Chemo-enzymatic synthesis of optically active polymeric prodrug of naproxen, ketoprofen and ibuprofen

Dual Activity of Grubbs-Type Catalyst in the Transvinylation of Carboxylic Acids and Ring-Closing Metathesis Reactions

The development of a multifunctional catalyst, which mimics the promiscuity of enzymes, that would catalyze more than one chemical transformation in a single reaction vessel is one of the key points of modern sustainable chemistry. The results of our experiments indicated that Grubbs-type catalysts possess such multitask activity, catalyzing the transvinylation reaction of carboxylic acids without losing their original metathetic activity. This new activity of Grubbs catalysts was evidenced on several examples. It allows us to design a transvinylation/ring-closing metathesis (RCM) cascade reaction leading to the formation of endocyclic enol lactones from unsaturated carboxylic acids in an one-pot procedure. This unique ability of Grubbs catalyst to catalyze multiple mechanically distinct cascade reactions in a chemoselective way offers the new possibility for the synthesis of complex compounds from simple, easily accessible substrates.

Synthesis and Pharmacological Evaluation of Acrylate-Based Gastrosparing NSAID Prodrugs

Dexibuprofen and aceclofenac are well-known NSAID molecules, their oral use leads to gastrointestinal (GI) toxicity. To circumvent that GI toxicity, the prodrug approach is a better alternative. Hence, this research was undertaken to synthesize prodrugs of dexibuprofen and aceclofenac using acrylic polymers with degradable ester bonds. Dexibuprofen was linked to 2-hydroxypropyl methacrylate by an activated ester technique. The resulting material was copolymerized with 2-hydroxyethyl methacrylate and methyl methacrylate (in 1:3 mole ratios) by the free radical polymerization method, utilizing azoisobutyronitrile at 65-70°C. Similarly aceclofenac was also processed. The resulting prodrugs were characterized by IR, NMR, and elemental analysis. The synthesized prodrugs possess optimal physicochemical characteristics such as the intended molecular weight, lipophilicity, partition coefficient, and protein binding. The drug release on hydrolysis was studied in various fluids such as SGF (pH 1.2), SIF (pH 7.4), and SCF (pH 6.8), to establish the drug release kinetics. Pharmacological evaluation exhibited anti-inflammatory activity with remarkable reduction in ulcerogenicity compared to the parent drug. Under the conditions used, the prodrugs showed no antigenicity in Wistar rats. Thus, it was concluded that acrylic-based prodrugs were efficient in drug localization in the stomach, without gastric problems.

Improved activity of lipase immobilized in microemulsion-based organogels for (R, S)-ketoprofen ester resolution: Long-term stability and reusability

Microemulsion-based organogels (MBGs) were effectively employed for the immobilization of four commonly used lipases. During the asymmetric hydrolysis of ketoprofen vinyl ester at 30 °C for 24 h, lipase from Rhizomucor miehei and Mucor javanicus immobilized in microemulsion-based organogels (RML MBGs and MJL MBGs) maintained good enantioselectivities (ee_p were 86.2% and 99.2%, respectively), and their activities increased 12.8-fold and 7.8-fold, respectively, compared with their free forms. They gave higher yields compared with other lipase MBGs and exhibited better enantioselectivity than commercial immobilized lipases. Immobilization considerably increased the tolerance to organic solvents and high temperature. Both MJL MBGs and RML MBGs showed excellent reusability during 30 cycles of repeated 24 h reactions at 30 °C (over 40 days). The system maintained yields of greater than 50%, while the ee_s values of RML MBGs and MJL MBGs remained nearly constant at 95% and 88%, respectively.

Two Enzyme Cooperatively Catalyzed Tandem Polymerization for the Synthesis of Polyester Containing Chiral (R)- or (S)-Ibuprofen Pendants

An interesting cooperation between Candida antarctica Lipase B (CAL-B) and alkaline protease from Bacillus subtilis (BSP) in the copolymerization of bulky ibuprofen-containing hydroxyacid methyl ester (HAEP) and ε-caprolactone (ε-CL) is observed. This cooperation improved the M¯n of the polymers from 3130 (CAL-B) to 9200 g mol-1 (CAL-B/BSP). Experimental results clearly indicate that CAL-B mainly catalyzes the ring-opening polymerization (ROP) of ε-CL under the initiation of HAEP to form the homopolymer of ε-CL, while BSP catalyzes the subsequent polycondensation of the ROP product to yield the copolymer with increased molecular weight. Furthermore, using suitable chemo-enzymatic methods, valuable polyesters with chiral (R)- or (S)-ibuprofen pendants can be tailor-made.