Post-Treatment with Amorfrutin B Evokes PPARγ-Mediated Neuroprotection against Hypoxia and Ischemia

In this study, we demonstrate for the first time that amorfrutin B, a selective modulator of peroxisome proliferator-activated receptor gamma-PPAR gamma, can protect brain neurons from hypoxia- and ischemia-induced degeneration when applied at 6 h post-treatment in primary cultures. The neuroprotective effect of amorfrutin B suggests that it promotes mitochondrial integrity and is capable of inhibiting reactive oxygen species-ROS activity and ROS-mediated DNA damage. PPAR gamma antagonist and Pparg mRNA silencing abolished the neuroprotective effect of amorfrutin B, which points to agonistic action of the compound on the respective receptor. Interestingly, amorfrutin B stimulated the methylation of the Pparg gene, both during hypoxia and ischemia. Amorfrutin B also increased the protein level of PPAR gamma during hypoxia but decreased the mRNA and protein levels of PPAR gamma during ischemia. Under ischemic conditions, amorfrutin B-evoked hypermethylation of the Pparg gene is in line with the decrease in the mRNA and protein expression of PPAR gamma. However, under hypoxic conditions, amorfrutin B-dependent hypermethylation of the Pparg gene does not explain the amorfrutin B-dependent increase in receptor protein expression, which suggests other regulatory mechanisms. Other epigenetic parameters, such as HAT and/or sirtuins activities, were affected by amorfrutin B under hypoxic and ischemic conditions. These properties position the compound among the most promising anti-stroke and wide-window therapeutics.

Automated summary

Amorfrutin B exhibits neuroprotective effects by modulating the PPARγ receptor, promoting mitochondrial integrity, and inhibiting ROS activity and DNA damage. The compound's actions on the PPARγ gene methylation and protein expression vary under hypoxic and ischemic conditions, suggesting complex regulatory mechanisms involved in its neuroprotective effects. Amorfrutin B also affects other epigenetic parameters, making it a promising therapeutic option for stroke treatment with a wide treatment window.