A Novel Cyclic Mobile Transporter Can Induce Apoptosis by Facilitating Chloride Anion Transport into Cells.

We report here the preparation of an aminoxy amide-based pseudopeptide-derived building block using furanoid sugar molecules. Through the cyclo-oligomerization reaction, we generate a hybrid triazole/aminoxy amide macrocycle using the as-prepared building block. The novel conformation of the macrocycle has been characterized using NMR and molecular modeling studies, which show a strong resemblance of our synthesized compound to d-,l-α-aminoxy acid-based cyclic peptides that contain uniform backbone chirality. We observe that the macrocycle can efficiently and selectively bind Cl- ion and transport Cl- ion across a lipid bilayer. 1H NMR anion binding studies suggest a coherent relationship between the acidity of aminoxy amide N-H and triazole C-H proton binding strength. Using time-based fluorescence assay, we show that the macrocycle acts as a mobile transporter and follows an antiport mechanism. Our synthesized macrocycle imposes cancer cell death by disrupting ionic homeostasis through Cl- ion transport. The macrocycle induced cytochrome c leakage and changes in mitochondrial membrane potential along with activation of family of caspases, suggesting that the cellular apoptosis occurs through a caspase-dependent intrinsic pathway. The present results suggest the possibility of using the macrocycle as a biological tool of high therapeutic value.

Therapeutic potentials of plant iridoids in Alzheimer's and Parkinson's diseases: A review.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common age-related neurodegenerative disorders, affecting several millions of aged people globally. Among these disorders, AD is more severe, affecting about 7% of individuals aged 65 and above. AD is primarily a dementia-related disorder from progressive cognitive deterioration and memory impairment, while PD is primarily a movement disorder illness having three major kinesia or movement disorder symptoms, bradykinesia (slowness of movements), hypokinesia (reduction of movement amplitude), and akinesia (absence of normal unconscious movements) along with muscle rigidity and tremor at rest. AD is characterized by deposition of extracellular beta-amyloid (Aß) proteins and intracellular neurofibrillary tangles (NFT), composed of hyperphosphorylated tau proteins in the neurons located particularly in hippocampus and cerebral cortex regions of brain, resulting the neuronal loss, while PD is characterized by deposition of intraneuronal aggregates of mostly composed of alpha-synuclein gene as Lewy bodies (LB) in the striatal region, known as substantia nigra pars compacta (SNpc) of brain, leading to the death of dopaminergic neurons. These are known as pathological hallmarks of these diseases. However, in some overlapping cases, known as Alzheimer with Parkinson disease or vice versa, alpha-synuclein deposition in AD and tau deposition in PD patients are found. Oxidative stress-induced glial cells activation, neuroinflammation and mitochondrial dysfunction lead to various molecular events in brain neurons causing neuronal cell death in these neurodegenerative disorders. Currently used drugs for treatment of AD and PD only reduce the symptoms of these diseases, but unable to stop the process of neurodegeneration. Therefore, innovation of new synthetic drugs or discovery of natural drugs for the treatment of AD and PD, is a challenging task of basic science and clinical medicine. Plant iridoids such as catalpol and its 10-O-trans-p-coumaroyl derivative, geniposide, harpagoside, and loganin, and seco-iridoids, oleuropein and its aglycone and oleocanthal have been found to exhibit significant neuroprotective effect and the property of slowing down the process of neurogedeneration in AD and PD. These plant metabolites have been shown to ameliorate AD by increasing the expression of insulin degrading enzyme (IDE), neprilysin (NEP), PPAR-γ, and α-secretase, and decreasing the expression of ß-secretase (BACE-1) to reduce the levels of Aß oligomers (AßO) deposition in brain neurons. These plant metabolites reduced the expression of GSK-3ß and its receptor gene, PTEN to reduce hyperphosphorylation of tau proteins and neurofibrillary tangles (NFTs) formation. These metabolites improved the expressions of neuroprotective proteins, Bcl-2 via activations of growth-related protein-1 receptor (GLP-1R), PKC, MEK, MAPK/PI3K, and AMPK, and suppressed the expressions of pro-apoptotic proteins, Bax and caspase-3. Furthermore, these plant metabolites improved the lysosomal autophagy process by increasing the expression levels of Beclin-1, LC3II and cathepsin B genes for clearance of Aß and NFT, and increased the expression of transporter proteins, P-glycoprotein (P-gp) and low density lipoprotein receptor-related protein-1 (LRP-1) for the clearance of Aß load from brain across the blood-brain barrier (BBB) as well as increased the expression of PPAR-γ and ApoE proteins for clearance of Aß in ApoE mediated pathway from brain. Moreover, these plant metabolites reduced the cognitive impairment by increasing the expression of synaptic proteins, BDNF, PSD-95, SNAP-25, SYP and GAP-43 for improvement of learning and memory functions in AD. While among these iridoids, catalpol, 10-O-trans-p-coumaroylcatalpol, geniposide and harpagoside, in PD improved the expressions of GDNF and Bcl-2 proteins and TH-positive neurons by increasing the levels of antioxidant enzymes, SOD and GSH-PX and down-regulating insulin/IGF signalling via activation of MEK protein. Moreover, catalpol and its p-coumaroyl derivative in mutant nematode C. elegans model, up-regulated the expression of DAF-16, a FOXO family transcription factor and SKN-1 genes for improvement of lifespan and resistance against oxidative- and other stresses of mutated worms. Furthermore, geniposide increased the expression of autophagy-related LAMP-2A-protein for clearance of LB from dopaminergic neurons in PD brain via improving lysosomal autophagy process. The present review summarizes the neuroprotective activities and molecular mechanisms of these iridoids and secoiridoids, in prevention and/or treatment of both AD and PD. This review will be helpful to find out the research gap on these plant metabolites in this field to use them as potential drugs against these disorders.

Novel ruthenium(II) triazine complex [Ru(bdpta)(tpy)]2+ co-targeting drug resistant GRP78 and subcellular organelles in cancer stem cells.

Ruthenium(II/III) metal complexes have been widely recognized as the alternative chemotherapeutic agents to overcome the drug resistance and tumor recurrence associated with platinum derivatives. In this work, a novel ruthenium(II) triazine complex namely, 1 ([Ru(bdpta)(tpy)]2+) was synthesized and spectroscopically characterized. Drug resistant cancer stem cells (CSCs) were used to evaluate the cytotoxicity of Ru(II) complex 1. The complex 1 showed a greater cytotoxic potential with IC50 values lower than that of cisplatin. The intracellular localization assay confirmed that the complex 1 was effectively distributed into mitochondria as well as endoplasmic reticulum (ER), and executed a ROS-mediated calcium and Bax/Bak dependent intrinsic apoptosis. Interestingly, direct interaction between complex 1 and glucose regulated protein 78 (GRP78), a protein associated with drug resistance caused the ROS-mediated ubiquitination of GRP78. Notably, western blot and confocal microscopy analysis confirmed that complex 1 significantly reduced the protein levels of GRP78. Dose-dependent in vivo antitumor efficacy against CD133+HCT-116 CSCs derived tumor xenograft further validated that complex 1 could be an effective chemotherapeutic agent.

Design, synthesis, and biological evaluation of novel catecholopyrimidine based PDE4 inhibitor for the treatment of atopic dermatitis.

Selective inhibition of phosphodiesterase (PDE) 4B favorably suppresses the synthesis of inflammatory cytokines and subsequently arrest the development of atopic dermatitis via modulating the intracellular cAMP levels. Considering the side effects of corticosteroids, selective PDE4 inhibition could constitute an effective alternative therapy for the treatment of atopic dermatitis (AD). In this study, a series of novel catechol based compounds bearing pyrimidine as the core have been synthesized and screened for the PDE4 inhibitory properties. The PDE4 selectivity of the active compounds over other PDEs has been investigated. Compound 23 bearing pyrimidine core functionalized with catechol, pyridine and trifluoromethyl groups can effectively inhibit the PDE4B with IC50 value in nanomolar range (IC50 = 15 ±â€¯0.4 nM). Compound 23 exhibited seven fold higher selectivity towards PDE4B over PDE4D. Molecular Docking study confirmed its stronger affinity towards catalytic domain of PDE4B. In-vivo analysis confirmed that compound 23 effectively alleviated the symptoms of atopic dermatitis in DNCB-treated Balb/c mice by suppressing the synthesis of inflammatory mediators such as TNF-α, and Ig-E. Taken together, this study suggested that compound 23 could be an effective PDE4 inhibitor for the potential treatment of AD.

Simultaneous parallel and antiparallel self-assembly in a triazole/amide macrocycle conformationally homologous to D-,L-α-amino acid based cyclic peptides: NMR and molecular modeling study.

A 1,4-linked triazole/amide based peptidomimetic macrocycle, synthesized from a triazole amide oligomer of cis-furanoid sugar triazole amino acids, possesses a conformation resembling the D-,L-α-amino acid based cyclic peptides despite having uniform backbone chirality. It undergoes a unique mode of self-assembly through an antiparallel backbone to backbone intermolecular H-bonding involving amide NH and triazole N2/N3 as well as parallel stacking via amide NH and carbonyl oxygen H-bonding, leading to the formation of a tubular nanostructure.