%) was formulated and chloroquine
suppositories prepared by incorporating chloroquine
phosphate into these bases was further evaluated.
The physiological studies on adult rats fed
with this formulated seed fat for four weeks, showed
significant increase in the serum cholesterol,
triglyceride and t o t a l l i p i d levels, indicating that
pharmaceutical applications of the seed fat should be
regulated to avoid i t s possible side effects.
This work highlights the economic potentials
of the plant I. gabonensis and indicates the p o s s i b i l i ty
of exploiting i t s fat content in addition to the kernel
mucilage as a source of raw materials for the
pharmaceutical industry.
Description
A DISSERTATION SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR
THE DEGREE OF DOCTOR OF PHILOSOPHY
IN PHARMACOGNOSY
DEPARTMENT OF PHARMACOGNOSY AND DRUG DEVELOPMENT
FACULTY OF PHARMACEUTICAL SCIENCES
AHMADU BELLO UNIVERSITY
ZARIA, NIGERIA
Keywords
PHARMACEUTICAL,, EVALUATION,, I. GABONENSIS