Synchronous Fluorescence Determination of Al3+ Using 3-Hydroxy-2-(4-Methoxy Phenyl)-4H-Chromen-4-One as a Fluorescent Probe.

A simple synchronous fluorescent chemosensor 3-hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (3-HC) has been synthesized for the selective analysis of Al3+. On the addition of Al3+, 3-HC displayed a redshift with a change in wavelength of emission maximum from 436 to 465 nm along with enhancement in fluorescence intensity, which formed the basis for its sensitive detection. Under optimized conditions, 3-HC was applied for the determination of Al3+ in the concentration range of 1 × 10-7-1 × 10-6 M. The limit of detection (LOD) and limit of quantification (LOQ) values were found out to be 1.69 × 10-8 and 5.07 × 10-8 M respectively. Further, the developed method was applied for the analysis of Al3+ in real water samples (tap water, bottled water, and tube well water) which showed good recovery values in the range of 95-99.7% with RSD less than 4%.

Surface Molecularly Imprinted Carbon Dots Based Core-Shell Material for Selective Fluorescence Sensing of Ketoprofen.

In this work, we report an environment friendly core-shell material based on Carbon Dot core and Molecularly Imprinted Polymer shell as sensor for highly selective fluorescence detection of ketoprofen. The Carbon Dots (CDs) were prepared by a hydrothermal method and the polymer layer around the CDs core was synthesised by sol-gel polymerisation. The prepared material was characterized by Fluorescence Spectroscopy, FT-IR Spectroscopy and Transmission Electron Spectroscopy (TEM). Fluorescence from the Carbon Dots- Molecularly Imprinted Polymer (CDs-MIP) was found to quench selectively in the presence of ketoprofen and quenching effect was found to be greater than for Non-Imprinted Polymer (CDs-NIP) which indicated the potential of CDs-MIP as a fluorescence sensing material for ketoprofen. The imprinting factor was obtained to be 2.35. Under optimized conditions, a linear response was obtained in the concentration range from 0.039 to 3.9 µM with a detection limit of 0.01 µM. The correlation coefficient was 0.999. The developed sensor was applied to determination of ketoprofen in human serum and urine samples with good recoveries ranging from 96 to 104% indicating successful application of the proposed sensor in biological fluids.

Angelman Syndrome Protein Ube3a Regulates Synaptic Growth and Endocytosis by Inhibiting BMP Signaling in Drosophila.

Altered expression of the E3 ubiquitin ligase UBE3A, which is involved in protein degradation through the proteasome-mediated pathway, is associated with neurodevelopmental and behavioral defects observed in Angelman syndrome (AS) and autism. However, little is known about the neuronal function of UBE3A and the pathogenesis of UBE3A-associated disorders. To understand the in vivo function of UBE3A in the nervous system, we generated multiple mutations of ube3a, the Drosophila ortholog of UBE3A. We found a significantly increased number of total boutons and satellite boutons in conjunction with compromised endocytosis in the neuromuscular junctions (NMJs) of ube3a mutants compared to the wild type. Genetic and biochemical analysis showed upregulation of bone morphogenetic protein (BMP) signaling in the nervous system of ube3a mutants. An immunochemical study revealed a specific increase in the protein level of Thickveins (Tkv), a type I BMP receptor, but not other BMP receptors Wishful thinking (Wit) and Saxophone (Sax), in ube3a mutants. Ube3a was associated with and specifically ubiquitinated lysine 227 within the cytoplasmic tail of Tkv, and promoted its proteasomal degradation in Schneider 2 cells. Negative regulation of Tkv by Ube3a was conserved in mammalian cells. These results reveal a critical role for Ube3a in regulating NMJ synapse development by repressing BMP signaling. This study sheds new light onto the neuronal functions of UBE3A and provides novel perspectives for understanding the pathogenesis of UBE3A-associated disorders.

Study on the fluorescence quenching reaction of amitriptyline and clomipramine hydrochlorides with eosin Y and its analytical application.

Amitriptyline.HCl (AMI) and clomipramine.HCl (CMI) react with eosin Y (EY) in pH 3.8 NaAc-AcH buffer solution to form ion association complex which results in quenching of fluorescence of EY and appearance of a new resonance Rayleigh scattering (RSS) spectrum at 620 nm. The spectral characteristics of absorption, fluorescence and RSS spectra have been investigated. The factors influencing the reaction were studied and optimum conditions for the reaction have been determined. Based on fluorescence quenching, a simple and sensitive spectrofluorimetric method for determination of AMI and CMI has been developed. The fluorescence quenching intensity was measured at 550 nm using an excitation wavelength of 310 nm. The calibration graph was found to be rectilinear in the range 0.08-2.0 µg mL(-1) with detection limit of 0.017 µg mL(-1) for AMI and 0.06-2.0 µg mL(-1) with detection limit of 0.015 µg mL(-1) for CMI. The method can be satisfactorily applied to the determination of AMI and CMI in tablets without interference from commonly occurring exicipients. The recovery and RSD values obtained indicate good accuracy and precision of the method. The mechanism of the reaction and fluorescence quenching has also been discussed.

Highly sensitive synchronous fluorescence measurement of danofloxacin in pharmaceutical and milk samples using aluminium (III) enhanced fluorescence.

A simple, rapid and sensitive constant wavelength synchronous fluorescence method is developed for the determination of danofloxacin (DAN) in pharmaceutical formulations and its residue in milk based on Al(III) enhanced fluorescence. The synchronous fluorescence intensity of the system is measured at 435 nm using ∆ λ = 80 nm and an excitation wavelength of 280 nm. A good linear relationship between enhanced fluorescence intensity and DAN concentration is obtained in the range of 3-100 ng mL(-1)(r (2) = 0.9991). The limit of detection (LOD, S/N = 3) of the present method is 0.9 ng mL(-1). The proposed method can be successfully applied to the determination of DAN in pharmaceutical formulations and in milk without serious interferences from common excipients, metal ions and other co-existing substances. The method can be used as a rapid screening to judge whether the DAN residues in milk exceed Maximum Residue Limits (MRLs) or not.

Critical factors influencing in vitro propagation and modulation of important secondary metabolites in Withania somnifera (L.) dunal.

Withania somnifera (L.) Dunal is a valuable medicinal plant in the Solanaceae family. It is commonly known as Ashwagandha and is widely distributed around the globe. It has multiple pharmacological properties owing to the existence of diverse secondary metabolites viz., withanolide A, withanolide D, withaferin A, and withanone. It is in great demand in the herbal industry because of its extensive use. In this background, the major challenge lies in the rapid multiplication of elite cultivars of W. somnifera in order to produce genetically and phytoconstituents uniform plant material for pharmaceutical industries. Thus it is necessary to explore various biotechnological approaches for the clonal mass propagation and synthesis of pharmaceutically important constituents in W. somnifera. Though there are several studies on in vitro propagation on W. somnifera, yet many factors that critically influence the in vitro response and withanolides production need to be fine-tuned in the pretext of the existing knowledge. The current review focuses on the advancements and prospects in biotechnological interventions to meet the worldwide demands for W. somnifera and its bioactive compounds. This update on in vitro studies on W. somnifera will be useful to many researchers, entrepreneurs, and herbal industries looking for its in vitro mass multiplication and scientific utilization.

Identification of potential inhibitors of brain-specific CYP46A1 from phytoconstituents in Indian traditional medicinal plants.

Cytochrome P450 46A1 (CYP46A1) is a crucial enzyme in brain that converts cholesterol to 24 (S) hydroxy cholesterol thereby increasing its polarity to facilitate removal of excess cholesterol from the CNS. The inhibition of CYP46A1 with several synthetic molecules has been investigated extensively for treatment of Alzheimer's disease, Huntington's disease, glaucoma, and in hippocampal neurons from aged mice. However, phytochemicals have received far little attention in studies involving development of potential CYP46A1 inhibitors. Thus, in the present study phytoconstituents from Indian traditional medicinal plants; Bacopa monnieri, Piper longum, and Withania somnifera, were virtually screened for interaction with CYP46A1 using computational tools. Out of three plants, six molecules from P. longum and three molecules from W. somnifera were shortlisted to study interactions with CYP46A1 based on the physio-chemical parameters. Fargesin, piperolactam A and coumaperine from P. longum showed the higher binding affinity and the values were - 10.3, - 9.5, - 9.0 kcal/moles respectively, whereas, withaferin A from W. somnifera had a binding affinity of - 12.9 kcal/mol. These were selected as potential modulators as they exhibited suitable interactions with active site residues; Tyr109, Leu112, Trp368, Gly369, and Ala474. The selected molecules were further subjected to molecular dynamics simulation. Further, the pharmacological properties of molecules were also predicted using ADMET calculator and the data revealed that all the selected compounds had good absorption as well as solubility characteristics. In addition, sesamin, fargesin, piperolactam A, and coumaperine had minimal or no toxic effects. Thus, the study successfully identified compounds from Indian medicinal plants that may serve as potential inhibitors of CYP46A1 or base structures to design novel CYP46A1 inhibitors, which may be effective in treating neurological conditions involving perturbed cholesterol homeostasis. Supplementary Information: The online version contains supplementary material available at 10.1007/s42485-022-00098-x.

Self-polymerized polydopamine-imprinted layer-coated carbon dots as a fluorescent sensor for selective and sensitive detection of 17ß-oestradiol.

The compound 17ß-oestradiol (E2) is a steroidal oestrogen used extensively in food processing and animal husbandry. As E2 is well-known as a typical endocrine disrupting chemical, its release, penetration, and exposure create serious environmental concerns. Carbon dots (CDs) have attracted great attention due to their excellent fluorescent and non-toxic properties. To help improve the selectivity of CDs, they can be combined with molecularly-imprinted polymers (MIPs). In light of the limitations involved in the fabrication of MIP layer on CDs (e.g., time consumption and low controllability of imprinted layer), the mussel inspired dopamine self-polymerization can be considered as an alternative option. As functional monomer in molecular imprinted technology, dopamine can be used efficiently to polymerize in weak alkaline condition (e.g., formation of polydopamine). In this research, a new method was developed for selective and sensitive fluorescent detection of E2 based on self-polymerization of dopamine (functional monomer) on fluorescent carbon dots (CDs@MI-PDA). The developed sensor selectively binds with E2 to quench the fluorescence intensity of CDs by photo-induced electron transfer. The sensor showcases a detection limit of E2 as 0.34 ng/mL with a linearity over 1-50 ng/mL. Furthermore, the probe was successfully applied to water (tap and river water) and milk samples with recoveries of 96.4-102.2 %. This study is expected to open a new path for the development of a simple and convenient detection approach for E2 present in complex matrices.

Mesoporous silica imprinted carbon dots for the selective fluorescent detection of triclosan.

A molecularly imprinted fluorescence sensor built as a mesoporous structured silica imprinted layer on the surface of carbon dots (CDs@m-MIP) was employed for the selective detection of triclosan (TRI). The fluorescence of this CDs@m-MIP was affected sensitively and selectively by TRI via an electron transfer-induced fluorescence quenching mechanism with a detection limit of TRI at 1.08 nM (range 1.72-138 nM) under the optimum setup (e.g., pH, response time, and CDs@m-MIP dose). This approach was used successfully to detect TRI in real water samples (e.g., sewage, river, and tap water). The recoveries of TRI were satisfactory in spiked river and tap water (in 94.7-99.5 %). The outcome of this research is thus expected to help develop highly efficient fluorescent sensing systems towards diverse hazardous compounds including TRI.

Diversity of structure and function of alpha1alpha6beta3delta GABAA receptors: comparison with alpha1beta3delta and alpha6beta3delta receptors.

delta subunit-containing gamma-aminobutyric acid, type A (GABA(A))receptors are expressed extrasynaptically and mediate tonic inhibition. In cerebellar granule cells, they often form receptors together with alpha(1) and/or alpha(6) subunits. We were interested in determining the architecture of receptors containing both subunits. We predefined the subunit arrangement of several different GABA(A) receptor pentamers by concatenation. These receptors composed of alpha(1), alpha(6), beta(3), and delta subunits were expressed in Xenopus oocytes. Currents elicited in response to GABA were determined in the presence and absence of 3alpha,21-dihydroxy-5alpha-pregnan-20-one (THDOC) or ethanol, or currents were elicited by 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol (THIP). Several subunit configurations formed active channels. We therefore conclude that delta can assume multiple positions in a receptor pentamer made up of alpha(1), alpha(6), beta(3), and delta subunits. The different receptors differ in their functional properties. Functional expression of one receptor type was only evident in the combined presence of the neurosteroid THDOC with the channel agonist GABA. Most, but not all, receptors active with GABA/THDOC responded to THIP. None of the receptors was modulated by ethanol concentrations up to 30 mm. Several observations point to a preferred position of delta subunits between two alpha subunits in alpha(1)alpha(6)beta(3)delta receptors. This property is shared by alpha(1)beta(3)delta and alpha(6)beta(3)delta receptors, but there are differences in the additionally expressed isoforms.

Hollow porous molecularly imprinted polymers as emerging adsorbents.

Hollow porous molecularly imprinted polymers (HPMIPs) are identified as promising adsorbents with many advantageous properties (e.g., large number of imprinted cavities, highly accessible binding sites, controllable pore structure, and fast mass transfer). Because of such properties, HPMIPs can exhibit improved binding capacity and kinetics to make analyte molecules readily interact with a greater number of recognition sites on the imprinted shell. This review highlights the synthesis and utility of HPMIPs as adsorbents to cover diverse targets of interest (e.g., endocrine disrupting chemicals, pharmaceuticals, pesticides, and heavy metal ions). The overall potential of HPMIPs is thus discussed in the context of analytical chemistry with particular focus on the efficient extraction of trace-level targets from complex matrices.

Dual-template magnetic molecularly imprinted polymer-based sorbent for simultaneous and selective detection of phenolic endocrine disrupting compounds in foodstuffs.

In this research, an efficient (94.9-99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe3O4@SiO2 (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL-1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL-1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL-1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.

Primary low-grade mucinous adenocarcinoma spleen resulting in Pseudomyxoma peritonei: A case report.

A 61-year-old man presented with complaints of abdominal pain, loss of weight, and splenomegaly since past 6 months. On computed tomography, the spleen was totally replaced by multiloculated cysts and splenectomy was performed. Pathological examination revealed a low-grade mucinous adenocarcinoma. Postoperative PET scan was negative, and in the absence of a primary tumor elsewhere, we considered this tumor to be primary in the spleen, and it was presumed that the tumor arose from invaginated capsular mesothelium of the spleen.

Anti-neuroinflammatory potential of Tylophora indica (Burm. f) Merrill and development of an efficient in vitro propagation system for its clinical use.

Neuroinflammation is a major risk factor associated with the pathogenesis of neurodegenerative diseases. Conventional non-steroidal anti-inflammatory drugs are prescribed but their long term use is associated with adverse effects. Thus, herbal based medicines are attracting major attraction worldwide as potential therapeutic candidates. Tylophora indica (Burm. f) Merrill is a valuable medicinal plant well known in Ayurvedic practices for its immunomodulatory, anti-oxidant, anti-asthmatic and antirheumatic activities. The present study aimed to elucidate the anti-neuroinflammatory potential of water and hydroalcoholic leaf extracts of micropropagated plants of T. indica using BV-2 microglia activated with lipopolysaccharide as an in vitro model system and development of an efficient reproducible protocol for its in vitro cloning. Non cytotoxic doses of the water and hydroalcoholic extracts (0.2µg/ml and 20µg/ml, respectively) were selected using MTT assay. α-Tubulin, Iba-1 and inflammatory cascade proteins like NFκB, AP1 expression was studied using immunostaining to ascertain the anti-neuroinflammatory potential of these extracts. Further, anti-migratory activity was also analyzed by Wound Scratch Assay. Both extracts effectively attenuated lipopolysaccharide induced microglial activation, migration and the production of nitrite via regulation of the expression of NFκB and AP1 as the possible underlying target molecules. An efficient and reproducible protocol for in vitro cloning of T. indica through multiple shoot proliferation from nodal segments was established on both solid and liquid Murashige and Skoog's (MS) media supplemented with 15µM and 10µM of Benzyl Amino Purine respectively. Regenerated shoots were rooted on both solid and liquid MS media supplemented with Indole-3-butyric acid (5-15µM) and the rooted plantlets were successfully acclimatized and transferred to open field conditions showing 90% survivability. The present study suggests that T. indica may prove to be a potential anti-neuroinflammatory agent and may be further explored as a potential therapeutic candidate for the management of neurodegenerative diseases. Further, the current study will expedite the conservation of T. indica ensuring ample supply of this threatened medicinal plant to fulfill its increasing demand in herbal industry.

Structure of alpha6 beta3 delta GABA(A) receptors and their lack of ethanol sensitivity.

Delta (delta) subunit containing GABA(A) receptors are expressed extra-synaptically and mediate tonic inhibition. In cerebellar granule cells, they often form a receptor together with alpha(6) subunits. We were interested to determine the architecture of these receptors. We predefined the subunit arrangement of 24 different GABA(A) receptor pentamers by subunit concatenation. These receptors (composed of alpha(6), beta(3) and delta subunits) were expressed in Xenopus oocytes and their electrophysiological properties analyzed. Currents elicited in response to GABA were determined in presence and absence of 3alpha, 21-dihydroxy-5alpha-pregnan-20-one and to 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol. alpha(6)-beta(3)-alpha(6)/delta receptors showed a substantial response to GABA alone. Three receptors, beta(3)-alpha(6)-delta/alpha(6)-beta(3), alpha(6)-beta(3)-alpha(6)/beta(3)-delta and beta(3)-delta-beta(3)/alpha(6)-beta(3), were only uncovered in the combined presence of the neurosteroid 3alpha, 21-dihydroxy-5alpha-pregnan-20-one with GABA. All four receptors were activated by 4,5,6,7-tetrahydroisoxazolo[5,4-c]-pyridin-3-ol. None of the functional receptors was modulated by physiological concentrations (up to 30 mM) of ethanol. GABA concentration response curves indicated that the delta subunit can contribute to the formation of an agonist site. We conclude from the investigated receptors that the delta subunit can assume multiple positions in a receptor pentamer composed of alpha(6), beta(3) and delta subunits.

Use of concatamers to study GABAA receptor architecture and function: application to delta-subunit-containing receptors and possible pitfalls.

Many membrane proteins, including the GABA(A) [GABA (gamma-aminobutyric acid) type A] receptors, are oligomers often built from different subunits. As an example, the major adult isoform of the GABA(A) receptor is a pentamer built from three different subunits. Theoretically, co-expression of three subunits may result in many different receptor pentamers. Subunit concatenation allows us to pre-define the relative arrangement of the subunits. This method may thus be used to study receptor architecture, but also the nature of binding sites. Indeed, it made possible the discovery of a novel benzodiazepine site. We use here subunit concatenation to study delta-subunit-containing GABA(A) receptors. We provide evidence for the formation of different functional subunit arrangements in recombinant alpha(1)beta(3)delta and alpha(6)beta(3)delta receptors. As with all valuable techniques, subunit concatenation has also some pitfalls. Most of these can be avoided by carefully titrating and minimizing the length of the linker sequences joining the two linked subunits and avoiding inclusion of the signal sequence of all but the N-terminal subunit of a multi-subunit construct. Maybe the most common error found in the literature is that low expression can be overcome by simply overloading the expression system with genetic information. As some concatenated constructs result by themselves in a low level of expression, this erroneous assembly leading to receptor function may be promoted by overloading the expression system and leads to wrong conclusions.

Clinical and prognostic association of total atrial conduction time in patients with heart failure: a report from Studies Investigating Co-morbidities Aggravating Heart Failure.

BACKGROUND: The total atrial conduction time can be measured as the time from the onset of the P wave on the ECG to the peak of the A wave recorded at the mitral annulus using tissue Doppler imaging (A'; P-A'TDI); when prolonged, it might predict incident atrial fibrillation. METHODS: We measured P-A'TDI in outpatients with heart failure and sinus rhythm enrolled in the SICA-HF programme. RESULTS: P-A'TDI measured at the lateral mitral annulus was longer in patients with HF with reduced [LVEF<50%, N = 141; 126 (112-146) ms; P = 0.005] or preserved left ventricular ejection fraction [LVEF>50% and NT-proBNP > 125 ng/l, N = 71; 128 (108-145) ms; P = 0.026] compared to controls [N = 117; 120 (106-135) ms]. Increasing age, left atrial volume and PR interval were independently associated with prolonged P-A'TDI. During a median follow-up of 1251 (956-1602) days, 73 patients with heart failure died (N = 42) or developed atrial fibrillation (N = 31). In univariable analysis, P-A'TDI was associated with an increased risk of the composite outcome of death or atrial fibrillation, but only increasing log [NT-proBNP], age and more severe symptoms (NYHA III vs. I/II) were independently related to this outcome. Patients in whom both P-A'TDI and left atrial volume were above the median (127 ms and 64 ml, respectively) had the highest incidence of atrial fibrillation (hazard ratio 6.61, 95% CI 2.27-19.31; P < 0.001 compared with those with both P-A'TDI and LA volume below the median). CONCLUSION: Measuring P-A'TDI interval identifies patients with chronic heart failure at higher risk of dying or developing atrial fibrillation during follow-up.

Prevalence and Incidence of Atrial Fibrillation in Ambulatory Patients With Heart Failure.

Heart failure (HF) and atrial fibrillation (AF) commonly co-exist. We aimed to determine the prevalence and incidence of AF in ambulatory patients with HF. HF was defined by the presence of symptoms or signs supported by objective evidence of cardiac dysfunction: either a left ventricular ejection fraction (LVEF) ≤45% (HF and a reduced ejection fraction, HFrEF), or LVEF >45% and a raised plasma concentration of amino-terminal pro-B type natriuretic peptide (NT-proBNP >220 ng/L; HFpEF). Of 3,570 patients with HF, 1,164 were in AF at baseline (33%), with a higher prevalence among patients with HFpEF compared with HFrEF (40% vs 26%, respectively, p <0.001). Compared with patients with HF in sinus rhythm, those in AF were older, had more severe symptoms and higher NT-proBNP, worse renal function, and were more likely to receive loop diuretics, despite having a higher LVEF. Of those in sinus rhythm, 1,372 patients had HFrEF and 1,034 had HFpEF. The incidence of AF at 1 year (3.0%) was similar for each phenotype (p = 0.73). Increasing age, male gender, history of paroxysmal AF, and higher plasma concentrations of NT-proBNP were independent predictors of incident AF during a median follow-up of 1,574 (interquartile range: 749 to 2,821) days; the predictors were similar for each phenotype. In conclusion, the prevalence of AF is high, especially in patients with HFpEF, but its incidence is modest. This may be because their onset is near simultaneous with the development of AF precipitating the onset of HF.

Addressing Challenges to Enhance the Bioactives of Withania somnifera through Organ, Tissue, and Cell Culture Based Approaches.

Withania somnifera is a highly valued medicinal plant in traditional home medicine and is known for a wide range of bioactivities. Its commercial cultivation is adversely affected by poor seed viability and germination. Infestation by various pests and pathogens, survival under unfavourable environmental conditions, narrow genetic base, and meager information regarding biosynthesis of secondary metabolites are some of the other existing challenges in the crop. Biotechnological interventions through organ, tissue, and cell culture provide promising options for addressing some of these issues. In vitro propagation facilitates conservation and sustainable utilization of the existing germplasms and broadening the genetic base. It would also provide means for efficient and rapid mass propagation of elite chemotypes and generating uniform plant material round the year for experimentation and industrial applications. The potential of in vitro cell/organ cultures for the production of therapeutically valuable compounds and their large-scale production in bioreactors has received significant attention in recent years. In vitro culture system further provides distinct advantage for studying various cellular and molecular processes leading to secondary metabolite accumulation and their regulation. Engineering plants through genetic transformation and development of hairy root culture system are powerful strategies for modulation of secondary metabolites. The present review highlights the developments and sketches current scenario in this field.

Photopharmacological control of bipolar cells restores visual function in blind mice.

Photopharmacological control of neuronal activity using synthetic photochromic ligands, or photoswitches, is a promising approach for restoring visual function in patients suffering from degenerative retinal diseases. Azobenzene photoswitches, such as AAQ and DENAQ, have been shown to restore the responses of retinal ganglion cells to light in mouse models of retinal degeneration but do not recapitulate native retinal signal processing. Here, we describe diethylamino-azo-diethylamino (DAD), a third-generation photoswitch that is capable of restoring retinal ganglion cell light responses to blue or white light. In acute brain slices of murine layer 2/3 cortical neurons, we determined that the photoswitch quickly relaxes to its inactive form in the dark. DAD is not permanently charged, and the uncharged form enables the photoswitch to rapidly and effectively cross biological barriers and thereby access and photosensitize retinal neurons. Intravitreal injection of DAD restored retinal light responses and light-driven behavior to blind mice. Unlike DENAQ, DAD acts upstream of retinal ganglion cells, primarily conferring light sensitivity to bipolar cells. Moreover, DAD was capable of generating ON and OFF visual responses in the blind retina by utilizing intrinsic retinal circuitry, which may be advantageous for restoring visual function.