Evaluation of Antipyretic Potential of Lagerstroemia parviflora. Extract in Rats

Abstract

The methanol extract of Lagerstroemia parviflora. Roxb leaves was tested for antipyretic effects on rats. The extract (200 and 300 mg/kg, p.o.) showed very significant reduction of yeast-induced pyrexia in rats with respect to the control group. The antipyretic activity of the extract was comparable to the standard prototype, paracetamol.

Keywords:

• Antipyretic
• Lagerstroemia parviflora
• leaves
• methanol extract

Introduction

Lagerstroemia parviflora. Roxb (Lythraceae) is a medium-sized deciduous plant indigenous to India and available even up to a height of 900 m in the Himalayas. The plant is used for the treatment of syphilis, sores, and carbuncles (Jain & Tarafdar, 1970). Mazumder et al. (2003) reported the antibacterial activities of the leaves of the plant and Bhakuni et al. (1969) reported the antiasthmatic activity of the flowers of Lagerstroem parviflora.. The evaluation of antipyretic potential of Jussiaceae suffruticosa. (Murugesan et al., 2000) has been reported from our laboratory. The leaf juice of this plant is used in traditional medicine to treat fever in Jharkhand, India (Jain & Tarafdar, 1970). To substantiate this claim, the current study was undertaken to evaluate the antipyretic effect of the leaf extract in rats.

Materials and Methods

Plant material and extraction

The leaves of Lagerstroemia parviflora. Roxb were collected in Ranchi, India, during September 2000. The plant was identified by Botanical Survey of India, Howrah, West Bengal, and a voucher specimen is kept in our laboratory for future reference. The leaves were shade-dried, powdered, passed through a 40-mesh sieve, and then subjected to extraction with 1 l of methanol in a Soxhlet apparatus. The solvent was removed under vacuum and a solid mass (14.71% w/w with respect to dry starting material) was obtained. The methanol extract was stored in a desiccator and used for further experimental studies after suspending 2 g extract in 2% aqueous Tween 80 in specific doses as described later.

Animals used

Albino rats (Wistar strain) of either sex weighing 180–200 g were used in our study. The animals were maintained in the animal house of Birla Institute of Technology, Mesra, Ranchi, under suitable environmental conditions throughout the experiment. The animals were housed in standard metal cages and provided with food and water ad libitum..

Antipyretic evaluation

The antipyretic effect was examined by the method described by Chatterjee et al. (1993). The animals were given a subcutaneous injection of 10 ml/kg of 15% w/v yeast suspension in 0.5% w/v methyl cellulose solution after measuring the basal digital rectal temperature by inserting a thermister probe 3–4 cm deep into the rectum. Nineteen hours after the yeast injection, the animals were again placed in individual cages for recording of rectal temperature.

The methanol extract of the leaves of Lagerstroemia parviflora. (LPLE) at doses of 100, 200, and 300 mg/kg was administered orally 19 h after the yeast injection to three groups of rats, respectively. A similar volume (5 ml/kg) of 2% aqueous Tween 80 was administered orally to the control group of animals. The fifth group received the standard prototype antipyretic agent, paracetamol (150 mg/kg) orally. The rats were restrained for their rectal temperature to be recorded at the 19th hour, immediately before LPLE or vehicle or paracetamol administration and again at an hourly intervals up to the 23rd hour after yeast injection.

Statistical analysis

The data were expressed as mean ± standard error of the mean (SEM). Significance was evaluated by Student's t.-test (Woodson, 1987). p. values less than 0.05 imply significance.

Results

The subcutaneous injection of yeast caused a marked increase in rectal temperature at the 19th hour of administration. The antipyretic effect started within 1 h and was maintained until 4 h after administration. Table 1 suggests that LPLE at a dose of 100 mg/kg caused a significant reduction of body temperature up to 4 h after administration. However, the effect increases very significantly at doses of 200 and 300 mg/kg until the fifth hour after administration. The antipyretic effect was comparable with that of a standard, paracetamol.

Table 1.. Effect of LPLE on yeast-induced pyrexia in rats.

		Rectal temperature (^oC) (mean ± SEM) after yeast administration at
Treatment	No. of animals	0 h	19 h	20 h	21 h	22 h	23 h
Control (5 ml/kg)	6	37.6 ± 0.02	39.6 ± 0.05	39.5 ± 0.03	39.4 ± 0.07	39.2 ± 0.03	39.0 ± 0.02
Paracetamol (150 mg/kg)	6	37.8 ± 0.02	39.8 ± 0.02	38.4 ± 0.01**	38.0 ± 0.03**	37.7 ± 0.04**	37.6 ± 0.02**
LPLE (100 mg/kg)	6	37.5 ± 0.02	39.8 ± 0.09	39.7 ± 0.01	38.6 ± 0.03	38.4 ± 0.05	37.9 ± 0.08**
LPLE (200 mg/kg)	6	37.5 ± 0.02	39.8 ± 0.03	38.7 ± 0.03**	38.3 ± 0.02**	38.0 ± 0.04**	37.7 ± 0.06**
LPLE (300 mg/kg)	6	37.7 ± 0.02	39.7 ± 0.05	38.5 ± 0.01**	37.8 ± 0.01**	37.4 ± 0.03 **	37.5 ± 0.05**

Control 2% aqueous Tween 80 solution; LPLE, methanol extract of leaves of Lagerstroemia parviflora..

*p. < 0.01vs.. control.

**p. < 0.001 vs.. control.

Discussion

Fever may occur due to an external manifestation of some tissue damage, graft rejection, inflammation, or bacterial infections caused by Staphylococcus aureus.. Drugs having CNS depressant action demonstrate a potent hypothermic effect (Chatterjee, 1993). Moreover, the CNS depressant effect of LPLE in rats is well established (Mazumder et al., 2004). Thus, it can be concluded that the hypothermic effect of the leaves of Lagerstroemia parviflora. is partly due to CNS depressant activity and partly due to action against S. aureus.. As β-sitosterol has already been reported by Murugesan et al. (2000) to possess an antipyretic effect, it can be concluded that β-sitosterol, proved to be present in the leaf extract, is responsible for the antipyretic action.

Acknowledgment

The authors are thankful to AICTE for financial support of this work.