Antiproliferative action of isatine-beta-thiocarbohydrazone and N-ethylisatine-beta-thiocarbohydrazone on human PBMC and on two neoplastic cell lines

The antiproliferative action of two synthetic compounds, isatine-b-thiocarb ohydrazone (IsTCH) and N-ethyl isatine-beta-thiocarbohydrazone (N-Et-IsTCH) , towards healthy human peripheral blood mononuclear cells (PBMC) and two n eoplastic cell lines in vitro, was investigated. IsTCH and N-Et-IsTCH were dissolved in DMSO and then diluted with nutrient medium to desired final co ncentration. Target cells were PBMC, as well as human cervix carcinoma - He La cells, and murine melanoma B16 cells. Five different concentrations (3 mu M to 50 mu M) of investigated agents we re applied on target cells. Cell survival was determined 72 h after the age nt's action using MTT test. Results obtained showed that both investigated compounds exerted a dose dependent antiproliferative action to neoplastic c ell lines. Their action was only cytostatic; trypan blue exclusion test did not show any sign of direct drug cytotoxicity when drugs concentration wer e less than 50 mu M ICs50 +/- SD for IsTCH antiproliferative action were 61 .69 +/- 4.25 mu M for HeLa cells; 34.1 +/- 7.15 mu M for B16 cells: 17.62 /- 7.11 mu M for nonstimulated and 30.0 +/- 9.46 mu M for stimulated (by 5m g/ml PHA) PBMC. ICs50 +/- SD for the action of N-Et-IsTCH were 21.86 +/- 1. 77 mu M for HeLa cells; 10.37 +/- 1.55 mu M for B16 cells; >47 mu M for bot h, nonstimulated and for stimulated, PBMC. Nonstimulated human PBMC appeare d to be the most sensitive to the cytostatic IsTCH action; while HeLa cells were the most resistant. N-Et-IsTCH showed more than two or five fold stro nger antiproliferative effect toward B16 cells than on HeLa or PBMC cells, respectively, and more than three times intensive activity compared to IsTC H, indicating specificity of N-Et-IsTCH towards inhibition of melanoma cell growth. While increasing concentrations of IsTCH led to decrease in the th e PBMC induced suppression of HeLa cell survival.; N-Et-Is-TCH in the diffe rence from IsTCH, in dose dependent way contributed to the PBMC induced sup pression of HeLa cell survival. In conclusion, the activity of N-Et-Istch o n malignant melanoma cells deserves further investigation.