Synthesis and cytotoxicity of novel artemisinin derivatives containing sulfur atoms

Discovery of Artesunate (ARS) PROTACs as GPX4 protein degraders for the treatment of bladder cancer

Bladder cancer is the second most prevalent malignancy of the urinary system worldwide, with high incidence and mortality rates. However, existing drugs for bladder cancer treatment often cause numerous adverse reactions. Although artesunate (ARS) exhibits anti-bladder cancer activity, its scope is rather limited and the specific targets remain unclear. Therefore, in this study, the Proteolysis-Targeting Chimera (PROTAC) technology was used to design and synthesize novel ARS derivatives. The antitumor activities of these compounds were evaluated against three human bladder cancer cell lines (T24, RT4, and J82). Of these compounds, A7 exhibited 12-fold stronger antiproliferative activity against bladder cancer cells than ARS. Molecular docking, surface plasmon resonance (SPR), cellular thermal shift assay (CETSA) and western blotting studies demonstrated that A7 directly targeted and degraded glutathione peroxidase 4 (GPX4) protein through the ubiquitin-proteasome system. A7 further induced bladder cancer cell ferroptosis. Furthermore, A7 showed potent tumor suppressive activity in a xenograft T24 nude mouse model. In conclusion, our findings indicate that A7 exerts notable antitumor effects against bladder cancer in vitro and in vivo. This study highlights the tremendous potential of the PROTAC technology in enhancing the efficacy of natural products and identifying therapeutic targets, demonstrating its broad application prospects in the development of natural products-based drugs.

Searching for the Holy Grail - Highly Potent Bridged Endoperoxides for Targeted Cancer Therapy

The International Agency for Research on Cancer (IARC) recently estimated the global cancer burden in 2050. The statistics are startling, with a 77% hike and 35 million new cancer cases per year. The present discoveries have recommended plant-derived bridged endoperoxides or artemisinin-based semisynthetic analogues as safe, well-tolerated and powerful substitutes that could be effectively utilized as a warhead to fight against global enemies like cancer. In addition, artemisinin-based drug repositioning crucially can reduce overriding drug development expenditures and establish accessibility of approved drugs with low risk to patients. Hence, the present review article provides a comprehensive account of the recent chemical and synthetic advancement of diverse cytotoxic artemisinin derivatives such as C(10)-O, C, N, S linked artemisinin analogues, artemisinin-derived metal complexes, artemisinin-derived hybrids/conjugates with other pharmaceutically active substances, and artemisinin-derived dimers, trimers and tetramers perceived during the last three decades (1997-2024). Moreover, the current preclinical and clinical anticancer application prospects of artemisinin derivatives with other defined drugs and their utilization in combination therapy and also nanoformulation approaches for targeted drug delivery have been discussed.

A comprehensive overview of Artemisinin and its derivatives as anticancer agents

Artemisinin is the crucial ingredient of artemisia annua, a traditional Chinese medicine used for the therapy of malaria in China for hundreds of years. In recent years, the anticancer properties of artemisinin and its derivatives have also been reported. This review has summarized the research and development of artemisinin and its derivatives as anticancer agents, which included both natural and synthetic monomers as well as their dimers. In addition, it highlights the antitumor effects of artemisinin and its derivatives after site-modification or after transformation to a nano-delivery system. Moreover, we have further explored their potential mechanisms of action and also discussed the clinical trials of ARTs used to treat cancer, which will facilitate in further development of novel anticancer drugs based on the scaffold of artemisinin.

Non-uniformity in in vitro drug-induced cytotoxicity as evidenced by differences in IC50 values - implications and way forward

Cell lines have proven indispensable for in vitro experiments and their utility as experimental models range from understanding the fundamental cell functioning to drug discovery. One of the most common utility of cell lines is for in vitro drug testing. Drug testing involves determining the cytotoxic effects of the drugs and such a measurement is expressed as the IC₅₀ values of drugs. Although determination of IC₅₀ values of drugs on cell lines is one of the most common in vitro experimental approaches, a significant amount of variations can be observed in the results obtained from such studies. Although the variations in the IC₅₀ values of a drug on different cells lines can and should vary, the non-uniformity of such results reported from different studies using a particular drug on a specific cell line is a matter of concern. We present the IC₅₀ values of 5 most commonly used drugs 5-fluorouracil, bleomycin, cisplatin, doxorubicin and methotrexate obtained from several in vitro cell line-based studies. Some of the factors which contribute to the non-uniformity of the IC₅₀ values for a particular drug from different studies are discussed as three types of factors, the biological, non-biological and human factors. Also, ways in which such variations can be reduced to obtain universally common, reliable results are presented.

Thioethers: An Overview

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Spreading rapidly in recent years, cancer has become one of the causes of the highest mor-tality rates after cardiovascular diseases. The reason for cancer development is still not clearly under-stood despite enormous research activities in this area. Scientists are now working on the biology of cancer, especially on the root cause of cancer development. The aim is to treat the cancer disease and thus cure the patients. The continuing efforts for the development of novel molecules as potential anti-cancer agents are essential for this purpose. The main aim of this review was to present a survey on the medicinal chemistry of thioethers and provide practical data on their cytotoxicities against various cancer cell lines. The research articles published between 2001-2020 were consulted to pre-pare this review article; however, patent literature has not been included. The thioether-containing heterocyclic compounds may emerge as a new class of potent and effective anti-cancer agents in the future.

Artemisinin and Derivatives-Based Hybrid Compounds: Promising Therapeutics for the Treatment of Cancer and Malaria

Cancer and malaria are major health conditions around the world despite many strategies and therapeutics available for their treatment. The most used strategy for the treatment of these diseases is the administration of therapeutic drugs, which suffer from several shortcomings. Some of the pharmacological limitations associated with these drugs are multi-drug resistance, drug toxicity, poor biocompatibility and bioavailability, and poor water solubility. The currently ongoing preclinical studies have demonstrated that combination therapy is a potent approach that can overcome some of the aforementioned limitations. Artemisinin and its derivatives have been reported to exhibit potent efficacy as anticancer and antimalarial agents. This review reports hybrid compounds containing artemisinin scaffolds and their derivatives with promising therapeutic effects for the treatment of cancer and malaria.

Therapeutic Potentials and Mechanisms of Artemisinin and its Derivatives for Tumorigenesis and Metastasis

BACKGROUND

Tumor recurrence and metastasis are still leading causes of cancer mortality worldwide. The influence of traditional treatment strategies against metastatic tumors may still be limited. To search for novel and powerful agents against tumors has become a major research focus. In this study, Artemisinin (ARM), a natural compound isolated from herbs, Artemisia annua L., proceeding from drug repurposing methods, attracts more attention due to its good efficacy and tolerance in antimalarial practices, as well as newly confirmed anticancer activity.

METHODS

We have searched and reviewed the literatures about ARM and its derivatives (ARMs) for cancer using keywords "artemisinin" until May 2019.

RESULTS

In preclinical studies, ARMs can induce cell cycle arrest and cell death by apoptosis etc., to inhibit the progression of tumors, and suppress EMT and angiogenesis to inhibit the metastasis of tumors. Notably, the complex relationships of ARMs and autophagy are worth exploring. Inspired by the limitations of its antimalarial applications and the mechanical studies of artemisinin and cancer, people are also committed to develop safer and more potent ARM-based modified compounds (ARMs) or combination therapy, such as artemisinin dimers/ trimers, artemisinin-derived hybrids. Some clinical trials support artemisinins as promising candidates for cancer therapy.

CONCLUSION

ARMs show potent therapeutic potentials against carcinoma including metastatic tumors. Novel compounds derived from artemisinin and relevant combination therapies are supposed to be promising treatment strategies for tumors, as the important future research directions.

Structural optimization and biological evaluation for novel artemisinin derivatives against liver and ovarian cancers

An increasing number of artemisinin (ARS) and its derivatives have been reported for their potential therapeutic value of human cancer. However, their therapeutic potencies are limited owing to their poor pharmacokinetic profiles. Our previous studies showed that a lead compound ARS4 originated from incorporating the pharmacophore of the approved chemotherapeutic agent melphalan into the basic skeleton of artemisinin with a succinic linker exhibited an excellent toxicity to human ovarian cancer cells and low cytotoxicity to normal cells. The mechanism studies demonstrated that it inhibited the growth and proliferation of ovarian cancer cells and resulted in S-phase arrest, apoptosis and inhibition of migration. Meanwhile, it exhibited excellent antitumor activities in animal models. Herein, further structure optimization for this lead compound ARS4 was performed and nineteen novel derivatives were designed and synthesized. Among them, compounds 10-12, 15, 16, 18 and 19 demonstrated powerful cytotoxic effects against human liver cancer and ovarian cancer cell lines, with their IC_50s below 0.86 μM against Hep3B and A2780 cell lines, which are superior to that of ARS4. Four compounds (11, 15, 16 and 18) were selected to further evaluate their antitumor activities in in vitro and in vivo ovarian and liver cancer models, the results indicated that compound 18 exhibited the best therapeutic effect, not only effectively inhibited the growth of 7404 xenograft and Huh7 xenograft, but also presented a good dose-dependent inhibition toward the growth of A2780 xenograft. Overall, based on these positive results, these novel chemical structures may provide a new inspiration for the discovery of novel antitumor agents originated from artemisinin scaffolds.

S-(4-Methoxyphenyl)-4-methoxybenzenesulfonothioate as a Promising Lead Compound for the Development of a Renal Carcinoma Agent

Organosulfur compounds show cytotoxic potential towards many tumor cell lines. Disulfides and thiosulfonates act through apoptotic processes, inducing proteins associated with apoptosis, endoplasmic reticulum stress, and the unfolded protein response. Three p-substituted symmetric diaryl disulfides and three diaryl thiosulfonates were synthesized and analyzed for inhibition of tubulin polymerization and for human cancer cell cytotoxic activity against seven tumor cell lines and a non-tumor cell line. S-(4-methoxyphenyl)-4-methoxybenzenesulfonothioate (6) exhibited inhibition of tubulin polymerization and showed the best antiproliferative potential, especially against the 786-0 cell line, being six times more selective as compared with the non-tumor cell line. In addition, compound 6 was able to activate caspase-3 after 24 and 48 h treatments of the 786-0 cell line and induced cell-cycle arrest in the G2/M stage at the highest concentration evaluated at 24 and 48 h. Compound 6 was able to cause complete inhibition of proliferation, inducing the death of 786-0 cells, by increasing the number of cells at G2/M and greater activation of caspase-3.

Artemisinin-derived hybrids and their anticancer activity

The emergence of drug-resistance and the low specificity of anticancer agents are the major challenges in the treatment of cancer and can result in many side effects, creating an urgent demand to develop novel anticancer agents. Artemisinin-derived compounds, bearing a peroxide-containing sesquiterpene lactone moiety, could form free radicals with high reactivity and possess diverse pharmaceutical properties including in vitro and in vivo anticancer activity besides their typical antimalarial activity. Hybrid molecules have the potential to improve the specificity and overcome the drug resistance, therefore hybridization of artemisinin skeleton with other anticancer pharmacophores may provide novel anticancer candidates with high specificity and great potency against drug-resistant cancers. The review outlines the recent advances of artemisinin-derived hybrids as potential anticancer agents, and the structure-activity relationships are also discussed to provide an insight for rational designs of novel hybrids with high activity.

Novel dihydroartemisinin derivative DHA-37 induces autophagic cell death through upregulation of HMGB1 in A549 cells

Dihydroartemisinin (DHA) and its analogs are reported to possess selective anticancer activity. Here, we reported a novel DHA derivative DHA-37 that exhibited more potent anticancer activity on the cells tested. Distinct from DHA-induced apoptosis, DHA-37 triggered excessive autophagic cell death, and became the main contributor to DHA-37-induced A549 cell death. Incubation of the cells with DHA-37 but not DHA produced increased dots distribution of GFP-LC3 and expression ratio of LC3-II/LC3-I, and enhanced the formation of autophagic vacuoles as revealed by TEM. Treatment with the autophagy inhibitor 3-MA, LY294002, or chloroquine could reverse DHA-37-induced cell death. In addition, DHA-37-induced cell death was associated significantly with the increased expression of HMGB1, and knockdown of HMGB1 could reverse DHA-37-induced cell death. More importantly, the elevated HMGB1 expression induced autophagy through the activation of the MAPK signal but not PI3K-AKT–mTOR pathway. In addition, DHA-37 also showed a wonderful performance in A549 xenograft mice model. These findings suggest that HMGB1 as a target candidate for apoptosis-resistant cancer treatment and artemisinin-based drugs could be used in inducing autophagic cell death.

Recyclable imidazolium ion-tagged nickel catalyst for microwave-assisted C–S cross-coupling in water using sulfonyl hydrazide as the sulfur source

Recyclable nickel(ii) catalyst promoted sulfenylation of aryl halides with sulfonyl hydrazides in water using microwave irradiation under mild conditions is reported.

More insights into the pharmacological effects of artemisinin

Artemisinin is one of the most widely prescribed drugs against malaria and has recently received increased attention because of its other potential biological effects. The aim of this review is to summarize recent discoveries of the pharmaceutical effects of artemisinin in basic science along with its mechanistic action, as well as the intriguing results of recent clinical studies, with a focus on its antitumor activity. Scientific evidence indicates that artemisinin exerts its biological activity by generating reactive oxygen species that damage the DNA, mitochondrial depolarization, and cell death. In the present article review, scientific evidence suggests that artemisinin is a potential therapeutic agent for various diseases. Thus, this review is expected to encourage interested scientists to conduct further preclinical and clinical studies to evaluate these biological activities.

Selective fluorescent turn-off sensing of Pd2+ ion: applications as paper strips, polystyrene films, and in cell imaging

Pyridine-2,6-dicarboxamide based scaffolds with appended naphthyl groups act as fluorescent probes for the selective detection of Pd²⁺ ions in aqueous medium and have applications as paper-strip sensors, as polystyrene films, and in cell imaging.