Thirty-nine acrylates and methacrylates that had been used in dental resin materials were evaluated by a cytotoxicity test, and the relationships between their structures and cytotoxicity were studied to predict cytotoxic levels of dental resin materials in order to develop new low-toxic resin materials. All the acrylates evaluated were more toxic than corresponding methacrylates. In both the acrylates and methacrylates, a hydroxyl group seemed to enhance cytotoxicity. Dimethacrylates with 14 or fewer oxyethylene chains showed similar cytotoxicity while dimethacrylates with 23 oxyethylene chains showed lower cytotoxicity. The cytotoxicity ranking of monomers widely used in dental resin materials was bisphenol A bis 2-hydroxypropyl methacrylate (bisGMA) > urethane dimethacrylate (UDMA) > triethyleneglycol dimethacrylate (3G) > 2-hydroxyethyl methacrylate (HEMA) > methyl methacrylate (MMA). In acrylates, methacrylates, and ethylmethacrylates with either substituents, the lipophilicity of substituents affected their cytotoxicity, and an inverse correlation between IC50 and logP was observed. These results will be useful in developing new resin materials with low toxic monomer compositions.

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The top half models 11 and 25 of the antibiotic aglycone tetronolide (1) were prepared from tetrahydrophthalide and 2,4-hexadiene-l,6-diol in 8 and 12 steps, respectively. Compound 11 was coupled with the bottom half model 30a, which was prepared via Diels-Alder reaction of methacrolein with triene 27a or 33a to afford a-acyltetronate 38. The allyl chloride 39 derived from 38 was rather unstable, and attempts for macrocyclization resulted in decomposition of the key intermediate.