Newer insights into the mechanism of action of Psidium guajava L. leaves in infectious diarrhoea.

BACKGROUND: Psidium guajava L., Myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. However, the effect of the leaf extract of P. guajava on the pathogenesis of infectious diarrhoea has not been studied. The present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of P. guajava on parameters associated with pathogenicity of infectious diarrhoea. The aim was to understand its possible mechanism(s) of action in controlling infectious diarrhoea and compare it with quercetin, one of the most reported active constituents of P. guajava with antidiarrhoeal activity. METHODS: The crude decoction and quercetin were studied for their antibacterial activity and effect on virulence features of common diarrhoeal pathogens viz. colonization of epithelial cells and production and action of enterotoxins. Colonization as measured by adherence of enteropathogenic Escherichia coli (EPEC) and invasion of enteroinvasive E. coli (EIEC) and Shigella flexneri was assessed using HEp-2 cell line. The production of E. coli heat labile toxin (LT) and cholera toxin (CT) and their binding to ganglioside monosialic acid (GM1) were studied by GM1-ELISA whereas the production and action of E. coli heat stable toxin (ST) was assessed by suckling mouse assay. RESULTS: The decoction of P. guajava showed antibacterial activity towards S. flexneri and Vibrio cholerae. It decreased production of both LT and CT and their binding to GM1. However, it had no effect on production and action of ST. The decoction also inhibited the adherence of EPEC and invasion by both EIEC and S. flexneri to HEp-2 cells. Quercetin, on the other hand, had no antibacterial activity at the concentrations used nor did it affect any of the enterotoxins. Although it did not affect adherence of EPEC, it inhibited the invasion of both EIEC and S. flexneri to HEp-2 cells. CONCLUSION: Collectively, the results indicate that the decoction of P. guajava leaves is an effective antidiarrhoeal agent and that the entire spectrum of its antidiarrhoeal activity is not due to quercetin alone.

Studies on the antidiarrhoeal activity of Aegle marmelos unripe fruit: validating its traditional usage.

BACKGROUND: Aegle marmelos (L.) Correa has been widely used in indigenous systems of Indian medicine due to its various medicinal properties. However, despite its traditional usage as an anti-diarrhoeal there is limited information regarding its mode of action in infectious forms of diarrhoea. Hence, we evaluated the hot aqueous extract (decoction) of dried unripe fruit pulp of A. marmelos for its antimicrobial activity and effect on various aspects of pathogenicity of infectious diarrhoea. METHODS: The decoction was assessed for its antibacterial, antigiardial and antirotaviral activities. The effect of the decoction on adherence of enteropathogenic Escherichia coli and invasion of enteroinvasive E. coli and Shigella flexneri to HEp-2 cells were assessed as a measure of its effect on colonization. The effect of the decoction on production of E. coli heat labile toxin (LT) and cholera toxin (CT) and their binding to ganglioside monosialic acid receptor (GM1) were assessed by GM1-enzyme linked immuno sorbent assay whereas its effect on production and action of E. coli heat stable toxin (ST) was assessed by suckling mouse assay. RESULTS: The decoction showed cidal activity against Giardia and rotavirus whereas viability of none of the six bacterial strains tested was affected. It significantly reduced bacterial adherence to and invasion of HEp-2 cells. The extract also affected production of CT and binding of both LT and CT to GM1. However, it had no effect on ST. CONCLUSION: The decoction of the unripe fruit pulp of A. marmelos, despite having limited antimicrobial activity, affected the bacterial colonization to gut epithelium and production and action of certain enterotoxins. These observations suggest the varied possible modes of action of A. marmelos in infectious forms of diarrhoea thereby validating its mention in the ancient Indian texts and continued use by local communities for the treatment of diarrhoeal diseases.

Sacred Groves of Parinche Valley of Pune District of Maharashtra, India and their Importance.

Sacred groves are protected areas of forests because of religious beliefs and constitute an important aspect of the cultural life of various communities throughout the world. The source of this culture can be traced back to prehistoric times. The sacred groves of Parinche valley, Pune district of Maharashtra, India were studied to understand their status and importance in relation to common natural resource bases and cultural aspects. Through formal interviews and non-participatory observation undertaken in all seasons between October 2002 and February 2004, 14 sacred groves were documented. Both EMIC and ETIC dimensions were incorporated in the choice of subjects. The results show that they are important for various communities as a common natural resource base. They promote cultural bonding among various communities and maintain harmony in social life. This can be evidenced during annual village festivals and family celebrations, which invariably take place within the premises of sacred groves. They are also important for biodiversity as many groves function like mini sanctuaries and harbour endemic and threatened plant species. The natural vegetation of the groves comprises many medicinal plants that are regularly harvested by local medicine men ( Vaidus ). Water is a precious resource, especially during summer months, and the perennial water sources that are present in the sacred groves are the only remaining water sources for seven villages. There is a compunction, on the other hand, of the sacred groves being influenced by urbanization, resulting in the building of concrete temples by clearing natural vegetation and planting ornamental and other economically useful trees in the cleared areas of the groves. Such actions alter these fragile ecosystems and deplete or destroy the natural resource base for which this ancient culture is believed to have been originally evolved. We conclude here that sacred groves were originally a common natural resource which were assimilated into the social and cultural life of villages in the Parinche valley. Hence their protection and enhancement should become part of village and forest planning.