Isolation and Anti-Leukemic Characterization of Extracellular L-asparaginase From Endophytic Bacterium, Brevibacterium sp. M-R۲۱ Isolated Glycyrrhiza glabra Root

Introduction:L-Asparaginase (L-ASPase) is known as a potent anti-cancer drug against L-Asparagineauxotroph tumorcells. In this study, an endophytic L-ASPase producing bacterium of the genus Bervibacillus from the rootof Glycyrrhiza glabra was screened and characterized.Methods:After purification of the enzyme by ammonium sulfate precipitation, dialysis, and silica gel columnchromatography, anti-cancer studies were performed against MRC-۵ (normal lung cells) and U۹۳۷ cell(leukemia cell line). Additionally, optimization fermentation was performed in terms of significantvariables screened from a one-factor-at-the-time (OFAT) approach. The interactions of differentexperimental parameters were investigated using the response surface methodology (RSM) with the centralcomposite design (CCD) algorithm.Results:Cytotoxicity study showed that the dose-dependent effect of the L-ASPase at ۱۰۰ IU/ml had a lethality ofabout ۸۰% against leukemia cells. Therefore, the IC۵۰ of the enzyme for leukemia cells was calculated tobe approximately ۳۳.۵۴ IU/ml. Interestingly, the cytotoxicity of L-ASPase against normal lung cells wasonly about ۲۰% at L-ASPase activity of ۶۰-۱۰۰ IU/ml. Based on the quadratic model, the optimalfermentation conditions were predicted to be ۲% glucose, ۲% NaCl, pH۷, and incubation temperature ۳۰°C. Under these conditions, the highest enzyme activity was ۹۰ IU/ml, which had an efficiency of about۳۰% compared to non-optimized conditions.Conclusion:The results showed that L-ASPase isolated from Brevibacterium sp. M-R۲۱ with selective cytotoxicityagainst the leukemia cell line may be a potential candidate as an anti-cancer drug after further study.

Keywords:

L-Asparaginase , Anti-Leukemia activity , Brevibacterium sp. M-R۲۱ , Response Surface Methodology(RSM)