OBJECTIVE: The current research aimed to synthesize several Schiff base ligands from (3-formyl-4-hydroxyphenyl) methyltriphenylphosphonium (T). Additionally, the current research aimed to study the growth inhibitory effect of triphenylphosphonium containing thiosemicarbazone derivatives on PC-3 cells by deciphering the mechanisms involved in cell death.
METHOD: The compounds were characterized by various spectroscopic methods (infrared spectra, 1H NMR, 13C NMR, HRESIMS and X-ray crystallography) and the results were in conformity with the structure of the targeted compounds. Growth inhibitory effect of the compounds were performed against six human cell lines.
RESULTS: DM(tsc)T displayed most potent activity against PC-3 cells with IC50 value of 2.64 ± 0.33 μM, surpassing that of the positive control cisplatin (5.47 ± 0.06 μM). There were marked morphological changes observed in DM(tsc)T treated cells stained with acridine orange and ethidium bromide which were indicative of cell apoptosis. Treatment with DM(tsc)T showed that the cell cycle is arrested in the G0/G1 phase after 72 hours. Mitochondrial membrane potential loss was observed in cells treated with DM(tsc)T, indicating the apoptosis could be due to mitochondria mediated pathway.
CONCLUSION: This study indicates that DM(tsc)T would serve as a lead scaffold for rational anticancer agent development.
RESULTS AND DISCUSSION: The synthesized analogues were characterized by FT-IR, 1H/13C-NMR and MS studies as well C, H, N analysis. All synthesized compounds were evaluated for in vitro antibacterial activity against Gram-positive (B. subtilis), Gram-negative (E. coli, P. aeruginosa, K. pneumoniae and S. typhi) strains and in vitro antifungal activity against C. albicans and A. niger strains by serial dilution method, the minimum inhibitory concentration (MIC) described in μM/ml. The in vitro anticancer activity of synthesized compounds was determined against human colorectal carcinoma cell line (HCT- 116) using 5-fluorouracil as standard drug.
CONCLUSION: In general, most of the synthesized derivatives exhibited significant antimicrobial and anticancer activities. Compounds 8, 10, 15, 16, 17, 20 and 22 showed significant antimicrobial activity towards tested bacterial and fungal strains and compound 26 exhibited significant anticancer activity.
METHODOLOGY/PRINCIPAL FINDINGS: Four ligands (1-4) and their respective nickel-containing complexes (5-8) were synthesized and characterized. The compounds synthesized were tested for their effects on NF-κB nuclear translocation, pro-inflammatory cytokines secretion and NF-κB transactivation activity. The active compound was further evaluated on its ability to suppress carrageenan-induced acute inflammation in vivo. A potential binding target of the active compound was also predicted by molecular docking analysis.
CONCLUSIONS/SIGNIFICANCE: Among all synthesized compounds tested, we found that complex [Ni(H2L1)(PPh3)]Cl (5) (complex 5), potently inhibited IκBα degradation and NF-κB p65 nuclear translocation in LPS-stimulated RAW264.7 cells as well as TNFα-stimulated HeLa S3 cells. In addition, complex 5 significantly down-regulated LPS- or TNFα-induced transcription of NF-κB target genes, including genes that encode the pro-inflammatory cytokines TNFα, IFNβ and IL6. Luciferase reporter assays confirmed that complex 5 inhibited the transactivation activity of NF-κB. Furthermore, the anti-inflammatory effect of complex 5 was also supported by its suppressive effect on carrageenan-induced paw edema formation in wild type C57BL/6 mice. Interestingly, molecular docking study showed that complex 5 potentially interact with the active site of IKKβ. Taken together, we suggest complex 5 as a novel NF-κB inhibitor with potent anti-inflammatory effects.