|Year : 2022 | Volume
| Issue : 2 | Page : 60-64
Evaluation of the glycemic and lipidemic effect of Murraya koenigii (L.) spreng ethanolic leaf extract in alloxan-induced diabetic rats
Azubuike Raphael Nwaji1, Onyinye A Ugbala2, Iniobong A Ante3, Uduak A Inwang4, Favour-Ann K Nwoke4
1 Department of Physiology, College of Medical Sciences, Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State; Department of Physiology, Faculty of Basic Medical Sciences, University of Calabar, Calabar, Nigeria
2 Department of Physiology, College of Medical Sciences, Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State, Nigeria
3 Department of Physiology, Faculty of Basic Medical Sciences, University of Calabar, Calabar, Nigeria
4 Department of Physiology, College of Medical Sciences, Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State, Calabar, Nigeria
|Date of Submission||14-Jul-2022|
|Date of Decision||06-Aug-2022|
|Date of Acceptance||08-Aug-2022|
|Date of Web Publication||27-Oct-2022|
Mr. Azubuike Raphael Nwaji
Department of Physiology, College of Medical Sciences, Alex Ekwueme Federal University Ndufu-Alike, Ebonyi State
Source of Support: None, Conflict of Interest: None
Background: Diabetes is a group of metabolic diseases characterized by hyperglycemia and often accompanied by lipid abnormalities. The ongoing search for natural antidiabetic remedies is concentrated on plants used as such in ethnomedicine. Murraya koenigii is also known as curry leaf plant, belonging to the family Rutaceae. Few studies have shown the activity of M. koenigii in management of diabetes mellitus and lipidemic effect. Aim: This study evaluated the effect of M. koenigii leaf extract on glucose tolerance and lipid profile in alloxan-induced diabetic male rats. Materials and Methods: Twenty male Wistar rats were used for the study. The animals were randomly selected into four groups (1, 2, 3, and 4) of five rats each. Group 1 served as normal control, Group 2 as diabetic control, while Groups 3 and 4 were diabetic and orally treated with 200 and 400 mg/kg body weight of M. koenigii extract, respectively. After 14 days of administration, oral glucose tolerance test was performed on overnight fasted rats. Thereafter, the animals were anesthetized and blood samples obtained were used for biochemical assay. Results: There was no significant differences (P < 0.05) in the glucose tolerance between the normal control and the M. koenigii (200 and 400 mg/kg)-treated groups. However, a significant increase (P < 0.05) between the diabetic control group and the normal control was noted at 30, 60, and 120 min following glucose load. Furthermore, there was no significant changes (P < 0.05) in the lipid parameters between the normal control and the treated groups of the alloxan-induced hyperglycemic rats. Conclusion: The results of this study suggest that ethanolic extract of M. koenigii administered for a 2-week period had no effect on the glucose tolerance and lipid profile of the alloxan-induced hyperglycemic rats.
Keywords: Diabetes, glucose tolerance, lipid profile, Murraya koenigii, Wistar rats
|How to cite this article:|
Nwaji AR, Ugbala OA, Ante IA, Inwang UA, Nwoke FAK. Evaluation of the glycemic and lipidemic effect of Murraya koenigii (L.) spreng ethanolic leaf extract in alloxan-induced diabetic rats. Niger J Exp Clin Biosci 2022;10:60-4
|How to cite this URL:|
Nwaji AR, Ugbala OA, Ante IA, Inwang UA, Nwoke FAK. Evaluation of the glycemic and lipidemic effect of Murraya koenigii (L.) spreng ethanolic leaf extract in alloxan-induced diabetic rats. Niger J Exp Clin Biosci [serial online] 2022 [cited 2022 Dec 7];10:60-4. Available from: https://www.njecbonline.org/text.asp?2022/10/2/60/359781
| Introduction|| |
Diabetes is one of the five leading causes of death in the world. It is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, or action, or both. Type 2 diabetes is the most common form of diabetes constituting 90% of diabetic population and a multi-causal disease which develops slowly in a stepwise order. Initially, it starts with insulin resistance and progresses gradually with time until the body fails to maintain glucose homeostasis resulting in glucose intolerance. Systematically, these perturbations are accompanied by changes in a variety of biochemical processes such as obesity, an altered lipid profile, and lipid peroxidation. Thus, the assessment of various lipid fractions and lipid peroxide in the cases of diabetes mellitus may be of some help in the prognosis of patients and in preventing the possibilities of complications.
The management of diabetes without side effects is still a challenge and, therefore, new strategies need to be examined. For instance, many plants are reported to be used in traditional medicine for the management of diabetic complications due to their perceived hypoglycemic potentials., The hypoglycemic potentials of some of the plants have been investigated in humans, and also in experimental animals.,
Few studies have shown the activity of Murraya koenigii (L.) Spreng (family: Rutaceae), commonly known as curry leaf in management of diabetes mellitus. Isolated carbazole and alkaloids from fresh curry leaf have been reported to show antidiabetic properties. However, less work has reported the effects of Murraya on lipid parameters and glucose tolerance. Therefore, this study is designed to investigate the effect of M. koenigii leave extract on glucose tolerance and lipid profile in alloxan-induced diabetic male rats
| Materials and Methods|| |
Plant collection and identification
Fresh leaves of M. koenigii were collected from its natural habitat in Amechi Awkunanu, Nkanu West, Enugu State. The plant was identified and authenticated by a taxonomist of the Biotechnology Department in Alex Ekwueme Federal University Ndufu Alike, Ebonyi State. The leaves were washed and air-dried at room temperature.
Preparation of Murraya koenigii leaf extracts
The leaves were grounded using an electric blender to form powder and by macerating in an airtight container using ethanol as solvent. It was allowed to stand for 48 h and then filtered using Whatman No. 1 filter paper of pore size 125 mm. The extracted filtrate was concentrated by distilling off the solvent and evaporated to dryness on a water bath at 40°C to obtain a pasty dark-green extract with a characteristic aromatic smell. About 300 g of powdered M. koenigii leaves was dissolved in 2000 ml of distilled ethanol. The extract was weighed and kept in a refrigerator.
A total number of 20 male Wistar rats weighing 120–200 g used for the study were purchased from animal house, Department of Physiology, Alex Ekwueme Federal University Ndufu Alike, Ebonyi State. The rats were acclimatized for 2 weeks prior to the study and fed with standard commercial pelleted grower feed. The rats were kept in a cage and maintained under standard conditions with light-dark cycle. They were cared for and humanely treated according to the guide for the care and use of laboratory animals.
Induction of diabetes
Following 2 weeks of acclimatization, freshly prepared solution of alloxan was injected intraperitoneally to the experimental rats at a dosage of 160 mg/kg body weight at fasting state. Blood samples were collected from the tail vein after 3 days of induction of diabetes. Blood glucose concentration was analyzed using blood glucometer (Accu-Answer®, India) prior to the commencement of the administration of the extract. The alloxan-treated rats with fasting blood glucose level >200 mg/dl were considered diabetic and used for the study.
Grouping of the animals
The animals were randomly selected into four groups of five rats per group (n = 5) as follows:
Group 1 – Normal control
Group 2 – Diabetic control
Group 3 – Diabetic + M. koenigii (200 mg/kg bw)
Group 4 – Diabetic + M. koenigii (400 mg/kg bw).
Sample collection and analysis
Body weight of the animals (before and after administration) was measured using digital electronic weight Scout Pro SP-401 (China). The administration of the M. koenigii extract was done orally using oropharyngeal cannula once per day for 14 days. On the last day of experimental procedure, rats were fasted overnight and the Oral glucose tolerance test (OGTT) was performed on overnight fasted rats
Thereafter, the animals were anesthetized. Whole blood sample of about 5 ml was obtained via cardiac puncture into plain tubes and was allowed to clot. Sera obtained from the clotted sample after centrifuging at 3000 rpm for 10 min were used for the estimation of biochemical assay.
Glucose tolerance test
The was performed on overnight fasted rats following the modification of the method described by Marella et al. After 30 min of postextract and distilled water administration to respective groups, all the animals were orally fed with 2 g glucose (solution)/kg bw. Blood samples were collected and measured from tail vein prior to the treatment (0 min). Subsequently, the blood glucose levels were measured at 30, 60, 90, and 120 min following glucose load to access the effect of extract on blood glucose levels of the glucose-loaded animals. The blood glucose was measured using blood glucose test strips and glucometer (Accu-Answer®, India).
High-density lipoprotein (HDL) and total cholesterol (TC) were measured by automatic analyzer using Randox Diagnostic Kit while triglycerides (TGs) were analyzed using Teco Diagnostic Kit according to the procedures described by the manufacturer.
Very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) were estimated using Friedewald's equation as:
VLDL = TG/5 (mg/dl), LDL = TC-(HDL + VLDL).
Data were expressed as mean ± standard error of mean. Data were analyzed using GraphPad Prism version 7.0 for windows (GraphPad® software, San Diego, CA, USA). Mean differences were compared using one-way ANOVA and Student's t-test. The criteria for statistical significance were set at P > 0.05.
| Results|| |
The results of all the experiments carried out are shown in [Table 1], [Table 2] and [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]. All the values given are expressed as mean ± standard error of the mean, and asterisks in the table and bar charts indicate the values that are significantly different from the control values or treatment group of all the variables measured.
|Table 1: Effect of ethanolic extract of Murraya koenigii leaves on blood sugar level in glucose-loaded diabetic rats (oral glucose tolerance test)|
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|Table 2: Effects of ethanolic extract of Murraya koenigii leaf on lipid parameters of diabetic rats|
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|Figure 1: Effect of Murraya koenigii leaf on blood sugar level in glucose-loaded diabetic rats (OGTT). (n = 5; *P < 0.05, **P < 0.01 vs. control)|
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|Figure 2: Effect of Murraya koenigii leaf extract on HDL-c (n = 5). HDL: High-density lipoprotein cholesterol|
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|Figure 3: Effect of Murraya koenigii leaf extract on TGs (n = 5). TG: Triglyceride|
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|Figure 4: Effect of Murraya koenigii leaf extract on TC (n = 5). TC: Total cholesterol|
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|Figure 5: Effect of Murraya koenigii leaf extract on VLDL-c (n = 5). VLDL-c: Very low-density lipoprotein|
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|Figure 6: Effect of Murraya koenigii leaf extract on LDL-c (n = 5). LDL-c: Low-density lipoprotein cholesterol|
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Effect of ethanolic extract of Murraya koenigii leaf on oral glucose tolerance test and lipid parameters of diabetic rats
The effect of ethanolic extract of M. koenigii leaf on blood sugar level in glucose-loaded diabetic rats (OGTT) is shown in [Table 1].
The effect of oral administration of M. koenigii extract on glucose tolerance is presented in [Figure 1]. The blood glucose level in the control rats rose to a peak value at 30 min after glucose load and decreased to near basal levels after 120 min. In diabetic control rats, the baseline glucose level surprisingly was nonsignificantly reduced when compared to the treated groups.
However, the peak increase in blood glucose concentration was observed after 30 min and remained high throughout the observation period. There was no significant differences between the normal control and the M. koenigii (200 and 400 mg/kg)-treated groups. However, a significant increase between the diabetic control group and the normal control was noted at 30, 60, and 120 min following glucose load.
[Table 2] shows the effect of M. koenigii on HDL cholesterol (HDL-c), TGs, TC, VLDL cholesterol (VLDL-c), and LDL cholesterol (LDL-c).
[Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6] show the effects of M. koenigii leaf extract on HDL-c, TGs, TC, VLDL-c, and LDL-c, respectively. The extract had no significant effect between the normal control and the treated groups.
| Discussion|| |
Our previous investigation showed that M. koenigii exhibited a significant hypolipidemic effect on rats fed with cholesterol-enriched diets.
In the present study, we investigated whether the M. koenigii extract has any effect on glucose tolerance and lipid profile of alloxan-induced diabetic rats.
The result of this study shows that the continuous treatment for 14 days with the ethanolic extract had a weak effect on the glucose tolerance and lipid profile of diabetic rats. The surprisingly nonsignificant reduction in the baseline glucose level of the diabetic control may be a result of the reduced alloxan effect following 2 weeks post induction.
The result of this study is in agreement with previous findings of Adebajo et al., which refuted the antidiabetic potential claim of M. koenigii. Feeding of rats with a 10% and 15% diet of the dried leaf, leaf ash, and 95% ethanol extract has been shown to be ineffective in lowering blood sugar in normal and glucose-induced hyperglycemic rats of M. koenigii., The methanol extracts of the leaf and stem and the chloroform extract of the stem of M. koenigii were inactive in reducing blood sugar levels in normo- and alloxan-induced hyperglycemic rats. Furthermore, antihyperglycemic activity without any statistical significance has been reported on drug-induced mild and moderate diabetic rats fed with a 10%–15% diet of the leaf; as in case of our result.
Curry leaf powder supplementation for a period of 1 month in type 2 diabetes patients showed no significant changes in serum glycosylated LDL cholesterol, serum lipids, and lipoprotein cholesterol levels. Yadav et al. reported that feeding different doses of M. koenigii leaves to diabetic rats plays a role in control of mild diabetes, but in case of moderate, severe, and type I diabetes, this agent alone is not likely to be useful. Furthermore, the increased blood glucose level observed in the diabetic control group following glucose load agrees with the findings of Imad et al.
Conversely, the results of our study disagree with the reports of Kesari et al., who reported that aqueous extract exhibited strong hypolipidemic activity in addition to hypoglycemic action in diabetic animals. Furthermore, consistent hypoglycemic action has been reported in vitro.,,
It is possible therefore that water-soluble compounds that are insoluble in organic solvents present in the plant may be responsible for the activity.
These variations also may be related to species differences and/or the type and dose of the extract used and the duration of treatment.
| Conclusion|| |
The results of this study suggest that ethanolic extract of M. koenigii administered for a 2-week period had no effect on the glucose tolerance and lipid profile of the alloxan-induced hyperglycemic rats.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2]