In this study, we sought food components which reduce acrolein toxicity to identify novel anti-stroke compounds. Our previous work demonstrated that cysteine derivatives ameliorated tissue injury of brain stroke in a mouse model (Uemura et al. 2018). Thus, we tested the acrolein detoxification effect of sulfur containing compounds. Thiol compounds, i.e. 2-FMT and cysteine methyl and ethyl esters counteracted acrolein toxicity at 10–30 µM (Fig. 1). These compounds neutralized free acrolein in less than 20 seconds (Fig. 2), and prevented the decrease of glutathione by acrolein (Fig. 3). The results indicate that 2-FMT and cysteine methyl and ethyl esters neutralize free acrolein and rescued cells from acrolein toxicity. We suggest that taking foods and drink containing these components such as green onion and coffee can offer a benefit for preventing brain stroke.
We also found that sulfur-containing compounds alliin and taurine, and the amino acid lysine decreased acrolein toxicity. Alliin and lysine neutralized free acrolein even slower compared to 2-FMT and cysteine methyl and ethyl esters, but this ability to neutralize acrolein probably contributes to the acrolein detoxification. Interestingly, high concentrations of taurine rescued cells from acrolein toxicity. Taurine not only neutralizes acrolein weakly (Fig. 2), but also increases putrescine and spermidine levels (Fig. 5). These polyamines also neutralized acrolein (Fig. 6), suggesting that the increase in polyamine content is also involved in the decrease in acrolein toxicity by taurine. Western blot analysis revealed that ODC1 and AMD1, both of which are rate-limiting enzymes in polyamine synthesis (Pegg 2016), are upregulated by taurine in the presence of acrolein (Fig. 6). Acrolein also diminished mitochondrial potential (Fig. 7), but taurine protected the decrease in the mitochondrial potential from acrolein. These results indicate that taurine decreases acrolein toxicity due to direct interaction with acrolein as well as through the increases in polyamine contents and mitochondrial functions. Taurine (2 g/kg) could decrease significantly the size of brain infarction (Fig. 4). Recently, it has been reported that taurine chloramine (0.5 mg/kg) protects against postischemic brain injury (Seol et al. 2021). However, this may be due to the presence of chloramine together with taurine.
Brain stroke is one of the major causes of the decrease in quality of life (QOL) in the elderly (Johnson et al. 2016). Our results suggest that daily intake of foods and drink containing thiol compounds (2-FMT, CysMe and CysEt), alliin, lysine and taurine, such as coffee, garlic, green onions, beans, squid and clams is probably useful to prevent severe injury in brain stroke and to improve QOL.