Solution for Helminthes Parasites

J.K. Chamuah, C.C. Barua^*, A.G. Barua¹ and D. Lahkar

Department of Pharmacology and Toxicology, ¹Public Health and Hygiene

College of Veterinary Science, Khanapara, Guwahati – 781 022, Assam, India

ABSTRACT

Parasitic diseases is one of the constraints for profitable animal production in terms of meat and milk. Though treatment with chemical compound is the right solution, but it leads to development of resistance with frequent use. In recent times, the bio-prospection of natural resources has gained unprecedented impetus all over the world for search of new and novel molecules as therapeutic agents. Consequently, a number of clinically useful drugs have been discovered and many complex physiological and biochemical pathways have been defined and are now well understood. Many studies carried out in the last few years have also demonstrated that plants represent an unparallel source of molecular diversity for drug development. Research based pharmaceutical companies of developed countries like USA, UK, Japan, France, Germany and Switzerland are the major global players in the area of drug discovery. India’s contribution has been insignificant, but has attained some global visibility with respect to its self-reliant technological status. The prioritization of disease related search for new therapeutic agents may be different for developed and developing countries. Future studies on plant based anthelmintic in account of their suitable dosage regiments, effective formulation with other standard drugs will be one of the promising solution for development of anthelmintic resistance problem. This review article is intended to highlight the significant achievement of drug development from plant sources as anthelmintic and identification of Indian emerging medicinal plants for lead generation and development of novel herbal anthelmintic.

Keywords:Herbal drug therapy, Helminthes parasites, Parasitic diseases.

Introduction

The subcontinent of India possesses the largest livestock population in the world which comprises 7 per cent of its national income. India has a population of 185181 thousand cattle, 97922 thousand buffaloes, 124358 thousand goats, 61469 thousand sheep, 13518 thousand pigs, 751 thousand horses, 632 thousand camels, 65 thousand yaks, 278 thousand mithuns and 2489012 thousand poultry (17th livestock census, 2003.) The productivity of domesticated animals is poor due to complex factors which are many and varied, compounded by sub clinical or clinical often with multiple infections. An understanding of the epidemiology of parasites is crucial for development and implementation of effective management practices.

The hot and humid tropical climate is very much conducive for development and survival of pre-parasitic stages of the parasites. Owing to favorable climatic conditions for development and survival of pre-parasitic stages and in absence of alternate control strategies, control of parasitic problem in livestock is primarily attempted by the frequent use of anthelmintic at short intervals particularly in intensive and semi-intensive management system which has been shown to result in the emergence of anthelmintic resistance. Efforts are now being made to develop and use alternatives to chemotherapy viz. grazing, management, biological control and worm vaccine. However, use of commonly used anthelmintic not only induces resistance but also its residues produce toxicity in the host.

To overcome this problem, herbal remedies are considered to be one of the promising solution for control of parasites. Hence, efforts are now being made to develop herbal drugs by screening medicinal plants and their validation in clinical cases through in vitro and in vivo clinical trials. India has huge source of medicinal plants and enjoys a good place in terms of ayurvedic formulations from time immemorial. Herbal medicine is a practice that is as old as mankind and certainly older than agriculture or writing; every human culture in every continent on earth has practiced herbal medicine of one form or the other. Quite possibly the earliest form of herbal medicine was marshallow root, which is a common grass chewed for setting an upset stomach and has been eaten for presumably that reason by our closest evolutionary cousins, chimpanzee and baboons. In India, the herbalist tradition was ayurvedic, focusing on the use of metals, herbs and parts of animal generally considered inedible.

Modern herbal medicine takes a synergetic approach, trying to cross reference the benefits of various herbs and treatments from different traditions and find the best combination of herbal remedies. Most traditional herbs are aromatics–the compounds we use to treat illness are an effect of plants conducting chemical warfare on each other and fend off herbivores. The same compounds that make many herbs bitter or smell strongly are the one used in herbal medicine and clinical trials.

Among the plant based remedies, use of medicinal plant against parasitic disease in livestock is a great step towards the sustainable parasite control programme in India. The search for safe and efficacious herbal anthelmintic may overcome some of problems associated with synthetic drugs. In this paper, recent studies on anthelmintic evaluation of some indigenous plants against parasites have been reviewed.

Helminth Parasites

Helminth parasites from all three major groups have been utilized as experimental models to evaluate the anthelmintic activity of different plants. Different parasites namely Strongylus, Ascaris, Oesophagostomum, Ascaridia, Heterakis, Setaria, Haemonchus, Bunostomum, Dipylidium, Taenia, Moneizia, Hymenolepis, Raielletina, Fasciola and other flukes have been employed in vitro and in vivo studies in naturally infected animals.

Koko et al. (2000) evaluated the oral dose of 9g/kg body weight of Albizzia anthelmintica Brong. Mimoseae stem bark water extract and 9g/kg body weight. of B. aegyptica fruit mesocarp water extract which are traditionally used as an anthelmintic in Sudan and compared with 20 mg/kg body weight of albendazole against Fasciola gigantica. Based on percentage reduction in fluke count from the liver post mortem 2 weeks after treatment, the efficacy of mentioned therapeutic was 95.5, 93.2 and 97.7 per cent.

To control fascioliasis, extract from indigenous plants viz. Carica papaya, Mallotous philippinensis (Kamala), A. indica were screened against F. gigantica in vitro to develop safer, cheaper and more effective remedy for fascioliasis in ruminants. The in vitro activity of root-tuber peel extract of Flemingia vestita, an indigenous plant consumed by the natives of north east India was tested against Paramphistomum sp.by Tandon et al. (1997) from Shillong, Meghalaya. We have found encouraging result using crude, methanolic, hexane and chloroform extract of AAU-EVM-NW-3 on in vitro trial of F. gigantica.

With a view to clarify the induction of the “Crabtree consequence” in liver cells of Schistosoma mansoni infected mice, the curative effect of oil extract of C. longa was tested and compared to praziquantel (PZQ) the effective drug against all schistosome species occurring in man. Protein, glucose, glucose-6-phopsphatase, AMP-deaminase, adensoine deaminase, urea concentration, pyruvate kinase (PK), phosphorenol pyruvate carboxykinase (PEPCK) and PK/PEPCK ratio were estimated. In addition, worm burden and ova count in mice infected with S. mansoni were elucidated. The result showed that C. longa normalized the concentration of protein, glucose, AMP-deaminase and adenosine deaminase, which were changed by infection. Moreover, it lowered pyruvate kinase level, while PZQ-treatment induced more elevation of this enzyme. PZQ was more effective in lowering worm burden while C. longa extract was more potent in reducing egg count (El-Ansary et al., 2007).

The anthelmintic properties of tanniferous plants and of their secondary metabolites represent one possible alternative to chemotherapy that is currently being explored as a means of achieving sustainable control of gastrointestinal nematodes in ruminants. Previous in vivo and in vitro results suggest that tanniferous plants can have direct antiparasitic effect against different stages of nematodes. However, the mode of action of the bioactive plant compounds remains obscure. To examine the hypothesis that extracts of tanniferous plants might interfere with the exsheathment of third-stage infective larvae (L3) and to assess the role of tannins in the process by examining the consequence of adding an inhibitor of tannins (polyethylene glycol: PEG) to extracts, the effects of 4 tanniferous plant extracts on exsheathment have been examined on L3 of Haemonchus contortus and Trichostrongylus colubriformis.

Artificial exsheathment was induced in vitro by adding hypochloride solution to larval suspension. The evolution of exsheathment with time was measured by repeated observations at 10-min interval for 60 min. The selected plants were: genista (Sarothamnus scoparius), heather (Erica erigena), pine tree (Pinus sylvestris) and chestnut tree (Castanea sativa), with tannin contents ranging from 1.5 to 24.7 per cent of DM. Extracts of a non-tanniferous plant (rye grass, tannin content: 0.3 per cent of DM) were included in the assay as negative controls. The extracts were tested at the concentration of 600 µg/ml and the effects were compared to the rate of exsheathment of control larvae in PBS.

No statistical differences in the pattern of exsheathment was observed after addition of rye grass or genista extracts for both nematode species and with heather extracts for T. colubriformis. In contrast, pine tree extracts on larvae of both species and heather extracts with H. contortus induced a significant delay in exsheathment. Last, contact with chest nut extracts led to a total inhibition of the process for both nematodes. These results suggest that extracts of tanniferous plants might affect a key process in the very early stages of larval invasion of the host. In most cases, the addition of PEG led to a total or partial restoration towards control values. This suggests that tannins are largely involved in the inhibitory process. However, other secondary metabolites may also interfere with the process that would help to explain some of differences between two nematode species (Bahuaud et al., 2006).

Anthelmintic activity of Azadirachta indica and A. juss against sheep gastrointestinal nematodes was reviewed by Costa et al. (2006). The anthelmintic activity of A. indica was investigatedafter feeding sheep with the dried leaves. In this experiment, 40 sheep were allotted into four treatment groups. Group I received a treatment of A. indica dry leaves mixed in a concentrate at a rate of 0.1 g/kg dose for 3 months. Group II was treated with double the dose of Group I. Group III was treated with closantel (Diantel) at the manufacturer-recommended dose once at the beginning of the study and Group IV was not treated. To compare treatment effects, the following parameters were evaluated: egg count per gram of feces (EPG), worm burden, weight gain and haematocrit. EPG and worm burden results were statistically evaluated using the Kruskal-Wallis test. Haematocrit and live weight gain were submitted to analysis of variance (ANOVA) and the means evaluated by Tukey’s test with 95 per cent probability. None of the evaluated parameters of the treatment groups were statistically different when compared to the control group, demonstrating that, with the protocol used, A. indica has no anthelmintic effect.

Anthelmintic activity of Spigelia anthelmia extract against gastrointestinal nematodes of sheep using in vitro (larval development assay) and in vivo studies were conducted to determine possible direct anthelmintic effect of ethanolic and aqueous extracts of S. anthelmia towards different ovine gastrointestinal nematodes (Ademola et al., 2007). The effect of extracts on development and survival of infective larvae stage L(3)) was assessed. Best-fit LC (50) values were computed by global model of non-linear regression curve fitting (95 per cent confidence interval). Therapeutic efficacy of the ethanolic extracts administered orally at a dose rate of 125, 250, and 500 mg/kg, relative to a non-medicated control group of sheep harboring naturally acquired infection of gastrointestinal nematodes, was evaluated in vivo. The presence of S. anthelmia extracts in the cultures decreased the survival of L (3) larvae. The LC (50) of aqueous extract (0.714 mg/ml) differ significantly from the LC(50) of the ethanolic extract (0.628 mg/ml) against the strongyles (P < 0.05, paired t-test). Faecal egg counts on day 12 after treatment showed that the extract is effective, relative to control (one-way analysis of variance [ANOVA], Dunnett’s multiple comparison test) at 500 mg/kg against Strongyloides spp. (P<0.01), 250 mg/kg against Oesophagostomum spp., Trichuris spp. (P < 0.05), and 125 mg/kg against Haemonchus spp. and Trichostrongylus spp. (P < 0.01). The effect of the doses is significant in all cases, the day after treatment is also extremely significant in most cases, whereas interaction between dose and day after treatment is significant (two-way ANOVA). S. anthelmia extract could, therefore, find application in the control helminth in livestock by ethno veterinary approach.

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