Citation: Sengupta, S.; Das, P.; Sharma, S.; Shukla, M.K.; Kumar, R.; Kumar Tonk, R.; Pandey, S.; Kumar, D. Role and Application of Biocatalysts in Cancer Drug Discovery. Catalysts 2023, 13, 250. https://doi.org/10.3390/ catal13020250 Academic Editor: Chiching Hwang Received: 3 December 2022 Revised: 15 January 2023 Accepted: 18 January 2023 Published: 21 January 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). catalysts Review Role and Application of Biocatalysts in Cancer Drug Discovery Sounok Sengupta 1 , Prathama Das 2 , Samridhi Sharma 3 , Monu Kumar Shukla 3 , Rajesh Kumar 4 , Rajiv Kumar Tonk 5 , Sadanand Pandey 6, * and Deepak Kumar 3, * 1 Department of Pharmacology, School of Pharmaceutical Sciences, Shoolini University, Solan 173229, India 2 Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan 173229, India 3 Department of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Shoolini University, Solan 173229, India 4 Narayan Institute of Pharmacy, Gopal Narayan Singh University, Jamuhar, Sasaram 821305, India 5 Department of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Delhi Pharmaceutical Sciences and Research University, New Delhi 110017, India 6 Department of Chemistry, College of Natural Sciences, Yeungnam University, 280 Daehak-Ro, Gyeongsan 38541, Republic of Korea * Correspondence: sadanand.au@gmail.com or spandey@ynu.ac.kr (S.P.); guptadeepak002@gmail.com (D.K.) Abstract: A biocatalyst is an enzyme that speeds up or slows down the rate at which a chemical reaction occurs and speeds up certain processes by 10 8 times. It is used as an anticancer agent because it targets drug activation inside the tumor microenvironment while limiting damage to healthy cells. Biocatalysts have been used for the synthesis of different heterocyclic compounds and is also used in the nano drug delivery systems. The use of nano-biocatalysts for tumor-targeted delivery not only aids in tumor invasion, angiogenesis, and mutagenesis, but also provides information on the expression and activity of many markers related to the microenvironment. Iosmapinol, moclobemide, cinepazide, lysine dioxygenase, epothilone, 1-homophenylalanine, and many more are only some of the anticancer medicines that have been synthesised using biocatalysts. In this review, we have highlighted the application of biocatalysts in cancer therapies as well as the use of biocatalysts in the synthesis of drugs and drug-delivery systems in the tumor microenvironment. Keywords: biocatalyst; enzymatic catalysis; cancer; immune system; chemotherapy; nanomedicine 1. Introduction Biocatalysis has become an essential component of modern organic synthesis, both in the commercial and academic spheres of activity and in green synthesis. Its success may be attributed in large part to the creation of cutting-edge methodologies for the discovery of novel enzymes and the application of a high-throughput laboratory. Biocatalysts can be used for preparation on a grammes (g) to kilogrammes (kg) scale. It has also become an alternative to chemical catalysis in recent years, and it is currently being used in a diverse field [1–5]. Over the last two decades, the number of biocatalytic tools, such as newly developed catalysts with specifically tuned features and novel ideas for reaction, has expanded tremendously [5,6]. The initial stages in biocatalysis include identifying the target reaction, searching for biocatalysts, characterizing those biocatalysts, and using them in different fields. Biocatalysts are also used in recombinant enzyme systems; from the extraction of natural sources to gene mining using bioinformatics techniques, the screening of biocatalysts has evolved rapidly. They are effective in reactions having multiple steps as they offer an environment that is protective of enzymes (Figure 1)[7–10]. Catalysts 2023, 13, 250. https://doi.org/10.3390/catal13020250 https://www.mdpi.com/journal/catalysts