Isolation, structure elucidation, and synthesis of (±)-millpuline A with a suppressive effect in miR-144 expression

The isolation, characterization, and total synthesis of (-)-millpuline A and (+)-millpuline A were described here. Their structures were identified by spectral analyses and single-crystal X-ray diffraction. The total synthesis was carried out using 2,4-dihydroxybenzaldehyde in five key steps, including an important [2 + 2] photocycloaddition. The inhibitory activity on miR-144-3p expression of (+/-)-millpuline A was firstly revealed by western blot and RT-qPCR methods. Through the docking study based on the construction of the pre-miR-144 3D structure and the in vitro model of A549 cells transfected with pre-miR-144, the effects of (-)-millpuline A and (+)-millpuline A were examined, respectively. The results showed that only (-)-millpuline A could interfere with the pre-miR-144 dicing, and thereby modulated the down-stream Nrf2 and gamma-Gcsm expression accordingly. Our findings provided a stereo-selective skeleton targeting miR-144, and thereby, will find significance in the context of miR-144/oxidative stress-related diseases.