|
Biokemistri
Nigerian Society for Experimental Biology
ISSN: 0795-8080
Vol. 17, Num. 2, 2005, pp. 149-156
|
Biokemistri, Vol. 17, No. 2, Dec, 2005, pp. 149-156
Comparative study
of the hypoglycemic and biochemical effects of Catharanthus roseus (Linn)
g. apocynaceae (Madagascar periwinkle) and chlorpropamide (diabenese) on
alloxan-induced diabetic rats
Emeka E. J. IWEALA1*
and Clement U. OKEKE2
Departments of 1Biochemistry
and 2Botany, Abia State University,
P.M.B 2000, Uturu, Nigeria
*Author to whom all correspondence should be addressed. E-mail:emekaiweala@hotmail.com
Received
14 March 2004
MS/No BKM/2004/012,
All rights reserved.
Code Number: bk05021
Abstract
The effect of the aqueous
extracts of Catharanthus roseus and chlorpropamide (Diabenese) on the
levels of serum cholesterol, total protein, lipid peroxidation, blood glucose
and liver enzymes were compared in alloxan-induced diabetic rats. Four groups
namely A, B, C and D comprising of nine rats each were used. A and B were
administered with chlorpropamide and C. roseus extracts respectively,
while C and D served as diabetic and non-diabetic controls respectively. The
results showed comparatively significant reductions (P≤0.05) in the
levels of glucose, protein, cholesterol, lipid peroxidation and liver enzymes
in the groups administered C. roseus extracts and chlorpropamide
relative to the controls. The reductions were higher in the groups treated with
C. roseus extract than in the groups treated with diabenese.
Key words: Catharanthus
roseus, Diabenese, alloxan-induced
diabetes
INTRODUCTION
Diabetes
is not a single disease but a syndrome that is characterized by a total or
relative lack of insulin leading to persistent elevation of blood glucose as
well as alteration in lipid and protein metabolism1.This syndrome
can occur as a result of some secondary causes such as pancreatectomy and iron
overload of beta-cells resulting from haemachromatosis. Other causes include
excess cortisol production in Cushings syndrome and excess growth hormone
secretion in acromegaly and insulin-resistant syndrome2.Two basic
types of diabetes are common namely type 1 or insulin-dependent and type 2 or
non-insulin-dependent diabetes3. Type 1 commonly seen in juveniles
is characterized by failure to produce insulin due to autoimmune destruction of
beta-cells of the pancreas while type 2 is usually adult-onset and is
associated with insufficient production of insulin and loss of responsiveness
by cells to insulin4,5. Insulin is pivotal to carbohydrate
metabolism and controls the concentration of glucose in the blood via a
feedback mechanism.
Diabetes
is characterized by symptoms such as weakness, polyuria, excessive thirst as
well as ketonemia, ketouria and ketosis due to altered metabolism of lipids and
proteins. It is associated with abnormalities such as kidney failure, nervous
defect, impotence, blindness, stroke and heart diseases. Abnormalities in lipid
metabolism may contribute to excessive hepatic glucose through gluconeogenesis
as well as abnormal drive from the autonomic nervous system.
Diabetes
especially type 2 is difficult to treat and will continuously get worse with time.
The supplemental use of insulin in controlling blood sugar is complex and
involves accurate and timed injection of the hormone as food is ingested and
digested and usually leads to treatment failures. Commonly used oral
antiglycemic drugs used in the treatment of diabetes include the older sulfonylurea
which act by stimulating production of insulin and the newer ones that act by
increasing sensitivity of cells to insulin and prevents additional release of
glucose by the liver and intestines. Chlorpropamide (1-{p-chlorophenyl-sulfonyl-3-propylurea,
MW; 276.74) commercially sold as Diabenese is a sulfonamide derivative that
occurs as a white crystalline solid insoluble in water but soluble in alcohol.
It is rapidly absorbed and metabolized and excreted unchanged with a half life
of 36 hours6. Its metabolism contributes to its high antidiabetic
activity and minimal side effects compared to other antidiabetic drugs. However
its pronounced accumulation due to its long elimination period could be a
serious problem. The sulfonylurea moiety is responsible for its distribution
and binding to beta-cell surface and insulin producing actions7.
Treatment
failure and side effects associated with oral hypoglycemic drugs have led to
alternative forms of treatment and management of diabetes. Plants such as Catharanthus
roseus, Azadiracta indica, Ficus racemosa, Trignonella foenum etc are now
used in alternative therapy for diabetes as a result of their large content of
bioactive substances such as glycosides, sterols, flavonoids, alkaloids, tannins,
etc8-10. C.roseus, formerly known as Vinca rosea is
the common or Madagascar periwinkle. It is a perennial evergreen herb of the
family Apocynaceae originally native to Madagascar11,12. It grows to
a height of two feet and has dark green glossy leaves and pale pink or white flowers.
The organic extracts of C. roseus is used in the folklore treatment of
diabetes, malaria, leukemia wasp stings, sore throat, eye irritation,
infections and to stop bleeding13. It is also used a as an
astringent, diuretic and expectorant. The plant contains about seventy
alkaloids some of which include cartharathine, lochnenine, vindoline vindolinenine,
vincristine, vinblastine, vindoline, tetrahydroalstronine, reserpinne, serpentine,
etc14.
Diabetes
is assuming an increasing epidemic trend affecting about 10% of the worlds population15.
The consequent death and economic cost associated with diabetes is enormous and
its treatment needs to be reviewed and improved. There is perceived failure of
treating diabetes using drugs and emphasis is gradually shifting to use of
plant products, diet management and exercise16,17. The objective of
this study is geared in this direction by comparing the antidiabetic effects of
chlorpropamide and aqueous extracts of C. roseus instead of the organic
extracts on alloxan-induced diabetic rats. The results will further
substantiate or deny claims of the use of plants as better alternative
therapies to drugs in the treatment and management of diabetes.
MATERIALS
AND METHODS
Plant
The
plant used in this study was collected from the stand at the courtyard around
the Deans office, Faculty of Biological and Physical Sciences, AbiaStateUniversity, Uturu, Nigeria. The
specimens were authenticated by Dr. C. U Okeke, a botanist in the Department of
Botany, AbiaStateUniversity, Uturu, Nigeria.
Laboratory
animals
A
total of thirty six apparently healthy, male albino rats of about eight weeks old
and weighing between130 ±30.5grams were purchased from the animal house of the
Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Nigeria. The
Animals were housed in clean metallic cages and kept in a well ventilated room.
Their cages were cleaned every two days.
Preparation
of plant extract
200g
of the fresh, dried leaves, flowers and tender stems of C. roseus were
ground using a Gallenkamp electric blender. The sample was soaked in 200mls of
distilled water for 12hours and thereafter filtered with a cheese cloth. The
filtrate was concentrated using a rotary evaporator to obtain 20g powdered
extract.
Animal
grouping and treatment
Thirty
six albino rats were randomly assigned into four groups namely A, B, C, and D
comprising of nine animals each. Animals in A, B and C were each given single
doses of 70mg/ml of alloxan intraperitonealy to induce diabetes. Animals in
group D were not injected with alloxan and served as non-diabetic control.
Diabetes induction was confirmed by increased blood glucose in excess of
300mg/ml which occurred after four days of alloxan administration. Twenty four
hours following the induction of diabetes, treatment with the plant extract and
chlorpropamide commenced. Animals in group A were orally given 25mg/ml of
chlorpropamide while the animals in group B received 25mg/ml plant extract by
oral gavages. Animals in group C and D were neither treated with chlorpropamide
nor plant extracts and served as diabetic and non-diabetic controls respectively.
All the animals were fed ad libitum with the normal rat chow and water
for the period the treatments and experiments lasted.
Collection
of blood and serum preparation
Blood
samples were collected from the animals anaesthetized with chloroform through
cardiac puncture using a hypodermic needle and syringe. The blood was collected
24hours, 72hours and 7days after the induction of diabetes. The serum was
separated by centrifuging approximately 5ml each of the blood samples with an
MSE table centrifuge (Minor Gallenkamp) at 4,000×g for 10 minutes. The serum
obtained was used immediately for the estimation of blood glucose, total serum protein,
serum cholesterol, lipid per oxidation and activities of serum glutamic
pyruvate transaminase (SGPT) and serum glutamic oxaloacetate transaminase (SGOT)
.
Determination
of biochemical parameters
The
concentration of blood glucose was determined using the o-toludine method as previously
described18,19. The serum cholesterol was determined using the
Ilcas method as previously described19. Lipid per oxidation was
estimated using the method as previously described20. The serum
total protein was estimated using the Biuret method as previously described21
and the SGPT activity was determined using the method as previously described22
while the SGOT activity was also determined using the method as previously
described22.
Statistical
analysis
Data
were expressed as mean ± standard error of mean. Statistical analyses were done
by using the student t-test. Significance was checked at P≤0.05
RESULTS
Effects
of plant extract and chlorpropamide (diabenese) on blood glucose
The
plant extracts and chlorpropamide (diabenese) caused a reduction in the blood
glucose concentration of the rats. The plant extract reduced the concentration
of
glucose from 13.45±2.1 to10.98±1.6mM/L while chlorpropamide reduced it to
12.35±1.1mM/L after 24hours as shown in Table 1. Similar reductions in blood
glucose were observed after 3 and 7 days. The results show that the plant extracts
reduced blood glucose more than the chlorpropamide. These reductions were significant
(P≤0.05).
Table
1: Effects of plant extract and
chlorpropamide (diabenese) on blood glucose
Blood glucose level (mM/L)
Time
(Hours/Days)
|
Diabenese Treated Group (A)
|
Plant extract Treated Group (B)
|
Diabetic Control Group (C)
|
Non diabetic Control Group (D)
|
24 hours
|
12.35±1.1
|
10.98±1.6
|
13.45±2.1
|
9.02±0.3
|
3 days
|
11.77±3.2
|
10.40±1.3
|
13.98±0.5
|
9.20±0.1
|
7 days
|
10.31±2.1
|
9.71±0.5
|
14.75±0.1
|
9.37±0.6
|
TABLE
2: Effects of plant extract and chlorpropamide (diabenese) on serum cholesterol
level
Serum cholesterol level (mM/L)
|
Diabenese
Treated
Group
(A)
|
Plant extract
Treated
Group
(B)
|
Diabetic
Control
Group
(C)
|
Non diabetic
Control
Group
(D)
|
24 hours
|
9.40±3.4
|
8.70±2.7
|
10.40±1.0
|
6.80±0.2
|
3 days
|
8.10±0.3
|
7.60±1.1
|
11.90±2.1
|
6.89±1.7
|
7 days
|
7.90±1.6
|
7.00±1.6
|
12.06±0.8
|
6.98±1.7
|
Effects
of plant extract and chlorpropamide (diabenese) on serum cholesterol
Table
2 shows that both chlorpropamide (diabenese) and the plant extracts caused significant
(P≤0.05) reductions in serum cholesterol from 10.40±1.0mM/L to 9.40±3.4mM/L
and 8.70 ±2.7mM/L respectively after 24 hours. A higher reduction in serum
cholesterol was observed for both diabenese and the plant extracts after 3 and
7 days. The plant extracts caused more reductions in the serum cholesterol when
compared to diabenese.
Effects
of plant extract and chlorpropamide (diabenese) on serum protein
The
total serum protein was also reduced by both chlorpropamide (diabenese) and the
plant extracts with the plant extracts causing higher reductions when compared to
diabenese as shown in Table 3.
Table
3: Effects of plant extract and chlorpropamide (diabenese) on total serum
protein concentration
Serum protein concentration (mg/ml)
Time
(Hours/Days)
|
Diabinese Treated Group (A)
|
Plant extract Treated Group (B)
|
Diabetic Control Group (C)
|
Non diabetic Control Group (D)
|
24 hours
|
17.40±7.1
|
16.00±6.2
|
18.10±1.0
|
10.00±1.2
|
3 days
|
17.60±4.7
|
14.80±9.1
|
18.98±3.6
|
10.40±6.1
|
7 days
|
14.01±1.1
|
13.60±1.6
|
19.59±7.1
|
10.48±1.9
|
Effects
of plant extracts and chlorpropamide (diabenese) on serum lipid peroxidation
Table
4 shows that both the plant extracts and chlorpropamide (diabenese) almost
completely reduced the level of lipid peroxidation after 7 days from 13.40 ±1.5mM/L
to 1.5± 0.8 mM/L and 1.98± 6.2mM/L respectively. Also higher reductions in
lipid peroxidation were achieved with the plant extracts. These values were
significant at P≤0.05.
Effects
of plant extracts and chlorpropamide (diabenese) on serum glutamate pyruvate
transaminase (SGPT) activity
The
activity of serum glutamate pyruvate transaminase (SGPT) was significantly
reduced (P≤0.05) after 7 days by both the plant extracts and chlorpropamide
(diabenese) from 109.10± 0.8I.U/ml to 37.10± 0.1I.U/ml and 39.80± 1.7I.U/ml respectively.
These values are shown in Table 5.
Effects
of plant extract and chlorpropamide (diabenese) on serum glutamate oxaloacetate
transaminase (SGOT) activity
Reductions
in the activity of serum glutamate oxaloacetate transaminase (SGOT) occurred
with both the plant extracts and chlorpropamide (diabenese) only after 24 hours
and 3 days. The plant extracts caused more reductions than the diabenese
especially after 3 days as shown in Table 4. These reductions were also
significant at P≤0.05.
Table
4: Effects of plant extract and chlorpropamide (diabenese) on serum lipid
peroxidation
Serum lipid peroxidation (mM/L)
Time (Hours/Days)
|
Diabinese Treated Group (A)
|
Plant extract Treated Group (B)
|
Diabetic Control Group (C)
|
Non diabetic Control Group (D)
|
24 hours
|
5.40±3.7
|
3.60±1.1
|
7.20±0.7
|
1.60±2.1
|
3 days
|
4.20±1.8
|
2.51±0.9
|
9.81±2.0
|
1.51±0.5
|
7 days
|
1.98±6.2
|
1.50±0.8
|
13.40±1.5
|
1.45±1.4
|
Table
5: Effects of plant extract and chlorpropamide (diabenese) on serum glutamate
pyruvate transaminase (SGPT) activity
SGPT activity (I.U/ml)
Time
(Hours/Days)
|
Diabinese
Treated
Group
(A)
|
Plant Extract
Treated
Group
(B)
|
Diabetic
Control
Group
(C)
|
Non Diabetic
Control
Group
(D)
|
24 hours
|
92.60±5.6
|
80.10±2.2
|
99.10±1.2
|
34.16±6.7
|
3 days
|
72.10±3.0
|
55.22±1.7
|
106.20±3.1
|
33.08±0.2
|
7 days
|
39.80±1.7
|
37.10±0.1
|
109.10±0.8
|
32.10±1.7
|
Table
6: Effects of plant extract and chlorpropamide (diabenese) on serum glutamate
oxaloacetate transaminase (SGOT) activity
SGOT
activity (I.U/ml)
|
Diabenese
Treated
Group
(A)
|
Plant Extract
Treated
Group
(B)
|
Diabetic
Control
Group
(C)
|
Non Diabetic
Control
Group
(D)
|
24 hours
|
105.10±2.5
|
100.80±6.0
|
109.10±1.1
|
70.10±3.2
|
3 days
|
90.26±0.8
|
72.17±0.3
|
118.06±3.6
|
71.0±1.7
|
7 days
|
73.07±1.2
|
73.07±1.2
|
66.12±2.9
|
71.98±0.6
|
DISCUSSION
Diabetes
characterized by deleterious hyperglycemia is one of the leading diseases in
the world23. There is a high level of treatment failures and
unpleasant side effects associated with oral anti-diabetic drugs generating an
urgent need and desire for alternative treatments24. Folklore and the
use of plant based products are becoming popular in the treatment and
management of diabetes. Catharanthus roseus is used in the treatment of
diabetes in India.
The
effect of the organic extracts of the leaves of C. roseus on blood
glucose has been studied in rats25. This study investigated the
effects of the aqueous extracts of flowers, leaves and tender stems of C.roseus
on blood glucose and some other associated parameters. In this present study,
diabetes was successfully induced as seen in increase in blood glucose in
excess of 300mg/ml in the rats administered alloxan. This is in accordance with
the work done by Olajide et al26. Oral administration of
aqueous extracts of C.roseus and diabenese caused a significant reduction
(P≤0.05) in the blood glucose concentration of the albino rats. Data from
other results27 tallies with our observations on the reduction of
blood glucose by the aqueous extract of C. roseus. Also the reduction in
blood glucose by chlorpropamide (diabenese) which was not as much as that
caused by aqueous extract of C.roseus is similar to the result obtained
by Levine28. Alloxan induces diabetes by destroying the beta-cells
of the Islets of Langerhans in the pancreas leading to reduction in synthesis
and release of insulin29. Sulfonylureas such as chlorpropamide are
known to produce hypoglycemia by acting on the beta-cells and thus increasing
secretion of insulin.C.roseus acts in a similar fashion in
alloxan-induced diabetes, but the enhanced reduction of blood glucose by
aqueous extracts of the plant as compared to diabenese could be attributed to
the action of C.roseus on multiple sites on the beta-cells so as to
sustain increases in synthesis and release of insulin. Also enhanced tissue
response to glucose cannot be ruled out as a possible mechanism of action by C.
roseus. Further work is needed to substantiate this possibility.
Serum
cholesterol concentrations following the treatments with diabenese and the
plant extract were found to be decreased significantly (P≤0.05).High
cholesterol levels is associated with coronary heart disease (CHD) observed in
diabetic patients. The implication of this is that the use of aqueous extracts
of C. roseus in the treatment of diabetes will also ameliorate the
occurrence of CHD in addition to reducing glucose levels.
Assay
of liver enzymes SGOT and SGPT indicated a decrease in their activities in both
chlorpropamide (diabenese) and plant extract treated groups, eventhough the reductions
were more in the C.roseus treated group. Increase in these liver enzymes
is an indication of liver damage30 and so from the results obtained
in this study, the plant extract of C. roseus and diabenese had
protective effects on the liver.
Oxidative
stress is associated with diseases and occurs in alloxan-induced diabetic rats
seen as an increase in malondialdehyde (MDA), an end product of lipid peroxidation31,32.There
was far more increase in lipid peroxidation in the negative control group than
in the group treated with diabenese and C. roseus extract. This shows
that both diabenese and C. roseus has anti-oxidant activity, an
attribute required in the treatment of diseases.
There
were also decreases in total serum protein in the groups treated with C. roseus
and diabenese which could be attributed to increased binding of the drug and
plant components to serum albumins.
Generally
the significant effects of the aqueous extracts of the flowers, leaves and
tender stems of C. roseus which were higher than those produced by
chlorpropamide (diabenese) in alloxan-induced diabetic rats is attributable to
its content of some bioactive phytochemicals notably alkaloids such as
vindoline and vindolinenine which are known to reduce sugar levels33.
Other bioactive alkaloids that could contribute to the high anti-diabetic
actions of C. roseus include reserpine, a tranquilizer and vincristine, an
anti-carcinogen.
In
conclusion, there was a profound reduction in glucose levels and other
biochemical parameters assayed in the rats treated with aqueous extracts of C.
roseus compared to those treated with chlorpropamide (diabenese) relative
to the controls. Thus plants such as C. roseus may complement the use of
such effective antidiabetic drugs as chlorpropamide (diabenese) in treatment
of diabetes and also contribute to the development of new prescription drugs
for treatment of diabetes as either biochemical models or templates for drug
synthesis.
REFERENCES
- Spencer, K. M. and Cudworth, A.G.
(1989) Diabetes in epidemiological Perspective. (1st Edn)Churchill Livingstone,
Edinburgh.pp 99-111.
- Lernmark, A., Hagglof, P., and
Freedman, Z. (1981) A prospective analysis of antibodies reacting with
pancreatic islet cells in insulin-dependent diabetic children. Diabetologia 20:471-474
- Defronzon, R. A. (1988) The
triumvirate: beta-cells, Muscle, Liver; Collusion responsible for NIDDM.
Diabetes 37: 667- 687
- Hawk, P. B. and Bernard, L. O. (1954)
Practical physiological chemistry. (13th Edn) McGraw
Hill Co, New York.pp 573-575
- Yallow, R. S., Black, H.,
Villazan, M. and Berson, S. A. (1960) Comparison of plasma Insulin levels
following administration of Tolbutamide and glucose. Diabetes 9:356-362
- Ferner, R. E. and Chaplin, S.
(1987) The relationship between the pharmacokinetic And Pharmacodynamic
effects of oral Hypoglycemic drugs. Clin. Pharmacokin. 12:379-401
- Melander, A., Bitzen, P. O.,
Faber, O. and Group, L. (1989) Sulfonylurea antidiabetic drugs; an update of
their clinical pharmacology and rational therapeutic use. Drugs 37:58-72
- Chattopadhyay, R. R. (1999) A
comparative evaluation of some blood Glucose lowering agents of plant origin. J.
Ethnopharmacol. 67:367-372 .
- Chopra, R. N., Nayer, S. L. and Chopra,
I. C. (1956) Glossary
of Indian medicinal plants.New
Delhi, CSIR
- Abayomi, S. (1993) Medicinal
and Traditional Medicine in Africa, (1st Ed), Spectrum Books, Nigeria, p 165
- Don, G. (1999) Catharanthus
roseus.In; Medicinal plants of the World (edited by Ross.I.A) Human
press, Totowa, New Jersey, pp109-118
- Morton, J. F. (1991) Major
medicinal plants; botany, culture and Use (1st Ed) Charles.C. Thomas
Publishing Company, USA pp 236-241
- Stolle, K. and Greoger, D. (1967)
Catharanthus roseus-A new medicinal plant. Pharm. Zentralh. Deut.
106:285-306
- Gordon, S. H., Marvin, G. and
Marry, R. A. (1964) Alkaloids of Vinca rosea; A Preliminary report
on hypoglycemic activity. Lloydia 27:361-363
- Burke, J. P., Williams, K.,
Nayaran, K. M. V., Liebson, C., Haffner, S. M. and Stern, M. P. (2003) A
population perspective on diabetes Prevention; whom should we target for preventing
Weight Gain? Diabetes care 26:1999-2004
- Grover, J. K., Yadav, S. and Vats,
V. (2002) Medicinal plants of India with antidiabetic potential. J. Ethnopharmacol.
81:81-100
- Baily, C. J. and Flatt, P. R. (1986)
Antidiabetic drugs, new developments. Ind.Biotech. 6:139-142
- Nelson, N. (1944) A
Photometric adaptation of the Somogyis method for the Determination of
glucose. J. Biol. Chem.153: 375-380
- Stroev E. A. and Makarova V.G. (1989)
Laboratory manual in Biochemistry, (1st Ed.)Mir publishers. Moscow.
- Albro, P. W., Corbett, J. J. and
Schneider, J.C. (1986) Application of the Thiobarbiturate to the Measurement
of Lipid Per oxidation Products in Microsomes. J. Biochem. Biophys. 184-194
- Gornall, A. G., Barckwill, C. J. and
Maxima, D. (1949) Determination of serum Protein by means of the Biuret
reaction.Biol. Chem.177:751-766
- Reitman, S. N. and Frankel, S. (1957)
A colorimetric method for the determination of serum glutamic oxaloacetic and
glutamic pyruvic transaminases. Am. J. clin. Pathol. 28:56-63
- WHO (1985) World health
organization study group technical Report on Diabetes mellitus. Report
series 727, WHO, Geneva.pp 1-113
- Swanston-Flatt, S. K., Day, C. K.,
Flatt, P. R., Gould, B. J. and Bailey, C. J. (1989) Glycemic effects of
traditional European plant Treatments for diabetes. Studies in normal and
Streoptozotocin diabetic mice. Diabetes Res.10:69-73
- Ghosh, R. K. and Gupta, I. (1980) Effect of Vinca rosea and Ficus racemososus
on hypoglycemia in rats.Ind. J. Anim. Hlth. 19:145-148
- Olajide, O. A., Awe, S. O., Makinde,
J. M. and Morebise, O. (1999) Evaluation Of antidiabetic property of Morhinda
lucida Leaves in steptozotocin diabetic rats. J. Pharm Pharmacol. 5:1321-1324
- Chatopadhyay, R. R., Sarker, S. K.,
Ganguli, S., Banerjee, R. N. and Basu, T. K. (1991) Hypoglycemic
and antihyperglycemic effect of Leaves of Vinca rosea Linn. Ind. J.
Physiol. Pharmacol. 35:145-151
- Levine, R. (1984) Sulfonylureas;
background development of the Field. Diabetes care 7:3-7
- Lazarow, A. (1964) Alloxan
diabetes and mechanism of beta-cell Damage by chemical Agents. In;
Experimental Diabetes (edited by Lazarow, A), Blackwell Scientific
Publication.pp 49-69
- Dame, S. S. (1981) Drug and
the liver: Diseases of the Liver and The Bilary System, Drugs 6:
295-317
- Rauscher, F. M., Sanders, R. A. and
Wattkins, J. B. (2000) Effects of new Antioxidant compounds PNU-104067f and
PNU-74389g on antioxidant defense in normal and diabetic rats. J. Biochem. Mol.
Toxicol. 14:189-194.
- Zheng, W. and Wang, W. (2001)
Antioxidant activity and phenolic compounds in selected herbs. J. Agric. Food.
Chem. 49:5162-5270
- Ivorra, M. D., Paya, M., and Villar,
A. (1989) A Review of natural products and plants as Potential antidiabetic
drugs. J. Ethnopharmacol. 27:243-275.
© 2005 Nigerian Society for Experimental Biology.
|