Discovery of novel selective norepinephrine inhibitors: 1-(2-morpholin-2-ylethyl)-3-aryl-1,3-dihydro-2,1,3-benzothiadiazole 2,2-dioxides (WYE-114152)

Direct C-H Alkylation of Benzothiadiazoles via Organic Photoredox Catalysis

2,1,3-Benzothiadiazole is widely used as a privileged scaffold in pharmaceuticals and organic functional materials. Nonetheless, many current methods for the functionalization of 2,1,3-benzothiadiazole rely on preactivation, transition metal catalysts/promoters, or an elevated reaction temperature. Herein we disclose a transition-metal-free visible-light-induced photocatalytic method for the direct C-H alkylation of 2,1,3-benzothiadiazole using readily accessible carboxylic acid derivatives, i.e., N-hydroxyphthalimide esters (NHPEs), as alkylating reagents under room temperature. This mild and scalable method is highlighted by the late-stage installation of the benzothiadiazole scaffold in drugs and natural products.

Simultaneous Monitoring of Intracellular Temperature and Norepinephrine Variation by Fluorescent Probes during Norepinephrine Reuptake

A long-standing challenge has been the simultaneous sensing of intracellular temperature and norepinephrine (NE) variations to explore signaling pathways and depression pathogeny. Here, we designed a fluorescent probe using poly(N-isopropylacrylamide) and 1-[4-(7-nitro-benzo [1,2,5]oxadiazol-4-yl)-piperazin-1-yl]-propenone (PNIPAm-AANBD) and (E)-1-(4-boronobenzyl)-2-(2-(1,3-dioxo-1H,3H-benzo[de]isochromen-6-yl)vinyl)pyridin-1-ium bromide (PHE) for simultaneously measuring the temperature and NE with high selectivity. The fluorescence intensity of the PNIPAm-AANBD moiety exhibited a good response to temperature changes. The PHE moiety could selectively sense NE due to the naphthalic anhydride group in PHE, which formed naphthalimide upon bonding with the primary amino group of NE. The hydroxyl-terminated ligand recognized the phenolic hydroxyl group of NE through the formation of hydrogen bonds. Using the proposed fluorescent probe, variations in the intracellular temperature and NE during NE reuptake could be simultaneously measured. It was first discovered that with the inhibition of antidepressant drugs, the intracellular temperature increased by 1.2-2.1 °C, and the NE reuptake decreased by about 21.5 μM. The measured variations in intracellular temperature and NE during neurotransmitter reuptake can shed light on the underlying mechanism of neurotransmitter signaling pathways, which may facilitate the treatment of depression.

Dezocine exhibits antihypersensitivity activities in neuropathy through spinal μ-opioid receptor activation and norepinephrine reuptake inhibition

Dezocine is the number one opioid painkiller prescribed and sold in China, occupying 44% of the nation’s opioid analgesics market today and far ahead of the gold-standard morphine. We discovered the mechanisms underlying dezocine antihypersensitivity activity and assessed their implications to antihypersensitivity tolerance. Dezocine, given subcutaneously in spinal nerve-ligated neuropathic rats, time- and dose-dependently produced mechanical antiallodynia and thermal antihyperalgesia, significantly increased ipsilateral spinal norepinephrine and serotonin levels, and induced less antiallodynic tolerance than morphine. Its mechanical antiallodynia was partially (40% or 60%) and completely (100%) attenuated by spinal μ-opioid receptor (MOR) antagonism or norepinephrine depletion/α₂-adrenoceptor antagonism and combined antagonism of MORs and α₂-adenoceptors, respectively. In contrast, antagonism of spinal κ-opioid receptors (KORs) and δ-opioid receptors (DORs) or depletion of spinal serotonin did not significantly alter dezocine antiallodynia. In addition, dezocine-delayed antiallodynic tolerance was accelerated by spinal norepinephrine depletion/α₂-adenoceptor antagonism. Thus dezocine produces antihypersensitivity activity through spinal MOR activation and norepinephrine reuptake inhibition (NRI), but apparently not through spinal KOR and DOR activation, serotonin reuptake inhibition or other mechanisms. Our findings reclassify dezocine as the first analgesic of the recently proposed MOR-NRI, and reveal its potential as an alternative to as well as concurrent use with morphine in treating pain.

Radiosynthesis and first preclinical evaluation of the novel norepinephrine transporter pet-ligand [(11)C]ME@HAPTHI

Background

The norepinephrine transporter (NET) has been demonstrated to be relevant to a multitude of neurological, psychiatric and cardiovascular pathologies. Due to the wide range of possible applications for PET imaging of the NET together with the limitations of currently available radioligands, novel PET tracers for imaging of the cerebral NET with improved pharmacological and pharmacodynamic properties are needed.

Methods

The present study addresses the radiosynthesis and first preclinical evaluation of the novel NET PET tracer [¹¹C]Me@HAPTHI by describing its affinity, selectivity, metabolic stability, plasma free fraction, blood–brain barrier (BBB) penetration and binding behaviour in in vitro autoradiography.

Results

[¹¹C]Me@HAPTHI was prepared and displayed outstanding affinity and selectivity as well as excellent in vitro metabolic stability, and it is likely to penetrate the BBB. Moreover, selective NET binding in in vitro autoradiography was observed in human brain and rat heart tissue samples.

Conclusions

All preclinical results and radiosynthetic key-parameters indicate that the novel benzothiadiazole dioxide-based PET tracer [¹¹C]Me@HAPTHI is a feasible and improved NET radioligand and might prospectively facilitate clinical NET imaging.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-015-0113-3) contains supplementary material, which is available to authorized users.