Abstract

This work aimed to study the cytotoxic effect of L-asparaginase isolated from local Withania somnifera plant on lymphocyte leukemia cells. To achieve this goal, L-asparaginase was purified from W. somnifera fruits by two purification steps, ion-exchange chromatography using DEAE-cellulose and gel filtration chromatography using Sephadex G-150, and the study utilized an in vitro evaluation for the cytotoxic effect of the partially purified L-asparaginase with concentrations ranging (12.5 to 100 μg/ml) in a two fold serial dilutions on some cell suspension culture including, acute lymphocyte leukemia and chronic lymphocyte leukemia culture at different concentrations (12.5 to 100 μg/ml) and different exposure time of treatment (24, 48 and 72 h). This two purification steps raised the specific activity from 1.73 U/mg in crude extract to 2.29 U/mg after ion-exchange and 10.5 U/mg after gel filtration; the purification fold was 1.32 after ion-exchange and 6.06 after gel filtration, the enzyme recovery was 56% after two purification steps and the results, pointed that acute lymphocyte leukemia culture showed highest sensitivity toward the cytotoxic effect (62.3±0.9%) of the partial purified L-asparaginase (100 μg/ml) than other culture after 48 h in a dose dependent manner, and highest cytotoxic inhibitory effect (73.2±1.6%) after 48 h of exposure on chronic lymphocyte leukemia culture, while healthy lymphocyte culture showed novel behavior. The lowest concentration of cell treatment gave the most significant (P< 0.01) inhibitory effect. The conclusion is that there is enough evidence to support the claim that L-asparaginase from W. somnifera may be considered chemotherapeutic agent against cancer, such as acute lymphoblastic leukemia and lymphosarcoma.

Key words: Acute lymphocyte leukemia (ALL), chronic lymphocyte leukemia (CLL), L-asparaginase, cytotoxic assay.