Design, synthesis, and biological evaluation of optimized phthalazine derivatives as hedgehog signaling pathway inhibitors

Challenges and Recent Advances of Novel Chemical Inhibitors in Medulloblastoma Therapy

Medulloblastoma is a common term used for the juvenile malignant brain tumor, and its treatment is exciting due to different genetic origins, improper transportation of drug across the blood-brain barrier, and chemo-resistance with various side effects. Currently, medulloblastoma divided into four significant subsections (Wnt, Shh, Group 3, and Group 4) is based on their hereditary modulation and histopathological advancement. In this chapter, we tried to combine several novel chemical therapeutic agents active toward medulloblastoma therapy. All these compounds have potent activity to inhibit the medulloblastoma.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.

I2/NaH2PO2-mediated deoxyamination of cyclic ethers for the synthesis of N-aryl-substituted azacycles

We have developed a protocol for efficient synthesis of N-aryl-substituted azacycles from aryl amines and cyclic ethers using I2/NaH2PO2 as the mediator.

Synthetic and medicinal chemistry of phthalazines: Recent developments, opportunities and challenges

Fused diaza-heterocycles constitute the core structure of numerous bioactive natural products and effective therapeutic drugs. Among them, phthalazines have been recognized as remarkable structural leads in medicinal chemistry due to their wide application in pharmaceutical and agrochemical industries. Accessing such challenging pharmaceutical agents/drug candidates with high chemical complexity through synthetically efficient approaches remains an attractive goal in the contemporary medicinal chemistry and drug discovery arena. In this review, we focus on the recent developments in the synthetic routes towards the generation of phthalazine-based active pharmaceutical ingredients and their biological potential against various targets. The general reaction scope of these innovative and easily accessible strategies was emphasized focusing on the functional group tolerance, substrate and coupling partner compatibility/limitation, the choice of catalyst, and product diversification. These processes were also accompanied by the mechanistic insights where deemed appropriate to demonstrate meaningful information. Moreover, the rapid examination of the structure-activity relationship analyses around the phthalazine core enabled by the pharmacophore replacement/integration revealed the generation of robust, efficient, and more selective compounds with pronounced biological effects. A large variety of in silico methods and ADME profiling tools were also employed to provide a global appraisal of the pharmacokinetics profile of diaza-heterocycles. Thus, the discovery of new structural leads offers the promise of improving treatments for various tropical diseases such as tuberculosis, leishmaniasis, malaria, Chagas disease, among many others including various cancers, atherosclerosis, HIV, inflammatory, and cardiovascular diseases. We hope this review would serve as an informative collection of structurally diverse molecules enabling the generation of mature, high-quality, and innovative routes to support the drug discovery endeavors.

Design of Hedgehog pathway inhibitors for cancer treatment

Hedgehog (Hh) signaling is involved in the initiation and progression of various cancers and is essential for embryonic and postnatal development. This pathway remains in the quiescent state in adult tissues but gets activated upon inflammation and injuries. Inhibition of Hh signaling pathway using natural and synthetic compounds has provided an attractive approach for treating cancer and inflammatory diseases. While the majority of Hh pathway inhibitors target the transmembrane protein Smoothened (SMO), some small molecules that target the signaling cascade downstream of SMO are of particular interest. Substantial efforts are being made to develop new molecules targeting various components of the Hh signaling pathway. Here, we have discussed the discovery of small molecules as Hh inhibitors from the diverse chemical background. Also, some of the recently identified natural products have been included as a separate section. Extensive structure-activity relationship (SAR) of each chemical class is the focus of this review. Also, clinically advanced molecules are discussed from the last 5 to 7 years. Nanomedicine-based delivery approaches for Hh pathway inhibitors are also discussed concisely.

Potential use of CXCL12/CXCR4 and sonic hedgehog pathways as therapeutic targets in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor occurring in children, and although high long-term survival rates have been reached with current therapeutic protocols, several neurological injuries are still observed among survivors. It has been shown that the development of MB is highly dependent on the microenvironment surrounding it and that the CXCL12 chemokine and its receptor, CXCR4 and the Sonic Hedgehog (SHH) pathway are crucial for cerebellar development, coordinating proliferation and migration of embryonic cells and malfunctions in these axes can lead to MB development. Indeed, the concomitant overactivation of these axes was suggested to define a new MB molecular subgroup. New molecules are being studied, aiming to inhibit either CXCR4 or the SHH pathways and have been tested in preclinical settings for the treatment of cancers. The use of these molecules could improve MB treatment and save patients from aggressive surgery, chemotherapy and radiotherapy regimens, which are responsible for severe neurological consequences. This review aims to summarize current data about the experimental inhibition of CXCR4 and SHH pathways in MB and its potential implications in treatment of this cancer.

Synthesis and evaluation of novel dimethylpyridazine derivatives as hedgehog signaling pathway inhibitors

We report herein the design and synthesis of a series of structural modified dimethylpyridazine compounds as novel hedgehog signaling pathway inhibitors. The bicyclic phthalazine core and 4-methylamino-piperidine moiety of Taladegib were replaced with dimethylpyridazine and different azacycle building blocks, respectively. The in vitro Gli-luciferase assay results demonstrate that the new scaffold still retained potent inhibitory potency. Piperidin-4-amine moiety was found to be the best linker between pharmacophores dimethylpyridazine and fluorine substituted benzoyl group. Furthermore, the optimization of 1-methyl-1H-pyrazol and 4-fluoro-2-(trifluoromethyl)benzamide by different aliphatic or aromatic rings were also investigated and the SAR were described. Several new derivatives were found to show potent Hh signaling inhibitory activity with nanomolar IC₅₀ values. Among these compounds, compound 11c showed the highest inhibitory potency with an IC₅₀ value of 2.33 nM, which was comparable to the lead compound Taladegib. In vivo efficacy of 11c in a ptch^+/-p53^-/- mouse medulloblastoma allograft model also indicated encouraging results.