Biocatalyst-mediated selective acylation and deacylation chemistry on the secondary hydroxyl/amine groups of nucleosides

Different (±)-4-(3/4-acetoxyaryl)-5-ethoxycarbonyl-6-methyl-3,4-dihydropyrimidin-2-ones have been synthesized and subjected to enantioselective deacetylation reactions mediated by different lipases in organic media. Novozyme 435 in tetrahydrofuran:diisopropyl ether was found to be the catalyst of choice for efficient enantioselective deacetylation of dihydropyrimidinones under study. Further, we discovered that lipase isolated from Pseudomonas aeruginosa can be used for selective acylation of secondary hydroxyl groups in nucleosides. This observation can be very useful for selective manipulation of different hydroxyl groups in nucleosides.

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A greener and sustainable approach for converting polyurethane foam rejects into superior polyurethane coatings

10.31221/osf.io/k3n2u ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Mechanical Properties ◽

Polyurethane Foam ◽

Sebacic Acid ◽

Polyurethane Foams ◽

Hexamethylene Diisocyanate ◽

Alkali Resistance ◽

Microwave Reaction ◽

P Recycling ◽

Amine Groups ◽

Green Polymer

Recycling is a crucial area of research in green polymer chemistry. Various developments in recycling are driven by Environmental concerns, interest in sustainability and desire to decrease the dependence on non-renewable petroleum based materials. Polyurethane foams [PUF] are widely used due to their light weight and superior heat insulation as well as good mechanical properties. As per survey carried Polyurethane Foam Association, 12 metric tonnes of polyurethane foam are discharged during manufacturing and/or processing and hence recycling of PUF is necessary for better economics and ecological reasons. In present study, rejects of PUF is subjected to reaction with a diethylene amine in presence of sodium hydroxide [NaOH] as catalyst, as a result depolymerised product containing hydroxyl and amine groups is obtained. Conventional and Microwave reaction for depolymerizing polyurethane foam have been carried, and best results are obtained by Microwave reaction. Further depolymerised product with hydroxyl and amine functionalities are reacted with bis (2-hydroxyethyl terephthalate) [BHET] obtained by recycling polyethylene terephthalate [PET] and sebacic acid, with stannous oxalate [FASCAT 2100 series] as catalyst to obtain Polyester amides. These Polyester amides having hydroxyl and amino groups in excess are cured with isocyanates-hexamethylene diisocyanate biuret [HDI biuret] and isophorone diisocyanate [IPDI] for coating applications. The coated films are characterized using physical, mechanical and chemical tests, which shows comparable physical, mechanical properties but alkali resistance is poor.

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Preparation of prednisolone‐appended α‐, β‐ and γ‐cyclodextrins: Substitution at secondary hydroxyl groups and in vitro hydrolysis behavior

Journal of Pharmaceutical Sciences ◽

10.1002/1520-6017(200104)90:4<493::aid-jps1007>3.3.co;2-n ◽

2001 ◽

Vol 90 (4) ◽

pp. 493-503

Author(s):

Hideki Yano ◽

Fumitoshi Hirayama ◽

Hidetoshi Arima ◽

Kaneto Uekama

Keyword(s):

Hydroxyl Groups ◽

Secondary Hydroxyl ◽

In Vitro Hydrolysis

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Biotin-Containing Third Generation Glucoheptoamidated Polyamidoamine Dendrimer for 5-Aminolevulinic Acid Delivery System

International Journal of Molecular Sciences ◽

10.3390/ijms22041982 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1982 ◽

Cited By ~ 1

Author(s):

Aleksandra Kaczorowska ◽

Małgorzata Malinga-Drozd ◽

Wojciech Kałas ◽

Marta Kopaczyńska ◽

Stanisław Wołowiec ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Aminolevulinic Acid ◽

Reactive Oxygen ◽

Pamam Dendrimer ◽

Variable Number ◽

Amide Bond ◽

Oxygen Species ◽

Nmr Spectrum ◽

Guest Molecules ◽

Amine Groups

Polyamidoamine PAMAM dendrimer generation 3 (G3) was modified by attachment of biotin via amide bond and glucoheptoamidated by addition of α-D-glucoheptono-1,4-lacton to obtain a series of conjugates with a variable number of biotin residues. The composition of conjugates was determined by detailed 1-D and 2-D NMR spectroscopy to reveal the number of biotin residues, which were 1, 2, 4, 6, or 8, while the number of glucoheptoamide residues substituted most of the remaining primary amine groups of PAMAM G3. The conjugates were then used as host molecules to encapsulate the 5-aminolevulinic acid. The solubility of 5-aminolevulinic acid increased twice in the presence of the 5-mM guest in water. The interaction between host and guest was accompanied by deprotonation of the carboxylic group of 5-aminolevulinic acid and proton transfer into internal ternary nitrogen atoms of the guest as evidenced by a characteristic chemical shift of resonances in the 1H NMR spectrum of associates. The guest molecules were most likely encapsulated inside inner shell voids of the host. The number of guest molecules depended on the number of biotin residues of the host, which was 15 for non-biotin-containing glucoheptoamidated G3 down to 6 for glucoheptoamidated G3 with 8 biotin residues on the host surface. The encapsulates were not cytotoxic against Caco-2 cells up to 200-µM concentration in the dark. All encapsulates were able to deliver 5-aminolevulinic acid to cells but aqueous encapsulates were more active in this regard. Simultaneously, the reactive oxygen species were detected by staining with H2DCFDA in Caco-2 cells incubated with encapsulates. The amount of PpIX was sufficient for induction of reactive oxygen species upon 30-s illumination with a 655-nm laser beam.

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The thioamidation of gem-dibromoalkenes in an aqueous medium

Organic & Biomolecular Chemistry ◽

10.1039/d0ob02319a ◽

2021 ◽

Vol 19 (11) ◽

pp. 2473-2480

Author(s):

Jigarkumar K. Vankar ◽

Ankush Gupta ◽

Jaydeepbhai P. Jadav ◽

Shankara H. Nanjegowda ◽

Guddeangadi N. Gururaja

Keyword(s):

Aqueous Medium ◽

Direct Integration ◽

Amine Groups

The direct integration of sulphur and amine groups with 1,1-dibromoalkenes for thioamide synthesis has been achieved in an aqueous medium.

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Effect of H2O-Based Low-Pressure Plasma (LPP) Treatment on the Germination of Bambara Groundnut Seeds

Agronomy ◽

10.3390/agronomy11020338 ◽

2021 ◽

Vol 11 (2) ◽

pp. 338

Author(s):

Naeem Ahmed ◽

Asad Masood ◽

Kim S. Siow ◽

M. F. Mohd Razip Wee ◽

Rahmat Zaki Auliya ◽

...

Keyword(s):

Food Security ◽

Seed Germination ◽

Chemical Modification ◽

Low Pressure ◽

Germination Percentage ◽

Bambara Groundnut ◽

Pressure Plasma ◽

Low Pressure Plasma ◽

Amine Groups

In general, seed germination is improved by low-pressure plasma (LPP) treatment using precursors such as air, nitrogen, argon, or water (H2O). Here, H2O-based LPP treatment using the optimized parameters of 10 W and 10 s improves the germination of Bambara groundnut seeds by 22%. LPP increases the wettability and roughness of the seed hilum while oxidizing the surface with carboxyl and amine groups. In this H2O-based treatment of Bambara groundnut seeds, combinatory etching and chemical modification facilitated the imbibition process and increased the germination percentage. The success of this method has the potential to be scaled up to solve food security with seeds otherwise facing germination-related issues.

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