A rapid 1,2-dihydroxylation of alkenes using a lipase and hydrogen peroxide under microwave conditions

Comprehensive study on transglycosylation of CGTase from various sources

Transglycosylation is the in-vivo or in-vitro process of transferring glycosyl groups from a donor to an acceptor, which is usually performed by enzymatic reactions because of their simplicity, low steric hindrance, high region-specificity, low production cost, and mild processing conditions. One of the enzymes commonly used in the transglycosylation reaction is cyclodextrin glucanotransferase (CGTase). The transglycosylated products, catalyzed by CGTase, are widely used in food additives, supplements, and personal care and cosmetic products. This is due to improvements in the solubility, stability, bioactivity and length of the synthesized products. This paper's focus is on the importance of enzymes used in the transglycosylation reaction, their characteristics and mechanism of action, sources and production yield, and donor and acceptor specificities. Moreover, the influence of intrinsic and extrinsic factors on the enzymatic reaction, catalysis of glycosidic linkages, and advantages of CGTase transglycosylation reactions are discussed in detail.

Recent advances in cholesterol chemistry

This review article presents advances in cholesterol chemistry since 2000. Various transformations (chemical, enzymatic, electrochemical, etc.) of cholesterol are presented. A special emphasis is given to cholesterol oxidation reactions, but also substitution of the 3β-hydroxyl group, addition to the C5-C6 double bond, C-H functionalization, and C-C bond forming reactions are discussed.

Chemoenzymatic epoxidation of alkenes and reusability study of the phenylacetic acid

Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The immobilised Candida antarctica lipase B, Novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide (H₂O₂) and phenylacetic acid. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. A variety of alkenes were oxidised with this system, resulting in 75–99% yield of the respective epoxides. On the other hand, the phenylacetic acid was recovered from the reaction media and reused for more epoxidation. Interestingly, the waste phenylacetic acid had the ability to be reused for epoxidation of the 1-nonene to 1-nonene oxide, giving an excellent yield of 90%.

Microwave accelerated transglycosylation of rutin by cyclodextrin glucanotransferase from Bacillus sp. SK13.002

Rutin was subjected to intermolecular transglycosylation assisted with microwave irradiation using cyclodextrin glucanotransferase (CGTase) produced from Bacillus sp. SK13.002. Compared with the conventional enzymatic method for rutin transglycosylation (without microwave irradiation), microwave-assisted reaction (MAR) was much faster and thus more efficient. While the conventional reaction took dozens of hours to reach the highest conversion rate of rutin and yield of transglycosylated rutin, MAR of rutin transglycosylation completed within only 6 min providing almost the same conversion rate of rutin and yield of products consisting of mono-, di-, tri-, tetra-, penta-glucosylated rutins. The optimum transglycosylation conditions for microwave irradiation were 40 °C and 60 W with the reaction system consisting mainly of the mixture of 0.3 g rutin (0.49 mmol) pre-dissolved in 15 mL methanol, 1.8 g maltodextrin in 15 mL of 0.2 M sodium acetate buffer (pH 5.5) and CGTase (900 U). Results from this study indicated that MAR could be a potentially useful and economical technique for a faster and more efficient transglycosylation of rutin.