Synthetic stigmastanes with dual antiherpetic and immunomodulating activities inhibit ERK and Akt signaling pathways without binding to glucocorticoid receptors

Abstract

Background: We have previously shown that some synthetic hydroxylated stigmastanes derived from plant sterols inhibit in vitro HSV-1 replication in ocular cell lines and decrease cytokine production in stimulated macrophages, suggesting that these steroids might combine antiviral and immunomodulating properties. In this paper we report the synthesis of some analogues fluorinated at C-6 in order to study the effect of this modification on bioactivity.Methods: The following methods were used: organic synthesis of fluorinated analogs, cytotoxicity determination with MTT assays, cytokine production quantification with ELISAs, glucocorticoid activity determination by displacement assays, immunofluorescence and transcriptional activity assays, studies of the activation of signaling pathways by Western blot, antiviral activity evaluation through virus yield reduction assays.Results: We report the chemical synthesis of new fluorinated stigmastanes and show that thisfamily of steroidal compounds exerts its immunomodulating activity by inhibiting ERK and Akt signaling pathways, but do not act as glucocorticoids. We also demonstrate that fluorination enhances the antiviral activity.Conclusions: Fluorination on C-6 did not enhance the anti-inflammatory effect, however, an increase in the in vitro antiviral activity was observed. Thus, our results suggest that it is possible to introduce chemical modifications on the parent steroids in order to selectively modulate one of the effects.General significance: This family of steroids could allow the development of an alternative treatment for ocular immunopathologies triggered by HSV-1, without the undesirable side effects of the currently used drugs.