Effects of Irvingia grandifolia, Urena lobata and Carica papaya on the Oxidative Status of Normal Rabbits
A Omonkhua, I Onoagbe
anti-diabetic plants, catalase, lipid peroxidation, malondialdehyde, medicinal plants, superoxide dismutase
A Omonkhua, I Onoagbe. Effects of Irvingia grandifolia, Urena lobata and Carica papaya on the Oxidative Status of Normal Rabbits. The Internet Journal of Nutrition and Wellness. 2007 Volume 6 Number 2.
The hypoglycemic effects of
Focus on plant research has increased worldwide in recent times and a large body of evidence has been collected to show the immense potentials of medicinal plants used in various traditional systems. Various medicinal plants have been studied using modern scientific approaches. Results from these plants have revealed the potentials of medicinal plants in the area of pharmacology. 1,2,3,4
Urena lobata Linn (Malvaceae), otherwise called Caesar weed, is a shrub that grows between 0.6- 3m
tall and up to 7 cm in basal diameter. 9,10 Various extracts of leaves and roots are used in herbal medicine to treat such diverse ailments as colic, malaria, gonorrhea, fever, wounds, toothache, and rheumatism. 11,12 The methanol extract of
Irvingia species, including
The hypoglycemic effects of
Oxidative stress is the imbalance between production and removal of reactive oxygen species (ROS). Increased oxidative stress, which contributes substantially to the pathogenesis of diabetic complications, is the consequences of either enhanced ROS production or attenuated ROS scavenging capacity. Several reports have shown the alterations in the antioxidant enzymes during diabetic condition. 18,19 The antioxidative defense system, like superoxide dismutase and catalase, showed lower activities in diabetic subjects. The decreased activities of SOD and Catalase may be a response to increased production of hydrogen peroxide snd superoxide ion the auto oxidation of excess glucose and non-enzymatic glycation of proteins. 20
Millions of people in various traditional systems, including Nigeria, have resorted to the use of medicinal plants to treat their ailments; this could be as a result of the high cost of orthodox health care, or lack of faith in it, or maybe as a result of the global shift towards the use of natural, rather than synthetic products. While the craze for natural products has its merits, care must be taken not to consume plants or plant extracts that could have deleterious effects on the body, either on the short term or on the long term. It therefore means that these plants must be studied for their biochemical/toxicological effects.
In this study, the sub-chronic effects of the aqueous extracts of
Materials and methods
Chemical and reagents
Adrenaline, trichloroacetic acid and thiobarbituric acid (Sigma, London), other analytical grade chemicals were products of BDH Chemical Limited, Poole, England. Randox kits for blood glucose assay was obtained from C.C. Obi Nigeria Limited, Ashogbon Street, Idumota Lagos.
Twenty-four weaned male and female rabbits were obtained from local breeders in Oke Aro, Akure, Ondo State. The animals were placed on commercial feed (Ewu growers from the Bendel Feed and Flour Mill Ewu, Nigeria) and allowed to drink water freely; they weighed between 500 g and 1100 g. The rabbits were examined by a veterinary doctor and allowed to acclimatize for two weeks before the commencement of the experiments. Treatment of the animals was in accordance with the Principles of Laboratory Animal Care (NIH Publication 85-93, revised 1985).
The root of
Preparation of plant extract
The aqueous plant extracts were prepared by the method of Onoagbe
Administration of the plant extract
The plant extracts were orally administered to the rabbits at 200 mg/kg body weight daily for 24 weeks.
GROUP I: Distilled water
The rabbits were weighed weekly.
During the monitoring phase, blood was collected from the ventral vein of the rabbits' ear, at the end of the monitoring phase, the rabbits were stunned and in this unconscious state, the thoracic and abdominal regions were opened to expose the heart and other organs. Blood was obtained through heart puncture, the liver, kidneys, heart and pancreas, were also collected. Blood for glucose assay was collected in fluoride bottles while sterile bottles were used for other biochemical assays.
Centrifugation of sample
Blood samples were allowed to clot and centrifuge at 5,000 rpm for 5 minutes, the serum was then separated for analysis. Tissues were homogenized in ice cold normal saline (1:4 w/v), centrifuged and the supernatant stored at 4°C until analysis.
Blood glucose estimation
Fasting blood glucose was measured by the glucose oxidase method, 22 as described in the manual of the Randox glucose kit.
The malondialdehyde (MDA) levels were used to estimate the level of lipid peroxidation. MDA levels were determined in the serum, liver, kidney, heart and pancreas by the thiobarbituric acid reactive substances (TBARS) method. 23
Catalase activity was determined in the serum, liver, kidney, heart and pancreas by the method of Sinha ( 24 ).
Superoxide Dismutase (SOD)
Superoxide dismutase activity was determined in the serum, liver, kidney, heart and pancreas by the method of Misra and Fridovich, ( 25 ).
The data are expressed as mean of 4-6 determinations ± S.E.M. The differences between means were analyzed by the Independent Samples T-test on SPSS 11.0, SPSS Inc., Chicago, Illinois, USA. A value of
Results and Discussion
More than 400 plant species having hypoglycemic activity are available in literature, 26,27 however, searching for new anti-diabetic drugs from natural plants is still attractive because they contain substances that have alternative and perhaps safer effects on diabetes mellitus. 28 The pathogenesis of diabetes mellitus and the possibility of its management by the oral administration of hypoglycemic agents have stimulated greater interest in recent years. 29 Oxidative stress is suggested to play a prominent role in the pathogenesis of diabetes mellitus, since most of these plants contain glycosides, alkaloids, terpenoids, flavonoids, cartenoids, etc., that are frequently implicated as having anti-diabetic, 28 as well as anti-oxidant effects, it is plausible that some of these medicinal plants exert their hypoglycemic effects by protecting pancreatic cells from oxidative damage. Herbal remedies from medicinal plants have been used traditionally in many parts of the world where access to formal healthcare is limited. There are several reasons why the use of medicinal plants should be studied: herbal remedies may have recognizable therapeutic effects; 30 they may also have toxic side-effect. 31
This study was designed to evaluate the sub-chronic effect of three hypoglycemic plants on the oxidative status of normal rabbits, in order to ascertain their safety.
Effects of , and on Body weight and Relative Organ Weight
The overall effects of sub-chronic administration of
The relative liver, kidney, heart and pancreas weight for all three medicinal plants were comparable to control. Generally, the increase or decrease in the weight of an organ may be due to inflammation or a series of reactions taking place within the organism in response to an imposed factor. The results indicate that under the conditions of this study, the medicinal plants did not affect the relative organ weights of the rabbits.
Effects of , and on Fasting Blood Glucose levels
Figures 2.1, 2.2 and 2.3 shows the results for fasting blood glucose of normal rabbits exposed to
Evaluating Oxidative Status
Oxidative stress is characterized by increased lipid peroxidation and/or altered non-enzymatic and
enzymatic antioxidant systems. 33 To ascertain the oxidative status of the experimental animals exposed to
Effects of , and on Serum SOD Activity
The results of serum SOD for
Effects of , and on Tissue SOD Activity
Figures 4.1, 4.2 and 4.3 show the results for tissue SOD for
Effects of , and on Serum Catalase Activity
Results for serum catalase activity for
Effects of , and on Tissue Catalase Activity
The results for the tissue catalase activities are shown in figures 6.1, 6.2 and 6.3.
Effects of , and on Serum Malondialdehyde Levels
As shown in figures 7.1, 7.2 and 7.3, for all three plants extracts the serum MDA levels of test animal were comparable to control through out the monitoring period. Jyoti
Effects of , and on Tissue Malondialdehyde Levels
Figures 8.1, 8.2 and 8.3 show the results for MDA levels for
Most hypoglycemic plants also have anti-oxidant properties, it is thus not surprising that for most part, our study showed that sub-chronic exposure of normal rabbits to these hypoglycemic plants did not exert any form of oxidative damage, indeed in some instances, such as liver and pancreatic MDA levels, as well as, the increases observed in serum and tissue anti-oxidant enzymes, the plants were even protective against oxidative damage.