II.3. In vivo study
II.3.1. Experimental animals
Three month old male Wistar Albino rats weighing
175-225g were obtained from the animal house of the laboratory of Biochemistry,
Department of Biochemistry, University of Yaoundé I, Cameroon. All
animals were kept in an environmentally controlled room with a 12h light/12h
dark cycle .The animals had free access to water and standard rat diet. These
rats were used for the BGT, OGTT and the acute preventive treatment. Small male
Wistar rats of age 2 months with average weight 100-120 g was use for
acute toxicity study.
Experimental food: The animals where fed on
standard laboratory diet made up of corn flour (60%), wheat (10%), fish (12%),
soya beans (15%), palm oil (2%), vitamin complex (0.5%), and minerals
(1.5%).
II.3.2. Evaluation of the acute toxicity effect of
hydroethanolic extracts
This was aimed at evaluating the toxic effect of a single dose
of a product administrated once. The protocol use was that of test limit
proposed by OECD (2004). It recommended the administration of
a single dose (=5000 mg/kg of the body weight) of a substance to experimental
animals (rats) after which an intensive observation of the physiological
changes was done for 48 hours. The animals were observed for 2 weeks and their
physiological parameters registered. After two weeks those that survived were
sacrificed and their blood collected for appropriate analysis (markers of
toxicity). The rats were treated as follows; 3 groups of 5 rats were
constituted as seen below (table VII)
Table VII: Repartition of animals for acute
toxicity study of extracts
|
Groups
|
Treatment
|
|
Control
|
Distilled water
|
|
FOHF 5000mg/kg
|
Single dose of 5000mg/kg body weight of hydroethanolic fruit
extract of F ovata
|
|
FOHT 5000mg/kg
|
Single dose of 5000mg/kg body weight of hydroethanolic twig
extract of F ovata
|
II.3.4. Effect of extracts on glycemia
Glycemia was evaluated using a glucose meter
(SD-check) and blood glucose test strips. The principle includes quantifying
the blood glucose based on the enzymatic conversion of glucose into gluconic
acid in the presence of glucose oxydase (300unites/100strip) and potassium
ferrocyanide (mediator 9.0mg/100strip). The strip is made up of electrodes that
measure the level of glycemia. Glucose in blood mixed with reagent on the test
strip creates a small electric current. The intensity of the current created
depends on the quantity of glucose in blood. The quantity of gluconic acid
formed, measured by electric impedance is directly proportional to the quantity
of glucose contained in the test zone (Ellen et al.,
2003).
Procedure: A drop of fresh blood placed on
the microplate will migrate by capillarity and filled the test zone. Few
seconds after, the quantity of glucose appears on the screen of the apparatus
in mg/dl.
II.3.4.1. Evaluation of hypoglycemic activity in hyperglycemic
rats
For this, 3 groups of 5 hyperglycemic rats where constituted
and treated as follows:
Table VIII: Repartition of animals for the
hypoglycemic test
|
Groups
|
Treatment
|
|
Control
|
Distilled water (control)
|
|
FOHF 300mg/kg BW
|
300mg/kg body weight of hydroethanolic fruits extract
|
|
FOHT 300mg/kg BW
|
300 mg/kg body weight of hydroethanolic twigs extract
|
All the rats being at fasted state throughout the experiment,
the fasting blood glucose test of the various rats was done before
administration of our extracts (0h). The extracts were administrated orally by
intra-gastric route using an oesophageal probe followed by successive glucose
test measurement determined at instants of 2h, 5h, by incision of the tail and
placing a drop of blood on the glucose strips and the glucose meter reading
registered.
| 
