Photoresponsive transformation from spherical to nanotubular assemblies: anticancer drug delivery using macrocyclic cationic gemini amphiphiles.

We developed NIR-light-responsive macrocyclic cationic gemini amphiphiles, one of which displayed various favorable properties of lipids. The NIR-light-mediated cleavage of the strained dioxacycloundecine ring led to the conversion of the spherical to a nanotubular self-assembly in the aqueous medium. This photo-mediated transformation from the spherical to nanotubular self-assembly resulted in the release of encapsulated hydrophobic anticancer drug molecule doxorubicin (Dox) in a controlled manner. The potent cationic gemini amphiphile also displayed lower cytotoxicity and efficient NIR-light-mediated Dox release efficacy to cancerous cells.

Inhibition of immunosuppressive indoleamine 2,3-dioxygenase by targeting the heme and apo-form.

Inhibition of immunomodulating enzyme indoleamine 2,3-dioxygenase 1 (IDO1) is considered one of the potential approaches in the fight against cancer and other diseases. Comprehensive biophysical and cellular studies have shown that quinine derivatives effectively inhibit the activity of IDO1. Mechanistic studies revealed that the potent quinine derivatives compete with heme for binding to apo-IDO1 and perturb its reversible binding propensity to apo-IDO1 via the formation of a heme-inhibitor complex. This IDO1 inhibitory pathway could provide new avenues to immunotherapy-based drug discovery strategies.

Quinine-Based Semisynthetic Ion Transporters with Potential Antiproliferative Activities.

Synthetic ion transporters have attracted tremendous attention for their therapeutic potential against various ion-transport-related diseases, including cancer. Inspired by the structure and biological activities of natural products, we synthesized a small series of squaramide and thiourea derivatives of quinine and investigated their ion transport activities. The involvement of a quinuclidine moiety for the cooperative interactions of Cl- and H+ ions with the thiourea or squaramide moiety resulted in an effectual transport of these ions across membranes. The interference of ionic equilibrium by the potent Cl- ion carrier selectively induced cancer cell death by endorsing caspase-arbitrated apoptosis. In vivo assessment of the potent ionophore showed an efficient reduction in tumor growth with negligible immunotoxicity to other organs.

A stimuli-responsive anticancer drug delivery system with inherent antibacterial activities.

We describe a novel class of stimuli-sensitive sulfonium-based synthetic lipids, which exhibit several favorable biophysical properties of phospholipids. The potent sulfonium-based lipid was successfully disassembled by glutathione to release the encapsulated drug molecules in a controlled manner. The cationic lipid also showed lower cytotoxicity against mammalian cells and displayed moderate antibacterial activities.

Favorable outcomes and reduced toxicity with a novel vinblastine-based non-high dose methotrexate (HDMTX) regimen (modified MCP-842) in pediatric anaplastic large cell lymphoma (ALCL): experience from India.

Anaplastic large cell lymphoma (ALCL) is a rare form of non-Hodgkin lymphoma (NHL) in children. Most treatment regimens include high-dose methotrexate (HDMTX), which is logistically difficult to administer in resource-limited settings. We evaluated the outcomes of pediatric ALCL patients treated on a uniform protocol (Modified Multicentric Protocol, MCP-842 regimen) at our hospital between January 2005 and December 2016. Of the 68 patients who received treatment on the Modified MCP842 protocol, 46 patients are alive in remission, 11(16%) had disease progression, 9(13%) relapsed after achieving remission, and 5(7%) had treatment-related mortality (TRM). Seventeen of 20 relapsed/progressed patients subsequently expired. With a median follow-up of 55 months (range 2-165 months), the 4-year event-free survival (EFS) and overall survival (OS) are 63% (95% CI of 50-73%) and 70%(95% CI of 57-79%), respectively. An indigenous protocol using vinblastine (without HDMTX and steroids) is feasible in a resource-limited setting and achieves outcomes comparable to regimens incorporating HDMTX, with lower toxicity.

4,5-Disubstituted 1,2,3-triazoles: Effective Inhibition of Indoleamine 2,3-Dioxygenase 1 Enzyme Regulates T cell Activity and Mitigates Tumor Growth.

The improvement of body's own immune system is considered one of the safest approaches to fight against cancer and several other diseases. Excessive catabolism of the essential amino acid, L-tryptophan (L-Trp) assists the cancer cells to escape normal immune obliteration. The formation of disproportionate kynurenine and other downstream metabolites suppress the T cell functions. Blocking of this immunosuppressive mechanism is considered as a promising approach against cancer, neurological disorders, autoimmunity, and other immune-mediated diseases. Overexpression of indoleamine 2,3-dioxygenase 1 (IDO1) enzyme is directly related to the induction of immunosuppressive mechanisms and represents an important therapeutic target. Several classes of small molecule-based IDO1 inhibitors have been already reported, but only few compounds are currently being evaluated in various stages of clinical trials as adjuvants or in combination with chemo- and radiotherapies. In the quest for novel structural class(s) of IDO1 inhibitors, we developed a series of 4,5-disubstituted 1,2,3-triazole derivatives. The optimization of 4,5-disubstituted 1,2,3-triazole scaffold and comprehensive biochemical and biophysical studies led to the identification of compounds, 3i, 4i, and 4k as potent and selective inhibitors of IDO1 enzyme with IC50 values at a low nanomolar level. These potent compounds also showed strong IDO1 inhibitory activities in MDA-MB-231 cells with no/negligible level of cytotoxicity. The T cell activity studies revealed that controlled regulation of IDO1 enzyme activity in the presence of these potent compounds could induce immune response against breast cancer cells. The compounds also showed excellent in vivo antitumor efficacy (of tumor growth inhibition = 79-96%) in the female Swiss albino mice. As a consequence, this study describes the first example of 4,5-disubstituted 1,2,3-triazole based IDO1 inhibitors with potential applications for immunotherapeutic studies.

Tuning the solubility of ionophores: glutathione-mediated transport of chloride ions across hydrophobic membranes.

A stimuli-responsive anion transport strategy was successfully employed to regulate the water solubility of ionophores and promote controlled transport of Cl- ions across lipid bilayers. A sulfonium-based proanionophore was efficiently activated by glutathione to regenerate the active anionophore, which allowed controlled transport of Cl- ions in a cellular environment with lower cytotoxicity.

Diphenylethylenediamine-Based Potent Anionophores: Transmembrane Chloride Ion Transport and Apoptosis Inducing Activities.

Synthetic anion transporters have been recognized as one of the potential therapeutic agents for the treatment of diseases including cystic fibrosis, myotonia, and epilepsy that originate due to the malfunctioning of natural Cl- ion transport systems. Recent studies showed that the synthetic Cl- ion transporters can also disrupt cellular ion-homeostasis and induce apoptosis in cancer cell lines, leading to a revived attention for synthetic Cl- ion transporters. Herein, we report the development of conformationally controlled 1,2-diphenylethylenediamine-based bis(thiourea) derivatives as a new class of selective Cl- ion carrier. The strong Cl- ion binding properties ( Kd = 3.87-6.66 mM) of the bis(thiourea) derivatives of diamine-based compounds correlate well with their transmembrane anion transport activities (EC50 = 2.09-4.15 nM). The transport of Cl- ions via Cl-/NO3- antiport mechanism was confirmed for the most active molecule. Perturbation of Cl- ion homeostasis by this anion carrier induces cell death by promoting the caspase-mediated intrinsic pathway of apoptosis.

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1 H-Pyrazoles Using Lewis Acid.

An unusual transformation of indoles to pyrazoles via an aromatic ring-opening strategy has been developed. The salient feature of this strategy involves the C2-N1 bond opening and concomitant cyclization reaction of the C2═C3 bond of the indole moiety with the tosylhydrazone, which proceeds under transition-metal and ligand free conditions. This ring-opening functionalization of indoles provides a wide scope of differently substituted pyrazoles.

Azidophosphonate Chemistry as a Route for a Novel Class of Vesicle-Forming Phosphonolipids.

Membrane forming synthetic lipids constitutes a new class of biomaterials with impressive applications in the field of biological and pharmaceutical sciences. Interestingly, alteration(s) in the headgroup region of the lipids offer a wide chemical space to investigate their specific properties. In this regard, we have utilized ß-azidophosphonate chemistry to gain access to a novel class of triazole-phosphonate (TP) amphiphiles with fascinating physicochemical properties of lipids. TP lipids form stable vesicles that exhibit negative surface potential across a broad pH range. These anionic lipids have high phase-transition temperatures, phospholipase resistance, slow vesicle leakage profiles, and doxorubicin delivery efficacy. We hypothesize that these readily synthesizable phosphonolipids could find several applications as phospholipid substituents.