Synthesis of crosslinked lipase aggregates and their use in the synthesis of aspirin

• New crosslinked lipase aggregates, CLLAs, were directly obtained by crosslinking a crude lipase.
• N,N-Methylenebisacrylamide, is a biocompatible and tetrafunctional crosslinker.
• Crosslinking was carried out by ammonium persulphate or gamma rays irradiation as initiators.
• Activity of CLLAs is near to that of free lipase and radiochemical initiation gave better results.
• CLLAs were effectively reusable for 10 cycles in, aspirin synthesis, esterification reaction.

Biocatalytic synthesis of drugs is imperative to avoid the hazardous environmental effects of the pharmaceutical production processes. In view of this, biocatalytic synthesis of aspirin is discussed in the present work. A crude lipase extracted from Geobacillus sp. was crosslinked using N,N-methylenebisacrylamide (N,N-MBAAm) and two different initiators: ammonium persulphate (APS) and γ-irradiation. The crude lipase was crosslinked as such bypassing the separation procedures using a biocompatible crosslinker. The crosslinked lipase was characterized by various techniques and evaluated for its activity profile as a function of time, temperature, pH and substrate concentration and results were compared to its free form. The activity profile of the crosslinked lipase was observed to be only marginally lower than the free lipase. The crosslinked lipases were used as catalysts in the green synthesis of acetylsalicylic acid, aspirin, directly from the acetic acid. The reusability studies of the crosslinked lipases were carried out up to 10 cycles.

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