Effect of Solvent Extracts of Tephrosia vogelii Leaves and Stem on Lipid Profile of Poloxamer 407-Induced Hyperlipidemic Rats

Abstract

Introduction There are claims by traditional medicine practitioners in Nigeria and valuable scientific reports that the leaves of Tephrosia vogelii (TV) hook are used for the treatment of various diseases; however, there is paucity of information on it used in the management of cardiovascular complications despite the rich presence of phytochemicals. This study aimed at investigating effects of solvents extracts of TV leaves and stem on lipid profile of poloxamer 407-induced hyperlipidemic rats.

Materials and Methods Varying doses of the solvent extracts (water, ethanol, and acetic acid) of plant material were administered to experimental animals (Albino Wistar rats) induced with hyperlipidemia using poloxamer 407 (P-407).

Results The results of the phytochemical screening of leaves and stem revealed the presence of alkaloids, saponins, phlobatannins, and flavonoids in powdered sample of leaves and stem of TV. Aqueous extract of the leaves had the highest yield (18.21 ± 1.12%), while acetic acid extract of stem had the lowest yield (7.21 ± 1.21%). The cholesterol and triacylglycerol level of rats induced with P-407 was significantly (p≤0.05) higher than normal rats. This study showed that aqueous extract at 50mg/kg body weight significantly (p≤0.05) lower cholesterol, low-density lipoprotein, very low-density lipoprotein, and triacylglycerol levels. Indices of cardiovascular function atherogenic coefficient, atherogenic index, coronary risk index, and cardioprotective index were positively modulated by the treatment.

Conclusion The study indicated that the aqueous leaves extract of TV possesses antihyperlipidemic effects and may explains why it has been found to be useful in the management of cardiovascular diseases by traditional medicine practitioners.

Keywords

Tephrosia vogelii leaves - cardiovascular function - hyperlipidemia - phytochemicals - poloxamer 407

Introduction

Cardiovascular diseases (CVDs) such as myocardial infarction (heart attacks), coronary heart disease, high blood pressure, peripheral vascular diseases, and stroke and metabolism-based disease like diabetes are the leading causes of death for both men and women among all racial and ethnic groups.[1] They lead to nearly 50% of all deaths in the developed world.[2] If this continues, the future will even be more challenging considering that globalization and wide spread of western diet to the developing world resulting to high rates of obesity, diabetes, and hyperlipidemia in developing countries.[3] Thus, hyperlipidemia and its associated CVDs are considered as one of the highest worldwide economic, social, and medical challenges.[4] The elevation levels of serum total cholesterol and more importantly low-density lipoprotein cholesterol (LDL-c) have been implicated as primary risk factor for CVD.[5]

Medicinal plants have been used in many African countries and today almost every part of the world use herbal plants for the treatment of different diseases.[6] Medicinal plants are the main sources of chemical substances with potential therapeutic effects. The use of medicinal plants for the treatment and management of many diseases is associated with folk medicine from different parts of the world. Studies have revealed that the reduction in LDL-c with different medicinal plants will reduce the incidence of the diseases associated with CVDs and overall death rate. Hence, Tephrosia vogelii (TV) hook f a potential natural resource for sourcing antihyperlipidemic therapeutics, is a good candidate in the management of cardiovascular complications as a potent and rich source of hypolidemic phytochemicals.[7] TV hook. f. belongs to the family Fabaceae, genus Tephrosia and species vogelii. It is a native to Nigeria, Kenya, South Africa, Zambia, tropical America, Southeast Asia, and Malaysia as a cover crop. It is commonly called fish-poison bean in English and in Nigeria, TV is locally called Oha [Idoma] and Kuhwa [Tiv] as well as GolonZaki [Hausa].[8] [9] The plant is well known to the people of Ugboju and Okokolo Agatu of Benue state of Nigeria.

However, the plant TV is used in South West Nigeria in the treatment of hypertension and other related diseases.[10] This study is reporting for the first time to our knowledge the medicinal potentials of TV in hyperlipidemic animal models

Materials and Methods

Plant Sample Collection

The leaves of TV leaves and stem were harvested from their natural habitats, Ugboju Agatu, Benue State, Nigeria. They were identified/authenticated at the herbarium unit, Department of Botany University of Agriculture, Makurdi, where a voucher specimen number (2234) was deposited.

Preparation of Plant Sample

The fresh leaves and stem bark were sorted out and washed to remove particles and dust. The washed parts were dried at room temperature. The dried parts were grinded into powder using mortar and pestle before being separately milled into fine powder using an electric blender to pass through a sieve. The sample was sieved with 0.03mm sieve made of brass material and the powder obtained was then used for subsequent analyses.

Qualitative Phytochemical Screening of Plant Materials

Chemical tests were performed on the powdered sample using standard procedures to identify the constituents that are active as described by Sofowara, 1993, Evans, 2002, and De et al, 2010.[11] [12] [13] They were used in the determination of tannins, saponins, phlobatannins, alkaloids, steroids, terpenoids, flavonoids, and anthraquinones

Preparation of Extracts

Based on the sample to solvent ratio of 1:10 (w/v),[13] 100 g of each of the ground samples (leaves and stem bark) were suspended in 1,000 mL of different extraction solvents in 100% distilled water, acetic acid, and 70% ethanol on a shaker for 48 hours at room temperature. Each extract was filtered using a sterilized Buchner funnel and Whatman No. 1 filter papers. The filtrates were concentrated by drying in a water bath maintained at a temperature of 45°C until a brownish black residue was obtained and the weights of the extracts were determined as the percentage weight of the extract to the original weight of the sample used, using the formula below. The extracts were kept in the sealed containers and refrigerated at 2 to 4°C from where aliquots were reconstituted for the experiment.

Quantitative Determination of Phytochemical Constituents in the Most Potent Extract (Aqueous Leaves) of Tephrosia vogelii

Saponins determination in the extract was determined using the method of Obdoni,[14] alkaloids were determined according to the method of Harbone.[15] Determination of total phenols was done by the method of Ezeonu and Ejikeme,[16] and flavonoids determination was done by the method of Boham.[17]

Lethal Dose 50

Doses were chosen after carrying out toxicity experiments of lethal dose 50 (LD50) as described by Lorke[18] and modified by Omage et al[19] using doses ranged between 10 and 5000 mg/kg.

In Vivo Biological Screening of the Extracts

Six different solvent extracts (aqueous, acetic acid and 70% ethanol) of leaves and stem were used for in vivo study to ascertain the extract with the highest antihyperlipidemic activity.

Experimental Animals

Permission was granted by animals' caretakers of Department of Pharmacology, Vom, and Jos Plateau State to obtain some rats for scientific research. A total of 60 Wistar albino rats (Rattus norvegicus) of both sexes of approximately 2 months old weighing between 100 and 200 g were bought from National Institute of Tryapanosomiasis Research, Vom, Jos Plateau State and taken to the University of Agriculture Makurdi where the study was performed. The animals were housed in a well-aerated clean large plastic cages lined with husk renewed every 24 hours, at a room temperature of 25°C, relative humidity of 75, and 12 hours dark-light cycle. The animals were fed with grower and starter mash purchased from vital feeds company in Zaria, Kaduna State, Nigeria, and water was provided ad libitum throughout the experiment and allowed to acclimatize for 2 weeks before beginning the experiment.

Animal Grouping

A total of 60 healthy rats were used for the study. The rats were divided into nine groups (n = 6–7), while 3 rats were used for the confirmation of hyperlipidemic state after induction. Wistar rats of both sexes totaling 60 were chosen at random and put into plastic cages marked with the numbers 1 and 2. Group 1 served as the control and received normal saline, while group 2 received three intraperitoneal administrations of poloxamer P-407 (BASF Corporation; Mount Olive, New Jersey, United States): the initial induction of 1 g/kg body weight and two additional doses for maintaining hyperlipidemia (0.5 g/kg doses of P-407 on days 7 and 11 following the initial induction).[20] P-407 was dissolved in distilled water and chilled for a whole night before administration to aid in its disintegration. According to Johnston et al, administration-related needles and syringes were put on ice to prevent syringe gelation during injection.[21] Three rats each from both groups (1 and 2) were randomly selected and sacrificed, 48 hours after first hyperlipidemic induction. Blood collected via cardiac puncture was used to ascertain hyperlipidemic state of the rats using cardio check device (Mission Cholesterol Meter, model number: CCM-111, Germany). This study was approved by the Department of Biochemistry Ethical Committee on Research, Innovation and Institutional Ethical Committee on animal's right (FUHSO/ET/BCH/22/001).

Animal Grouping

Group1: Normal rats administered distilled water and feed only (normal control).

Group2: Induced with poloxamer 407 (1 g/kg body weight) (PLX) + distilled water and feed only (hyperlipidemic control).

Group 3: Hyperlipidemic (PLX) rats, administered 10 mg/kg body weight of atorvastatin

Group 4: Hyperlipidemic (PLX) rats, administered 50mg/kg body weight of aqueous leaf extract

Group 5: Hyperlipidemic (PLX) rats, administered 50mg/kg body weight of ethanolic leaf extract

Group 6: Hyperlipidemic (PLX) rats, administered 50mg/kg body weight of acetic acid leaf extract

Group 7: Hyperlipidemic (PLX) rats, administered 50mg/kg body weight of aqueous stem extract

Group 8: Hyperlipidemic (PLX) rats, administered 50mg/kg body weight of ethanolic stem extract

Group 9: Hyperlipidemic (PLX) rats, administered 50 mg/kg body weight of acetic acid stem extract

Key: PLX-Poloxamer

Preparation of Standard Drug

Atorvastatin (10 mg) was purchased in a tablet form from Binka Pharmacy Makurdi, Benue State. Tablets were dissolved in 20 mL of normal saline to desired concentrations and administered orally. This preparation was done daily at the time of administration.

Termination, Collection and Preparation of Sera Samples

At the end of the 14 days, animals were fasted for 12 hours, and then the animals were sacrificed by chloroform-inhalation anesthesia[22] and the blood sample was collected from the heart of each into plain bottles (for biochemical analysis) and vacutainers containing ethylene diamine tetra acetic acid. The blood samples collected in plain sample bottles were centrifuged at a speed of 3000 × g for 10 minutes and the supernatant (serum) collected was then subjected to biochemical analysis.

Determination of Biochemical Parameters

The serum level of total cholesterol was quantified by spectrophotometric methods as described by Igharo et al.[23] The serum triacylglycerols level was also determined by method of Heber et al.[24] Using Randox kit (Randox Laboratories Limited, United Kingdom). However, the serum level of high-density lipoprotein-cholesterol (HDL-c) was measured by the method described by Warnick and Albers[25] following the manufacturer's instructions. The serum level of LDL-c was measured according to protocol of Friedewald and Levy[26] using this equation: LDL-c (mg/dL) =TG/5-HDL-c. The value was expressed in the unit of mg/dL. The assessment of cardioprotective index (CPI) was based on HDL-c/LDL-c ratio, while atherogenic coefficient (AC), atherogenic index (AI), and coronary risk indices (CRI) were determined using the formula: AC = [TC − HDL-c / HDL-c], AI = Log[TG/HDL-c] and CRI = [TC/HDL-C], respectively, as described earlier.[27]

Statistical Analysis

The results were expressed as the mean ± standard deviation, and the differences between treated and control groups were statistically assessed using one-way analysis of variance and paired with one sample t-test. All statistical calculations were performed using the GraphPad Prism 7. The results were considered significant at p < 0.05

Results

Qualitative Analysis on Phytochemical Constituents of Powdered Sample of Leaves and Stem of Tephrosia vogelii Hook. F

Qualitative analysis on phytochemical constituents of powdered sample of leaves and stem of TV is shown in [Table 1]. The results revealed the presence of alkaloids, saponins, phlobatannins, and flavonoids in powdered sample of leaves and stem of TV. Terpenes and anthraquinones were only present in the leaves but absent in stem. Tannins were absent in both leaves and stem.

Table 1 Qualitative analysis on phytochemical constituents of powdered sample of leaves and stem of Tephrosia vogelii hook. F.

Phytochemical	Leaves powder	Stem powder
Alkaloids	+	+
Saponins	+	+
Flavonoids	+	+
Phlobatannins	+	+
Terpenes and steroids	+	_
Anthraquinones	+	–
Tannins	_	+

+, Present; –, Absent.

Percentage Yield of Aqueous, Acetic Acid, and Ethanol Extracts of the Leaves and Stem of Tephrosia vogelii

Percentage yield of aqueous, acetic acid, and ethanol extracts of the leaves and stem of TV is presented in [Table 2]. The results revealed that the yield of the aqueous extract of the leaves was significantly (p≤0.05) higher than other extracts. The yield of ethanol extract of the leaves and aqueous extract of the stem were not significant different but were significantly (p≤0.05) higher than the remaining extracts that intend recorded no significant difference.

Table 2 Percentage yield of aqueous, acetic acid, and ethanol extracts of leaves and stem of Tephrosia vogelii

Plant parts	Extracts	Percentage yield, %
Leaves	Aqueous	18.21 ± 1.12c
	Ethanol	12.24 ± 3.15b
	Acetic acid	9.13 ± 2.11a
Stem	Aqueous	11.32 ± 4.23b
	Ethanol	9.31 + 2.04a
	Acetic acid	7.21+ 1.01a

Values are means ± standard deviation of four determinations. values with different superscripts in the same column are significantly different (p≤0.05).

Quantitative Phytochemical Constituents of Aqueous Leaves Extract of Tephrosia vogelii

The quantitative analysis of phytochemical constituents of aqueous leaves extract of TV is presented in [Fig. 1]. which indicates a high presence of saponins and some amounts of alkaloids, flavonoids and phenolics

Fig. 1 Quantitative phytochemical constituents of aqueous leaves extract of Tephrosia vogelii.

Lethal Dose (LD₅₀) Determination of Aqueous Leaves Extract of Tephrosia vogelii in Albino Rats

The lethal dose determination of aqueous leaves extract of TV in albino rats for 48 hours is presented in [Table 3]. There was no mortality within 48 hours after oral administration of 10, 100 and 1,000 mg/kg body weight of aqueous leaf extract to albino rats in the first phase. However, upon oral administration of 1,000, 1,600, 2,900, and 5,000 mg/kg body weight of the extract to a different set of albino rats in the second phase, there was 100% mortality in the group administered 2,900 mg/kg and 5,000 mg/kg body weight within 48 hours. Thus, the lowest lethal dose was taken as 2,900 mg/kg body weight and the highest nonlethal dose was 1,600 mg/kg body weight.

Table 3 Lethal dose (LD₅₀) determination of aqueous leaves extract of Tephrosia vogelii in albino rats

First phase	Dose (mg/kg)	Number of animals	Number of deaths after 48 hours	% Mortality
Group 1	10	5	0	0
Group 2	100	5	0	0
Group 3	1,000	5	0	0
Second phase	Dose (mg/kg)	Number of animals	Number of deaths after 48 hours	% Mortality
Group 1	1,000	3	0	0
Group 2	1,600	3	0	0
Group 3	2,900	3	3	100
Group 4	5,000	3	3	100

LD ₅₀= √ Highest nonlethal dose x lowest lethal dose; highest nonlethal dose =1,600 mg/kg body eight; lowest lethal dose was = 2,900 mg/kg body weight; LD ₅₀= √1,600 × 2,900; LD ₅₀ = 2,154 mg/kg body weight.

Therefore, the oral LD₅₀ value was calculated as the square root of the products of the highest nonlethal dose and the lowest lethal dose to be 2,154 mg/kg body weight.

Effects of Aqueous, Ethanol, and Acetic Acid Extracts of Tephrosia vogelii Leaves Extracts on Lipid Profile in Poloxamer 407-Induced Hyperlipidemic Rats

Effects of the aqueous, ethanol, and acetic acid extracts of TV leaves on poloxamer 407 and induced hyperlipidemic rats are shown in [Fig. 2]. The results showed that poloxamer generated a significant (p≤0.05) increase in serum level of total cholesterol, triacylglycerol, and LDL-c, and very low-density lipoprotein (VLDL)-c and a significant (p≤0.05) decrease in HDL-c, compared with the normal control. In the treated groups, there was a significant (p≤0.05) decrease in total cholesterol, triacylglycerol, LDL-c, and VLDL-c when compared with poloxamer control groups. Also, there was a significant (p≤0.05) increase when compared with the normal control with the exception of triacylglycerol levels of the group treated with 50mg/kg of aqueous extract that recorded no significant difference compared with the normal control. In HDL-c levels, group receiving aqueous extract recorded no significant difference compared with the normal control, while there was a significant increase (p≤0.05) compared with the poloxamer control. The groups receiving acetic acid and ethanol recorded significant increase in HDL-c comparable to normal control, significantly higher (p < 0.05) compared with the poloxamer control. The result further indicates that poloxamer 407 caused an induction of dyslipidemia. In hyperlipidemic rats, the three different extracts significantly lowered the lipid with the groups administered 50mg/kg aqueous extract showing the highest reduction of 49%

Fig. 2 Effects of aqueous, ethanol, and acetic acid extracts of Tephrosia vogelii leaves extracts on lipid profile in poloxamer 407-induced hyperlipidemic rats. Values are means ± standard deviation (SD) of six determinations. Values with different superscripts are significantly different (p < 0.05). *Significantly different versus NC; ^aSignificantly different versus other treatment groups. NC, normal rats control; HypCpolox, hyperlipidemic rats control of poloxamer 407; Hyppolox +Std, hyperlipidemic rats of poloxamer 407 + standard drug (atorvastatin 10 mg/kg); Hyppolox + Aq50, hyperlipidemic rats of poloxamer 407 + aqueous extract (50mg/kg); Hyppolox +AA50, hyperlipidemic rats of poloxamer 407 + acetic acid extract (50 mg/kg); Hyppolox +Eth50, hyperlipidemic rats of poloxamer 407 + ethanolic extract (50 mg/kg); TC, total cholesterol; TAG, triacylglycerol; HDL-c, high-density lipoprotein cholesterol; LDL-c, low-density lipoprotein cholesterol; VLDL, very low-density lipoprotein cholesterol.

Effects of Aqueous, Ethanol, and Acetic Acid of Tephrosia vogelii Stem Extracts on Lipid Profile in Poloxamer 407-Induced Hyperlipidemic Rats

The effects of the aqueous, ethanol, and acetic acid of TV stem extracts on poloxamer 407 induced hyperlipidemic rats are shown in [Fig. 3]. The result indicates that there was a significant (p≤0.05) increase in total cholesterol, triacylglycerol, LDL-c, and VLDL-c and a significant (p≤0.05) decrease in HDL-c in the poloxamer control groups, compared with the normal control. In the groups treated with extract, there was significant (p≤0.05) decrease in total cholesterol, triacylglycerol, and LDL-c and VLDL-c compared with the poloxamer control, while a significant (p < 0.05) increase was recorded compared with the normal control. In HDL-c levels, group receiving aqueous extract recorded nonsignificant difference compared with the normal control and a significant increase compared with the poloxamer controls, while the group receiving acetic acid recorded a significant (p≤0.05) decrease compared with normal control and a nonsignificant difference compared with poloxamer control. The group receiving ethyl acetate extract recorded a significant (p≤0.05) decrease in HDL-c compared with the normal control and poloxamer controls. Therefore, in hyperlipidemic rats, the three different extracts significantly (p≤0.05) lowered their lipid with the groups administered 50mg/kg aqueous extract showing the highest percentage reduction.

Fig. 3 Effects of aqueous, ethanol, and acetic acid of Tephrosia vogelii stem extracts on lipid profile of poloxamer 407 hyperlipidemic rats. Values are means ± standard deviation (SD) of six determinations. Values with different superscripts are significantly different (p < 0.05). *Significantly different versus NC; ^aSignificantly different versus other treatment groups; ^bSignificantly different versus Hyppolox + Aq50 and Hyppolox +AA50. NC, normal rats control; HypCpolox, hyperlipidemic rats control of poloxamer 407; Hyppolox +Std, hyperlipidemic rats of poloxamer 407 + standard drug (atorvastatin10mg/kg); Hyppolox + Aq50, hyperlipidemic rats of poloxamer 407 + aqueous extract (50mg/kg); Hyppolox +AA50, hyperlipidemic rats of poloxamer 407 + acetic acid extract (50mg/kg); Hyppolox +Eth50, hyperlipidemic rats of poloxamer 407 + ethanolic extract (50mg/kg); TC, total cholesterol; TAG, triacylglycerol; HDL-c, high-density lipoprotein cholesterol; LDL-c, low-density lipoprotein cholesterol.

Effect of Treatment on Indices of Cardiovascular Function

AC, AI, CRI, and CPI were evaluated as indicators of cardiovascular function for both the stem and the leaves and extracts, respectively ([Figs. 4] and [5]). The outcomes demonstrated that TV therapies outperformed atorvastatin as the standard treatment in protecting the rats against cardiovascular risk markers. While all TV treatments considerably (p < 0.05) decreased the increased cardiovascular risk indices (AC, AI, and CRI) seen in hyperlipidemic conditions, and the decreased CPI seen in hyperlipidemic conditions significantly (p < 0.05) increased on treatment with TV dosages

Fig. 4 Effect of Tephrosia vogelii leaves extract treatment on indices of cardiovascular function. Atherogenic coefficient (AC), atherogenic index (AI), coronary risk index (CRI), and cardio protective index (CPI). *Significantly different versus NC, ^aSignificantly different versus other treatment groups. NC, normal rats control; HypCpolox, hyperlipidemic rats control of poloxamer 407; Hyppolox +Std, hyperlipidemic rats of poloxamer 407 + standard drug (atorvastatin10mg/kg); Hyppolox + Aq50, hyperlipidemic rats of poloxamer 407 + aqueous extract (50mg/kg); Hyppolox +AA50, hyperlipidemic rats of poloxamer 407 + acetic acid extract (50mg/kg); Hyppolox +Eth50, hyperlipidemic rats of poloxamer 407 + ethanolic extract (50mg/kg).

Fig. 5 Effect of Tephrosia vogelii stem extract treatment on indices of cardiovascular function atherogenic coefficient (AC), atherogenic index (AI), coronary risk index (CRI), and cardio protective index (CPI). *Significantly different versus NC, ^aSignificantly different versus Hyppolox+ Std, ^bSignificantly different versus HypCpolox: Hyperlipidemic rats Control, ^c Significantly different versus Hyppolox +AA50 and Hyppolox +Eth50. NC, normal rats control; HypCpolox, hyperlipidemic rats control of poloxamer 407; Hyppolox +Std, hyperlipidemic rats of poloxamer 407 + standard drug (atorvastatin10mg/kg); Hyppolox + Aq50, hyperlipidemic rats of poloxamer 407 + aqueous extract (50mg/kg); Hyppolox +AA50, hyperlipidemic rats of poloxamer 407 + acetic acid extract (50 mg/kg); Hyppolox +Eth50, hyperlipidemic rats of poloxamer 407 + ethanolic extract (50mg/kg).

Discussion

The inverse relationship between plants intake and the risk of oxidative stress associated diseases such as CVDs has been partially ascribed to active components.[28]

The poloxamer 407 gave a good induction of hyperlipidemia, via increased total cholesterol (TC), triacyl glyceride (TAG), and LDL in hyperlipidemic rats ([Figs. 2] and [3]). It increases serum lipoproteins possibly via its actions at various levels in lipid metabolism, largely by inhibiting lipoprotein lipase, which facilitates the hydrolysis of triglycerides. P407 also causes indirect stimulation of 3hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase that is involved in cholesterol biosynthesis.[20] The elevated lipid levels in the poloxamer 407 hyperlipidemic rats indicate persistent hyperlipidemia in the rats used and correspond well with results of previous works.[29] The three different extracts significantly (p≤ 0.05) reduced TC, TAG, and LDL levels with aqueous leaves extract being the highest ([Figs. 2] and [3]). The highest percentage reduction found in the aqueous extract suggested that aqueous extract of the leaves of TV probably inhibited more of HMGCoA reductase activity.

The presence of the secondary metabolites, alkaloids, saponins, and flavonoids that has been reported to be responsible for protecting the plants[30] and some associated with numerous physiological activities in mammalian cells in various studies[31] may explain the various uses of TV for traditional medicine. The pharmacological and other beneficial effects of these secondary metabolites in plants have been reviewed by.[32] The quantitative analysis of phytochemical constituents of aqueous leaves extract of TV revealed that the saponins is significantly (p≤0.05) higher than the alkaloids and flavonoids ([Fig. 1]). This may be responsible for the observed antihyperlipidemic potentials as it has been reported to possess hypolipidemic activity.[29] [32] Aqueous extract had the highest yield compared with acetic acid and ethanolic extracts that could be due to the greater polarity of water this agrees with the work of Soetan.[33]

It is very necessary to determine LD₅₀ to prevent eventualities of drug or compounds overdose that may hinder the therapeutic value of the drug.[34] The study is also useful in understanding toxicity profiles of plant extracts.[35] The result of acute oral toxicity study in the rats recorded an LD₅₀ of less than5000 mg/kg ([Table 3]). For the aqueous leaves extract, the rats tolerated the extracts without any symptoms of acute toxicity that is, there was no mortality at first phase within 48 hours using lower doses; 10, 100, 1000, 1600 mg/kg body weight of aqueous leaf extract to albino rats even at larger doses of extracts administered. It has been reported that lower LD₅₀ implies a more toxic extract and may induce more animals. According to Lorke,[18] an LD₅₀ value beyond 5000 mg/kg is of no toxicological significance.

Conclusion

In summary, data obtained from this study have shown that TV exert antihyperlipidemic activity by modulating key indicators of dyslipidemia, namely decreased cholesterol, LDL, and triacylglycerol (TG) levels with a reciprocal increase in HDL levels, hence, presenting it a promising candidate in further studies on the possible biochemical and molecular mechanism behind this modulation effects.

Conflict of Interest

None declared.

Availability of Data

Available from the corresponding authors on request.

Authors' Contributions

IB and DEU conceived and designed the study. MOI, SZ, and UNO performed literature research. IB wrote the manuscript. GUU and DEU read, edited, and revised the manuscript for intellectual content. All authors have read and approved the final manuscript.

Ethical Approval

This study followed the Convention on Trade in Endangered Species of Wild Fauna and Flora. Furthermore, the study was approved by the Department of Biochemistry Ethical Committee on Research, Innovation and Institutional Ethical Committee on animal's right (FUHSO/ET/BCH/22/001).

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Publication History

Article published online:
07 February 2023