Scytophycins, including tolytoxin, represent a class of actin disrupting macrolides with strong antiproliferative effects on human cells. Despite intense research, little attention has been paid to scytophycin-induced cell death or the structural features affecting its potency. We show that tolytoxin and its natural analogue, 7-O-methylscytophycin B, lacking the hydroxyl substitution in its macrolactone ring, differ substantially in their cytotoxic effect. Both compounds increase the level of caspases 3/7, which are the main executioner proteases during apoptosis, in HeLa wild-type (WT) cells. However, no caspase activity was detected in HeLa cells lacking Bax/Bak proteins crucial for caspase activation via the mitochondrial pathway. Obtained data strongly suggests that scytophycins are capable of inducing mitochondria-dependent apoptosis. These findings encourage further research in structure-activity relationships in scytophycins and highlight the potential of these compounds in targeted drug delivery.
Keywords: actin disruption; apoptosis; cancer; scytophycines; tolytoxin.
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