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DOI: 10.1055/s-0035-1565502
Antiadhesive effect of leaves extracts from Orthosiphon stamineus extract against uropathogenic E. coli
Uropathogenic Escherichia coli (UPEC) colonize host cells and tissue of the urogenital tract after specific attachment to cell surface structures by mainly type 1 and P-fimbriae. Specific inhibition of bacterial adhesion is an alternative approach for specific prevention. The following study investigated the in vitro antiadhesive potential of extracts from leaves of Orthosiphon stamineus B. against UPEC to T24 bladder cells.
Dried plant material was extracted with water (OWE, drug-extract ratio 100:20) and acetone (OAE, drug-extract ratio 100:4.5). Both extracts did not influence cell viability of T24 cells (MTT assay) or exhibited cytotoxicity against UPEC (agar diffusion assay). OAE significantly decreased bacterial adhesion at 100 µg/mL (Fig. 1) while OWE increased the adhesion due to bacterial agglomeration as shown by flow cytometry and Giemsa staining. Tannin-like compounds were removed from OWE by treatment of the extract with polyvinylpyrrolidone and skin powder, resulting in a tannin-free extract OWEøTannin which did not cause any more bacterial aggregation, but did also not influence the bacterial adhesion significantly.
Interestingly preincubation of bacteria with pooled urine and OWE led to 40% reduction of bacterial adhesion. This means that OWE in combination with human urine is capable to exert significant antiadhesive effects, a phenomenon which cannot be explained at the moment.
Beside antiadhesive effects of the extracts the influence of OWE and OAE on UPEC-induced biofilm formation was also monitored (crystal violet assay). Additionally the effect of the extracts against UPEC invasion into T24 bladder cells was studied by gentamicin protection assay.