Cytomorphological study of cultured mammalian cells treated with benzaldehyde, catechol and their derivatives with special reference to inhibition of DNA synthesis.

Cytotoxicity and cytomorphological changes induced in cultured mammalian cells by the application of benzaldehyde, pyrocatechol and their derivatives were examined. Among the compounds tested, 3,4-dihydroxybenzaldehyde (protocatechualdehyde) and 1,2-dihydroxybenzene (pyrocatechol) produced cytomorphological changes characteristic of specific inhibitors of DNA synthesis in V79 cells and EJ-1 cells. However, they did not induce such changes in HeLa cells. 2,3-Dihydroxybenzaldehyde and catecholamines did not produce such characteristic changes in V79 cells. The cytological effects of protocatechualdehyde and pyrocatechol were confirmed by a study on the incorporation of 3H-precursors of DNA, RNA and protein into 3 cell lines.

Antiproliferative activity of protocatechualdehyde on Chinese hamster cells grown in culture.

The mode of cytotoxic action of protocatechualdehyde on V79 cells was examined. The cytotoxicity of protocatechualdehyde on V79 cells was time- and cell cycle-dependent. The lethal action is selective for the cells at S phase only. The cells lethally damaged at S phase seemed to complete their DNA synthesis, although the rate of DNA synthesis became lower and the duration of S phase was prolonged. Some cells arriving at G2 phase directly entered the next S phase without cell division and died of karyorrhexis or karyolysis. Cells treated at stages of the cell cycle other than S showed normal progression of their cell cycle to the G1/S boundary. The block point of the cell cycle seemed to lie a little behind that with hydroxyurea. When the cells at phases other than S were blocked with protocatechualdehyde for 14 hr, elongation of the next S phase occurred after removal of protocatechualdehyde. On alkaline sucrose gradient analysis, little scission of parental DNA was observed in the cells treated with protocatechualdehyde.