Antiadhesive activity and phytochemical characterisation of the aerial parts of Tropaeolum majus L.

Tropaeolum majus L. is used within rational phytotherapy against urinary and respiratory tract infections due to its content of the antibacterial mustard oil benzylisothiocyanate, which is formed by enzymatic conversion from the glucosinolate glucotropaeolin. This study aims at elucidating other potentially antibacterial compounds in the herbal material.

Powdered plant material was fermented and its metabolic profile compared with that of an unfermented 70% methanol extract by using UHPLC-qTOF-ESIMS and multivariate data analysis. Besides glucotropaeolin, other compounds were found to be decomposed during fermentation. In total, 30 different compounds were identified or widely characterized on the basis of these data.

In vitro antibacterial activity of unfermented extract and an enzyme preparation of T. majus against uropathogenic Escherichia coli (UPEC) strain UTI89 was tested. Both samples showed no antibacterial activity (1 to 2000 µg/mL). The unfermented extract did neither influence cell viability of T24 bladder cells. The adhesion of UPEC strain NU14 to T24 bladder cells was significantly inhibited by about 25% when the bladder cells were coincubated with bacteria and 1000 µg/mL of unfermented extract.