Structural analysis of compounds with actions similar to local anesthetics and antipsychotic phenothiazines in yeast

Abstract

Local anesthetics and antipsychotic phenothiazines cause a rapid shutdown of both actin polarization and translation initiation in yeast cells, like some environmental stresses. These compounds all have an amphiphilic structure, surfactant activity and the ability to lyse yeast cells. To elucidate the structures responsible for the shutdown activity and cell lysis, we investigated a variety of amphiphiles. In the hydrophobic region, the straight alkyl structure was sufficient for the shutdown of actin polarization and translational initiation. In the hydrophilic region of the straight alkyl compounds, cationic trimethyl ammonium (TMA) and non-ionic hydroxyl structure (alcohols) shut down both reactions, while an anionic structure, sulphate, with a long alkyl chain (≥C6) shut down actin polarization only. On the compounds that shut down both reactions, including the clinical drugs, TMA compounds and alcohols, the potencies of shutdown and lysis exponentially increased with increasing the number of carbons in the hydrophobic region, whereas safety was affected by the structures of both hydrophilic and hydrophobic regions. These results indicate that the yeast system can easily evaluate clinical drugs, and provide a structural basis for designing compounds to shut down intracellular reactions.

Local Anesthetics and Antipsychotic Phenothiazines Interact Nonspecifically with Membranes and Inhibit Hexose Transporters in Yeast

“…The experimental octanol-water partition coefficients (logP) serve as a measure of the lipophilicity of the compounds (PhysProp Database, http://esc.syrres.com/ fatepointer/search.asp). The correlation between the IC 50 and logP values of local anesthetics, phenothiazines, and alcohols obeys the Meyer-Overton rule even in yeast (Uesono et al 2011) (Figure 1B). The rule is confirmed in yeast between the growth-inhibitory activities of volatile anesthetics and their lipophilicities (Keil et al 1996), the growth-inhibitory activities of alcohols and their chain lengths (lipophilicity) (Kato and Shibasaki 1980;Kubo et al 1995), and the IC 50 values of QACs and their chain lengths (Uesono et al 2011).…”

“…Alkaline phosphatase (ALP) activity was determined as described previously (Toh-e et al 1976;Uesono et al 2011). Because mature ALP is localized in the vacuoles, the activity is detected in the cells permeabilized by clinical drugs but not in living cells without the drugs.…”

“…The destruction of membranes by surfactant activity accounts for the antibiotic-effect mechanism at high concentrations, but the antibiotic-effect mechanism at lower concentrations, where membranes are not destroyed, remains unknown (Wessels and Ingmer 2013). Structures of local anesthetics, phenothiazines, alcohols, and QACs are largely different, but they are all amphiphiles and thus, at high concentrations, have sufficient surfactant-like activity to lyse erythrocytes (Seeman 1972;Sheetz and Singer 1974), model membranes (Kitagawa et al 2004), and the budding yeast Saccharomyces cerevisiae (Uesono et al 2008(Uesono et al , 2011. This activity accounts for the common toxicity of these compounds at high concentrations.…”

“…This activity accounts for the common toxicity of these compounds at high concentrations. At low concentrations that do not cause cell lysis, these compounds induce similar responses, including the inhibition of both translation initiation and polarization of the actin cytoskeleton, nuclear localization of the stress-responsible transcription factor Msn2, and processingbody (P-body) formation for messenger RNA (mRNA) decay in a dose-dependent manner in yeast (Uesono et al 2008(Uesono et al , 2011Araki et al 2015). Volatile anesthetics (Bruce 1975;Heys et al 1989;Horber et al 1988), local anesthetics (Banerjee and Redman 1977;Wang et al 2011), and phenothiazines (Raghupathy et al 1970;Kumar et al 1991) are known to inhibit protein synthesis in animals at cellular, tissue, and whole-body levels.…”

“…The dose-response curves are obtained by plotting the percentages of cells with polarized actin vs. the drug concentrations. A half-inhibitory concentration (IC 50 ) of polarized actin serves as a measure of a drug's potency to inhibit intracellular processes, and it makes pharmacologic analysis possible in yeast (Uesono et al 2011). The experimental octanol-water partition coefficients (logP) serve as a measure of the lipophilicity of the compounds (PhysProp Database, http://esc.syrres.com/ fatepointer/search.asp).…”