Lectins in fruits having gastrointestinal activity: their participation in the hemagglutinating property of Escherichia coli 0157:H7.
Coutiño-Rodríguez R., Hernández-Cruz P., Giles-Ríos H.
Author Affiliation: Laboratorio de Salud y Ecología, Instituto de Salud Pública, Universidad Veracruzana, Calle Ernesto Medina #3, 91020 Xalapa, Veracruz, Mexico.
Archives of Medical Research 32 : 251-257
Abstract : This study identifies lectins in crude extracts from fruits such as Tamarindus indica (tamarind), Spontia vulgaris (plum), Psidium guajava (guava), Mangifera indica (mango), Cydonia vulgaris [Cydonia oblonga] (quince), and Crataegus mexicana (tejocote). To verify the procedures, extracts from Ricinus communis (castor bean), Glycine max (soyabean), Phaseolus vulgaris (kidney beans), Vicia faba (faba bean), and Solanum tuberosum (potato) were used as controls for lectin activity. Both sources of lectins were analysed to determine their participation in the host-parasite interaction, using as a model the haemagglutinating properties of Escherichia coli 0157:H7 (EHA). All extracts showed haemagglutination to group O erythrocytes test (HA) with the exception of mango. Two new galactose-specific lectins were identified from tamarind and guava. When analysed for participation in EHA, only guava lectins inhibited this, while soyabean lectin induced haemolysis; as both lectins bind to galactose, it is probable that their recognition occurs in different domains. Sugars involved in the attachment between E. coli 0157:H7 and red cells were identified and again, galactose in addition to mannose was found to be related in EHA. On the other hand, guava lectins also agglutinated E. coli 0157:H7, perhaps due to the same galactose-specific lectin or to another type of lectin. It is concluded that guava has a galactose-specific lectin that prevents adhesion of E. coli 0157:H7 to red cells; this lectin is mediated by galactose. Prevention could also be due to their capacity of agglutinating E. coli by guava lectins. Soyabean lectin induces haemolysis only when bacteria is present, but not with floating secretions. This finding showed that guava is a source of lectin that can be explored to prevent adhesion of E. coli to epithelial intestinal cells; contrariwise, soya must be studied to see its participation in the uraemia caused during E. coli 0157:H7 pathogenesis.