Context: Multiple drug resistance is the major obstacle to conventional chemotherapy. Silibinin, a nontoxic naturally occurring compound, has anticancer activity and can increase the cytotoxic effects of chemotherapy in various cancer models.Objective: To evaluate the effects of silibinin on enhancing the sensitivity of chemo-resistant human breast cell lines to doxorubicin (DOX) and paclitaxel (PAC).Materials and methods: The cells were treated with silibinin (at 50 to 600 μM concentrations) and/or chemo drugs for 24 and 48 h, then cell viability and changes in oncogenic proteins were determined by MTT assay and Western blotting/RT-PCR, respectively. Flow cytometry was used to study apoptosis in the cells receiving different treatments. The antitumorigenic effects of silibinin (at 200 to 400 μM concentration) were evaluated by mammosphere assay.Results: Silibinin exerted significant growth inhibitory effects with IC50 ranging from 200 to 570 μM in different cell lines. Treatment of DOX-resistant MDA-MB-435 cells with silibinin at 200 μM reduced DOX IC50 from 71 to 10 μg/mL and significantly suppressed the key oncogenic pathways including STAT3, AKT, and ERK in these cells. Interestingly treatment of DOX-resistant MDA-MB-435 cells with silibinin at 400 μM concentration for 48 h induced a 50% decrease in the numbers of colonies as compared with DMSO-treated cells. Treatment of PAC-resistant MCF-7 cells with silibinin at 400 μM concentration generated synergistic effects when it was used in combination with PAC at 250 nM concentration (CI = 0.81).Conclusion: Silibinin sensitizes chemo-resistant cells to chemotherapeutic agents and can be useful in treating breast cancers.

Multi-target anti Alzheimer’s disease (AD) compounds are promising leads for the development of AD modifying agents. Ionic compounds containing quaternary ammonium moiety were synthesized and their multi-targeted anti-AD effects were examined in the current study. Compound 5g possessed suitable aqueous solubility and cell toxicity. It also showed non-competitive dual hAChE/hBuChE inhibition activity. Compound 5g reversed the Aβ-treated PC12 cells’ morphology alteration and reduced PC12 cells’ death. Compound 5g possessed anti-oxidative stress activity through anti-oxidant, anti-ROS production and anti-lipid peroxidation mechanisms. It also reduced the expression of IL-1β and TNF-α genes. Furthermore, compound 5g LDH inhibition, reduction of neuro-inflammation and prevention of autophagy-apoptosis were approved by the results of in vitro studies. Compound 5g delivery to brain was confirmed by in vivo studies. Administration of compound 5g to Aβ-induced AD rat models improved their cognition function and spatial memory learning behavior. TNF-α and NFkB down-regulated in compound 5g treated AD rats’ hippocamp. Besides, compound 5g reversed the up-regulation of AChE in Aβ treated rats’ hippocamp. Molecular modeling studies confirmed the interaction of compound 5g with both steric and catalytic sites of ChE enzymes. The newly synthesized quaternary ammonium containing derivative (compound 5g) possessed multi-target anti-AD efficacy based on in vitro and in vivo studies and its efficacy in AD rat models were approved by behavioral and molecular investigations.