Insertion of Degradable Thioester Linkages into Styrene and Methacrylate Polymers

The thionolactone 3,3-dimethyl-2,3-dihydro-5H-benzo[e][1,4]dioxepine-5-thione (DBT) is shown to homopolymerize and, for the first time, copolymerize with styrene and methacrylates, introducing degradable thioester backbone functionality. The rapid copolymerization with styrene was exploited to produce copolymers through free-radical polymerization in a starve-fed semi-batch setup. The copolymerization of DBT with tert-butyl methacrylate under RAFT conditions was hypothesized to involve selective retardation of DBT-terminal chains that led to a more uniform distribution of degradable thioester linkages between chains. Surprisingly, the aminolysis of DBT homopolymers was accompanied by the intramolecular ether cleavage within the primary degradation product leading to the formation of 2,2-dimethylthiirane and salic-ylamides.

Pengaruh Proses Fermentasi pada Daun Centella asiatica oleh Acetobacter tropicalis Terhadap Aktivitas Trombolitik

Agen trombolitik merupakan plasminogen activator yang dapat memecah fibrin menjadi fibrin degradation product (FDP) dan dapat digunakan pada terapi penyakit kardiovaskular. Agen trombolitik dapat diperoleh dari mikroorganisme seperti Acetobacter tropicalis InaCC B374 dan dari tanaman seperti Centella asiatica. Kedua sumber agen trombolitik tersebut dapat dilakukan kombinasi melalui proses fermentasi untuk meningkatkan efek terapetiknya. Proses fermentasi sendiri dipengaruhi oleh beberapa faktor termasuk media fermentasi dan waktu fermentasi. Penelitian ini bertujuan untuk mengetahui pengaruh proses fermentasi terhadap peningkatan aktivitas trombolitik dari hasil fermentasi Centella asiatica oleh Acetobacter tropicalis InaCC B374 pada berbagai variasi waktu fermentasi. Preparasi dilakukan dengan memfermentasi Centella asiatica selama 24, 48, dan 72 jam pada suhu 30°±1°C dengan kecepatan pengocokan 100 rpm kemudian ditentukan aktivitas trombolitiknya dengan metode clot lysis yang dilakukan inkubasi pada suhu 37°±1°C selama 60 menit. Hasil pengujian aktivitas trombolitik menunjukkan bahwa terjadi peningkatan aktivitas trombolitik setelah dilakukan proses fermentasi selama 24, 48 dan 72 jam dan aktivitas trombolitik maksimum tercapai pada hasil fermentasi 72 jam. Centella asiatica yang difermentasi selama 72 jam menunjukkan nilai indeks trombolitik yang paling besar (82,03) jika dibandingkan dengan infusa Centella asiatica tanpa fermentasi (37,39) dan Acetobacter tropicalis InaCC B374 (37,68). Disimpulkan bahwa proses fermentasi Centella asiatica oleh Acetobacter tropicalis InaCC B374 secara signifikan dapat meningkatkan aktivitas trombolitik keduanya

The ChpR transcriptional regulator of Sinorhizobium meliloti senses 3,5,6-trichloropyridinol, a degradation product of the organophosphate pesticide chlorpyrifos

The global use of organophosphate insecticides (OPPs) and the growing concern of off-target side effects due to OPP exposure has prompted the need for sensitive and economical detection methods. Here we set out to engineer a previously identified OPP responsive transcription factor, ChpR, from Sinorhizobium melilotii to respond to alternative OPPs and generate a repertoire of whole-cell biosensors for OPPs. The ChpR transcription factor and cognate promoter P chpA, have been shown to activate transcription in the presence of the OPP chlorpyrifos (CPF). Utilizing a GFP reporter regulated by ChpR in a whole-cell biosensor we found that the system responds significantly better to 3,5,6-trichloro-2-pyridinol (TCP), the main degradation product of CPF, compared to CPF itself. This biosensor was able to respond to TCP at 390 nM within 4 h compared to 50 µM of CPF in 7 h. The ChpR-P chpA , and the activating ligand TCP, were able to regulate expression of a kanamycin resistance/sucrose sensitivity (kan/sacB) selection/counterselection module suitable for high throughput mutagenesis screening studies. The ability to control both GFP and the kan/sacB module demonstrates the utility of this reporter for the detection of CPF affected areas. The ChpR-P chpA system serves as an additional positive regulator switch to add to the growing repertoire of controllers available within synthetic biology.

Antibacterial Polymers Based on Poly(2-hydroxyethyl methacrylate) and Thiazolium Groups with Hydrolytically Labile Linkages Leading to Inactive and Low Cytotoxic Compounds

Herein, we develop a well-defined antibacterial polymer based on poly(2-hydroxyethyl methacrylate) (PHEMA) and a derivative of vitamin B1, easily degradable into inactive and biocompatible compounds. Hence, thiazole moiety was attached to HEMA monomer through a carbonate pH-sensitive linkage and the resulting monomer was polymerized via reversible addition-fragmentation chain transfer (RAFT) polymerization. N-alkylation reaction of the thiazole groups leads to cationic polymer with thiazolium groups. This polymer exhibits excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) with an MIC value of 78 µg mL−1, whereas its degradation product, thiazolium small molecule, was found to be inactive. Hemotoxicity studies confirm the negligible cytotoxicity of the degradation product in comparison with the original antibacterial polymer. The degradation of the polymer at physiological pH was found to be progressive and slow, thus the cationic polymer is expected to maintain its antibacterial characteristics at physiological conditions for a relative long period of time before its degradation. This degradation minimizes antimicrobial pollution in the environment and side effects in the body after eradicating bacterial infection.

Degradation product of curcumin restrain Salmonella typhimurium virulent protein L-asparaginase

Objectives Salmonella typhimurium is a pathogen responsible for causing a wide range of infectious diseases. The emergence of multi-drug resistance (MDR) in this microbe is a big challenge. L-asparaginase (less explored drug target) is selected as a drug target because it is actively involved in the virulence mechanism. To block this virulent enzyme, curcumin that is traditionally renowned for its medicinal properties was examined. However, its pharmacological behavior and targeting property is less understood because of its poor bioavailability. Therefore, the present work explores the antimicrobial effect of both curcumin and its degradation product against the MDR pathogen. Methods Molecular docking studies were carried out to evaluate the inhibitory effect of curcumin and its degradation product against the L-asparaginase enzyme using Schrodinger Maestro interface tools. The Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) profile of all the test ligands was also performed. Results The docking score of curcumin was −5.465 kcal/mol while its degradation product curcumin glucuronide has the lowest i.e., −6.240 kcal/mol. All the test ligands showed better or comparable docking scores with respect to control (Ciprofloxacin). Arg 142 and Asn 84 amino acid residues of L-asparaginase were found to be interacting with test ligands inside the binding pocket of the target protein. ADME/toxicology study also indicated the potency of curcumin/curcumin degradation products as a potent inhibitor. Conclusions It was found that both curcumin and its degradation products have the potential to inhibit Salmonella. This information could be valuable for futuristic drug candidate development against this pathogen and could be a potential lead for mitigation of MDR.