Acceleration of hydrolytic ring opening of N7-alkylguanine by the terminal carbamoyl group of glycidamide.

Hydrolytic ring opening of guanine N7-adducts with compounds containing an oxacyclopropane ring, namely glycidamide, glycidol and 1,2-epoxybutane, was analyzed, and the reaction of the glycidamide adduct was the fastest. The differences in the reaction rates were confirmed by theoretical calculations.

A formamidopyrimidine derivative from the deoxyguanosine adduct produced by food contaminant acrylamide induces DNA replication block and mutagenesis.

Acrylamide, a common food contaminant, is metabolically activated to glycidamide, which reacts with DNA at the N7 position of dG, forming N7-(2-carbamoyl-2-hydroxyethyl)-dG (GA7dG). Owing to its chemical lability, the mutagenic potency of GA7dG has not yet been clarified. We found that GA7dG undergoes ring-opening hydrolysis to form N6-(2-deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-[N-(2-carbamoyl-2-hydroxyethyl)formamido]pyrimidine (GA-FAPy-dG), even at neutral pH. Therefore, we aimed to examine the effects of GA-FAPy-dG on the efficiency and fidelity of DNA replication using an oligonucleotide carrying GA-FAPy-9-(2-deoxy-2-fluoro-ß-d-arabinofuranosyl)guanine (dfG), a 2'-fluorine substituted analog of GA-FAPy-dG. GA-FAPy-dfG inhibited primer extension by both human replicative DNA polymerase ε and the translesion DNA synthesis polymerases (Polη, Polι, Polκ, and Polζ) and reduced the replication efficiency by less than half in human cells, with single base substitution at the site of GA-FAPy-dfG. Unlike other formamidopyrimidine derivatives, the most abundant mutation was G:C > A:T transition, which was decreased in Polκ- or REV1-KO cells. Molecular modeling suggested that a 2-carbamoyl-2-hydroxyethyl group at the N5 position of GA-FAPy-dfG can form an additional H-bond with thymidine, thereby contributing to the mutation. Collectively, our results provide further insight into the mechanisms underlying the mutagenic effects of acrylamide.

Synthetic Studies on Spirolides A and B: Formation of the Upper Carbon Framework Based on a Lewis Acid Template-Catalyzed Diels-Alder Reaction.

The upper fragment of spirolides A and B, which are marine phycotoxins that exhibit strong antagonistic activities on nicotinic acetylcholine receptors, was constructed. The functionalized cyclohexene in spirolides was stereoselectively synthesized from the bicyclic lactone, which could be readily accessed by the Lewis acid template-catalyzed asymmetric Diels-Alder reaction of the pentadienol and methyl acrylate.

[Assessing the Effects of Prescription Adjustment and Medication Non-adherence Associated with Medication Efficacy Classifications from Leftover Drugs through the SETSUYAKU-BAG Campaign].

　The increase in medical expenditure has been worsening and poses a serious social problem. Commonly, leftover drugs are retained by patients. We estimated the possible reduction in prescription rates by appropriately reusing leftover drugs, and investigated the medication efficacy classifications that render leftover drugs due to the medication non-adherence. A retrospective cross-sectional survey of prescription data was performed at community pharmacies engaged in the appropriate reuse of leftover drugs through the SETSUYAKU-BAG campaign. We evaluated the drug costs and number of drugs originally prescribed, the reduction in expenditure and numbers after the use of leftover drugs, and then calculated the prescription reduction ratio (PRR) based on the number of drugs. Factors contributing to non-adherence were analyzed by the PRR. After reviewing the prescription information of 1792 patients, the reduction rate in drug expenditure was found to be 20.1%. Purgatives, Chinese medicines, and agents for peptic ulcer had higher PRRs and belonged to the top ten medications according to the prescription efficacy classifications. Non-adherence associated with the medication efficacy classifications was assessed by analyzing 5466 formulations. Thirty percent of formulations were found to be non-adherent. According to the medication efficacy classifications, six medications including agents for hyperlipidemias, peptic ulcer, psychotropics agents, and others, were less adherent than antihypertensives. These results suggest that adjusting prescriptions by appropriately reusing leftover drugs in community pharmacies could reduce medical costs. Further considerations are necessary for improving medication adherence in Japan. Healthcare providers should monitor medication adherence more carefully, with the results identified in this study.

Alteration of the carbohydrate-binding specificity of a C-type lectin CEL-I mutant with an EPN carbohydrate-binding motif.

CEL-I is a Gal/GalNAc-specific C-type lectin isolated from the sea cucumber Cucumaria echinata. This lectin is composed of two carbohydrate-recognition domains (CRDs) with the carbohydrate-recognition motif QPD (Gln-Pro- Asp), which is generally known to exist in galactose-specific C-type CRDs. In the present study, a mutant CEL-I with EPN (Glu-Pro-Asn) motif, which is thought to be responsible for the carbohydrate-recognition of mannose-specific Ctype CRDs, was produced in Escherichia coli, and its effects on the carbohydrate-binding specificity were examined using polyamidoamine dendrimer (PD) conjugated with carbohydrates. Although wild-type CEL-I effectively formed complexes with N-acetylgalactosamine (GalNAc)-PD but not with mannose-PD, the mutant CEL-I showed relatively weak but definite affinity for mannose-PD. These results indicated that the QPD and EPN motifs play a significant role in the carbohydrate-recognition mechanism of CEL-I, especially in the discrimination of galactose and mannose. Additional mutations in the recombinant CEL-I binding site may further increase its specificity for mannose, and should provide insights into designing novel carbohydrate-recognition proteins.