Furoxan-piplartine hybrids as effective NO donors and ROS inducers in PC3 cancer cells: design, synthesis, and biological evaluation

Conjugation of the naturally occurring product piplartine (PPT, 1), which is a potent cytotoxic compound and ROS inducer, with a diphenyl sulfonyl-substituted furoxan moiety (namely, 3,4-bis(phenylsulfonyl)-1,2,5-oxadiazole-2-oxide), an important type of NO donor, via an ether linker of different chain lengths is described, characterized and screened for the anticancer potential. The cytotoxicity of the new hybrids was evaluated on a panel of human cancer cell lines (MCF-7, PC3 and OVCAR-3) and two non-cancer human cells (MCF10A and PNT2). In general, the synthesized hybrids were more cytotoxic and selective compared to their furoxan precursors 4-6 and PPT in the above cancer cells. Particularly, PC3 cells are the most sensitive to hybrids 7 and 9 (IC50 values of 240 nM and 50 nM, respectively), while a lower potency was found for the prostate normal cells (IC50 = 17.8 μM and 14.1 μM, respectively), corresponding to selectivity indices of ca. 75 and 280, respectively. NO generation by the PPT-furoxan compounds in PC3 cells was confirmed using the Griess reaction. Furthermore, the cell growth inhibitory effect of 9 was significantly attenuated by the NO scavenger carboxy-PTIO. The intracellular ROS generation by 7 and 9 was also verified, and different assays showed that co-treatment with the antioxidant N-acetyl-l-cysteine (NAC) provided protection against PPT-induced ROS generation. Further mechanistic studies revealed that 7 and 9 had strong cytotoxicity to induce apoptosis in PC3 cells, being mediated, at least in part, by the NO-release and increase in ROS production. Notably, the ability of 9 to induce apoptosis was stronger than that of 7, which may be attributed to higher levels of NO released by 9. Compounds 7 and 9 modulated the expression profiles of critical regulators of cell cycle, such as CDKN1A (p21), c-MYC, and CCND1 (cyclin D1), as well as induced DNA damage. Overall, tethering the furoxan NO-releasing moiety to the cytotoxic natural product PPT had significant impact on the potential anticancer activity and selectivity of the novel hybrid drug candidates, especially 9, as a result of synergistic effects of both furoxan and PPT's ability to release NO, generate ROS, induce DNA damage, and trigger apoptosis.

Piperlongumine and its derivatives against cancer: A recent update and future prospective

Piperlongumine, or piplartine (PL), is a bioactive alkaloid isolated from Piper longum L. and a potent phytoconstituent in Indian Ayurveda and traditional Chinese medicine with a lot of therapeutic benefits. Apart from all of its biological activities, it demonstrates multimodal anticancer activity by targeting various cancer-associated pathways and being less toxic to normal cells. According to their structure-activity relationship (SAR), the trimethylphenyl ring (cinnamoyl core) and 5,6-dihydropyridin-2-(1H)-one (piperdine core) are responsible for the potent anticancer activity. However, it has poor intrinsic properties (low aqueous solubility, poor bioavailability, etc.). As a result, pharmaceutical researchers have been trying to optimise or modify the structure of PL to improve the drug-likeness profiles. The present review selected 26 eligible research articles on PL derivatives published between 2012 and 2023, followed by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) format. We have thoroughly summarised the anticancer potency, mode of action, SAR and drug chemistry of the proposed PL-derivatives against different cancer cells. Overall, SAR analyses with respect to anticancer potency and drug-ability revealed that substitution of methoxy to hydroxyl, attachment of ligustrazine and 4-hydroxycoumarin heterocyclic rings in place of phenyl rings, and attachment of heterocyclic rings like indole at the C7-C8 olefin position in native PL can help to improve anticancer activity, aqueous solubility, cell permeability, and bioavailability, making them potential leads. Hopefully, the large-scale collection and critical drug-chemistry analyses will be helpful to pharmaceutical and academic researchers in developing potential, less-toxic and cost-effective PL-derivatives that can be used against different cancers.

Alkaloids as Additional Weapons in the Fight against Breast Cancer: A Review

Breast carcinoma is among the most frequent cancerous tumour in females around the globe. The major modalities now employed in the therapeutic management of breast cancer include surgeries, chemotherapy, and specialized medicines. Despite their potential to help individuals' problems, they are also associated with many negative impacts. As a result, natural products are increasingly regarded to be a preferable alternative. Alkaloids are essential biochemical substances that can be used to develop new drugs. Numerous alkaloids that originate from natural plants have been shown in vitro and in vivo to have anti-proliferation and anti-metastasis actions on different kinds of carcinoma. According to the data collected in this study, the utilization of alkaloids as anti-tumor medicines appears to be extremely potent; nevertheless, extensive studies and clinical trials are required before utilizing individual alkaloids. In this overview, we provide a detailed and vital exploration of pre-existing alkaloids possessing anti-tumor activities due to bioactive compounds. This study also includes an overview of synthesized analogues and pharmacological characteristics that will be beneficial to scientists working on alkaloids for medicinal purposes. In a recent survey of the literature, alkaloids are an important component of plantderived antitumor medicines that hold great potential for the future development of cancer therapy and preventive therapies. We have also discussed structural analysis relationship (SAR) studies. Moreover, it covers clinical trial medications and FDA-approved medicines from the last five years that will be useful in further research.

Cinnamic acid hybrids as anticancer agents: A mini-review

Cancer, as a long-lasting and dramatic disease, affects almost one-third of human beings globally. Chemotherapeutics play an important role in cancer treatment, but multidrug resistance and severe adverse effects have already become the main causes of failure in tumor chemotherapy. Therefore, it is an urgent need to develop novel chemotherapeutics. Cinnamic acid contains a ubiquitous α,β-unsaturated acid moiety presenting potential therapeutic effects in the treatment of cancer as these derivatives could act on cancer cells by diverse mechanisms of action. Accordingly, cinnamic acid derivatives are critical scaffolds in discovering novel anticancer agents. This review provides a comprehensive overview of cinnamic acid hybrids as anticancer agents. The structure-activity relationship, as well as the mechanisms of action, are also discussed, covering articles published from 2012 to 2021.