Fig. 3. 4 in Undescribed polyether ionophores from Streptomyces cacaoi and their antibacterial and antiproliferative activities

Fig. 3. 4 treatment results in proteasome inhibition and ER stress. A) Proteasomal activity was determined via Suc-Leu-Leu-Val-Tyr AMC. 1 μM Mg132 was used as a proteasome inhibitor. Reported values were normalized to cells treated with vehicle. Error bars represent standard deviation. p-values were calculated with respect to the vehicle-treated cells (****p <0.0001). B) The level of K48-linked ubiquitinated proteins was determined by IB. C) After cells were treated with 4 or vehicle for 24 h, soluble and insoluble protein fractions were prepared, then the levels of K48-linked ubiquitinated proteins were investigated. D) Following A549 cells were treated with 10 and 20 μM 4 or vehicle for 24 h, CHOP and BIP protein levels were determined via IB. E) ROS production was determined via 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH). 200 mM H2O2 was used as a positive control (1 h). Error bars represent standard deviation and p-values were calculated with respect to vehicle-treated cells. (**p = 0.009, ***p = 0.0002, ****p <0.0001).