Spatholobus suberectus Dunn. constituents inhibit sortase A and Staphylococcus aureus cell clumping to fibrinogen

Sortases are a family of Gram-positive transpeptidases responsible for anchoring surface protein virulence factors to the peptidoglycan cell wall layer. In Staphylococcus aureus ( S. aureus ), deletion of sortase isoform results in a significant reduction in virulence and infection potential. Twenty flavonoids were isolated from the stem of the folk medicinal plant Spatholobus suberectus Dunn. These compounds were tested against S. aureus -derived sortase A (SrtA), a key transpeptidase for bacterial virulence. Among these active flavonoids, 7-hydroxy-6-methoxy-flavanone ( 3 ) and formononetin ( 10 ) were identified as compounds with promising SrtA inhibitory activity. These compounds also exhibited inhibitory activity against S. aureus cell clumping to fibrinogen. The suppression of cell-clumping activity indicates the potential of these compounds in the treatment of S. aureus infections via the inhibition of SrtA.