Sub-acute Toxicity Effects of the Methanolic Extract from Searsia longipes on the Hematological,Biochemical and Histopathological Parameters of Wilstar Albino Rats

Abstract

Background: Searsia longipes is a medicinal plant used in Tanzania and other parts of Africa in the management of various diseases. Despite its wide utilization as folk medicine, there is a paucity of safety information about the extract from this plant. Objectives: The present study aimed at investigating the sub-acute toxicity of the methanolic extract from this plant. Methods: The crude extract from the stem bark of S. longipes was extracted by using methanol, after which the assessment of its toxicity was done on Wilstar albino rats. Parameters including haematological, biochemical, histopathological, as well as organ and animal weight were examined to unveil the toxic effect of the plant extract. Results: The plant extract did not induce significant changes to most hematological parameters except for white blood cells, which demonstrated a dose-dependent increase. Notably, thrombocytes showed an increase that was directly proportional to the increase in the extract dose, although not significant. The biochemical parameters did not show significant increase, whereas the histopathological analysis demonstrated mild morphological changes to the liver and kidney at the highest dose used. There were no significant variations in the organ weights; meanwhile, the body weights in treatment groups expressed time-dependent increases, which is similar to that of the control group. Conclusion: This study reports the sub-acute toxicity profile of the extract from S. longipes for the first time. This information is crucial as it not only fills a significant gap in our knowledge but also paves the way for further exploration of this plant as a potential source of diverse therapeutic agents.

Keywords

crude extract stem bark toxicity Tanzania

Introduction

Traditional medicine, with its significant role in managing various ailments, especially in resource limited communities, is a field of widespread use and accessibility. It's been reported that about 60% of the global population and 80% of the people in developing nations turn to traditional medicines for curative purposes.^1,2 This high demand for traditional medicines is due to their accessibility, affordability and most importantly, they are perceived to be safe compared to modern drugs.³ Beyond its uses in folklore, traditional medicine, particularly medicinal plants, for many years has been a substantial contributor to orthodox medicine. As such, more than 30% of contemporary drugs originate from medicinal plants.⁴ In recent decades, drugs like arteether, a derivative from artemisinin originating from Artemisia annua, Nitisinone originating from Callistenone citrinus, galantamine derived from Galathus nivalis, dronabinol and cannabidiol originating from Cannabis sativa and capsaisin from Capsicum annuum exemplifies such drugs used in the management of malaria, tyrosinaemia, Alzhemer's disease, pain, respectively.⁵

Plants contain various secondary metabolites as the result of their normal metabolic processes, response to stresses as well as climatic or geographical conditions.⁶ Reports show that there are more than 2,140,000 plant secondary metabolites which play disparate functionalities to plants, including growth and development as well as defensive duties that enhance their adaptation to the environment.⁷ On the other hand, these compounds offer curative potentials against disease causing agents such as bacteria, parasites and viruses, to mention some. Phenolics (including Tannins, flavonoids, simple phenolics and coumarins), saponins, alkaloids, terpenoids and lipids are common groups of plant secondary metabolites possessing various therapeutic potentials.⁸

S. longipes are among the common medicinal plants in the African pharmacopoeia.⁹ The plant belongs to the family Anarcadiaceae and the genus Searsia. This genus is commonly known as sumac, which contains more than 250 plant species.¹⁰ The plants from this genus grow in the temperate and subtropical regions globally and are characterized by spirally arranged deciduous leaves, which exist in a spike of 5 to 30 mm in length. The flowers contain five petals with colour ranging from greenish-white to creamy white or red. Their fruits are round to oval in shape and formed in dense clusters of 100–700 fruits, having a deep red colour.¹¹ Plants from this genus are widely known for their therapeutic uses in various parts of the world, including African countries, especially in the management of an array of medical conditions. As such, fresh fruits from Rhus javanica are employed for the management of stomach problems, including dysentery and stomachache.¹² The root of the Rhus divaricata is used for the management of diabetes,¹² whereas the Rhus mysorensis is used to treat infertility complications.¹³ Rhus coriaria is used in Asian and Middle Eastern countries for the management of cancer, urinary system problems, liver diseases as well as ulcers.¹⁴

For S. longipes in particular, its various parts have been used in disparate forms, including decoctions, syrup, powders, ointments and infusions in many African societies for the management of an array of ailments.^1,15 Its decoction is used in Tanzania for the treatment of schistosomiasis, malaria, abdominal pain, indigestion, fever, inflammation, constipation, cancer, stomachache, toothache, and diarrhoea, as well as used as a de-worming agent.^16–20 It is also employed in other countries such as Nigeria, Zimbabwe and Kenya for the management of asthma, diabetes and ventral arches, respectively.^21,22 The pharmacological potentials of this plant have been reported in several studies, whereby its ethanol extract is reported to possess anti-oxidant properties.^22,23 Anti-schistosomal activity has been reported from the methanol extract of Rhus longipes,¹⁶ whereas it's aqueous and ethanol extract has been reported to possess anti-bacterial properties.²⁴ The leaf and stem bark infusion from this plant has also demonstrated anti-diabetic activity.²² In addition, the extracts from S. longipes have been revealed to possess various phytochemical compounds, including flavonoids, terpenoids, tannins and phenolic glycosides.²⁵

Notably, decoctions from S. longipes have been reported for many therapeutic values in our African societies and have also been validated for various pharmacological activities. However, its safety is a significant issue of concern. We have therefore conducted a sub-acute toxicity study to investigate the effects of the extract from S. longipes on haematological, biochemical and histopathological parameters. This is a significant step forward towards the exploration of this plant as a safe and potential source of novel therapeutic agents, highlighting the need for continued investigation.

Methodology

Sample Collection

Stem bark samples of S. longipes were collected from the Manyara region in a place called Endasaki in May 2023. Prior to sample collection, plants were identified by a qualified Taxonomist (Mr Emmanuel Mboya) and voucher specimens were processed and preserved in the National Hebarium of Tanzania (NHT) with the number NM 1.

Sample Preparation and Extraction

Collected plant samples were cleaned using running tape water and dried under shade for about two weeks. The dried samples were triturated into fine powder by using an electric grinder. 500 g of the grinded samples were soaked in 1.3L of Methanol 99.9 v/v for 48 h with constant shaking. Afterwards, the solution was filtered using Whatman filter paper number one and the obtained filtrate was concentrated by using a Rotary evaporator under reduced pressure and a temperature of 55 °C. The obtained crude extract was placed in petri dishes and left to dry at room temperature for about one week to remove the remained solvent. The dried extract was stored at −4 °C for use in the present study.

Sub-Acute Toxicity Testing

Animal Handling

The animals used in the present study (Wilstar albino rats) were procured from the animal facility at the College of Veterinary Medicine and Biomedical Sciences, Sokoine University Agriculture. Animals were handled as regards to considerations given in the national and international ethical guidelines for animal rights, including the Tanzania animal welfare act and guide for the care and use of laboratory animals.^26,27 The guidelines suggested the use of a few number of animals as well as the treatment of animals in a manner that will introduce no or minimal pain.²⁶ About 20 rats having weights of 140 ± 15 g and age range between 8 to 10 weeks were used. Animals were kept in cages containing animal beds (wooden chips) with a constant supply of food and water. The experimental environment was maintained clean at a temperature ranging between 23 to 25 °C and the lighting condition of 12 h light and darkness cycle. Prior to the commencement of the study, animals were maintained for 7 days for acclimatization to the experimental conditions. At the end of the study, animals were sacrificed using an overdose of general anaesthesia (Pentobarbital sodium solution), which was induced via the intraperitoneal route. The bodies of sacrificed animals were pooled in a biohazard plastic bag, after which they were incinerated.

Experimental Procedures

Sub-acute toxicity assessments of the plant extract were conducted based on the protocol given by OECD guideline number 407 with modest changes ie, the use of single sex (male rats).²⁸ The male rats were used because of their reported good sensitivity in acute and sub-acute toxicity assessments.^29,30 Following 7 days of acclimatization, rats were grouped into four groups, each containing five rats. Three groups received disparate concentrations of the plant extract (1000 mg/kg, 500 mg/kg and 250 mg/kg), respectively. The remaining group was employed as a control and hence received distilled water. The mentioned extract doses were subsequent to the previously determined LD₅₀, which was > 2000 mg/kg body weight.²⁵ All doses were administered orally by using an oral gavage, and each mouse received 2 ml of their respective dose for 28 consecutive days. Over the course of the study, food and water intake, as well as behavioural changes, including tremors, locomotion, respiration, aggressiveness, convulsion, eyes and fur conditions, were assessed. In addition, animal weights were meticulously recorded in an interval of 7 days. On the 29th day, animals were anaesthetized by using 3% pentobarbital sodium, following their overnight fastening. Afterwards, blood was collected through the cardiac puncture into non-EDTA (plane) and EDTA containing vacutainer tubes for biochemical and haematological parameters analysis, respectively. Organs, including the liver, kidney and heart, were collected, and their weights were recorded. The former two mentioned organs were preserved by using 10% neutral buffered formalin for use in the histopathological analysis.

Hematological Parameters Testing

2 ml of the blood collected into the vacutainer tube containing EDTA was used for haematological analysis. An automated haematology analyzer (M4C) from Melet Schloesing Laboratories, France, was used for the haematological analysis. The mentioned machine uses the flow cytometry principle to count and differentiate cells. Whereby parameters including White Blood Cells (WBC), Lymphocytes (Lym), Monocytes (Mon), Granulocytes (Gra), Red Blood Cells (RBC), Hemoglobin (Hb), Hematocrit (Hct), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin Concentration (MCHC), Mean Corpuscular Hemoglobin (MCH), Red Cell Distribution Width (RDW), Thrombocytes (THR), Mean Platelet Volume (MPV), Procalcitonin (PCT) and Platelet Distribution Width (PDW) were analyzed from the collected blood samples.

Biochemical Parameters Testing

The analysis of the biochemical parameters was conducted on the blood collected into the plane vacutainer tubes. The tubes containing blood were centrifuged at 3000 rpm for 5 min to get serum. The obtained serums were subjected to GENESYS 10 UV Scanning UV/Visible Spectrophotometer from Thermo Scientific™, USA, for the analysis of biochemical parameters. The analyses were done using kits from ERBA Mannheim (Biotechnology Company in Mannheim, Germany). As such, parameters including Total protein, Alanine aminotransferase, Aspartate aminotransferase, Creatine phosphate and Urea were analyzed.

Histopathology Analysis

Small representative sections of the liver and kidney (4 mm thick) fixed in 10% neutral buffered formalin were sliced and dehydrated in ascending alcohol concentrations (70%, 90%, 95% and 100%). The dehydrated tissues were cleaned in xylene and then embedded in melted paraffin wax. The embedded blocks were sectioned 3 μm, after which were mounted on the microtome slide and dried in a hot air oven for 12 h. The dried tissues were stained by using haematoxylin and eosin dye, and then the slides were mounted by a cover slip. The stained tissues were visualized and photographed on an Olympus light microscope (Olympus Corporation, Model D21-CB, SN 0010842A2, Tokyo, Japan) at ×40, x100 and x400 magnification. Two independent pathologists examined the photomicrographs for any histopathological changes.

Data Analysis

All data, including animal weight, organ weight, haematological and biochemical parameters were presented as mean ± standard error of the mean. Differences across groups were determined by using one-way ANOVA, and pair wise comparisons between treatment groups and control were done by using student t-tests. All statistical analyses were conducted in R software.

Results

Assessment of Behavioural Changes, Death and Food and Water Intake

Results for behavioural changes, death cases, and water and food intake are presented in Table 1. Behavioural assessment revealed that there were no observable changes to all assessed parameters in rats treated with different doses of S. longipes. The assessed parameters include tremors, locomotion, respiration, aggressiveness, convulsion, eyes condition as well as fur condition. Throughout the experiment no death case was recorded in the treatment groups and the control. Additionally, food and water intake were normal in both treatment groups and control.

Table 1.

Results of the Assessment of Behavioral Changes, Death, Water and Food Intake.

S/N	Observed parameters	Doses (mg/kg Body weights)
S/N	Observed parameters	1000	500	250	Control
1.	Food intake	N	N	N	N
2.	Water intake	N	N	N	N
3.	Convulsion	N	N	N	N
4.	Tremors	N	N	N	N
5.	Salivation	N	N	N	N
6.	Fur	N	N	N	N
7.	Eyes and mucosa membrane	N	N	N	N
8.	Locomotion	N	N	N	N
9.	Respiration	N	N	N	N
10.	Aggressiveness	N	N	N	N
11.	Death/Survive	S	S	S	S

Key: N = Normal and S = Survived.

Animal Body and Organ Weights

The body weights of animals in all experimental groups divulged an increasing trend, as it is shown in Figure 1. There were no significant differences in the animal weights between the treatment groups and the control on the last day of treatment at p-value > 0.05 (Figure 1). In addition, all treatment groups have demonstrated significant weight gain following a comparison of the animal weights on the initial treatment day to that of the last day at p-value < 0.01 (Figure 1). The result is comparable to that of the control, which has also shown significant weight gain at p-value < 0.001 (Figure 1). On the other hand, the weights of vital organs, including the liver, kidney and heart, are presented in Figure 2. Whereby there were no significant differences in the organ weights between treatment and control groups at p-value > 0.05 (Figure 2).

Figure 1.

Mean body weights of the rats treated with disparate concentrations of S. longipes and the control at various time intervals.

Figure 2.

Mean organ weight of the rats treated with disparate concentrations of S. longipes and the control.

Hematological Parameters

The haematological indices of the rats treated with different doses of the plant extract and the control group are presented in Table 2. The haematological analysis revealed no significant differences in parameters, including RBC_S, MCV, Hematocrit (Hct), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC), RDW, haemoglobin (Hb), MPV, procalcitonin (Pct), and PDW between the treatment groups and the control. Whereas the white blood cell (WBC) count was significantly higher in the groups that received all tested doses of the extract (1000 mg/kg, 500 mg/kg and 250 mg/kg) compared to the control group. The monocytes, eosinophile and basophile have demonstrated dose dependent increase, and the latter two parameters at 1000 mg/kg and 500 mg/kg extract doses have expressed significant differences compared to the control group at p-value < 0.05. In addition, the thrombocytes (THR) level has also divulged a dose dependent increase; however, the observed changes were not significantly different to that of the control group.

Table 2.

Mean of the Hematological Parameters from the Treatment Groups and the Control.

S/N	Parameter		Doses (mg/kg) Body Weight
S/N	Parameter		1000	500	250	Control
1.	WBC(m/mm³)		4.288 ± 0.38^a	3.236 ± 0.096^a	3.298 ± 0.44^a	2.57 ± 0.14
2.		Lym(%)	80.62 ± 2.55^b	83.16 ± 3.56^b	90.98 ± 1.58^b	88.54 ± 2.46
3.		Mon(%)	11.34 ± 1.97^b	10.38 ± 1.87^b	5.4 ± 0.90^b	6.92 ± 1.55
4.		Neu(%)	3.18 ± 0.65^b	3.94 ± 0.86^b	3.62 ± 0.69^b	4.54 ± 1.00
5.		Eo(%)	4.72 ± 1.79^a	2.42 ± 1.63^a	0.00 ± 0.00^b	0.00 ± 0.00
6.		Bas(%)	0.14 ± 0.05^a	0.1 ± 0.06^a	0.00 ± 0.00^b	0.00 ± 0.00
7.	RBC(M/mm³)		8.24 ± 0.39^b	8.024 ± 0.15^b	8.436 ± 0.27^b	8.118 ± 0.22
8.	MCV(ft)		62.74 ± 0.42^b	61.88 ± 0.76^b	62.98 ± 0.44^b	62.08 ± 0.74
9.	Hct(%)		51.62 ± 2.32^b	49.58 ± 1.11^b	53.08 ± 1.79^b	50.3 ± 0.99
10.	MCH(pg)		18.34 ± 0.45^b	18.4 ± 0.21^b	18.46 ± 0.42^b	18.2 ± 0.29
11.	MCHC(g/dl)		29.3 ± 0.61^b	29.88 ± 0.62^b	29.4 ± 0.78^b	29.4 ± 0.35
12.	RDW		11.94 ± 0.44^b	12.86 ± 0.24^b	12.08 ± 0.45^b	11.16 ± 0.28
13.	Hb(g/dl)		15.1 ± 0.41^b	14.82 ± 0.36^b	15.6 ± 0.38^b	14.8 ± 0.29
14.	THR(M/mm³)		722.8 ± 81.49^b	478.6 ± 25.70^b	465.2 ± 51.64^b	578.4 ± 69.47
15.	MPV(fl)		6.24 ± 0.20^b	6.38 ± 0.07^b	6.04 ± 0.10^b	6.24 ± 0.10
16.	Pct(%)		0.456 ± 0.06^b	0.304 ± 0.01^b	0.28 ± 0.03^b	0.362 ± 0.05
17.	PDW		6.88 ± 0.35^b	6.88 ± 0.20^b	6.62 ± 0.11^b	6.8 ± 0.28

Key: WBC = White blood cells, RBC = Red blood cells, MCV = Mean corpuscular volume, Hct%=Hematocrit, MCH = Mean corpuscular hemoglobin, MCHC = Mean corpuscular hemoglobin concentration, RDW = Red cell distribution width, Hemoglobin concentration, THR = Thrombocytes, MPV = Mean platelets volume, Pct(%)= Procalcitonin test, PDW = Platelet distribution width, a = significant deference between treatment groups and control, b = no significant deference between treatment groups and control.

Biochemical Parameters

The blood biomarkers for liver and kidney toxicity are shown in Table 3. The analysis of the blood biochemical indices demonstrated no significant difference in the parameters, including total protein (TP), creatine phosphate (CRET), aspartate aminotransferase (AST) and urea, between the treatment groups and the control at p-value > 0.05 (Table 3). Interestingly, alanine aminotransferase (ALT) at the lowest (250 mg/kg body weight) and the highest (1000 mg/kg body weight) extract dose used have demonstrated a significant decrease in comparison to the control at p-value < 0.05 (Table 3).

Table 3.

Mean of the Biochemical Parameter from Treatment Groups and Control.

S/N	Parameter	Doses (mg/kg) Body Weight
S/N	Parameter	1000	500	250	Control
1.	TP(g/dl)	5.31 ± 0.27^b	5.65 ± 0.21^b	5.56 ± 0.19^b	5.40 ± 0.26
2.	ALT(U/L)	24.37 ± 3.52^a	36.37 ± 2.24^b	27.80 ± 1.52^a	37.89 ± 2.68
3.	AST(U/L)	46.46 ± 4.61^b	61.12 ± 6.93^b	54.64 ± 3.31^b	56.93 ± 5.78
4.	CRET(mg/dl)	0.89 ± 0.15^b	0.77 ± 0.06^b	0.86 ± 0.10^b	0.86 ± 0.05
5.	UREA(mg/dl)	45 ± 4.66^b	43.77 ± 5.09^b	46.5 ± 2.28^b	47.32 ± 2.27

Key: TP = Total protein, ALT = Alanine aminotransferase, AST = Aspatate aminotransferase, CRET = Createnine phosphate, a = significant deference between treatment groups and control, b = no significant deference between treatment groups and control.

Histopathological Analysis

Both liver and kidney from the groups treated with 250 mg/kg and 500 mg/kg body weight and the control have demonstrated normal morphology. As such, the kidneys showed normal glomerulus, distal convoluted tubules, bowman's capsule, proximal convoluted tubules, a loop of Henle and the medullary part also showed normal cellularity (Figure 3). At the same time, the livers demonstrated normal hepatocytes, intact cytoplasm of hepatocytes, normal bile ducts hepatocytes, as well as normal central veins (Figure 3). Contrary, the kidney and liver from the group treated with the highest dose (1000 mg/kg) divulged mild changes. For the kidney, the glomerulus showed mild low cellularity, with a loose knot of capillaries, which were shown to have been slightly loaded with RBCs. The bowman's capsules were normal, with double walls of epithelial layers; the visceral and parietal between them and the capsular space with normal size. Other features, including the medullary part, have shown mild low cellularity. Meanwhile the distal and proximal convoluted tubules were also normal.

Figure 3.

Photomicrograph of the kidney and liver sections from the rats treated with the S. longipes extract (A) Kidney section of the rat treated with the 250 mg/kg (Black arrow indicating normal renal capsule), (B) Kidney section of the rat treated with 500 mg/kg (Black arrow indicating normal renal capsule), (C) Kidney section of the rat treated with the 1000 mg/kg(Red arrow indicating renal capsule slightly loaded with RBCs), (D) Kidney section of the rat from the control group (Black arrow indicating normal renal capsule), (E) Liver section of the rat treated with the 250 mg/kg (Black arrow indicating normal central vein), (F) Liver section of the rat treated with the 500 mg/kg, (G) Liver section of the rat treated with the 1000 mg/kg (Red arrow indicating central vein with endothelium mildly disrupted and slightly infiltrated with cells, whereas the white arrow indicating slight dilation of the sinusoids), (H) Liver section of the rat from the control group (Black arrow indicating normal central vein).

On the other hand, the liver has demonstrated central vein endothelium disrupter and lost cellular architecture (Necrotic). The portal vein was slightly congested, and some sinusoids were slightly dilated, thus losing cellular architecture (Necrotic). Bile ducts were normal, and there were also few hepatocytes with mild DNA fragmentation (Karyorrhesis) as well as slight enlargement with empty spaces in the cytoplasm (vacuolation).

Discussion

Given the extensive use of medicinal plants for disease management in developing nations, where 80% of the population relies on them, safety is a crucial concern.^1,2 In this context, we have conducted a sub-acute toxicity assessment of the S. longipes extract, the plant which is widely employed in many African societies for the management of various diseases.^16–18 This study is a significant step towards establishing the safety profile of this plant and is of utmost importance for further exploration of its potential as a source for modern drugs. Notably, this is the first study to evaluate the sub-acute toxicity of the S. longipes extract in animal models, underscoring its significance.

Various toxicity indicators were examined including animal weight, organ weight, haematological, biochemical and histopathological parameters. Animal weights have shown a significant increase, which indicates that the plant extract, even at the highest dose used, did not affect the feeding pattern and metabolism of the animals. Changes in the weights of the vital organs of animals normally serve as a substantial toxicity indicator of the test substance.^31,32 However, the organ weights of the animals treated with the plant extract did not show a significant difference relative to that of the control. Based on the previous reports, the reduced weights of these organs in most cases suggest the toxic effect of the tested drug.^31,33 In view of this, the results literally suggest that there were no substantial toxic effects imparted by the test extract to the animal organs.

The blood system plays a substantial role in the distribution of various nutrients as well as foreign compounds in the body. Thus, it is a vulnerable target to drugs and toxic substances.^34,35 In this respect, the assessments of haematological parameters were done to determine the effect of the S. longipes extract on the hematopoietic system. Most of the assessed haematological parameters, including RBC, Hb, Hct, MCV, MCHC, MCH, RDW, MPV, PCT and PDW, did not show significant variations when compared to the control. This also suggests that the tested extract does not have an impact on the mentioned parameters. Additionally, both WBC and THR have shown dose dependent increases; however, for the latter, the observed changes were not statistically significant. Eosinophils and basophils are the WBC which show a dose dependent increase. This observation suggests that the methanolic extract from S. longipes contains a bioactive compound that has an amplifying effect on the immune system, which stimulates the production of WBC. Similar findings were reported with the aqueous extract from Viscum album and methanolic extract from Erodium guttatum, which were reported to possess an amplifying effect on the WBC.^35,36

Meanwhile, the manifested increase in the thrombocyte count suggests that the tested extract also contains secondary metabolite with the potential to stimulate the thrombopoiesis process.³⁷ This could be attributed to the ability of the plant's secondary metabolites to stimulate the production of the megakaryocyte progenitor cells in the bone marrow and spleen, which in turn leads to an increased thrombocyte count.³⁸ The fact that the platelets distribution width (PDW) remained unchanged in the treatment groups thus portrayed that the plant extract has no effect on ready produced platelets but rather acts on the progenitor cells. Similar findings were reported by Orumor and Osime (2024),³⁸ who reported the ability of Jatropha tanjorensis to enhance the thrombopoietic process. This finding suggests the potential application of this extract in the treatment of blood clotting disorders such as thrombocytopenia.

Blood biochemical parameters were examined to determine the potential effect of the plant extract on vital organs such as the liver and kidney. The elevated level of these biochemical indices normally indicates potential damage to the kidney and liver tissues. The extract did not induce a significant increase in all tested biochemical parameters when compared to the control. This result suggests that the extract did not cause significant damage to the tissues of the vital organs, including the liver, kidney, and heart, as well as spleen. Unexpectedly, S. longipes extract at the lowest and the highest dose used has demonstrated a significant decrease in the ALT level when compared to the control group. Since the observed decrease was not dose dependent, thus could be explained as an outcome of random variations rather than the effect of the plant extract.

The histopathology result of the liver and kidney tissues displayed normal morphology, except for those collected from the rat treated with the highest dose of the extract, which demonstrated slight changes in their morphologies. This observation is consistent with the above discussed results of the biochemical parameters, which did not show significant changes. As such, this indicates that the observed damage in the liver and kidney, especially at the highest dose used, was not substantial enough to cause a significant elevation of the biochemical indices, reinforcing the safety of the plant extract.

The present study has the limitation that, it only assessed the sub-acute toxic effects of the methanol extract from S. longipes. However, in order to fully understand the toxicity profile of the mentioned plant, sub-chronic and chronic toxicity assessments are recommended.

Conclusion and Recommendation

Sub-acute toxicity of the methanolic extract from S. longipes against rats was performed to assess its effect on various parameters. The results highlighted that there were no significant effects imparted by the extract on the biochemical and most hematological parameters except for WBC, which demonstrated a significant increment. This suggests that the extract contains compounds which stimulate the production of WBC. The histopathology analyses of the liver and kidney tissue have shown mild abnormalities at the highest dose used. In view of this, people should be cautious regarding the use of this plant for medicinal purposes; as such, it's use at high doses and prolonged exposure should be avoided.

Footnotes

Acknowledgment

The authors acknowledge Mr Mwinyi Masala and other staff at the college of Veterinary Medicine and Biomedical Sciences, Sokoine University of Agriculture for their technical assistance over the course of the present study.

CRediT Authorship Contribution Statement

Nicolaus Omari Mbugi: Writing – review & editing, Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Musa Chacha: Supervision, Writing – review & editing. Ernest Mbega: Supervision, Writing – review & editing.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The present study was funded by the ministry of Education, Science and Technology of the United Republic of Tanzania, through High Education for Economic Transformation (HEET) project.

Ethical Approval

This study was approved by the Kibong'oto-Nelson Mandela-Cedha Health Research Ethical Committee (KNCHREC), and given an ethical clearance number KNCHREC00008/09/2023.

ORCID iD

Nicolaus Omari Mbugi

Statement of Human and Animal Right

All of the experimental procedures involving animals were conducted in accordance with the animal care guidelines.

Statement of the Informed Consent

There are no human subjects in this article and informed consent is not applicable

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