Celosiadines A and B, unusual guanidine alkaloids from Iresine diffusa.

Two unusual di-isopentenyl guanidine alkaloids, named celosiadines A (1) and B (2), were isolated from Iresine diffusa aerial parts. The structures of the compounds were elucidated from extensive spectroscopic analyses including HRMS, NMR and ECD. Celosiadines A and B showed favorable binding affinity to the androgen receptor (AR) in silico and were cytotoxic towards AR-sensitive (LNCaP) but not AR-insensitive (PC3) human prostate cancer cells in vitro.