Exposure of CCRF-CEM cells to acridone derivative 8a triggers tumor death via multiple mechanisms.

A newly synthesized acridone derivative 8a shows potent antitumor activity against CCRF-CEM leukemia cells. Herein, the first proteomic study of 8a effects in CCRF-CEM cells was performed by 2D nano-LC-ESI-MS/MS to better understand the mechanisms of action of 8a. Data analyses based on PLGS, STRING, Cytoscape, and database for annotation, visualization, and integrated discovery identified 55 proteins that were differentially expressed in response to 8a exposure. Multiple cellular pathways were affected, including chromatin organization, energy metabolism, DNA repair, oxidative-stress, and apoptosis. The changes in protein expression were further verified for PKM2. Moreover, 8a lowered down the expression of HEX and PFK-1. Lactate production was decreased in 8a-treated cells, indicating suppression of glycolysis. The elevated XRCC6 and decreased histone expression levels suggested increased DNA damage in 8a-treated cells, which was confirmed by the increased γ-H2AX foci. Molecular docking of 8a with DNA demonstrated direct interactions of 8a with DNA through three hydrogen bonds and four π-π interactions, potentially explaining the mode of action that 8a damaged to DNA. The differential protein profiling and dysfunction of metabolic pathways induced by 8a provide novel insights into the potential action mechanisms of 8a.

Synthesis of polyhalo acridones as pH-sensitive fluorescence probes.

Polyhalo isophthalonitriles were reacted with substituted anilines and subsequently cyclocondensed in the presence of sulfuric acid to give polyhalo acridones. These polyhalo acridones were proven to be useful as pH-sensitive fluorescent probes for a wide range of acidic and basic conditions.

Synthesis of new acridone derivatives, inhibitors of NS3 helicase, which efficiently and specifically inhibit subgenomic HCV replication.

A new goup of acridone derivatives, obtained by reaction of acridone-4-carboxylic acid derivatives with aromatic amines, was tested to determine the inhibitory properties toward the NS3 helicase of hepatitis C virus (HCV). Six compounds inhibited the NS3 helicase at low concentrations (IC(50) from 1.5 to 20 microM). The acridone derivatives probably act via intercalation into double-stranded nucleic acids with a strong specificity for double-stranded RNA, although an interaction with the enzyme cannot be excluded. Testing in the subgenomic HCV replicon system revealed that compounds 10 and 13 are efficient RNA replication inhibitors, with EC(50) of 3.5 and 1 microM and therapeutic indexes of >28 and 20, respectively. Compound 16, with EC(50) < 1 microM and TI > 1000, is extremely specific and practically noncytotoxic at the concentrations tested, proving that the acridone derivatives may be regarded as potential antiviral agents. Although the mechanism of action of 16 in the replicon system remains unclear, it is the key lead compound for further development of anti-HCV drugs.

Chloro acridone derivatives as cytotoxic agents active on multidrug-resistant cell lines and their duplex DNA complex studies by electrospray ionization mass spectrometry.

We report herein in vitro anti-proliferative activity and duplex DNA complex studies of a series of N10-substituted acridone derivatives. All the molecules have been designed on the basis of the presence of specific recognition patterns consisting of hydrogen bond acceptors (or electron donors), carbonyl, chloro groups with precise spatial separation and structural features (lipophilicity, positive charge at neutral pH and presence of aromatic rings). The in vitro cytotoxic effects have been demonstrated against human promyelocytic leukemia sensitive cell line (HL-60), including its multidrug cross-resistance of two main (P-gp and MRP) phenotype sublines vincristine-resistant (HL-60/VINC) and doxorubicin-resistant (HL-60/DX) cancer cell lines. Compound 4 showed very good activity against sensitive and resistant cell lines. The noncovalent complexes of these molecules with DNA duplex has been investigated in gas phase by using a fast, robust and sensitive electrospray ionization mass spectrometry (ESI-MS) technique. Equilibrium association constants (K1) and percentage of intact complexes were determined. The combined results show that these acridone derivatives interact with DNA duplex by intercalation between the base pairs, possess higher affinity to GC than AT base pairs of the DNA and they could not interact noncovalently with the minor grooves of the DNA in solution-free gas phase. Examination of the relationship between lipophilicity and cytotoxic properties of acridone derivatives showed a poor correlation. The in vitro cytotoxic studies in resistant cancer cell lines of compound 4 showed that it might be a promising new hit for further development of anti-MDR agent.