Abstract Colebrookea oppositifolia is a highly used medicinal plant and an enriched source of essential oils. Therefore, the present study was designed with the aim to extract the chemical constituents and to evaluate its antioxidant potential. Fresh plant parts were subjected to the extraction of volatile chemical constituents by maceration using n-hexane as the menstruum. The resulting n-hexane fractions were purified and then subjected to GC-MS and FTIR analysis. In-vitro antioxidant abilities were evaluated by, DPPH, total phenolic content (TPC), total flavonoid content (TFC) method against the standard solutions of (Gallic acid, Quercetin) as a positive control. The GC-MS analysis of leaves, stem and inflorescence showed a total of 100, 98 and 48 components out of which 47, 16 and 17 peaks were identified representing the 67.64 %, 73.16 % and 61.93 % of the total oily fractions, respectively. The FTIR spectrum indicated the presence of various functional groups. In-vitro antioxidant results exhibited that leaves showed the highest antioxidant potential by DPPH (3.365 ± 0.002), and the highest total phenolic content by FC method (203.00 ± 0.091). Foliar micromorphological features were found significant in the authentication of C. oppositifolia. Further pharmacognostic studies of this plant are recommended to evaluate its therapeutic potential.
Enterotoxigenic Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. Adhesion is the first step in pathogenesis of ETEC infections and ETEC pili designated colonization factor antigens (CFAs) are believed to be important in the biofim formation, colonization and host cell adhesions. As a first step, we have determined the biofilm capability of ETEC expressing various types of pili (CFA/I, CfaE-R181A mutant/ CfaE tip mutant, CFA/II and CS2). Further, enzyme-linked immunosorbent assay (ELISA) assay were developed to compare the binding specificity of CFA/I, CFA/II (CS1 - CS3) and CS2 of ETEC, using extracted pili and piliated bacteria. CFA/II strain (E24377a) as well as extracted pili exhibited significantly higher binding both in biofilm and ELISA assays compared to non piliated wild type E24377a, CFA/I and CS2 strains. This indicates that co-expression of two or more CS2 in same strain is more efficient in increasing adherence. Significant decrease in binding specificity of DH5αF'lacIq/∆cotD (CS2) strain and MC4100/pEU2124 (CfaE-R181A) mutant strain indicated the important contribution of tip proteins in adherence assays. However, CS2 tip mutant strain (DH5αF'lacIq/pEU5881) showed that this specific residue may not be important as adhesions in these strains. In summary, our data suggest that pili, their minor subunits are important for biofilm formation and adherence mechanisms. Overall, the functional reactivity of strains co expressing various antigens, particularly minor subunit antigen observed in this study suggest that fewer antibodies may be required to elicit immunity to ETEC expressing a wider array of related pili.