Cationic surfactants induce apoptosis in normal and cancer cells.

Cationic surfactants, such as benzalkonium chloride and benzethonium chloride, possess quaternary ammonium salt. These surfactants have antimicrobial action and are used as a preservative and an antiseptic. The positively charged polar head of cationic surfactants seems to play a role in the antimicrobial action of these compounds. Recently, benzalkonium chloride in eye drops has been reported to induce apoptosis in conjunctival cells. Here, we examined whether various types of surfactants including anionic and amphoteric surfactants induce apoptosis or not in mammalian cells. Antimicrobial cationic surfactants induced apoptosis at lower concentration than its critical micelle concentration (CMC) in rat thymocytes. Other quaternary ammonium surfactants, such as cetyltrimethylammonium bromide, similarly increased biochemical and morphological features of apoptosis, whereas both anionic and amphoteric surfactants had no significant effect on these apoptotic features. These results suggest that the positive charge of quaternary ammonium surfactants is involved with onset of the apoptotic process. The treatment of benzethonium chloride also led to apoptotic cell death in Jurkat cells. These results indicate that cationic surfactants induce apoptosis in the normal and cancer cells.

Wogonin prevents immunosuppressive action but not anti-inflammatory effect induced by glucocorticoid.

Glucocorticoid, such as dexamethasone, has anti-inflammatory and immunosuppressive action as major pharmacological effects. The latter action caused by lymphocyte apoptosis is not only a therapeutic effect but also an adverse reaction. Wogonin, a plant flavone found in Scutellaria baicalensis Georgi, inhibited dexamethasone-induced apoptotic changes, such as DNA fragmentation, nuclear condensation, phosphatidylserine translocation, and caspase activation in rat thymocytes. Since wogonin inhibited dexamethasone-induced DNA fragmentation in a noncompetitive manner, a target of this flavone is unlikely to be an antagonist of glucocorticoid receptor. Wogonin did not only act as an inhibitor of caspases, but also protected apoptosis induced by other glucocorticoids. Since wogonin reduced one of the major pharmacological effects of dexamethasone, we examined whether this flavone diminishes the anti-inflammatory action, another pharmacological effect. The anti-inflammatory action of dexamethasone was evaluated by carrageenan-induced paw edema model. Although dexamethasone significantly suppressed paw edema induced by carrageenan, wogonin had no effect on the anti-inflammatory action of dexamethasone. These results suggest that wogonin may be a useful compound to reduce the immunosuppressive side effect of glucocorticoid.