Acute Toxicity of Pentaclethra macrophylla and Psidium guajava Use as Antiprotozoan Medicinal Plants

Research Article

J Drug Discov Develop and Deliv. 2020; 6(1): 1037.

Acute Toxicity of Pentaclethra macrophylla and Psidium guajava Use as Antiprotozoan Medicinal Plants

Yamssi C1*, Payne VK2, Noumedem Anangmo CN3, Tateng Ngouateu A2, Megwi L2 and Kuiate JR4

1Department of Biomedical Sciences, University of Bamenda, Cameroon

2Department of Animal Biology, University of Dschang, Cameroon

3Department of Microbiology, Haematology and Immunology, University of Dschang, Cameroon

4Research Unit of Microbiology and Antimicrobial Substances, University of Dschang, Cameroon

*Corresponding author: Yamssi Cedric, Department of Biomedical Sciences, University of Bamenda, Faculty of Health Sciences, Cameroon, PO Box 39 Bambili, Cameroon

Received: May 23, 2020; Accepted: June 12, 2020; Published: June 19, 2020


Background: Tropical protozoan diseases are currently a major veterinary and medical health problem throughout the world. Medicinal plants have long been used for the treatment of certain tropical protozoan diseases. The aim of this study was to evaluate acute toxicity effects of methanol extract of the stem bark of Pentaclethra macrophylla and leaves of Psidium guajava in rats.

Materials and Methods: The control group received 3% DMSO, while the experimental groups received a single dose of 5000mg/kg extract of the stem bark of Pentaclethra macrophylla and leaves of Psidium guajava per oral. General appearance and behavior were observed for 14 consecutive days. Effect on haematological parameters and histopathological changes were also monitored.

Results: The methanol extracts of P. macrophylla and P. guajava showed no evidence of single dose toxicity (5000mg/kg) when studying. The acute toxicity study showed no signs of toxicity, hematological or histological parameters. So the LD50 values of the tested extracts were more than 5000mg/kg bwt.

Conclusion: The methanol extracts of P. macrophylla and P. guajava do not produce adverse effects in rats after acute treatment. However, further studies to determine subchronic and chronic toxicity are needed to establish an antiprotozoal drug.

Keywords: Psidium guajava; Pentaclethra macrophylla; Acute toxicity; Protozoan


Coccidiosis is an infection caused by Eimeria spp protozoa and this infection and disease are considered a major obstacle in raising rabbits. Coccidial infection is initiated by oral ingestion of sporulated oocysts by the susceptible host and the infection can lead to clinical coccidiosis primarily in kits, whereas adults are mostly healthy carriers [1]. Eleven distinct Eimeria species have been identified in rabbits (Oryctolagus cuniculus), with 10 species colonizing the intestinal tract and one species (Eimeria stiedae) infecting the biliary ducts of the liver [2]. The anticoccidiosis drug in rabbits is relatively inexpensive medicine. However, there are several weak¬nesses, such as the fecal excretion which still may pollute the environment, especially when utilized as a fertilizer. Alternative approaches to control coccidiosis by medicinal plant extracts have promising prospects for anticoccidiosis agents [3].

In Dschang (West Region of Cameroon), the stem bark of Pentaclethra macrophylla (Common name Capres) and the leaves of Psidium guajava are used in combination by farmers to treat bacterial infections as gonorrhoea, syphilis and typhoid, protozoan diseases such as coccidioses and malaria [4,5]. They are also used to treat cases of stomach-ache, waist pain and even diarrhoea. Pentaclethra macrophylla commonly called African oil bean belongs to the Family Fabaceae. Antimicrobial property and the oil extracted from the seeds of P. macrophylla are used in the preparation of drugs against pruritus, intestinal worms and dysentery [6,7]. Psidium guajava is a medicinal plant used in tropical and subtropical countries to treat health disorders such as diarrhea, dysentery, vomiting, sore throat and also to regulate menstrual cycles [6,7].

No drug should be used clinically without its clinical trials and toxicity studies [8]. Sub-acute oral toxicity studies of herbal medicines are essential to identify the safety and the determination of dose level that could be used subsequently. It also helps in the investigation of the therapeutic index of drugs and xenobiotics [9].

It is on the basis of the traditional use of the stem bark of P. macrophylla and leaves of P. guajava in combination as an anticoccidial agent that we found it necessary to investigate the acute toxicity effects of methanol extract of the stem bark of P. macrophylla and leaves of P. guajava in rats.

Materials and Methods

Collection and identification of plant samples

The stem bark of P. macrophylla was collected (March 2014) in Melong Littoral Region of Cameroon while the leaves of P. guajava were collected in Dschang, Western Region of Cameroon. These plants were identified by Mr. NGANSOP Eric, a Botanist at the Cameroon National Herbarium (Yaoundé) using a voucher specimen registered under the Reference No 2328/SRFCam for P. macrophylla and No 2884/SRF for P. guajava.

Preparation of organic extracts

The stem bark of P. macrophylla and the leaves of P. guajava were air-dried at room temperature under shade in the Laboratory of Biology and Applied Ecology. The dried stem bark of P. macrophylla and the leaves of P. guajava were pulverized using an electrical grinder under strict hygienic conditions. One hundred grams of plant powder were macerated in 1.5L of methanol. This helped to extract the principal natural compounds of the plants [10]. The mixture was stirred daily and 72 hours later, the resulting solutions were then filtered using Whatman Paper No 3. The filtrate was concentrated by evaporating the solvent using a rotatory evaporator (Buchi R-200) to obtain the extracts.

Acute toxicity study

Acute toxicity of the plant extract was carried out according to the Organisation of Economic Co-operation and Development (OECD) guideline 425 [11]. A limit test was performed using healthy female albino rats weighing 175-200g of age 3 months. Prior to dosing, animals were fasted overnight and the dose for each animal was determined based on body weight. Initially, the extract was administered to one animal in a single dose of 5000mg/kg by gavage using a stomach tube. After the administration, food was withheld for a further 3-4 hours. The animal was observed once during the first 4 h after dosing, then periodically, during the first 24 hours. As the animal did not die, 4 additional animals were given the same dose and observed similarly. All the survived animals were kept for 14 days for observation. The animals were observed for general behavioral changes; symptoms of toxicity and mortality after treatment for the first four (critical) hours. The LD50 is greater than 5000mg/kg if three or more animals survive. The oral route was selected for use because oral route is considered to be the proposed therapeutic route.

The animals were divided into 3 groups consisting of 5 female rats of matched body weight and age in each group.

Group I: Control rats (received 3% DMSO);

Group II: 5000mg/kg, of P. macrophylla methanol extract;

Group III: 5000mg/kg, of P. guajava methanol extract.

Vital organ weight changes: At the end of the experiment, animals were sacrificed using chloroform vapors. The vital organs mainly liver, lungs, kidney, heart and pancreas were removed, cleaned with saline, weighed and preserved in 10% formalin for further histopathology observation. Relative organ weight was calculated as (weight of organ/bodyweight of rat on day of sacrifice)×100. Liver, kidney, lungs and spleen were isolated and their weights noted.

Histopathological studies: Histological cross sections of the liver and kidney were done in the Laboratory of Animal Physiology of the University of Yaounde I.

Ethical consideration

Experimental protocol used in this study strictly conformed to internationally accept standard ethical guidelines for laboratory animal use and care as described in the European Community guideline, EEC Directives 86/609/EEC, of the 24th November 1986 [12].

Statistical analysis

Animal toxicity results were expressed as mean±Standard Error of Mean (SEM). The data obtained from acute toxicity studies was analyzed using Student’s t-test. P values less than 0.05 were considered significant.


Table 1 shows general behavioral changes, symptoms of toxicity and mortality after treatment. From this Table, it appears that the oral administration of P. macrophylla and P. guajava methanol extracts at 5000mg/kg neither caused any death nor clinical sign of toxicity in rats. As there were no mortality and clinical signs of toxicity in both extracts tested, LD50 value of P. macrophylla and P. guajava methanol extracts were found to be greater than 5000mg/kg.