Non‐Identical Stepwise Reversible Double‐Redox Coupled Bond Activation Reactions

This work presents a stepwise reversible two‐electron transfer induced hydrogen shift leading to the conversion of a bis‐pyrrolinium cation to an E ‐diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi‐pyrrolinium cation scaffold‐based organic redox systems, which constitute decidedly sought‐after molecules in contemporary chemistry

N,N′‐ethylene‐bridged bis‐2‐aryl‐pyrrolinium cations to E‐diaminoalkenes : non‐identical stepwise reversible double‐redox coupled bond activation reactions

This work presents a stepwise reversible two‐electron transfer induced hydrogen shift leading to the conversion of a bis‐pyrrolinium cation to an E‐diaminoalkene and vice versa. Remarkably, the forward and the reverse reaction, which are both reversible, follow two completely different reaction pathways. Establishing such unprecedented property in this type of processes was possible by developing a novel synthetic route towards the starting dication. All intermediates involved in both the forward and the backward reactions were comprehensively characterized by a combination of spectroscopic, crystallographic, electrochemical, spectroelectrochemical, and theoretical methods. The presented synthetic route opens up new possibilities for the generation of multi‐pyrrolinium cation scaffold‐based organic redox systems, which constitute decidedly sought‐after molecules in contemporary chemistry.Tata Institute of Fundamental Research (TIFR) HyderabadDepartment of Atomic Energy (DAE), Government of Indi

Molecular Insight into the Adsorption of Spruce Budworm Antifreeze Protein to an Ice Surface: A Clathrate-Mediated Recognition Mechanism

The principal mechanism of ice recognition by antifreeze protein (AFP) has been a topic of intense discussion in recent times. Despite many experimental and theoretical studies, the detailed understanding of the process remains elusive. The present work aims to explore the molecular mechanism of ice recognition by an insect AFP from the spruce budworm, <i>sbw</i>AFP. As evident from our simulation, the water dynamics becomes very sluggish around the ice binding surface (IBS) as a result of the combined effect of confinement and ordering induced by the perfectly aligned methyl side chains of threonine residues, the THR ladder. The hydroxyl groups of threonine form strong hydrogen bonds with few of those highly ordered water molecules that are close to the THR ladder, which is the origin of anchored clathrate water at the IBS of <i>sbw</i>AFP. We propose anchored clathrate-mediated basal plane recognition by <i>sbw</i>AFP. The AFP adsorbed on the basal plane through water clathrate framed around the IBS. The surface of the basal plane and anchored clathrate water completes the caging around the threonine residues, which is the origin of the binding plane specificity of <i>sbw</i>AFP. This adsorbed AFP-ice complex undergoes dynamic crossover to a hydrogen-bonded complex within the thermal hysteresis (TH) regime of this particular AFP. The anchored clathrate water becomes part of the newly grown basal front as a result of the geometrical matches between the basal plane and the anchored clathrate water repeat distance. This observation provides a structural rationale for the experimentally observed time-dependent increase in TH activity for insect AFP. Our study proposes clathrate-mediated ice recognition by AFP and elucidates the dynamic events involved during ice binding by the insect AFP

Anti - diabetic activity of aeschynanthus sikkimensis (clarke) stapf. extract in streptozotocin induced hyperglycemic rats

Objective: The research was design to conduct anti-diabetic activity of methanol extract of Aeschynanthus sikkimensis (Clarke) Stapf. in streptozotocin induce hyperglycemic rats. Material and method: Streptozotocin 35mg/kg body weight was injected intraperitoneal to produce hyperglycemia rats which were pretreated with a high fat diet.72 hours after introduction of STZ, the hyperglycemic rats received MEAS at dose 200 and 400 mg/kg body weight for 28 days. Reference drug used was Glibenclamide (0.5 mg/kg, orally). During the 28 days treatment fasting blood glucose level were determined on every 7th day. Serum and hepato renal biochemical parameters were estimated. Result: MEAS at the dose of 200 and 400mg/kg outstandingly (P &lt;0.05) and dosage dependently reduce blood glucose levels towards normal as differentiate to STZ control group Serum and hepato renal biochemical parameter were altogether (P&lt;0.05) restore towards the typical levels in MEAS sedated rats as differentiated to STZ control group. Conclusion: It may be concluded that the whole plant extract of Aeschynanthus sikkimensis (Clarke) Stapf which belong to the family Gesneriaceae showed encouraging hypoglycemic action in STZ induced diabetic rats

Synthesis of (E)-nitroolefins via decarboxylative nitration using t-butylnitrite (t-BuONO) and TEMPO.

Nitroolefins are usually synthesized using the Henry reaction. Here we report an alternative metal-free decarboxylative nitration protocol for the preparation of the nitroolefins from α,β-unsaturated carboxylic acids using t-butylnitrite (t-BuONO) and TEMPO. α,β-Unsaturated carboxylic acids bearing β-aromatic and β-heteroaromatic substituents gave (E)-nitroolefins exclusively under mild conditions. A radical based pathway has been proposed for this decarboxylative nitration reaction

Multiple paralogues of α-SNAP in Giardia lamblia exhibit independent subcellular localization and redistribution during encystation and stress

Abstract Background The differently-diverged parasitic protist Giardia lamblia is known to have minimal machinery for vesicular transport. Yet, it has three paralogues of SNAP, a crucial component that together with NSF brings about disassembly of the cis-SNARE complex formed following vesicle fusion to target membranes. Given that most opisthokont hosts of this gut parasite express only one α-SNAP, this study was undertaken to determine whether these giardial SNAP proteins have undergone functional divergence. Results All three SNAP paralogues are expressed in trophozoites, encysting trophozoites and cysts. Even though one of them clusters with γ-SNAP sequences in a phylogenetic tree, functional complementation analysis in yeast indicates that all the three proteins are functionally orthologous to α-SNAP. Localization studies showed a mostly non-overlapping distribution of these α-SNAPs in trophozoites, encysting cells and cysts. In addition, two of the paralogues exhibit substantial subcellular redistribution during encystation, which was also seen following exposure to oxidative stress. However, the expression of the three genes remained unchanged during this redistribution process. There is also a difference in the affinity of each of these α-SNAP paralogues for GlNSF. Conclusions None of the genes encoding the three α-SNAPs are pseudogenes and the encoded proteins are likely to discharge non-redundant functions in the different morphological states of G. lamblia. Based on the difference in the interaction of individual α-SNAPs with GlNSF and their non-overlapping pattern of subcellular redistribution during encystation and under stress conditions, it may be concluded that the three giardial α-SNAP paralogues have undergone functional divergence. Presence of one of the giardial α-SNAPs at the PDRs of flagella, where neither GlNSF nor any of the SNAREs localize, indicates that this α-SNAP discharges a SNARE-independent role in this gut pathogen

Molecular Factors of Ice Growth Inhibition for Hyperactive and Globular Antifreeze Proteins: Insights from Molecular Dynamics Simulation

The molecular mechanism behind the ice growth inhibition by antifreeze proteins (AFPs) is yet to be understood completely. Also, what physical parameters differentiate between the AFP and non-AFP are largely unknown. Thus, to get an atomistic overview of the differential antifreeze activities of different classes of AFPs, we have studied ice growth from different ice surfaces in the presence of a moderately active globular type III AFP and a hyperactive spruce budworm (sbw) AFP. Results are compared with the observations of ice growth simulations in the presence of topologically similar non-AFPs using all-atom molecular dynamics simulations. Simulation data suggest that the ice surface coverage is a critical factor in ice growth inhibition. Due to the presence of an ice binding surface (IBS), AFPs form a high affinity complex with ice, accompanied by a transition of hydration water around the IBS from clathrate-like to ice-like. Several residues around the periphery of the IBS anchor the AFP to the curved ice surface mediated by multiple strong hydrogen bonds, stabilizing the complex immensely. In the high surface coverage regime, the slow unbinding kinetics dominates over the ice growth kinetics and thus facilitates the ice growth inhibition. Due to the non-availability of a proper IBS, non-AFPs form a low-affinity complex with the growing ice surface. As a result, the non-AFPs are continuously repelled by the surface. If the concentration of AFPs is low, then the effective surface coverage is reduced significantly. In this low surface coverage regime, AFPs can also behave like impurities and are engulfed by the growing ice crystal

A Hybrid Recommendation System of Upcoming Movies Using Sentiment Analysis of YouTube Trailer Reviews

Movies are one of the integral components of our everyday entertainment. In today’s world, people prefer to watch movies on their personal devices. Many movies are available on all popular Over the Top (OTT) platforms. Multiple new movies are released onto these platforms every day. The recommendation system is beneficial for guiding the user to a choice from among the overloaded contents. Most of the research on these recommendation systems has been conducted based on existing movies. We need a recommendation system for forthcoming movies in order to help viewers make a personalized decision regarding which upcoming new movies to watch. In this article, we have proposed a framework combining sentiment analysis and a hybrid recommendation system for recommending movies that are not yet released, but the trailer has been released. In the first module, we extracted comments about the movie trailer from the official YouTube channel for Netflix, computed the overall sentiment, and predicted the rating of the upcoming movies. Next, in the second module, our proposed hybrid recommendation system produced a list of preferred upcoming movies for individual users. In the third module, we finally were able to offer recommendations regarding potentially popular forthcoming movies to the user, according to their personal preferences. This method fuses the predicted rating and preferred list of upcoming movies from modules one and two. This study used publicly available data from The Movie Database (TMDb). We also created a dataset of new movies by randomly selecting a list of one hundred movies released between 2020 and 2021 on Netflix. Our experimental results established that the predicted rating of unreleased movies had the lowest error. Additionally, we showed that the proposed hybrid recommendation system recommends movies according to the user’s preferences and potentially promising forthcoming movies

Anti - Diabetic Activity of Aeschynanthus Sikkimensis (Clarke) Stapf. Extract in Streptozotocin Induced Hyperglycemic Rats

Objective: The research was design to conduct anti-diabetic activity of methanol extract of Aeschynanthus sikkimensis (Clarke) Stapf. in streptozotocin induce hyperglycemic rats. Material and method: Streptozotocin 35mg/kg body weight was injected intraperitoneal to produce hyperglycemia rats which were pretreated with a high fat diet.72 hours after introduction of STZ, the hyperglycemic rats received MEAS at dose 200 and 400 mg/kg body weight for 28 days. Reference drug used was Glibenclamide (0.5 mg/kg, orally). During the 28 days treatment Fasting blood glucose level were determined on every 7th day. Serum and hepato renal biochemical parameters were estimated. Result: MEAS at the dose of 200 and 400mg/kg outstandingly (P &lt;0.05) and dosage dependently reduce blood glucose levels towards normal as differentiate to STZ control group Serum and hepato renal biochemical parameter were altogether (P&lt;0.05) restore towards the typical levels in MEAS sedated rats as differentiated to STZ control group. Conclusion: It may be concluded that the whole plant extract of Aeschynanthus sikkimensis (Clarke) Stapf which belong to the family Gesneriaceae showed encouraging hypoglycemic action in STZ induced diabetic rats