|Year : 2020 | Volume
| Issue : 1 | Page : 41-45
Hypoglycemic effect of aqueous leaf extract of Senna singueana on alloxan-induced diabetic wistar rats
Isyaku Gwarzo Mukhtar, Bashir Wada Yakasai, Dalhat Taura Firdausi
Department of Human Physiology, Faculty of Basic Medical Sciences, Bayero University, Kano, Nigeria
|Date of Submission||17-Oct-2019|
|Date of Decision||11-Dec-2019|
|Date of Acceptance||19-Feb-2020|
|Date of Web Publication||20-May-2020|
Isyaku Gwarzo Mukhtar
Department of Human Physiology, Faculty of Basic Medical Sciences, Bayero University, Kano
Source of Support: None, Conflict of Interest: None
Background: Diabetes mellitus is a chronic metabolic disorder with significant morbidity, mortality, and high cost of care. Rising cost of treatment and incidence of the disease coupled with poor access to health facilities have compelled people to resort to use of plant products as sources of remedy. One of such plant that is been used as remedy for diabetes is Senna singueana. Aim: The aim of the study was to investigate the effect of aqueous leaf extract of Senna singueana on blood glucose level. Materials and Methods: Sixteen adult wistar rats weighing 80–120g randomly divided in to 4 groups (A–D) of four rats each were used for the study. Groups A and B served as normal and diabetic controls respectively. Diabetes was induced with 150 mg/Kg body weight (b.w) in groups B, C, and D intraperitoneally. Groups A and B received normal saline at 5 mL/Kg b.w while groups C and D were treated with 250 mg/Kg b.w of aqueous leaf extract of Senna singuea and 5 mg/Kg b.w of glibenclamide daily for 5 days, respectively. Blood glucose concentration was measured before induction of diabetes, 48 hours after induction but before treatment with extract, and 5 days after daily administration of the extract. Data were analyzed using International business machine statistical package for social science version 23.0 (IBM, Armonk, New York, USA). One-way ANOVA was used to compare mean blood glucose level between groups and Bonferroni post hoc test was used where there was statistical significance. P value ≤ 0.05 was considered statistically significant. Results: There was no significant difference in baseline blood glucose levels between the four groups (P = 0.130). Rats in groups B, C, and D had statistically significant higher blood glucose levels than group A 48 hours after treatment of groups B, C, and D with alloxan (P = 0.001). The extract treated group (C) had statistically significant reduction in blood glucose level after 5 days of oral administration of the extract (0.001). Similarly, the extract treated group (C) had statistically significant lower blood glucose level at the end of 5 day treatment compared with the diabetic control group (B) (P = 0.001). There was also significant reduction in blood glucose in the glibenclamide treated group (D) after 5 day treatment with the drug compared to diabetic control group (B) (P = 0.005). However, there was no significant difference in blood glucose level between the extract treated group (C) and glibenclamide treated group (D) after 5 day treatment with extract and glibenclamide respectively (P = 0.999). Conclusion: Aqueous leaf extract of Senna singueana significantly reduced blood glucose level after 5 day daily oral treatment at 250mg/Kg b.w.
Keywords: Antidiabetic, extract, leaf, Senna singueana
|How to cite this article:|
Mukhtar IG, Yakasai BW, Firdausi DT. Hypoglycemic effect of aqueous leaf extract of Senna singueana on alloxan-induced diabetic wistar rats. J Med Trop 2020;22:41-5
|How to cite this URL:|
Mukhtar IG, Yakasai BW, Firdausi DT. Hypoglycemic effect of aqueous leaf extract of Senna singueana on alloxan-induced diabetic wistar rats. J Med Trop [serial online] 2020 [cited 2020 Dec 2];22:41-5. Available from: https://www.jmedtropics.org/text.asp?2020/22/1/41/284639
| Introduction|| |
Diabetes mellitus is a chronic non-communicable disease that is assuming global epidemic. It is a metabolic disorder resulting from either insufficient secretion of insulin by pancreatic β cells or resistance to the physiological actions of the hormone by peripheral tissues. Clinically, the disease is characterized by disturbance in carbohydrate, fat, and protein metabolism leading to hyperglycemia. Globally, an estimated 425 million people were living with the disease in 2017, 3.3% (16 million) of which were in Africa. There has been steady rise in the prevalence of the disease globally and especially in Africa. While many parts of the world will experience relative decline in the prevalence of the disease in the next 45 years, African continent has been projected to have a 156% rise in prevalence with about 41 million people with the disease by 2045. Despite advancement in the diagnosis and treatment of the disease, a substantial number of people remain undiagnosed while others die of the disease. Diabetes mellitus has caused an estimated 230,000 deaths in Africa in 2017 making it the cause of about 77% of all deaths below the age of 60 years. Diabetes related treatment consumed about 6% of Africa’s healthcare budget amounting to 3.3 billion USD in 2017.
There has been a gradual increase in the prevalence of diabetes in Nigeria rising from 2.2% in 1991 to about 5.7% in 2018., In their systematic review of published works from 1990 to 2017, Uloko et al. reported north western part of Nigeria as having the least prevalence of 3.0% while south-south had the highest prevalence of 9.8%.
Rising cost of orthodox healthcare and lack of access to essential healthcare services in many rural areas of developing countries coupled with strong belief in culture and traditions have forced people seek use of traditional and complementary medicine in the treatment of minor ailments and chronic diseases. Indeed, world health organization has noted the growing number of people especially in Africa, Asia, and Latin America that use medicinal plants to meet their primary healthcare needs and has called for policies, laws, and regulations to safeguard the practice.
In Nigeria, Ezuruike and Prieto have documented over 100 plants that are used for treatment of diabetes across different parts of the country. The use of many of these plant products have over the years been backed by preclinical experimental evidences to their potential hypoglycemic effects. Many plant products have traditionally been used to treat disease conditions in northern Nigeria. One of such plant that is used to treat diabetes mellitus is Senna singueana (synonym: Cassia gorotensis).
Senna singueana is a tropical plant commonly found in East and West Africa belonging to the family Fabaceae, subfamily Caesalpinioideae, and tribe Cassieae. It is called Runhu in Hausa language. The plant’s root and bark extracts have been used for treatment of many diseases across African continent ranging from skin cancer in Ethiopia, liver diseases in Egypt, malaria in Ethiopia, and pain from any cause in Malawi. Other traditional uses of the plant are in the treatment of convulsion, inflammatory conditions, gonorrhea, constipation, heartburn, and wound healing. Despite widely reported beneficial effects of the plant in treating common illnesses and diseases, there has not been much investigation on its potential glucose lowering effects. Indeed, Abubakar et al. did not list it as one of the plants used in the treatment of diabetes in their ethnobotanical survey of anti-diabetic plants in Zaria, Kaduna state, Nigeria. Furthermore, most investigations looking at the potential glucose lowering effect of the plant used methanolic root or bark extracts not aqueous leaf extract, the form that is commonly used in real life. We therefore investigated the potential glucose lowering effect of aqueous leaf extract of Senna singueana in alloxan-induced diabetic wistar rats.
| Materials and methods|| |
The plant material
Fresh leaves of Senna singueana were obtained from the Kasuwar Rimi market in Kano state, Nigeria in October, 2017. Samples were taken to herbarium unit of the Department of Botany, Bayero university, Kano, for identification and authentication. The plant was authenticated, accession number BUKHAN 0316 assigned, and sample voucher prepared and deposited at the herbarium.
Aqueous leaf extract preparation
Fresh leaves of Senna singueana were thoroughly washed, shade-dried for 1 week, and ground in to powder. 250 g of the powder was soaked in 500 mL of distilled water (Dana pharmacy, Nigeria Ltd.), mixed and allowed to stand for 48 hours. The fluid was first filtered with Whatman filter paper No 1 and for the second time using cotton wool inserted in to a funnel. Rotary evaporator was used to further concentrate and oven dry the filtrate and the extract refrigerated until use.
Toxicity study and determination of test dose
Senna singueana is widely consumed across many parts of Africa with no reported cases of toxicity even when used in combination with other drugs like chloroquine. Shawa et al. reported only a mild toxicity resulting from use of the plant. Despite this, we used slightly modified organization for economic corporation and development’s (OECD) 2001 guidelines. Three animals were administered 2000 mg/Kg b.w of the extract orally and serially and were observed for 48 hours for signs of toxicity.
Sixteen adults (12–16 weeks) wistar rats of both sexes weighing 80–120 g were used for the study. The rats were obtained from the animal house of Department of Human Physiology, Bayero university, Kano. They were kept in metallic cages under standard laboratory conditions in terms of temperature and relative humidity, fed standard animal diet and allowed free access to water. Animals were denied food but allowed access to water for 18 hours prior to commencement of the experiment.
Diabetes was induced using 150 mg/Kg b.w of alloxan monohydrate intraperitoneally following 18 hour fasting period in which animals were only allowed access to water. Animals resumed normal feeds after the injection and blood glucose was checked before and 48 hours after diabetes induction using Accu-Chek glucometer (Roche Diabetes Care, Inc., Indianapolis, USA). Glucose level of above 150 mg/L was considered hyperglycemic and animals with values above 150mg/dL were selected for extract administration.
Sixteen rats were randomly assigned in to four groups (n = 4), A, B, C, and D. Group A were normal controls, they were not treated with alloxan and received normal saline at 5 mL/Kg b.w. Groups B, C, and, D were the diabetic groups. Group B received normal saline at 5 mL/Kg b.w (diabetic control), group C received 250 mg/Kg b.w of Senna singueana leaf extract orally while group D received glibenclamide 5 mg/Kg b.w. Blood glucose was measured after 7 days of daily oral administration of the extract.
Data were analyzed IBM SPSS_version 23.0. One-way ANOVA was used to compare mean blood glucose values between groups, Bonferroni post hoc was used where there is significance. Results are presented as mean ± standard deviation (SD) and P value of ≤ 0.05 was considered statistically significant.
| Results|| |
No sign of toxicity was observed neither was there any case of death in the animals 48 hours after oral administration of 2000 mg/Kg b.w of the extract. This implies safety of the plant extract as is widely reported. However, two rats out of the experimental groups (Group B) died in the course of the experiment. This is not related to any possible toxicity from the plant extract because the rats belong to a group that did not receive the extract.
Intraperitoneal injection of 150 mg/Kg b.w of alloxan monohydrate to the 12 experimental animals successfully induced diabetes after 48 hours in all the animals [Table 1].
|Table 1: Mean blood glucose concentration following oral administration of aqueous leaf extract of Senna singueana to the diabetic rats|
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Oral administration of 250 mg/Kg b.w of aqueous leaf extract of Senna singueana significantly reduced blood glucose level after 5 days of treatment. This implies that the extract significantly reduced blood glucose level compared to pre-treatment value and compared to the diabetic control group. Glibenclamide, a standard oral anti-diabetic agent with propensity for drug-induced hypoglycemia, significantly reduced blood glucose 5 days after commencement of oral administration. Similarly, there was no statistically significant difference in blood glucose levels between extract treated and glibenclamide treated groups suggesting similar hypoglycemic effects [Table 1].
| Discussion|| |
Administration of 2000 mg/Kg b.w test dose of the aqueous leaf extract of Senna singueana did not produce signs of toxicity neither did it cause death among the animals. Many workers have used even higher doses of the plant extract without any sign of toxicity.,,
Intraperitoneal injection of 150 mg/Kg b.w of alloxan monohydrate induced diabetes in all the 12 experimental animals that received the drug. The 100% diabetes induction success rate in this study is better than that of Etuk and Mohammed, who reported 70% success rate. This could be due to higher number of animals (60) in their study compared to ours. Alloxan is increasingly been used to induce diabetes in experimental animal models. The drug is used in various dosage formulations ranging from 90 mg/Kg b.w through 200 mg/Kg b.w. Various routes of administration have also been used to induce diabetes. This include intraperitoneal, intravenous, and subcutaneous routes. However, single intraperitoneal injection of 150 mg/Kg b.w is most commonly used dosage and route of administration respectively. Alloxan is highly selective to pancreatic β cells, it inhibits glucose mediated insulin secretion and increased generation of reactive oxygen species culminating in to toxic destruction of the cells.
Senna singueana aqueous leaf extract produced significant reduction in blood glucose 5 days after commencement of treatment with 250 mg/Kg b.w. The reduction in blood glucose was observed with the pre-treatment values and compared with the diabetic controls. The blood glucose reducing ability of the extract was similar to that of a standard antidiabetic drug, glibenclamide, as there was no significant difference in blood glucose levels between the extract and glibenclamide groups after 5 days of treatment. This is similar to what was reported by Etuk and Mohammed,6] in their study of the commonly used anti-diabetic plants in north west Nigeria. However, they reported significant reduction in blood glucose 90 and 120 minutes after administration of the extract while this study reported reduction in blood glucose after 5 days of daily oral extract administration. Alloxan induction of diabetes is characterized by multiphasic fluctuations in blood glucose concentration. The initial phase, which lasts about 30 minutes, involved transient hypoglycemia thought to be due to temporary increase in ATP level from inhibition of glucokinase. The next phase is that of surge in blood glucose level that is typical of alloxan-induced diabetes; it lasts for about 1–2 hours and is due to toxic effects of reactive oxygen species on the pancreatic β cells. The last phase, which occurs after 48 hours, is that of destruction of the pancreatic β cells and permanent hyperglycemia. Demonstration of reduction in blood glucose level in this study 5 days after the rat’s pancreatic β cells could have been destroyed by alloxan suggests either residual β cells function despite the alloxan administration or possible insulin-like activity by the extract. Gerezgher et al. have demonstrated presence of a number of secondary metabolites in their phytochemical analysis of various crude extracts of Senna singueana. Flavonoids, one of the secondary metabolite in the plant, has been reported to have potent antioxidant activity and could suppress the alloxan-induced oxidative damage on the pancreatic β cells. Another possible mechanism is activation of insulin receptor on the peripheral tissues thereby mimicking the action of insulin. Indeed, epicatechin, a component of flavonoids, has been reported to reduce most of the diabetes related tissue changes by activating insulin receptor and thus mimicking the hormone.Ibrahim and Islam reported reduction in blood glucose concentration and improvement in other markers of diabetes by acetone fraction of stem bark extract of Senna singueana in rats. Like in this study, the reduction in blood glucose concentration was observed after 4 weeks of intervention. However, their study employed streptozotocin as the diabetic inducing agent. They also reported potent inhibitory effect of the extract on α-glucosidase and α-amylase, two enzymes involved in hydrolysis and absorption of carbohydrate from the gastrointestinal tract. They suggested delayed absorption of carbohydrate from the gastrointestinal tract, increased insulin secretion by β cells, and improved pancreatic function as possible mechanisms mediating Senna singueana’s antidiabetic activity.
| Conclusion|| |
Senna singueana aqueous leaf extract reduced blood glucose level after 5 days of oral intervention. More studies focusing on the possible mechanisms mediating this effect should be conducted on parts of the plant.
We would like to acknowledge academic technologists of the Department of Human Physiology for their kind assistance in handling the animals.
Financial support and sponsorship
No financial support or sponsorship was received but we acknowledge in kind support from individuals and units/departments.
Conflicts of interest
We declare that there is no conflict of interest individually or collectively among the authors.
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