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Journal of Drug Delivery and Therapeutics

Open Access to Pharmaceutical and Medical Research

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Open Access  Full Text Article                                                                                                                                                          Research Article

Ethanolic Stem-Bark Extract of Blighia unijugata Possesses Anti-Hyperglycemic and Anti-Hyperlipidemic Activity in a Streptozotocin-Induced Diabetes Model 

Hope K. Fiadjoe ^1,2*, George A. Koffuor ¹⁺

¹ Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

² Department of Microbiology, Immunology and Genetics, University of North Texas Health Science Center, Fort Worth, TX

⁺Prof. George A. Koffuor died on February 5, 2021

 

 

INTRODUCTION 

Diabetes is a major cause of blindness, kidney failure, heart attacks, stroke, and lower limb amputation. In 2021, 537 million adults were reported to be living with diabetes. This number is predicted to increase to 643 million by 2030, and 783 million by 2045. Its prevalence has been rising more rapidly in low- and middle-income countries than in high-income countries ^{1, 2}. With the predicted exponential increase in occurrence, diabetes poses a high patient, social, and economic burden globally ^3-5.

Type 2 diabetes mellitus (T2DM), a predominant type of diabetes mellitus, is a metabolic disease characterized by hyperglycemia, caused mainly by insulin resistance or inadequate insulin production ^{2, 6}. Besides hyperglycemia associated with T2DM, abnormal lipid metabolism has also been reported, hence collectively named diabetic dyslipidemia ^7-9. Diabetic dyslipidemia is characterized by elevated triglycerides (TG), high very-low-density lipoprotein cholesterol (VLDL-c), postprandial hyperlipidemia, high low-density lipoprotein cholesterol (LDL-c), and reduced high-density lipoprotein cholesterol (HDL-c). The main association between diabetes and the higher risk of atherosclerosis and cardiovascular diseases is reflected by these lipid alterations which are more atherogenic than general dyslipidemia ^10-13. This means that patients with diabetic dyslipidemia are at an increased risk of developing the associated microvascular and macrovascular complications, morbidities, and mortalities ^{14, 15}.

The global rise in the incidences of T2DM, and its associated cardiovascular mortalities has called for improved preventive, diagnostic, and therapeutic measures to tackle this public health threat. Although several therapeutic interventions exist for managing T2DM, these existing pharmacological agents such as sulfonylureas, metformin, and thiazolidinediones cannot adequately improve the consequence of insulin resistance namely hyperglycemia and diabetic dyslipidemia. Furthermore, high rates of adverse effects and the cost of these drugs have limited their use. Therefore, research into viable drug alternatives, including herbal medicinal plants, to address these needs is at the core of several diabetes-related research pursuits. ^16-19. Research into medicinal plants will also serve the developing countries which are seeing greater increases in cases of diabetes and are more likely to face the issue of not being able to afford or readily access conventional medications.

Blighia unijugata Baker (Sapindaceae) is an evergreen shade-producing tree. It is common in tropical Africa and thrives best in sunny regions with moderate amounts of rainfall ^20-22. Locally, it is used as a purgative, sedative, analgesic, anti-emetic, anthelminthic, and for treating post-partum hemorrhage, vertigo, and boils ^23-25. The antimicrobial properties ^26-29, anti-oxidant activities ^29-31, cytotoxicity ^{28, 30}, molluscicidal activity ^{32, 33}, hypotensive effect ^{34, 35}, anti-inflammatory effect ³⁶, and anti-depressant properties ³⁷ of Blighia unijugata have been studied in pre-clinical models. Its effect on total body weight ^{24, 38}, estrogen, total protein, and total cholesterol ³⁸. The effect of its seed oil on weight gain, and lipid profile ³⁹ has been studied. Also, its ability to increase hemoglobin, white blood cells, and packed cell volume has been studied ²⁴. 

Previous studies done in our lab on the ethanolic stem bark extract of Blighia unijugata showed its ability to reduce serum total cholesterol in SD rats ³⁸. However, the activity of the stem bark extract on lipid profile, T2DM, diabetic dyslipidemia, and atherogenic indices have not been investigated. Also, Blighia sapida, a sister species, has been reported to have anti-hyperglycemic and anti-hyperlipidemic effects ⁴⁰ suggesting a possible family-wise property between the two species. This work studied the anti-hyperlipidemic and anti-hyperglycemic activities of the ethanolic extract of Blighia unijugata (EBU) in diabetic SD rats.

METHOD

Plant collection

The fresh stem bark of Blighia unijugata was harvested from Kwahu Asakraka in the Eastern Region of Ghana in the month of August 2016. It was authenticated by a Botanist of the Department of Herbal Medicine of the Faculty of Pharmacy and Pharmaceutical Sciences, KNUST, Kumasi, Ghana. A sample with voucher number KNUST/HM1/2016/SB 17 was prepared and kept at the herbarium of the department.

Preparation of Blighia unijugata stem bark extract

The collected plant material was air-dried and powdered using a hammer mill (Liming^®, China). An 800 g quantity was weighed, extracted with 70 % (v/v) ethanol by cold maceration for 3 days, and concentrated in a rotary evaporator (Rotavapor R-210, Buchi, Switzerland) at 60 °C. It was finally oven dried (Gallenkamp^®, UK) at 50 °C to a constant weight. A dark slurry residue of 31.3 g was obtained and refrigerated until reconstituted into a solution for administration. This extract was labeled as EBU and stored for use in this study.

Phytochemical screening

Screening of EBU for the presence of alkaloids, coumarins, flavonoids, glycosides, saponins, steroids, tannins, and triterpenoids was done using various tests previously described by  Sofowora ⁴¹, Evans ⁴², and Shaikh & Patil ⁴³. These tests are described below:

Alkaloids (Dragendorff’s Test)

A 0.5 g quantity of EBU was extracted with 20 ml of ammoniacal alcohol and filtered. The residue obtained after evaporating the filtrate was shaken with 1 % H₂SO₄ and filtered. The filtrate was made alkaline with dilute ammonia solution and shaken with chloroform; the chloroform layer was separated and evaporated to dryness. The residue was dissolved in 1 % H₂SO₄ and one drop of Dragendorff’s reagent (Sigma Aldrich Co. Ltd. Irvine, UK) was added. An orange-red precipitate shows alkaloids are present ^41-43.

Coumarins (NaOH paper test) 

0.5 g of moistened EBU is taken in a test tube. The mouth of the test tube is then covered with filter paper that has been treated with 1 M NaOH. This is heated for a few minutes in a water bath. The presence of a yellow fluorescence from the paper under the UV light indicates the presence of coumarins ⁴³.

Flavonoids (Kumar test) 

A 0.5 g quantity of EBU was dissolved in water and filtered; to this 2 ml of 10 % NaOH (BDH Laboratories, England) solution was added to produce a yellow coloration. A change in color from yellow to colorless on the addition of dilute HCl (BDH Laboratories, England) indicates the presence of flavonoids ^41-43.

Saponins (Frothing test)

A 1 g quantity of EBU was dissolved in distilled water and filtered. The filtrate was vigorously shaken and left to stand for 5 minutes. The presence of froth which persisted on standing indicated the presence of saponins in this extract ^41-43. 

Phytosterols (Lieberman Burchard’s test)

0.5 g of EBU was extracted with 5 ml chloroform and filtered into a test tube. Several drops of acetic anhydride (Sigma Aldrich Co. Ltd. Irvine, UK) were added and mixed carefully. Two (2) drops of concentrated H₂SO₄ (BDH Laboratories, England) were gently added to the test tube through the side. The formation of violet to blue colored ring at the junction of two liquids shows the presence of steroid moiety ^41-43.

Terpenoids (Salkowski test)

0.5 g of EBU was extracted with 5 ml chloroform, and filtered into a test tube. The careful addition of concentrated H₂SO₄ (BDH Laboratories, England) to the test tube wall produced a violet coloration showing the presence of terpenoids ^41-43.

Glycosides (General test)

A 0.5 g quantity of EBU was extracted by warming with 5 ml of dilute H₂SO₄ in a water bath for 2 minutes and filtered. The filtrate was turned alkaline by adding 2-5 drops of 20 % NaOH (BDH Laboratories, England). 1 ml of Fehling’s solution A and B (Sigma Aldrich Co. Ltd. Irvine, UK) was added to the filtrate and dried in a water bath for 2 minutes. The presence of a brick-red precipitate indicates the presence of glycosides ^41-43.

Tannins (Ferric Chloride test)

A 0.5 g quantity of EBU was boiled with distilled water for 5 minutes. The boiled extract was cooled, filtered, and made up to 25 ml. To 1 ml of the extract, 10 ml of distilled water was added followed by 2-10 drops of 1 % Ferric chloride solution (Sigma Aldrich Co. Ltd. Irvine, UK). A blue-black or blue-green coloration shows a positive test for tannins ^41-43.

Experimental animals and husbandry

The processes and procedures employed during the experiment stayed in agreement with the National Institute of Health Guidelines for the Care and Use of Laboratory Animals (NIH, Department of Health Services Publication). The procedures for the research work were approved by the Department of Pharmacology, KNUST, Ghana with an ethical approval number (FPPS/PCOL/0043/2015). 

Male SD rats (140-180 g) were procured from the Centre for Plant Medicine Research, Mampong, Ghana, and acclimatized for one week prior to study initiation. Rats were housed in sets of five (5) under controlled colony conditions and fed ad libitum.

Induction of hyperglycemia

 The procedure for induction was adopted from the works of Sridevi et al., (2011) and Ramachandra et al., (2012) with some modifications ^{44, 45}. Male rats were fasted overnight and given a single intraperitoneal injection of freshly prepared solution of STZ (50 mg/kg in 0.1 M citrate buffer, PH 4.5). Rats were given 20 % glucose for 24 hours thereafter to control for any STZ-induced hypoglycemia. Blood glucose was checked daily from tail vein bleeds using a glucometer (Acu-Chek®, Roche, Mannheim, Germany). Rats with consistent fasting blood glucose (FBG) greater than 250 mg/dl (13.8 mmol/L) after 7 days of induction were considered to be diabetic and included in the study. 

Drug preparation, animal groupings, and drug administration

EBU and glibenclamide (Daonil® 5 mg tablet, Sanofi-Aventis, Guildford, UK) were dissolved or suspended in measured quantities of distilled water and administered orally by gavage in volumes not greater 5 ml/dose/day. The diabetic rats were randomly divided into five groups (n=5) and treated with 2 ml/kg distilled water, 100 and 200 mg/kg of EBU, or 5 mg/kg glibenclamide respectively for 28 days (to mimic the commonly used drug course). Glibenclamide was selected as a positive control because we hypothesized that EBU similarly increases the secretion of insulin as glibenclamide. EBU doses were selected from an earlier experiment in the study of EBU on uterine fibroids ³⁸ and those for Glibenclamide were from what was commonly used in literature ^46-48. A normal control group (n=5), treated with distilled water was kept under similar experimental conditions. The rats in each group were weighed at the beginning and end of the experiment. 

On the 28th day after drug administration, blood samples (3 ml)were collected from the severed jugular vein of rats using serum-separating gel tubes (BD Vacutainer® blood collection Tube Product, USA). Blood was allowed to clot at room temperature (27 °C) after which the gel tubes were centrifuged (Heraeus Labofuge 300, UK) at 3000 rpm for 20 minutes. The clear supernatant was pipetted in plain tubes to conduct biochemical analysis. Serum lipid profiles (TC, TG, HDL-c, LDL-c, VLDL-c) and fasting blood glucose (FBG) was determined using an automated clinical chemistry analyzer (ABX Pentra C200, Horiba Medical, USA). Values of the atherogenic index (LDL-c / HDL-c), coronary risk index (TC/HDL-c), and log (TG /HDL-c) were calculated ^49-51. From the initial and final weights, the percentage changes in the body weight of each group were determined.

Statistical analysis 

The data obtained were analyzed with GraphPad Prism (version 6) and values were expressed as mean ± standard error of the mean (SEM). Data were analyzed with one-way analysis of variance (ANOVA) and suitable post hoc tests. P values ≤ 0.05 was considered statistically significant.

RESULTS

Phytochemical test 

Phytochemical tests are the preliminary tests that identify the presence of biologically active secondary metabolites. These secondary metabolites are considered to be responsible for the pharmacological action of various plant extracts. EBU stem-bark extract tested positive for tannins, saponins, terpenoids, glycosides, and flavonoids (Table 1.0).

Treatment with EBU reduces fasting blood glucose in STZ-induced diabetes mellitus rats

Administration of STZ caused a significant rise (p≤0.0001) in blood glucose as indicated by the increased fasting blood glucose in the diabetic rats when compared to the normal control group (Figure 1. a). Treatment of the hyperglycemic rats with EBU caused a significant reduction (p≤0.001) in fasting blood glucose in a manner like glibenclamide treatment (p≤0.001) when both treatment groups when compared with the diabetic control groups (Figure 1. b).

Table 1. Phytochemical Constituents of EBU
Constituent	Result
Alkaloids	-
Coumarins	-
Flavonoids	+
Glycosides	+
Saponins	+
Steroids	-
Tannins	+
Terpenoids	+
+, present; -, absent; EBU, ethanolic stem bark extract of Blighia unijugata.

 

 

 

 

 

 

 

 

 

                                         

Figure 1: Fasting blood glucose in control and STZ-treated rats.

1. Administration of STZ caused a significant rise in fasting blood glucose compared to the normal control (NC: no STZ, 2 ml/kg distilled water; ^****p≤0.0001)
2. Administration of EBU (100 & 200 mg/kg) to hyperglycemic rats caused a significant reduction (^††††p≤0.0001) in fasting blood glucose compared to the diabetic control group (DC: 2 ml/kg distilled water). This reduction by EBU was similar to that of the glibenclamide-treated group (GLIB, 5 mg/kg, ^††††p≤0.0001). 

 

Treatment with EBU mitigates dyslipidemia associated with diabetes rats 

The diabetic rats had significant elevation (all p-values ≤0.01) of TC, TG, LDL-c, and VLDL-c and a significant decrease (p≤0.01) in HDL-c when compared with the normal control group (Figure 2 a-e). Treatment of the diabetic rats with EBU caused a significant reduction (all p-values ≤0.01) in TC, TG, and VLDL-c, and a significant increase (all p-values p≤0.05) in HDL-c. LDL-c levels were not significantly (p>0.05) reduced when EBU treated group was compared with the diabetic control group. Similarly, glibenclamide caused a significant reduction (p≤0.001- p≤0.05) in serum TC, TG, VLDL-c, and LDL-c and a rise in HDL-c (p ≤ 0.01) when compared with the diabetic control group.

 

 

A.                                                                                                                                                   B.

 

 

 

 

 

 

 

      C.                                                                                                                                              D.

 

 

 

 

 

 

 

 

E. 

 

 

 

 

 

 

 

 

Figure 2: Lipid profile in normal control, diabetic control, EBU, and glibenclamide-treated groups of Sprague-Dawley rats after 28 days of treatment. 

1. A significant increase in total cholesterol (TC) was in the diabetic control group     (^****p≤0.0001) when compared with NC. There was a significant reduction in TC when the diabetic rats were treated with EBU (100 & 200 mg/kg; ^†††p≤0.001) and glibenclamide (GLIB, 5 mg/kg; ^†††p≤0.001). as compared to the diabetic control group).
2. A significant rise in triglycerides (TG) was observed in the diabetic control group  (^****p≤0.0001) when compared with the NC group. There was a significant reduction in TG when the diabetic rats were treated with EBU (100 & 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). (^†††p≤0.001- EBU & GLIB treated groups were compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons test).
3. Low-Density Lipoproteins: A significant rise in Low-Density Lipoprotein cholesterol (LDL-c) was observed in the diabetic control group (^***p≤0.001) when compared with the NC group. Treatment with EBU (100 & 200 mg/kg) caused a reduction in LDL-c but it was not significant when compared with the diabetic control. In the glibenclamide (GLIB, 5 mg/kg) group versus the DC group, a significant reduction (^†p≤0.05) in LDL-c was observed.
4. High-Density Lipoproteins: A significant decrease in HDL-c was observed in the diabetic control group (^**p≤0.01) when compared with the normal control group. There was a significant increase in HDL-c when the diabetic rats were treated with EBU (100 & 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). (^†p≤0.05, ^††p≤0.01- EBU & GLIB treated groups were compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons test).
5. Very Low-Density Lipoproteins: A significant rise in Very Low-Density Lipoprotein cholesterol (VLDL-c) was observed in the diabetic control group (^**p≤0.01) when compared with the NC group. There was a significant reduction in VLDL-c when the diabetic rats were treated with EBU (100 & 200 mg/kg, ^††p≤0.01 for both doses) and glibenclamide (GLIB, 5 mg/kg, ^†††p≤0.001). (EBU & GLIB treated groups were compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons test).

 

 

Treatment with EBU improves the poor atherogenic predictor indices associated with diabetes rats 

The risk of atherogenesis and coronary artery disease development in the diabetic rats was high as seen in the significant increase(p≤0.001) of the atherogenic index (AI), coronary risk index (CRI), and log (TG/HDL-c) when compared with the normal control group (Figure 3. a-c). EBU and glibenclamide treatment resulted in a significant reduction (p≤0.001) in AI, CRI, and log (TG/HDL-c) when compared to the diabetic control.

 

 

 

C.

 

 

 

 

 

 

 

 

 

 

 

Figure 3: Atherogenic predictor indices in normal control, diabetic control, EBU, and glibenclamide-treated groups of Sprague-Dawley rats after 28 days of treatment. 

1. Atherogenic Index: A significant increase in Atherogenic Index (AI) was observed in the diabetic control group (^***p≤0.001) when compared with the normal control group (NC). A significant reduction in AI was observed when the diabetic rats were treated with EBU (100 & 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). (^†††p≤0.001 for EBU & ^††††p≤0.001 for GLIB treated groups when compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons test).
2. Coronary Risk Index: A significant increase in coronary risk index (CRI) was observed in the diabetic control group (^****p≤0.0001) when compared with the NC group. A significant reduction in CRI was observed when the diabetic rats were treated with EBU (100 & 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). ^†††p≤0.00 - EBU & GLIB treated groups were compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons tests.
3. Log (TG/HDL-c): A significant increase in Log (TG/HDL-c) was observed in the diabetic control group (^****p≤0.0001) when compared with the normal control group (NC). A significant reduction in Log (TG/HDL-c) was observed when the diabetic rats were treated with EBU (100 & 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). (^†††p≤0.00 - EBU & GLIB treated groups were compared with the diabetic control group using one-way ANOVA followed by Tukey’s multiple comparisons test).

 

 

 

 

 

 

Treatment with EBU mitigates the weight loss associated with diabetes rats 

The diabetic control rats had a significant loss (p≤0.0001) in body weight (Figure 4). The loss in body weight was significantly lower (p≤0.01) after treatment of the diabetic rats with EBU when compared with the normal control group. Rats treated with glibenclamide had a non-significant (p>0.05) change in body weight when compared to the normal control group.

 

 

                         

Figure 4: Percentage Changes in body weights in normal control, diabetic control, EBU, and glibenclamide-treated groups of SD rats.

Rats in the Diabetic control group had a significant loss of body weight when compared to the normal control group. This loss in body weight was significantly improved after treatment with EBU (100 and 200 mg/kg) and glibenclamide (GLIB, 5 mg/kg). (Values are presented as means ± SEM, n = 5, ns: non-significant,^****p≤0.0001,^*p≤0.01-Diabetic control group and drug treatment groups were compared to the normal control group using one-way ANOVA followed by Tukey’s multiple comparisons test).

 

 

DISCUSSION

We studied the anti-hyperglycemic and anti-hyperlipidemic activities of the ethanolic stem bark extract of Blighia unijugata (EBU) in streptozotocin (STZ) - induced diabetic SD rats. Treatment of the hyperglycemic rats with EBU and glibenclamide reduced the elevated blood glucose levels. Glibenclamide stimulates high insulin release from the remaining beta cells and hence improves insulin function to cause the reduction of elevated blood glucose.

In diabetic rats, impaired insulin secretion leads to uncontrolled action of lipolytic hormones in the adipose tissue to release free fatty acids which are eventually converted by the liver. Triglycerides and cholesterol levels are elevated due to the inhibition of lipoprotein lipases and metabolic abnormalities respectively ⁵². An ideal therapeutic agent should be one that in addition to establishing a proper glycemic control, must have a favorable activity on plasma lipids, particularly LDL-c. In addition to the anti-hyperglycemic action, EBU also affected key markers of the lipid profile. EBU and glibenclamide showed a reduction in TG, TC, and VLDL-c and an elevation in HDL-c levels. Glibenclamide is a hypoglycemic agent and its’ effect on lipid profile could suggest this activity was achieved by resolving the primary diabetic condition. With EBU, this anti-hyperlipidemic activity seen could be from resolving the underlying diabetic condition and/or by a direct anti-hyperlipidemic effect. The ability of EBU to decrease total cholesterol in SD rats has been reported ³⁸, and unpublished data from our lab suggests an anti-hyperlipidemic activity of EBU in hyperlipidemic rats. EBU’s direct action on hyperlipidemia could account for its effect on the lipid profile.  The elevated level of HDL-c shown by treatment with EBU is highly desirable as it decreases the risk of cardiovascular complications. The findings from the reduction in the atherogenic risk predictor indices [atherogenic index, coronary risk index, and log (TG/HDL-c)] further corroborate the reduced risk of atherosclerosis and cardiovascular diseases.

Administering EBU caused a reduction in weight loss in diabetic rats. The loss in weight in T2DM can be attributed to protein wasting because carbohydrate is unavailable as an energy source ⁵³ and impaired insulin secretion and function decreases glycogen synthesis ^{44, 45}. The reduction in weight loss seen after treatment with EBU and glibenclamide may be due to increased insulin secretion. 

Mohammed et al reported similar anti-hyperglycemic and weight gain activity using the chloroform fraction of B. unijugata leaves. When administered, this fraction reduced glucose levels and caused a reversed the weight loss in diabetes albino rats ⁵⁴. This indicated the anti-diabetic agents found in the leaves, may also be present in the stem-bark. Also considering previous reports on Blighia sapida ⁴⁰, the similar findings with Blighia unijugata suggest the anti-hyperglycemic and anti-hyperlipidemic effects observed may be common among the members of the genus.   

The bioactive agents present in various medicinal plants have reduced blood glucose levels by mechanisms such as exerting insulin-like effects, protecting beta cells, acting as antioxidants, increasing glucose oxidation, hepatic glycogen, and glucose uptake, decreasing intestinal glucose absorption and gluconeogenesis among others ⁵⁵. EBU contained tannins, saponins, terpenoids, glycosides, and flavonoids. Glycosides, alkaloids, terpenoids, and flavonoids have been reported to have anti-diabetic effects by increasing the release of insulin and regeneration of the pancreatic beta cells ⁵⁶. Saponins stimulate insulin secretion hence lower blood glucose levels ⁵⁵. Flavonoids and terpenoids also have antioxidant properties and hence may mitigate oxidative stress and the destruction of the remnant beta cells ^{40, 56-61}. These actions may account for the anti-hyperglycemic effect of EBU. Alkaloids, flavonoids, saponins, triterpenoids, and polyphenols among others, have been reported to exert anti-hyperlipidemic effects by inhibiting lipid biosynthesis, increasing lipid metabolism, re-distribution, transport, and excretion, and mitigating insulin resistance ^{62, 63}. This may explain the anti-hyperlipidemic action of EBU which also contained saponins, terpenoids, glycosides, and flavonoids.  

In conclusion, our work reveals that EBU possesses anti-hyperglycemic and anti-hyperlipidemic properties as shown in the STZ-induced diabetes mellitus model. This study, therefore, adds to the growing body of work which gives scientific credence to the medicinal value of Blighia unijugata.  Further studies to isolate, purify and characterize the bioactive compounds, and to elucidate the exact mechanism will be required in future studies.

Disclosures: 

The authors have declared that no competing interests exist.

Acknowledgment: 

A special thanks to Dr. Ella A. Kasanga and Dr. Nana Ama Mireku Gyimah for their support during the proofreading and editing of this article. I thank Dr. Benjamin Kingsley Harley for supplying the STZ needed for the work and the Ghana Education Trust Fund for funding part of my studies.

REFERENCES

1. Mohan V, Khunti K, Chan SP, Filho FF, Tran NQ, Ramaiya K, et al. Management of Type 2 Diabetes in Developing Countries: Balancing Optimal Glycaemic Control and Outcomes with Affordability and Accessibility to Treatment. Diabetes Ther. 2020;11(1):15-35. https://doi.org/10.1007/s13300-019-00733-9 PMid:31773420 PMCid:PMC6965543

2. Cole JB, Florez JC. Genetics of diabetes mellitus and diabetes complications. Nat Rev Nephrol. 2020;16(7):377-90. https://doi.org/10.1038/s41581-020-0278-5 PMid:32398868 PMCid:PMC9639302

3. Lin X, Xu Y, Pan X, Xu J, Ding Y, Sun X, et al. Global, regional, and national burden and trend of diabetes in 195 countries and territories: an analysis from 1990 to 2025. Scientific Reports. 2020;10(1):14790. https://doi.org/10.1038/s41598-020-71908-9 PMid:32901098 PMCid:PMC7478957

4. Bommer C, Sagalova V, Heesemann E, Manne-Goehler J, Atun R, Bärnighausen T, et al. Global Economic Burden of Diabetes in Adults: Projections From 2015 to 2030. Diabetes Care. 2018;41(5):963-70. https://doi.org/10.2337/dc17-1962 PMid:29475843

5. Standl E, Khunti K, Hansen TB, Schnell O. The global epidemics of diabetes in the 21st century: Current situation and perspectives. European Journal of Preventive Cardiology. 2019;26(2_suppl):7-14. https://doi.org/10.1177/2047487319881021 PMid:31766915

6. Petersmann A, Müller-Wieland D, Müller UA, Landgraf R, Nauck M, Freckmann G, et al. Definition, Classification and Diagnosis of Diabetes Mellitus. Exp Clin Endocrinol Diabetes. 2019;127(S 01):S1-s7. https://doi.org/10.1055/a-1018-9078 PMid:31860923

7. Oloyede OBA, T.O.; Abdussalam, A.F.; Adeleye, A.O. Blighia sapida leaves halt elevated blood glucose,.pdf. 2014.

8. Srinivasan S, Pari L. Ameliorative effect of diosmin, a citrus flavonoid against streptozotocin-nicotinamide generated oxidative stress induced diabetic rats. Chemico-Biological Interactions. 2012;195(1):43-51. https://doi.org/10.1016/j.cbi.2011.10.003 PMid:22056647

9. P.A. Akah JAA, O.A. Salawu, T.C. Okoye, N.V. Offiah Effects of Vernonia amygdalina on biochemical and hematological parameters in diabetic rats. Asian Journal of Medical Sciences. 2009;1(3):108-13.

10. Athyros VG, Doumas M, Imprialos KP, Stavropoulos K, Georgianou E, Katsimardou A, et al. Diabetes and lipid metabolism. Hormones (Athens). 2018;17(1):61-7. https://doi.org/10.1007/s42000-018-0014-8 PMid:29858856

11. Bahiru E, Hsiao R, Phillipson D, Watson KE. Mechanisms and Treatment of Dyslipidemia in Diabetes. Curr Cardiol Rep. 2021;23(4):26. https://doi.org/10.1007/s11886-021-01455-w PMid:33655372

12. Wu L, Parhofer KG. Diabetic dyslipidemia. Metabolism. 2014;63(12):1469-79. https://doi.org/10.1016/j.metabol.2014.08.010 PMid:25242435

13. Hirano T. Pathophysiology of Diabetic Dyslipidemia. J Atheroscler Thromb. 2018;25(9):771-82. https://doi.org/10.5551/jat.RV17023 PMid:29998913 PMCid:PMC6143775

14. Einarson TR, Acs A, Ludwig C, Panton UH. Prevalence of cardiovascular disease in type 2 diabetes: a systematic literature review of scientific evidence from across the world in 2007-2017. Cardiovasc Diabetol. 2018;17(1):83. https://doi.org/10.1186/s12933-018-0728-6 PMid:29884191 PMCid:PMC5994068

15. Kane JP, Pullinger CR, Goldfine ID, Malloy MJ. Dyslipidemia and diabetes mellitus: Role of lipoprotein species and interrelated pathways of lipid metabolism in diabetes mellitus. Curr Opin Pharmacol. 2021;61:21-7. https://doi.org/10.1016/j.coph.2021.08.013 PMid:34562838

16. Setiyorini E, Qomaruddin MB, Wibisono S, Juwariah T, Setyowati A, Wulandari NA, et al. Complementary and alternative medicine for glycemic control of diabetes mellitus: A systematic review. J Public Health Res. 2022;11(3):22799036221106582. https://doi.org/10.1177/22799036221106582 PMid:35911428 PMCid:PMC9335474

17. Usai R, Majoni S, Rwere F. Natural products for the treatment and management of diabetes mellitus in Zimbabwe-a review. Front Pharmacol. 2022;13:980819. https://doi.org/10.3389/fphar.2022.980819 PMid:36091798 PMCid:PMC9449367

18. Kumar S, Mittal A, Babu D, Mittal A. Herbal Medicines for Diabetes Management and its Secondary Complications. Curr Diabetes Rev. 2021;17(4):437-56. https://doi.org/10.2174/18756417MTExfMTQ1z PMid:33143632

19. Salehi B, Ata A, N VAK, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, et al. Antidiabetic Potential of Medicinal Plants and Their Active Components. Biomolecules. 2019;9(10). https://doi.org/10.3390/biom9100551 PMid:31575072 PMCid:PMC6843349

20. Obeng EA. Blighia unijugata Baker. [Internet] Record from PROTA4U. Lemmens, R.H.M.J., Louppe, D. & Oteng-Amoako, A.A. (Editors). 2010. PROTA (Plant Resources of Tropical Africa / Ressources végétales de l'Afrique tropicale), Wageningen, Netherlands. http://www.prota4u.org/search.asp .

21. Burkill HM. The useful plants of West Tropical Africa. 2nd Edition. Volume 5, Families S-Z, Addenda. 2000. Royal Botanic Gardens, Kew, United Kingdom. 686 pp.

22. Hyde M, Wursten B, Ballings P, Coates Palgrave M. Flora of zimbabwe: species information: Blighia unijugata. CITIS Harare; 2002.

23. Offor CE, Onwe NJ, Agbafor KN, Nwangwu SCO, editors. Determination of Proximate and Vitamin Compositions of Blighia unijugata Leaves2015.

24. Agbafor KN, Offor C, Engwa G. Haemoglobin Level, Total White Blood Cell and Packed Cell Volume In The Albino Rats Treated With Aqueous Extract Of Fresh Leave Of Blighia Unijugata. Journal of Environmental Science, Toxicology and Food Technology. 2015;9(2):134-7.

25. Chhabra S, Mahunnah R, Mshiu E. Plants used in traditional medicine in Eastern Tanzania. V. Angiosperms (Passifloraceae to Sapindaceae). Journal of Ethnopharmacology. 1991;33(1-2):143-57. https://doi.org/10.1016/0378-8741(91)90173-B PMid:1943163

26. Ongarora DS. Phytochemical investigation and antimicrobial activity of Blighia unijugata bak (sapindaceae): University Of Nairobi; 2009.

27. Obasi N, Igbochi A. Antibacterial activity of a chemical isolate from stem bark of Blighia unijugata. African Journal of Pharmacology and Pharmaceutical Science. 1992;23:4750-61.

28. Adewuyi A, Oderinde RA, Omotosho M. Comparative Study of the Antibacterial and Cyctotoxicity of the Essential Oils from the Leaves, Stem Bark and Roots of Blighia unijugata Baker (Sapinadaceae). Medicinal and Aromatic Plant Science and Biotechnology. 2009;3:97-9.

29. Sofidiya MO, Jimoh FO, Aliero AA, Afoloyan A, Odukoya OA, Familoni OB. Evaluation of antioxidant and antibacterial properties of six Sapindaceae members. 2012.

30. Sonibare MA. Antioxidant and cytotoxicity evaluations of two species of Blighia providing clues to species diversity. Electronic Journal of Environmental, Agricultural and Food Chemistry (EJEAFChe). 2011;10(10):2960-71.

31. Ajiboye C, Moronkola D, Akinwumi A. Hydrogen Peroxide Free Radical Scavenging Activities of Leaf, Stem Bark, Root, Flower and Fruit of Blighia unijugata Baker (Sapindaceae) Extracts. Journal of Chemical and Pharmaceutical Research. 2017;9:8-12.

32. Agboola O, Ajayi G, Adesegun S, Adesanya S. Comparative molluscicidal activities of fruit pericarp, leaves, seed and stem bark of blighia unijugata baker. Pharmacognosy Journal. 2011;3(25):63-6. https://doi.org/10.5530/pj.2011.25.11

33. Anto F, Aryeetey M, Anyorigiya T, Asoala V, Kpikpi J. The relative susceptibilities of juvenile and adult Bulinus globosus and Bulinus truncatus to the molluscicidal activities in the fruit of Ghanaian Blighia sapida, Blighia unijugata and Balanites aegyptiaca. Annals of Tropical Medicine & Parasitology. 2005;99(2):211-7. https://doi.org/10.1179/136485905X24229 PMid:15814040

34. Paul YA, Etienne EE. Hypotensive effects of a butanol active fraction from leaves of blighia unijugata bak.(sapindaceae) on arterial blood pressure of rabbit. 2013.

35. Claude YAP, Etienne EE. Research Article Acute Toxicity in Mice and Effects of a Butanol Extract from the Leaves of Blighia Unijugata Bak.(Sapindaceae) on Electrocardiogram of Rabbits.

36. Osuala FN, Odoh UE, Onuigbo V, Ohadoma SC. Pharmacognostic Screening and Anti-inflammatory Investigation of the Methanol extract of stem bark of Blighia unijugata Baker (Sapindaceae). Journal of Drug Delivery and Therapeutics. 2020;10(4):146-52. https://doi.org/10.22270/jddt.v10i4.4167

37. Bakre AG, Olayemi JO, Ojo OR, Odusanya ST, Agu GA, Aderibigbe AO. Antidepressant-like effect of ethanol extract of Blighia unijugata Bak. (Sapindaceae) leaves in acute and chronic models of depression in mice. Niger J Physiol Sci. 2019;34(2):191-9.

38. Koffuor GA, Annan K, Kyekyeku JO, Fiadjoe HK, Enyan E. Effect of ethanolic stem bark extract of blighia unijugata (sapindaceae) on monosodium glutamate-induced uterine leiomyoma in Sprague-Dawley rats. British Journal of Pharmaceutical Research. 2013;3(4):880. https://doi.org/10.9734/BJPR/2013/5402

39. Oderinde RA, Ajayi I, Adewuyi A. Preliminary toxicological evaluation and effect of the seed oil of Hura crepitans and Blighia unijugata Bak. on the lipid profile of rat. EJEAFChe. 2009;8(3):209-17.

40. Oloyede O, Ajiboye T, Abdussalam A, Adeleye A. Blighia sapida leaves halt elevated blood glucose, dyslipidemia and oxidative stress in alloxan-induced diabetic rats. Journal of ethnopharmacology. 2014;157:309-19. https://doi.org/10.1016/j.jep.2014.08.022 PMid:25172468

41. Sofowora A. Phytochemical screening of medicinal plants and traditional medicine in Africa. Ibadan, Nigeria: Spectrum Books Limited; 1993:150-156.

42. Evans WC. Trease and Evans' pharmacognosy: Elsevier Health Sciences; 2009.

43. Shaikh JR, Patil M. Qualitative tests for preliminary phytochemical screening: An overview. International Journal of Chemical Studies. 2020;8(2):603-8. https://doi.org/10.22271/chemi.2020.v8.i2i.8834

44. Sridevi M, Kalaiarasi P, Pugalendi K. Antihyperlipidemic activity of alcoholic leaf extract of Solanum surattense in streptozotocin-diabetic rats. Asian Pacific Journal of Tropical Biomedicine. 2011;1(2):S276-S80. https://doi.org/10.1016/S2221-1691(11)60171-8

45. Ramachandran S, Rajasekaran A, Manisenthilkumar K. Investigation of hypoglycemic, hypolipidemic and antioxidant activities of aqueous extract of Terminalia paniculata bark in diabetic rats. Asian Pacific journal of tropical biomedicine. 2012;2(4):262-8. https://doi.org/10.1016/S2221-1691(12)60020-3 PMid:23569911

46. Balogun FO, Ashafa AOT. Aqueous root extracts of Dicoma anomala (Sond.) extenuates postprandial hyperglycaemia in vitro and its modulation on the activities of carbohydrate-metabolizing enzymes in streptozotocin-induced diabetic Wistar rats. South African Journal of Botany. 2017;112:102-11. https://doi.org/10.1016/j.sajb.2017.05.014

47. Gao J, Han Y-L, Jin Z-Y, Xu X-M, Zha X-Q, Chen H-Q, et al. Protective effect of polysaccharides from Opuntia dillenii Haw. fruits on streptozotocin-induced diabetic rats. Carbohydrate Polymers. 2015;124:25-34. https://doi.org/10.1016/j.carbpol.2015.01.068 PMid:25839790

48. Dickson RA, Harley BK, Berkoh D, Ngala RA, Titiloye N, Fleischer T. Antidiabetic and haematological effect of Myrianthus arboreus P. Beauv. Stem bark extract in streptozotocin-induced diabetic rats. 2016.

49. Ene BA. Hypolipidemic effect of biflavonoid fraction from root bark, stem bark, and seed of garcinia kola on poloxamer 407 induced hyperlipidemic rats 2014.

50. Machaba KE. Evaluation of the in vivo anti-hyperlipidemic activity of the triterpene from the stem bark of Protorhus longifolia (Benrh.) Engl: University of Zululand; 2014. https://doi.org/10.1186/1476-511X-13-131 PMid:25127687 PMCid:PMC4246574

51. Kamesh V, Sumathi T. Antihypercholesterolemic effect of Bacopa monniera linn. on high cholesterol diet induced hypercholesterolemia in rats. Asian Pacific Journal of Tropical Medicine. 2012;5(12):949-55. https://doi.org/10.1016/S1995-7645(12)60180-1 PMid:23199712

52. Kumar R, Pate DK, Prasad SK, Sairam K, Hemalatha S. Antidiabetic activity of alcoholic leaves extract of Alangium lamarckii Thwaites on streptozotocin-nicotinamide induced type 2 diabetic rats. Asian Pacific journal of tropical medicine. 2011;4(11):904-9. https://doi.org/10.1016/S1995-7645(11)60216-2 PMid:22078954

53. Kumar R, Patel D, Prasad SK, Sairam K, Hemalatha S. Antidiabetic activity of alcoholic root extract of Caesalpinia digyna in streptozotocin-nicotinamide induced diabetic rats. Asian Pacific Journal of tropical biomedicine. 2012;2(2):S934-S40. https://doi.org/10.1016/S2221-1691(12)60340-2

54. Mohammed RS, Abdulsalam MM, Kntapo FM. Hypoglycemic Effect of Anthocleista djalonensis and Blighi unijugata. Nigerian Journal of Chemical Research. 2023;28(1):025-39. https://doi.org/10.4314/njcr.v28i1.3

55. Tran N, Pham B, Le L. Bioactive Compounds in Anti-Diabetic Plants: From Herbal Medicine to Modern Drug Discovery. Biology (Basel). 2020;9(9). https://doi.org/10.3390/biology9090252 PMid:32872226 PMCid:PMC7563488

56. Khalivulla SI, Mohammed A, Mallikarjuna K. Novel Phytochemical Constituents and their Potential to Manage Diabetes. Curr Pharm Des. 2021;27(6):775-88. https://doi.org/10.2174/1381612826666201222154159 PMid:33355047

57. Singh SK, Kesari AN, Gupta RK, Jaiswal D, Watal G. Assessment of antidiabetic potential of Cynodon dactylon extract in streptozotocin diabetic rats. Journal of Ethnopharmacology. 2007;114(2):174-9. https://doi.org/10.1016/j.jep.2007.07.039 PMid:17889469

58. Firdous SM. Phytochemicals for treatment of diabetes. Excli j. 2014;13:451-3.

59. Oh YS. Plant-Derived Compounds Targeting Pancreatic Beta Cells for the Treatment of Diabetes. Evidence-Based Complementary and Alternative Medicine. 2015;2015:629863. https://doi.org/10.1155/2015/629863 PMid:26587047 PMCid:PMC4637477

60. Bacanli M, Dilsiz SA, Başaran N, Başaran AA. Chapter Five - Effects of phytochemicals against diabetes. In: Toldrá F, editor. Advances in Food and Nutrition Research. 89: Academic Press; 2019. p. 209-38. https://doi.org/10.1016/bs.afnr.2019.02.006 PMid:31351526

61. Ahangarpour A, Sayahi M, Sayahi M. The antidiabetic and antioxidant properties of some phenolic phytochemicals: A review study. Diabetes Metab Syndr. 2019;13(1):854-7. https://doi.org/10.1016/j.dsx.2018.11.051 PMid:30641821

62. Gong X, Li X, Xia Y, Xu J, Li Q, Zhang C, et al. Effects of phytochemicals from plant-based functional foods on hyperlipidemia and their underpinning mechanisms. Trends in Food Science & Technology. 2020;103:304-20. https://doi.org/10.1016/j.tifs.2020.07.026

63. Liu Y, Liu C, Kou X, Wang Y, Yu Y, Zhen N, et al. Synergistic Hypolipidemic Effects and Mechanisms of Phytochemicals: A Review. Foods. 2022;11(18). https://doi.org/10.3390/foods11182774 PMid:36140902 PMCid:PMC9497508