Structural characterization of tetranortriterpenes from Pseudrocedrela kotschyi and Trichilia emetica and study of their activity towards the chaperone Hsp90

► We performed structural characterization of 16 limonoids, including 5 natural compounds. ► A SPR-based screening was performed, demonstrating that kotschyin D interacts with Hsp90. ► Kotschyin D inhibits Hsp90 via an ATP-independent mechanism, binding its middle domain.