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Background: 3-Mercaptopyruvate sulfurtransferase (3-MST) is a multifunctional, mitochondrial and cytoplasmic sulphurtransferase that catalyses the detoxification of cyanide to a less toxic thiocyanate. Limicolaria flammea feeds majorly on green leaves, plants and other cyanide containing foods. Methods: 3-MST from the hemolymph of Limicolaria flammae was purified by 70 % ammonium sulphate precipitation and ion exchange chromatography. The purified enzyme was characterized at different levels such as optimal activity, inhibitors, substrate preference, thermal stability and analysis of ki-netic parameters. Results: 3-MST from the hemolymph of Limicolaria flammae had a yield of 0.75 % with specific activity of 0.42 μ/mg/ml. The Km values for the substrates; KCN and 2-Mercaptoethanol were 1.09 and 2.83 mM, while the Vmax values were 3.08 μml/mol/min and 6.17 μml/mol/min respectively. The optimum pH and temperature of the enzyme were 5.0 and 60° C respectively. The metals (Al3+, Ca2+, and K+) demonstrated inhibitory activity in a concentration dependent manner. The substrate specificity study showed that sodium sulphite, ammonium per sulphate and ammonium sulphite showed enzymatic interference. Conclusion: This study affirmed the presence of 3-MST activity in the hemolymph of Limicolaria flammea, an indication that the enzyme possesses functional cyanide detoxification mechanism necessary for the survival of the animal in the environment.

One major mechanism of death in cancer cells is via the induction of apoptosis, the best‐studied form of programmed cell death. Although apoptosis is essential in many normal physiological processes, including tissue sculpting during embryogenesis, development of the immune system and destruction of damaged cells, its alteration is a major cause of cancer. Having confirmed the cytotoxic effect of certain fractions derived from the crude water‐soluble extract (CWSE) of Momordica charantia Linn (MC) in a previous study (Ehigie et al., 2016), we investigated in this study, the mode of death induced by these fractions, both in human breast [MDA‐MB‐436] and lung cancer [A549] cell lines, using PI (Propidium Iodide), DAPI (4,6‐diamidino‐2‐phenylindole dihydrochloride) and Caspase‐3 Activation Determination Assays. Western blotting was also employed to verify the activation of caspase‐3 and the mitochondrial release of cytochrome c. The ethyl acetate (D3), n‐hexane (D4) and dichloromethane (D5) fractions were all obtained from the CWSE via solvent partitioning and then administered at 100 and 125 μg/mL for 24 h. Though we observed that the cancer cells treated with the ethyl acetate fraction of the CWSE of M. charantia were the most killed, we saw neither the evidence of chromatin condensation, cell shrinkage and apoptotic bodies, nor the activation of caspase‐3 or cytochrome c release! Data obtained for caspase‐3 activation by MC show no significant (P<0.05) difference between the negative control and all MC‐treated groups for both cell types with the negative control group for MDA‐MB 436 cells at 90.97±9.03 compared with D3‐treated (89.26±3.17 and 96.29±3.85), D4‐treated (90.99±19.78 and 91.71±4.83) and D5‐treated (93.95±2.95 and 88.91±1.00) cells at 100 and 125 μg/mL respectively, similar to values obtained for A549 cells; negative control (69.69±2.60) compared with D3‐treated (70.39±6.93 and 76.21±2.65), D4‐treated (73.67±1.32 and 74.25±0.00) and D5‐treated (71.80±3.26 and 71.17±14.85) cells at 100 and 125 μg/mL respectively. From the foregoing, we conclude that the cell death induced by the ethyl acetate, n‐hexane and dichloromethane fractions of MC in the selected cancer cell lines is by a non‐classical apoptotic mechanism.Support or Funding InformationOrganization for Women in Science for the Developing World (OWSD) and Swedish International Development Cooperation Agency (SIDA)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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