Anti-Cancer Agents in Medicinal Chemistry (v.16, #10)

Meet Our Editorial Board Member by A. Desideri (1203-1203).

Flavonoids with Therapeutic Potential in Prostate Cancer by Bao Vue, Sheng Zhang, Qiao-Hong Chen (1205-1229).
The term “flavonoids” is created for a large class of polyphenolic compounds featuring two aromatic rings (A and B) and a central heterocyclic ring C. More than 4,000 flavonoids have already been obtained throughout the plant kingdom. An inverse correlation between the intake of dietary flavonoids and the incidence of prostate cancer can be generally well-observed from several epidemiological studies worldwide, which encouraged several research groups to examine both in vitro and in vivo the potential of whole extracts of flavonoidenriched dietary plants and purified flavonoids in preventing and treating prostate cancer. Nine subclasses of naturally occurring dietary flavonoids have so far been explored and identified to possess clinical potential in preventing and treating prostate cancer. We review herein the antiprostate cancer potential (including in vitro potency, in vivo efficacy, and clinical studies), structure-activity relationships, and the mechanism of actions of the nine subclasses of naturally occurring flavonoids.

Inhibitors of Cancer Stem Cells by María E. García-Rubiño, César Lozano-López, Joaquín M. Campos (1230-1239).
The cancer stem cell (CSC) theory is current strategy of cancer treatment. Cancers follow pathways of cancer stem cell such as Notch, Wnt and Hedgehog can be addressed with natural products or synthetic drugs to diminish the chance of new tumours. The cancer growth can also be suppressed by aiming the tumourigenic stem cells alone, instead of targeting at reducing complete tumour dimension. The recurrence of tumours after years of disease-free survival has prompted interest in the concept that cancers may have a stem cell basis. Current assumption holds that < 5% of the tumour mass may be chemo-resistant and radio-resistant, harbouring stem-like properties that impel tumour survival, development, and metastasis. There is intense an investigation to interpret CSCs based on self-renewal and multi-lineage differentiation. Nevertheless, no successful targeted therapies have reached the clinic. The ionophore antibiotic salinomycin that selectively kills breast CSCs seems to be a promising anticancer drug. Clinical trials conducted by the NIH (National Institute of Health) on several synthetic drugs demonstrate the current importance of the issue and predict a bright future for such molecular weapons against cancer.

Diazenyl Derivatives and their Complexes as Anticancer Agents by Harmeet Kaur, Snehlata Yadav, Balasubramanian Narasimhan (1240-1265).
In the past years, many diazenyl compounds (i.e diazenecarboxamides, diazeniumdiolate prodrugs, diazenyl complexes etc.) have been prepared for the evaluation of their cytotoxic potential towards various cancer cell lines. Majority of them have shown promising cytotoxic activities even against several drug resistant cell lines. These derivatives have shown their effect by acting as alkylating agents, releasers of cytotoxic NO, targeting receptors like tyrosine kinase, EGFR or targeting enzymes like GST, AGT, CDKs etc. Their interaction with different receptors or enzymes leads to DNA damage, necrosis or apoptosis resulting in cell death. The present review will cover updated information on the synthetic methodologies and cytotoxic potential of diazenyl derivatives developed during the past years along with the recent developments. This may prove to be helpful for the researchers to develop novel anticancer drugs in future by molecular modifications of potential derivatives with better cytotoxic activities.

Synthesis of Diflunisal Thiazolidinones as Anticancer Agents by Sevil |enkarde|, &#214;zlem B. &#214;zakp|nar, Derya &#214;zsavc|, Azize |ener, &#214;zge &#199;evik, |. G&#252;niz K&#252;&#231;&#252;kg&#252;zel (1266-1274).
A series of diflunisal 4-thiazolidinones were synthesized. Some selected compounds were determined at one dose towards the full panel of 60 human cancer cell lines by National Cancer Institute. 2',4'-Difluoro-4-hydroxy-N-[4-oxo-2-(thiophen-2-yl)-1,3-thiazolidin-3-yl]biphenyl- 3-carboxamide (4a) demonstrated the most marked effect on K-562 cancer cell line with 58.59 % growth inhibition at 10 ?M. Compound 4a was evaluated in vitro using the MTT colorimetric method against human leukemia cell line K-562 and mouse embryonic fibroblasts cell line NIH- 3T3 at different doses for cell viability and growth inhibition. Compound 4a exhibited anticancer activity with IC50 value of 5.2 ?M against K-562 cells and did not display cytotoxicity towards NIH-3T3 cells compared with diflunisal. In addition, this compound could be an interesting prototype as an antiproliferative agent.

Targeting the Folate Receptor: Effects of Conjugating Folic Acid to DOX Loaded Polymeric Micelles by Mohamed A. Elkhodiry, Ghaleb A. Husseini, Diana Velluto (1275-1280).
In this paper, we report on a potential cancer drug delivery system that utilizes the ligand targeting of the folate receptor. Our drug delivery system consists of Pluronic-P105 micelles, targeted with folic acid moieties. A melanoma folate positive (FR+) (B16-F10), and a fibroblast folate negative (FR-) (NIH-3T3) cell lines are used to compare the cellular accumulation of a chemotherapeutic drug (Doxorubicin) when the delivery is mediated by folated Pluronic P105 micelles. In order to obtain a proper comparison, we corrected for the quenching of Doxorubicin by folic acid molecules and illustrated the significant effect of quenching on the analysis of similar systems. Results show an 80% increase in the accumulation of the antineoplastic agent in the FR+ cell line, when compared to the FR- cell line, thus providing evidence that the efficacy of Pluronic micelles, as drug delivery vehicles, can be enhanced via folic acid targeting.

Investigation of Fucoidan-Oleic Acid Conjugate for Delivery of Curcumin and Paclitaxel by Uyen T. Phan, Khanh T. Nguyen, Toi V. Vo, Wei Duan, Phuong H.L. Tran, T.D. Tran (1281-1287).
Nanoparticles for a specific delivery are likely to be designed for cancer therapeutic effectiveness and improvement. In this study, a fucoidan-oleic acid conjugate was prepared and investigated in terms of loading capacity for poorly water-soluble anti-cancer drugs to maximize effectiveness of the treatment. Fucoidan was used as a hydrophilic portion of an amphiphilic structure for improving cancer therapeutic effects. Paclitaxel and curcumin were chosen as other model drugs loaded in the conjugates. The results showed that self-assembled nanoparticles with different sizes and morphologies could be prepared with two different concentrations of oleic acid as hydrophobic portion. Moreover, loading efficiency and release patterns of these drugs were mainly dependent on the hydrophobic interaction between drugs and oleic acid. It was also revealed that fucoidan and curcumin were released higher at pH 4.5 than at the physiological condition (pH 7.4), thus, facilitating the delivery and maximizing effects of the anticancer agents on cancer cells. On the contrary, paclitaxel from fucoidan nanoparticles was released faster at pH 7.4. The exploration of fucoidan-oleic acid conjugate could be considered as promising nanomedicines for cancer therapeutics.

Macromolecular Drug Targets in Cancer Treatment and Thiosemicarbazides as Anticancer Agents by |. G&#252;niz K&#252;&#231;&#252;kg&#252;zel, G&#246;knil P. Co|kun (1288-1300).
Cancer is known as abnormal cell division and consisting of a group of diseases on various organ tissues. Many therapies are available in cancer treatment such as chemotherapy, radiotherapy etc. Without damaging normal tissue, there is a huge need for specified anticancer drugs which have effect only on abnormal cancer cells. Therefore, advances in anticancer drug discovery in treating cancer in the recent years, directed towards to the macromolecular targets. Heterocyclic molecules, such as fluconazole, acetazolamide, etc., have a significant role in health care and pharmaceutical drug design. Thiosemicarbazides (NH2-NH-CSNH2) are the simplest hydrazine derivatives of thiocarbamic acid and are not only transition compounds, but they are also very effective organic compounds. Thiosemicarbazides possess an amide and amine protons, carbonyl and thione carbons. These structures have attracted the attention of the researchers in the development of novel compounds with anticonvulsant, antiviral, anti-inflammatory, antibacterial, antimycobacterial, antifungal, antioxidant and anticancer activities. Recently, a number of thiosemicarbazides are available commercially as anticancer drugs for novel anticancer drug discovery. Antineoplastic or anticancer drugs prevent or inhibit the maturation and proliferation of neoplasms. These observations have been guiding the researchers for the development of new thiosemicarbazides that possess anticancer activity.

1,3,4-Thiadiazole Based Anticancer Agents by Alireza Aliabadi (1301-1314).
In recent years, researchers like medicinal chemists in the field of medicinal chemistry have widely utilized the 1,3,4-thiadiazole nucleus to investigate its biological and pharmacological effects. This heterocyclic structure has demonstrated various bioactivities such as antifungal, antimicrobial, antiviral, antileishmanial, anti-inflammatory, antihypertensive, antiepileptic, and anticancer effects among others. Anticancer activity is one of its promising effect as five membered heterocyclic rings have widely been investigated by researchers in the recent years. Herein, we reviewed the chemical structures bearing 1,3,4-thiadiazole template exerting anticancer activity.

Natural Product-Derived Spirooxindole Fragments Serve as Privileged Substructures for Discovery of New Anticancer Agents by Bin Yu, Yi-Chao Zheng, Xiao-Jing Shi, Ping-Ping Qi, Hong-Min Liu (1315-1324).
The utility of natural products for identifying anticancer agents has been highly pursued in the last decades and over 100 drug molecules in clinic are natural products or natural product-derived compounds. Natural products are believed to be able to cover unexplored chemical space that is normally not occupied by commercially available molecule libraries. However, the low abundance and synthetic intractability of natural products have limited their applications in drug discovery. Recently, the identification of biologically relevant fragments derived from biologically validated natural products has been recognized as a powerful strategy in searching new biological probes and drugs. The spirocyclic oxindoles, as privileged structural scaffolds, have shown their potential in designing new drugs. Several anticancer drug candidates such as SAR405838, RO8994, CFI-400945 and their bioisosteres are undergoing clinical trials or preclinical studies. To highlight the significant progress, we focus on illustrating the discovery of SAR405838, RO8994, CFI-400945 and their bioisosteres for cancer therapy using substructure-based strategies and discussing modes of action, binding models and preclinical data.

Microtubules are involved in many critical cellular processes including cell division, cell shape maintenance, vesicle transportation and motility regulation. Disruption of tubulin dynamics is a well-validated cancer drug target with several FDA approved, highly efficacious tubulin inhibitors targeting the taxane or the vinca binding sites. Despite the tremendous successes for these clinical tubulin inhibitors, their limitations are also apparent, particularly in the development of transporter mediated drug resistance. While currently there are no FDA approved inhibitors targeting the colchicine binding site in tubulin, extensive preclinical studies have suggested that colchicine binding site inhibitors (CBSIs) have significantly less susceptibility to transporter medicated drug resistance. The presence of one or more heterocyclic moieties is often critical for the antiproliferative activities for most of these CBSIs. This article aims to review the structures and antiproliferative activities of most recently developed heterocyclic CBSIs from 2013 to present. We focus this review on compounds that are designed based on the CA-4, chalcone and PTOX scaffolds which are well established to interact with the colchicine binding site in tubulin.

Quinoxaline Nucleus: A Promising Scaffold in Anti-cancer Drug Discovery by Alessandra C. Pinheiro, Thais C. Mendon&#231;a Nogueira, Marcus V.N. de Souza (1339-1352).
Heterocyclic compounds are a class of substances, which play a critical role in modern drug discovery being incorporated in the structure of a large variety of drugs used in many different types of diseases. Quinoxaline is an important heterocyclic nucleus with a wide spectrum of biological activities, and recently much attention has been found on anticancer drug discovery based on this class. Owing to the importance of this system, the aim of this review is to provide an update on the synthesis and anticancer activity of quinoxaline derivatives covering articles published between 2010 and 2015.