Introduction

Diarrhoea is a major public health problem in developing countries and is said to be endemic in many regions of Asia especially in India, and is the leading cause of high degree of morbidity and mortality among paediatrics. Enteric bacteria such as Salmonella, Shigella, Proteus, Klebsiella, E.coli, Pseudomonas and Vibrio cholerae, which are commonly associated with diarrhoea, comprise the major etiologic agents of sporadic and epidemic diarrhoea both in children and adults (WHO, 1985) Multiple drug resistance among enteropathogens in various geographic regions presents a major threat in the control of diarrhoea. Therefore indigenous medicinal plants as an alternative to antibiotic are said to play a significant role. In India, since ancient times, different parts of medicinal plants have been used for this particular aspect as a remedy or home cure for diarrhoea (Almeida et al, 1995). Due to the cost effectiveness, safety, increasing failure of chemotherapy and antibiotic resistance exhibited by pathogenic microbial agents, search for plant products has increased for their potential antimicrobial activity (Hammer et al, 1999).

Albizzia lebbeck. Benth belongs to family, Mimosaceae, commonly known as women’s tongue tree. It is native to tropical southern Asia, is a large, erect, unarmed, deciduous spreading tree found throughout India and has been used in Ayurveda, Sidha and Unani medicines (Kirikar and Basu 1981). Albizzia species is reported to have many important medicinal properties mainly anti-inflammatory and analgesic properties (Ayurvedic Pharmacopoeia, 2001). A. lebbeck barks has acrid taste and is used for bronchitis, leprosy, paralysis, and helminthes infections and is reported to have antidiarrhoeal activity. Barks were mainly used in dental infections (Besra et al, 2002). Decoction of the leaves and barks were used in cold and cough, respiratory problems and against bronchial asthuma. The plant extract were investigated against allergic rhinitis. (Pratibha et al, 2004). Seeds were used as astringent and also given for piles and diarrhoea (Besra et al, 2002). The extracts of the pods have antidiabetic activity and also used as anticancer. The phytochemical investigations showed that the pod of the A.lebbeck contains 3’, 5’ Dihydroxy 4’, 7 dimethoxty flavone and N-Benzoyl L phenol alanimol (Rashid et al, 2003). The plant contains saponins, tannins, macrolytic alkaloids, and Phenolic glycosides and flavonos (Agarwal et al, 1991; Pal et al, 1995; Ying-Tsun Ma et al, 1997; El-Mousallamy, 1998).

Materials And Methods

Plant Material

Preparation of Extracts

Isolation of Enteric pathogens

Screening of Antimicrobial activity

Determination of Minimum Inhibitory Concentration

Phytochemical evaluation

Results and Discussion

Total of one hundred diarrhoeal paediatric patients was screened and 52 (91.2%) bacterial pathogens and 5 (8.8%) Candida was isolated from 57 (57%) patients. The bacterial pathogens include Enteropathogenic E.coli 14 (24.5%), Enterotoxigenic E.coli 25 (43.8%), Salmonella typhimurium 6 (10.5%), Salmonella enteritis 4 (7%), Shigella dysenterae 3 (5.2%), Shigella flexneri 2 (3.5%), Candida albicans 3 (3.5%), Candida tropicalis 1 (1.7%) and Candida krusei 1 (1.7%) and multiple pathogens 15 (26.3%). The antimicrobial assay showed that the aqueous, methanol and chloroform extracts of Albizzia lebbeck barks exhibited activities against Enterotoxigenic E.coli, Enteropathogenic E.coli, Salmonella typhimurium, Salmonella enteritidis. Petroleum ether and hexane extracts did not exhibit any activity. The inhibitory zones produced by methanol extract against E.coli and Salmonella spp. were higher than chloroform and aqueous extract. No activity was observed against Shigella sp and Candida sp. Minimum inhibitory concentration of active extracts is shown in Table. 2. The MIC values observed for methanol extract was 2.5 mg/ml for E.coli strains and 5 mg/ml for Salmonella sp. The MBC values observed for E.coli was 5 mg/ml and for Salmonella sp was 10 mg/ml. Aqueous and chloroform extracts exhibited MIC and MBC values for E.coli and Salmonella sp. were 5 mg/ml and 10 mg/ml respectively.

Figure 1

Table. 1. Antimicrobial activity of . Benth bark extracts by disc diffusion assay.

Above values are the means of three assays. *indicates number of isolates; - indicates no activity; nt – not tested, 1+ indicates zone of inhibition in average of 7 to 10mm; 2+ indicates zone of inhibition in average of 11 to 14mm; 3+ indicates zone of inhibition in average of 15 to 18mm; 4+ indicates zone of inhibition in average of 19 to 22mm. ETEC- Enterotoxigenic E.coli, EPEC- Enteropathogenic E.coli, S.t - Salmonella typhimurium, S.e - Salmonella enteritidis, Sh.d - Shigella dysenteria, Sh.f - Shigella flexineri, C.a- Candida albicans, C.t- Candida tropicalis and C.k- Candida krusei.

The results reveal that the methanol extract of Albizzia lebbeck was effective against E.coli and Salmonella strains associated with infectious diarrhoea. A study by Srinivasan et al shows the aqueous extract possesses antibacterial activity against E.coli and Salmonella spp (Srinivasa et al, 2001). Preliminary phytochemical screening of the methanol extract showed presence of alkaloids, saponins, tannins, carbohydrates and amino acids. In India, medicinal plants are widely used by all sections of people either directly as folk remedies or in different indigenous system of medicine or indirectly in the pharmaceutical preparations (Yoganarasimhan, 2000). Ayurveda and Siddha are the two Indian traditional systems of medicine practiced in India wherein many herbs were used as therapeutics. There are few reports on the use of plants in traditional healing by tribal and indigenous communities in Tamilnadu for treating chronic diarrhoea (Durai Pandiayan et al, 2006). Plant based remedy for gastrointestinal problem is been practicing from ancient times. The vast knowledge about the use of plant against diarrhoeal disease has been accumulated in areas where the use of plants is till in use. Therefore it is essential to explore the potential use of these medicinal plants.

Figure 2

Table. 2 Antimicrobial activity of . Benth bark extracts by two-fold serial dilution method

Summary

In rural India, 70 percent of the population is dependent on the traditional system of medicine. To determine the potential and to promte the use of herbal medcine, it is essential to intensify the study of medicinal plants. Albizzia lebbeck is a popular tree, which is used by traditional practitioner to cure various ailments. Present study revealed the activity of methanol extract against some enteric pathogens. The detailed chemical nature of the active principles responsible for antibacterial activity is not known. Hence, further studies should be carried out to elucidate the active principles responsible for antimicrobial in Albizzia lebbeck.