Project Materials

NEMATOCIDAL ACTIVITY OF METHANOLIC EXTRACTS OF LEAF, STEM BARK AND ROOT OF AZADIRACHTA INDICA A. JUSS. (NEEM) AGAINST HAEMONCHUS CONTORTUS(RUDOLPHI 1803) COBB 1898

ABSTRACT

The antihelminthic activity of methanolic extracts of Azadirachta indica leaf, stembark, and root was tested in vitro against Haemonchuscontortus larvae. Phytochemical screening of all plant parts revealed the presence of carbohydrates, cardiac glycosides, saponins, flavonoids, tannins, and alkaloids; the leaf contained steroids, while the stembark and root contained triterpenes. The quantitative measurement of the phytochemical contents revealed a high proportion of flavonoids, followed by alkaloids and tannins, with the lowest quantitative percentage of insaponins: 20.21, 27.50, 20.95; 5.25, 5.48, 5.48; 4.95, 4.93, 4.15; and 0.75, 0.68, 0.67, respectively. H.contortus eggs were cultivated in culture plates in an incubator at 27 degrees Celsius. Infective third-stage larvae (L3) were recovered from sterilefaecal cultures that had been incubated for 7-9 days. The larvae were concentrated at 1000 rpm for 15 minutes, and 0.1 ml of the larvae containing 120 L3 were placed in wells of a microtitre plate, with concentrations of each extract (leaf, stembark, and root) at 0.1mg/ml, 1.0mg/ml, 10.0mg/ml, 100mg/ml, negative control (water), and positive control (Levamisole) added to each well with six replications. Following the addition of the therapies, it was examined under a microscope every 6 hours for 48 hours, and the number of deaths was recorded. The fatal concentration (LC50/EC) for the leaf is 12.30 mgml, 12.58 mgml-1 for the stem bark, and 15.84 mgml-1 for the root extract. The parasite mortality rate rose with increasing concentration and duration of exposure. Mortality rates were greater at the peak period of exposure (48 hours) and at the highest concentration of 100mgml-l compared to the lowest time of exposure (6 hours) and concentration of 0.1mgml-1. The data revealed extremely significant differences among the plant parts, time of exposure, concentration of the extracts, duration of exposure and concentration, and plant parts and concentration (p=0.001). Although parasite mortality increased over time, there were no significant differences between plant parts and time of exposure (p=0.92), or between plant parts, time of exposure, and concentration (p=0.99). Mortalities were high in the positive control wells, increasing with exposure duration, while no mortalities were documented in the negative control wells. The study finds that the recorded mortalities were caused by the extracts‘ effects on the parasite. The efficacy of these plant extracts should be validated to evaluate the impacts of natural or experimental haemonchosis in ruminants.

CHAPTER ONE

INTRODUCTION

Azadirachta indica, also known as neem in English and Dogonyaro in Hausa, is an evergreen tree from the Mahogany family Meliaceae. It is native to India, Pakistan, and Burma and grows in tropical and semi-tropical climates (Balakrishnan et al. 2007).

It is the most versatile and diverse tree in the tropics, growing to around 25m in height with a semi-straight to straight trunk, a 3m girth, and spreading branches generating a broad crown (Kumar and Gupta, 2002).

It produces more useful non-wood products (leaves, bark, flowers, fruits, seed, gum, oil, and neem cake) than any other tree species.

These non-wood products have been shown to have antidermatitis, antifeedant, antifungal, anti-inflammatory, antipyorrheic, antiscabic, cardiac, diuretic, insecticidal, larvicidal, nematocidal, spermicidal, and other biological properties (Brahmachari, 2004).

Neem has become a green treasure due to its vast range of applications and activities (Khanna, 1992; Suri and Mehrotra 1994).

The tree possesses tolerance to a wide range of climatic, geographic and edaphic variables. It grows well in dry, stony shallow soils and even in hard calcareous soils or clay pans at shallow depths (Koul et al., 1990; Schmutterer, 1990). Neem trees require little water and plenty of sunlight (Anonymous, 2006; Sateesh, 1998).

The tree grows naturally in areas with rainfall ranging from 450 to 1200 millimetres. However, it has been adopted effectively even in locations where the rainfall is as low as 150 to 250 mm. It can grow at altitudes of up to 1500 meters (Chari, 1996; Jattan et al., 1995; Tewari, 1992).