Pharmacological and Toxicological Appraisal of Promising Enzyme-tyrosinase Isolated from Soil Bacteria-an Update

Abstract

Aims: The membrane associated tyrosinase is an enzymatically active monomeric glycoprotein which is purified to only a low degree. It has gained importance in the present era due to its antioxidant and immunomodulatory properties as well as applications in industry. Moreover its role in the synthesis of melanin in skin for protection from UV radiations also paved the way towards the better understanding of this enzyme. Study Design: Biochemical and molecular characterization of tyrosinase producing soil bacterium had been followed by the assessment of its antioxidant, cytotoxic and anti-cancer activities. Place and Duration of Study: Whole work had been completed at the Microbiology and Molecular biology labs of IMBB during 2018- 2019. Methodology: Tyrosinase producing species were identified by biochemical characterization followed by their genomic DNA sequencing and BLAST analysis while crude tyrosinase was characterized by Bradford's methods, tyrosinase activity and total protein activity, followed by their molecular characterization on SDS-PAGE. The antioxidant and free radical scavenging properties of tyrosinase were evaluated via DPPH, ABTS and FRAP assays and cell proliferation inhibition and the cytotoxicity was calculated via antitumor and MTT assays. Results: P. putida, B. cereus, B. mycoides, M. luteus, K. pneumonia were found to be tyrosinase producing species while their SDS-PAGE analysis showed that the molecular mass of crude tyrosinase was about 39 kDa. Protein contents, total tyrosinase and specific tyrosinase activity was found to be highest in tyrosinase from B. mycoides [0.008±0.06 mg/ml, 1500±0.06 U/ml and 346820.8±0.03 U/mg of tyrosinase respectively]. The results of biological activities of crude tyrosinase vary from bacteria to bacteria. Tyrosinase from P. putida showed higher antioxidant [66.4±0.01% in DPPH assay, 32.04±0.06%in ABTS assay and 320.6±0.06 in FRAP assay], antitumor [67.8±0.01%] and cytotoxic activity [39±1.0% cell viability], followed by B. Cereus tyrosinase [64.7±0.06% antioxidant power in DPPH assay, 53.41±0.03% in ABTS assay and 159.6±0.06% in FRAP assay, 46.46±0.01% antitumor and 43±0.75% cell viability]. Conclusion: The study revealed that tyrosinase isolated from different bacterial strains depicted optimal percentage of anti-oxidative, anti-proliferative and cellular viability and can be used in the near future for medical and industrial purposes.