globimetula cupulata, hypoglycemic effects, leaf extract
D Edem. Effect Of Aqueous Extracts Of Leaves Of Globimetula Cupulata (Dc) Van Tieghem In Normoglycemic Rats. The Internet Journal of Alternative Medicine. 2008 Volume 8 Number 1.
Globimetula cupulata leaves were evaluated for their hypoglycemic activity in rats. The animals were divided into 4 groups (n=6). Water extract of
Globimetula cupulata (a mistletoe) is a member of the family Loranthaceae. It is a parasitic shrub which grows on some dicotyledonous trees and attaches itself to the host by modified roots. The plant is found in African countries like Togo, Senegal, Benin Republic, Cameroon, Gabon, Congo Democratic Republic, Angola, Tanzania, Uganda, Southern Nigeria and south east of Burkina Faso 1,2 . The leaves are short, 1 – 2 times as long as broad, large, thick and coriaceous, round –cordate at base, acute or obtuse at base. They are usually broadly ovate or elliptic, being 4.5 - 17 cm long and 3 – 12.5 cm broad, with petioles 6 -18 mm long 1 .
Globimetula cupulata is a medicinal plant used by some traditional herbalists in the management of high blood pressure and diabetes mellitus 3 . Little information exists in the literature regarding the effect of the plant on blood glucose levels. Reports are lacking on the effect of this plant on tissue histology. Thus the present study was undertaken to explore the effects of
Materials And Methods
Twenty four (24) male Wistar albino rats weighing 156.3 – 337.1g were
obtained from the Animal House of the College of Health Sciences, University of Uyo, Uyo, Nigeria. The rats were kept in clean and only dry plastic cages, with 12hrs light-dark cycle at 25
The rats were assigned into 4 groups of 6 rats each. Rats in group 1 were the control which did not receive any extract. Animals in the test groups (2, 3 and 4) were orally fed once daily with 300mg/kg, 600mg/kg and 900mg/kg body weight (wt) extracts respectively. Administration of the extracts was carried out for 14 days. All animals were treated in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals 4 .
Collection of Plant Materials
(c) Preparation of Aqueous Extract of
One hundred grams (100g) of the powdered material were brewed in
750ml of boiled tap water and allowed to stand for at least 30 minutes. The decoction was then filtered (through a plug of cotton wool) and stored in a clean bottle to be administered to rats. Twenty millilitre (20ml) aliquots of the decoction were dried at 50 0 C to constant weight using a rotary evaporator. The residue left was then used to determine (by gravimetric method) the concentrations of the mistletoe extract administered to different groups of the experimental animals. One milliliter (1 ml) of the extract produced a residue of 50.0mg. 1.10ml of the solution administered to 184.3g rat was equivalent to 300mg/kg body wt extract. Other doses per wt of rats were determined accordingly.
(d) Animal Treatments
The 4 group of rats were as follows: GLE -1, GLE -2, GLE -3 and NC. The groups GLE -1, GLE -2 and GLE -3 were administered with 300, 600 and 900mg/kg body wt of the extract, while the NC group which served as normal control was not given any extract. All treatments were given for 14 days, by oral gavage.
(e) Collection and Treatment of Blood Samples
After 14 days, the animals were anaesthetized under chloroform vapour. Blood samples were obtained by cardiac puncture. Aliquots of the blood were poured into screw-cap sample bottles containing fluoride /oxalate anticoagulant for blood glucose determination. All analyses were carried out within 24 hrs of blood collection.
(f) Blood Glucose Analysis
Blood glucose concentration was estimated by glucose oxidase method, using a reagent kit from Randox Laboratory Ltd, UK.
(g) Histopathological Study
On the last day of experiment, the tail parts of the pancreas were removed and kept in 10% formaldehyde. Tissue processing was carried out by autotechnicon and the prepared 5µ thick sections were mounted on slides and stained with hematoxylin and eosin (H & E). Stained sections were morphologically evaluated.
(h) Statistical Analysis
All data were expressed as means ± SD. Student’s t – test was used to compare the mean values of test groups and control. Differences in mean values were considered significant at p < 0.05.
The blood glucose concentrations in the experimental animals were 4.25 – 4.75 mmol/L before the start of the study. In comparison with the NC group, which had 4.15 mmol/L glucose, the other experimental groups had significantly lower final blood glucose concentrations of 2.60 – 3.05 mmol/L. (p < 0.05). No significant differences in blood glucose concentrations were observed between groups which received the plant extracts (p < 0.05). However, there were dose-dependent decreases in blood glucose concentrations with increasing levels of extracts.
Hypoglycemic Effects of Aqueous Extract of Globimetula cupulata leaf *
Legend: NC = Normal Control; GLE-1 = Globimetula leaf extract Group 1
GLE-2 = Globimetula leaf extract Group 2; GLE-3 = Globimetula leaf extract Group 3
*Values are means ± standard deviation (n = 5). Values in same row with different superscripts in a horizontal row represent means that are significantly different (p < 0.05).
Treatment of the GLE groups of rats with 300, 600 and 900mg/kg body wt of
Effects of Consumed Extracts on Histopathology of Pancreas: Histomorphologic Changes of Pancreas.
The cellular integrity and architecture were intact in the NC group (Figure 1). Pancreas of the GLE-1 group which consumed 300mg/kg body wt extract (Fig. 2), showed some similarity to group NC which did not consume any extract.
FIGURE: Histological Sections of Pancreas
Pancreas of Normal Health Rat, H & E Staining (x 40)
Pancreas of Rat Treated with 300mg/kg body wt extract, H & E Staining (x 40)
There was a relative increase of granulated and normal beta cells in the GLE-2 group which consumed 600mg/kg body wt extract (Fig 3), when compared with the GLE-1 group. However, the increases in size and number of islets especially around the central vessel were higher in the GLE-3 group (which consumed 900mg/kg body wt extract) than in the other experimental groups.
FIGURE: Histological Sections of Pancreas
Pancreas of Rat Treated with 600mg/kg body wt extract, H & E Staining (x 40)
Pancreas of Rat Treated with 900mg/kg body wt extract, H & E Staining (x 40)
The initial blood glucose concentrations of the experimental animals (4.25 – 4.75 mmol/L) is considered normoglycemic for the study 5, 6 . Furthermore, the percentage reduction in glucose levels was high for all groups treated with extract, when compared with that of the control. The results suggested hypoglycemic effects of the extracts. The findings may indicate the presence of some hypoglycemic agents in the leaves of
The pancreas is the primary organ involved in sensing the organism’s dietary and energetic states via glucose concentration in the blood. In response to elevated blood glucose, insulin is secreted. Insulin deficiency (or diabetes mellitus) causes excessive elevation of blood glucose and underutilization leading to hyperglycemia 13 . Hyperglycemia is the primary clinical manifestation of diabetes mellitus, a major degenerative disease affecting 3 – 5 % of the world’s population 14 . It is thought to contribute to diabetic complications by altering vascular cellular metabolism, vascular matrix molecules (especially glucose and lipids) and circulating lipoproteins 15 . The histopathological study of the pancreas indicated increased volume density of islets and increased percentage of beta cells, in the rats that received the extracts, which may be a sign of regeneration potential. Signs of regeneration of ß cells, potentiation of insulin secretion from surviving ß cells of the islets of Langerhans and decrease of blood glucose have been reported following consumption of some plant extracts (11, 16, 17, 18) .
The findings of this study indicated that consumption of the