Artemisinin-polypyrrole conjugates: synthesis, DNA binding studies and preliminary antiproliferative evaluation

Target-based anticancer indole derivatives and insight into structure‒activity relationship: A mechanistic review update (2018‒2021)

Cancer, which is the uncontrolled growth of cells, is the second leading cause of death after heart disease. Targeting drugs, especially to specific genes and proteins involved in growth and survival of cancer cells, is the prime need of research world-wide. Indole moiety, which is a combination of aromatic-heterocyclic compounds, is a constructive scaffold for the development of novel leads. Owing to its bioavailability, high unique chemical properties and significant pharmacological behaviours, indole is considered as the most inquisitive scaffold for anticancer drug research. This is illustrated by the fact that the U.S. Food and Drug Administration (FDA) has recently approved several indole-based anticancer agents such as panobinostat, alectinib, sunitinib, osimertinib, anlotinib and nintedanib for clinical use. Furthermore, hundreds of studies on the synthesis and activity of the indole ring have been published in the last three years. Taking into account the facts stated above, we have presented the most recent advances in medicinal chemistry of indole derivatives, encompassing hot articles published between 2018 and 2021 in anticancer drug research. The recent advances made towards the synthesis of promising indole-based anticancer compounds that may act via various targets such as topoisomerase, tubulin, apoptosis, aromatase, kinases, etc., have been discussed. This review also summarizes some of the recent efficient green chemical synthesis for indole rings using various catalysts for the period during 2018–2021. The review also covers the synthesis, structure‒activity relationship, and mechanism by which these leads have demonstrated improved and promising anticancer activity. Indole molecules under clinical and preclinical stages are classified into groups based on their cancer targets and presented in tabular form, along with their mechanism of action. The goal of this review article is to point the way for medicinal chemists to design and develop effective indole-based anticancer agents.

Ferroptosis: A Novel Mechanism of Artemisinin and its Derivatives in Cancer Therapy

BACKGROUND

Artemisinin is a sesquiterpene lactone compound with a special peroxide bridge that is tightly linked to the cytotoxicity involved in fighting malaria and cancer. Artemisinin and its derivatives (ARTs) are considered to be potential anticancer drugs that promote cancer cell apoptosis, induce cell cycle arrest and autophagy, inhibit cancer cell invasion and migration. Additionally, ARTs significantly increase intracellular Reactive Oxygen Species (ROS) in cancer cells, which result in ferroptosis, a new form of cell death, depending on the ferritin concentration. Ferroptosis is regarded as a cancer suppressor and as well as considered a new mechanism for cancer therapy.

METHODS

The anticancer activities of ARTs and reference molecules were compared by literature search and analysis. The latest research progress on ferroptosis was described, with a special focus on the molecular mechanism of artemisinin-induced ferroptosis.

RESULTS

Artemisinin derivatives, artemisinin-derived dimers, hybrids and artemisinin-transferrin conjugates, could significantly improve anticancer activity, and their IC50 values are lower than those of reference molecules such as doxorubicin and paclitaxel. The biological activities of linkers in dimers and hybrids are important in the drug design processes. ARTs induce ferroptosis mainly by triggering intracellular ROS production, promoting the lysosomal degradation of ferritin and regulating the System Xc-/Gpx4 axis. Interestingly, ARTs also stimulate the feedback inhibition pathway.

CONCLUSION

Artemisinin and its derivatives could be used in the future as cancer therapies with broader applications due to their induction of ferroptosis. Meanwhile, more attention should be paid to the development of novel artemisinin-related drugs based on the mechanism of artemisinininduced ferroptosis.

Medicinal chemistry updates on quinoline- and endoperoxide-based hybrids with potent antimalarial activity

The resistance of conventional antimalarial drugs against the malarial parasite continues to pose a challenge to control the disease. The indiscriminate exploitation of the available antimalarials has resulted in increasing treatment failures, which urges on the search for novel lead molecules. Artemisinin-based combination therapy (ACT) is the current WHO-recommended first-line treatment for the majority of malaria cases. Hybrid molecules offer a newer strategy for the development of next-generation antimalarial drugs. These comprise molecules, each with an individual pharmacological activity, linked together into a single hybrid molecule. This approach has been utilized by several research groups to develop molecules with potent antimalarial activity. In this review, we provide an overview of the pivotal roles of quinoline- and endoperoxide-based hybrids as inhibitors of the life-cycle progression of Plasmodium. Based on the exhaustive literature reports, we have collated the structural and functional analyses of quinoline- and endoperoxide-based hybrid molecules that show potency equal to or greater than those of the individual compounds, offering an effective therapeutics option for clinical use.

Artemisinin as an anticancer drug: Recent advances in target profiling and mechanisms of action

Artemisinin and its derivatives (collectively termed as artemisinins) are among the most important and effective antimalarial drugs, with proven safety and efficacy in clinical use. Beyond their antimalarial effects, artemisinins have also been shown to possess selective anticancer properties, demonstrating cytotoxic effects against a wide range of cancer types both in vitro and in vivo. These effects appear to be mediated by artemisinin-induced changes in multiple signaling pathways, interfering simultaneously with multiple hallmarks of cancer. Great strides have been taken to characterize these pathways and to reveal their anticancer mechanisms of action of artemisinin. Moreover, encouraging data have also been obtained from a limited number of clinical trials to support their anticancer property. However, there are several key gaps in knowledge that continue to serve as significant barriers to the repurposing of artemisinins as effective anticancer agents. This review focuses on important and emerging aspects of this field, highlighting breakthroughs in unresolved questions as well as novel techniques and approaches that have been taken in recent studies. We discuss the mechanism of artemisinin activation in cancer, novel and significant findings with regards to artemisinin target proteins and pathways, new understandings in artemisinin-induced cell death mechanisms, as well as the practical issues of repurposing artemisinin. We believe these will be important topics in realizing the potential of artemisinin and its derivatives as safe and potent anticancer agents.