Isolation and characterization of bioactive compounds of <i>Clematis gouriana</i> Roxb. ex DC against snake venom phospholipase A₂ (PLA₂) computational and <i>in vitro</i> insights

<p>Bioactive compounds were isolated from <i>Clematis gouriana</i> Roxb. ex DC. The compounds were separated, characterized, the structures elucidated and submitted to the PubChem Database. The PubChem Ids SID 249494134 and SID 249494135 were tested against phospholipases A₂ (PLA₂) of <i>Naja naja</i> (Indian cobra) venom for PLA₂ activity. Both the compounds showed promising inhibitory activity; computational data also substantiated the results. The two compounds underwent density functional theory calculation to observe the chemical stability and electrostatic potential profile. Molecular interactions between the compounds and PLA₂ were observed at the binding pocket of the PLA₂ protein. Further, this protein–ligand complexes were simulated for a timescale of 100 ns of molecular dynamics simulation. Experimental and computational results showed significant PLA₂ inhibition activity.</p

Palladium-Catalyzed Internal Nucleophile-Assisted Hydration–Olefin Insertion Cascade: Diastereoselective Synthesis of 2,3-Dihydro‑1<i>H</i>‑inden-1-ones

A novel palladium-catalyzed hydration–olefin insertion cascade assisted by internal nucleophiles was developed for the synthesis of biologically significant 2,3-dihydro-1<i>H</i>-inden-1-ones under mild conditions. A detailed mechanistic study revealed that the assistance of the internal nucleophiles is crucial to trigger the cascade reaction via nucleopalladation of the alkyne moiety. The overall reaction is equivalent to regioselective hydration of alkynes followed by intramolecular Michael addition. This highly efficient and 100% atom-economical domino sequence afforded <i>cis</i>-2,3-disubstituted 2,3-dihydro-1<i>H</i>-inden-1-ones in excellent yields (up to 99%) with complete diastereoselectivity

Remediation of Dyes Using Supramolecular Material Derived from Carbohydrate Based π‑Gelator Using the Bottom-Up Assembly Approach

As a consequence of rapid population growth, the earth has faced numerous environmental sustainability issues and crises, water pollution is one of the important points of concern because of industrialization. In particular, effluents discharged from dying industries are rated top among the various industrial effluents, especially by their volume and composition. Annually >7.5 × 105 metric tons of different dyes are produced and consumed in different industries. In order to dye 1 kg of fabric, approximately 100–150 L of water is required, and after the dying process, it is discharged as an effluent either on a landfill or in water bodies. It is our responsibility to conserve environmental sustainability. In this line, we have developed a simple protocol to generate carbohydrate-based amphiphile using D-sorbitol, and pyrene-1-carboxaldehyde in good yield. This carbohydrate-based π-gelator is prone to forming a gel in various solvents and oils by the bottom-up assembly process. Morphological analysis of the self-assembled structure was identified by using optical microscopy and SEM. The viscoelastic behavior of the gel was examined by using rheology. In this paper, we explored the dye adsorption and desorption characteristics of the gel. Further, we have developed a cartridge based on cellulose using a template-assisted assembly phenomenon and demonstrated its potential in adsorbing dyes such as methylene blue, crystal violet, rhodamine B, and Congo red

Synthesis of 6,12-Epiminodibenzo[<i>b</i>,<i>f</i>][1,5]diazocines via an Ytterbium Triflate-Catalyzed, AB₂ Three-Component Reaction

An efficient and selective procedure for the synthesis of epiminodibenzo­[<i>b</i>,<i>f</i>]­[1,5]­diazocines involving a AB₂ three-component reaction is developed. Two equivalents of suitably substituted 2-aminoarylaldehydes reacted with arylamines in the presence of Yb­(OTf)₃ to afford the desired products in high yields. The reaction is highly atom-economic and waste-free, in addition to allowing the generation of two heterocyclic rings and four C–N bonds in a single operation. Significantly, this approach is complementary to the existing literature procedures, affording arylamine-derived products that could not be accessed previously. A plausible mechanism is proposed involving an imine formation-intermolecular annulation-intramolecular iminium ion cyclization sequence

Synthesis of 5,6-Dihydrodibenzo[<i>b</i>,<i>h</i>][1,6]naphthyridines via Copper Bromide Catalyzed Intramolecular [4 + 2] Hetero-Diels–Alder Reactions

A highly efficient synthesis of 5,6-dihydrodibenzo­[<i>b</i>,<i>h</i>]­[1,6]­naphthyridines was achieved by reaction between 2-(<i>N</i>-propargylamino)­benzaldehydes and arylamines in the presence of CuBr₂. The in situ generated electron-deficient heterodienes bearing a tethered alkyne partner underwent an intramolecular inverse electron-demand hetero-Diels–Alder reaction followed by air oxidation to furnish the products in high yields. This reaction tolerated a large number of substituents to afford diverse products under mild conditions. This strategy was also successfully extended to the synthesis of 12,13-dihydro-6<i>H</i>-benzo­[<i>h</i>]­chromeno­[3,4-<i>b</i>]­[1,6]­naphthyridin-6-ones starting from 3-amino-2<i>H</i>-chromen-2-one, again in high yields

Intrinsic Hydrophobic Antibacterial Thin Film from Renewable Resources: Application in the Development of Anti-Biofilm Urinary Catheters

The use of renewable resources to develop functional materials is increasing in order to meet the sustainability challenges. In an era of inexorable evolution of antimicrobial resistance, there is a substantial increase in demand for the development of efficient antimicrobial thin film coating from renewable resources for public bacterial threats, food, biomedical, and industrial applications. In the present investigation, we have used cardanol, a phenolic compound having unsaturated hydrophobic tail isolated from cashew fruits, and linseed oil, a vegetable oil and an important biobased building block, which are cheap and easy to regenerate. This study reports the synthesis of cardanol based metal complexes having unsaturated hydrophobic unit and acrylated epoxidized linseed oil (AELO) prepared via epoxidation of double bonds followed by acrylation. The double bond present in the metal complexes and AELO is prone to form assembled thin film under atmospheric conditions, without the need of any initiators. Assembled thin film is one of the important aspects of nanotechnology holding a wide range of applications. ¹H NMR and FT-IR analysis revealed the existence of a strong interaction between ligand and metal, which paves a way to develop a nonleachable metal based thin film coating. The leaching behavior of thin film coating was investigated under various aggressive conditions with the aid of UV–vis spectroscopy. The mechanical properties of assembled thin film coating material composed of cardanol-based metal complex and AELO are described using oscillatory rheology. Morphological and SAXD analysis clearly revealed the formation of the assembled structure in thin films. Thermal response of these materials has been investigated using TGA and DSC measurements. Intrinsic hydrophobic character was identified by contact angle measurement. Antimicrobial and biofilm inhibitory behavior of synthesized compounds and thin films were investigated against various human pathogenic bacterial strains. The assembled thin film coated catheter tube completely inhibits the biofilm formation of uropathogenic Escherichia coli (UPEC). Thus, the developed thin film coating material holds promise to be used as metal enabled, nonleachable coating materials for public bacterial threats, and food and biomedical applications. In particular, this material can be potentially used for developing urinary catheter tubes with antibacterial properties

Disassembly of Bacterial Biofilms by the Self-Assembled Glycolipids Derived from Renewable Resources

More than 80% of chronic infections of bacteria are caused by biofilms. It is also a long-term survival strategy of the pathogens in a nonhost environment. Several amphiphilic molecules have been used in the past to potentially disrupt biofilms; however, the involvement of multistep synthesis, complicated purification and poor yield still remains a major problem. Herein, we report a facile synthesis of glycolipid based surfactant from renewable feedstocks in good yield. The nature of carbohydrate unit present in glycolipid influence the ring chain tautomerism, which resulted in the existence of either cyclic structure or both cyclic and acyclic structures. Interestingly, these glycolipids self-assemble into gel in highly hydrophobic solvents and vegetable oils, and displayed foam formation in water. The potential application of these self-assembled glycolipids to disrupt preformed biofilm was examined against various pathogens. It was observed that glycolipid <b>6a</b> disrupts <i>Staphylococcus aureus</i> and <i>Listeria monocytogenes</i> biofilm, while the compound <b>6c</b> was effective in disassembling uropathogenic <i>E. coli</i> and <i>Salmonella enterica</i> Typhimurium biofilms. Altogether, the supramolecular self-assembled materials, either as gel or as surfactant solution could be potentially used for surface cleansing in hospital environments or the food processing industries to effectively reduce pathogenic biofilms