Di-indenopyridines as topoisomerase II-selective anticancer agents: Design, synthesis, and structure-activity relationships.

Topoisomerases are key molecular enzymes responsible for altering DNA topology, thus they have long been considered as attractive targets for novel chemotherapeutic agents. Topoisomerase type II (Topo II) catalytic inhibitors embrace a fresh perspective meant to get beyond drawbacks caused by topo II poisons, such as cardiotoxicity and secondary malignancies. Based on previously reported 5H-indeno[1,2-b]pyridines, here we presented new twenty-three hybrid di-indenopyridines along with their topo I/IIα inhibitory and antiproliferative activity. Most of the prepared 11-phenyl-diindenopyridines showed negligible topo I inhibitory activity, showing selectivity over topo II. Among the series, we finally selected compound 17, which displayed 100 % topo IIα inhibition at 20 µM concentration and comparable antiproliferative activity against the tested cell lines. Through competitive EtBr displacement assay, cleavable complex assay, and comet assay, compound 17 was finally determined as a non-intercalative catalytic topo IIα inhibitor. The findings in this study highlight the significance of phenolic, halophenyl, thienyl, and furyl groups at the 4-position of the indane ring in the design and synthesis of di-indenopyridines as potent catalytic topo IIα inhibitors with remarkable anticancer effects.

Potent inhibitory activity of hydroxylated 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones on LPS-stimulated reactive oxygen species production in RAW 264.7 macrophages.

This study attempted to discover tetralone-derived potent ROS inhibitors by synthesizing sixty-six hydroxylated and halogenated 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones via Claisen-Schmidt condensation reaction. The majority of the synthesized and investigated compounds significantly inhibited ROS in LPS-stimulated RAW 264.7 macrophages. When compared to malvidin (IC50 = 9.00 µM), compound 28 (IC50 = 0.18 µM) possessing 6­hydroxyl and 2­trifluoromethylphenyl moiety showed the most potent ROS inhibition. In addition, the compounds 20, 31, 39, 45, 47-48, 52, 55-56, 58-60, and 62 also displayed ten folds greater ROS inhibitory activity relative to the reference compound. Based on the structure-activity relationship study, incorporating hydroxyl groups at the 6- and 7-positions of tetralone scaffold along with different halogen functionalities in phenyl ring B is crucial for potent ROS suppression. This study contributes to a better understanding of the effect of halogen and phenolic groups in ROS suppression, and further investigations on 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones will potentially lead to the discovery of effective anti-inflammatory agents.

Topoisomerase IIα inhibitory and antiproliferative activity of dihydroxylated 2,6-diphenyl-4-fluorophenylpyridines: Design, synthesis, and structure-activity relationships.

A new series of fifty-four 2-phenol-4-aryl-6-hydroxyphenylpyridines containing fluorophenyl, trifluoromethylphenyl, and trifluoromethoxy phenyl groups were synthesized and tested for topoisomerase IIα inhibitory and antiproliferative activity against different cancer cell lines in an attempt to look into topoisomerase IIα-targeted prospective anticancer agents to counter the limitations of available treatment options. When compared to positive controls, several compounds 11-12, 37, 50, and 51 showed high antiproliferative activity, while several 4-fluorophenyl substituted compounds 13-14 and 18 showed strong topoisomerase IIα inhibition. Surprisingly, most of the compounds had a significant antiproliferative effect on the HCT15 colorectal adenocarcinoma and T47D breast cancer cell lines. Moreover, compound 12 with para-fluorophenyl at the 4-position and meta-phenolic groups at the 2- and 6-positions inhibited proliferating HeLa cervix adenocarcinoma cells with an IC50 value of 1.28 µM. Based on biological results, the structure-activity relationships of the synthesized derivatives emphasized the significance of 4-trifluoromethoxyphenyl groups for strong antiproliferative activity and 4-fluorophenyl groups for strong topo IIα inhibition. Furthermore, meta- and para-phenolic groups at the 2- and 4-positions are favorable for strong topo IIα inhibitory and antiproliferative activity. The research findings provide insight into the effect of different fluorine functionalities in the discovery of novel topoisomerase IIα-targeted anticancer agents.

4-Flourophenyl-substituted 5H-indeno[1,2-b]pyridinols with enhanced topoisomerase IIα inhibitory activity: Synthesis, biological evaluation, and structure-activity relationships.

A series of fluorinated and hydroxylated 2,4-diphenyl indenopyridinols were designed and synthesized using l-proline-catalyzed and microwave-assisted synthetic methods for the development of new anticancer agents. Adriamycin and etoposide were used as reference compounds for the evaluation of topo IIα inhibitory and anti-proliferative activity of the synthesized compounds. Exploring the structure-activity relationships of 36 prepared compounds and biological results, most of the compounds with ortho- and para-fluorophenyl at 4-position of indenopyridinol ring displayed strong topo IIα inhibition. In addition, the majority of the ortho- and meta-fluorophenyl substituted compounds 1-24 displayed strong anti-proliferative activity against DU145 prostate cancer cell line compared to the positive controls. Interestingly, compound 4 possessing ortho-phenolic and ortho-fluorophenyl group at 2- and 4-position, respectively of the central pyridine ring showed high anti-proliferative activity (IC50 = 0.82 µM) against T47D human breast cancer cell line, while para-phenolic and para-fluorophenyl substituted compound 36 exhibited potent topo IIα inhibitory activity with 94.7% and 88.6% inhibition at 100 µM and 20 µM concentration, respectively. A systematic comparison between the results of this study and the previous study indicated that minor changes in the position of functional groups in the structure affect the topo IIα inhibitory activity and anti-proliferative activity of the compounds. The findings from this study will provide valuable information to the researchers working on the medicinal chemistry of topoisomerase IIα-targeted anticancer agents.

Antioxidative and anti-inflammatory activity of psiguadial B and its halogenated analogues as potential neuroprotective agents.

Psiguadial B (8), and its fluoro- (8a), chloro- (8b), and bromo- (8c) derivatives were synthesized using a sodium acetate-catalyzed single step coupling of three components: ß-caryophyllene (5), diformylphloroglucinol (11), and benzaldehyde (12). These compounds efficiently and dose-dependently decreased H2O2-induced cell death, a quantitative marker of cell death, in primary cultures of mouse cortical neurons. Psiguadial B also decreased neuronal death and accumulation of ROS induced by FeCl2 in cortical cultures. The in vitro effects of these compounds in lipopolysaccharide (LPS)-induced expression of nitric oxide (NO), and TNF-α and IL-6 by suppressing the NF-κB pathway in immune cells demonstrated their antioxidative and anti-inflammatory activity. The present findings warrant further research on the development of psiguadial B-based neuroprotective agents for the treatment of neurodegenerative diseases, acute brain injuries and immunological disorders.

Design, synthesis, biological evaluation, structure-activity relationship study, and mode of action of 2-phenol-4,6-dichlorophenyl-pyridines.

Human DNA topoisomerases (Topos) are essential nuclear enzyme whose level of expression is potential indicator for prediction of responsive result of chemotherapy. Topos has become a key cellular target for most of the anticancer agents that regulates topological problems of DNA during cellular metabolic processes such as replication, transcription, and recombination. Inspired by previous studies of 2,4,6-trisubstituted pyridines to find out safer and effective topoisomerase targeted anticancer agent, twenty-seven 2-phenol-4,6-dichlorophenyl-pyridines were designed, synthesized, and tested for their topo I and IIα inhibitory and anti-proliferative activity. Most of the dichlorinated meta- and para-phenolic series compounds (1-18) exhibited potent and selective topo IIα inhibition along with significant anti-proliferative activity in the HCT-15 and T47D cell lines compared to the positive control, etoposide. Interestingly, dichlorinated ortho-phenolic series compounds (19-27) exhibited potent and dual topo inhibition but very weak anti-proliferative activity in the tested cancer cell lines. Structure-activity relationship with previously synthesized compounds revealed the importance of chlorine moiety to improve the potency of topo inhibitory activity. Further mechanistic study confirmed that compounds 2 and 12 acted as non-intercalative specific topo IIα catalytic inhibitor with less DNA damage, and induced G1 arrest and apoptosis in HCT-15 and T47D cell lines, respectively.