1. O-Methylation of carboxylic acids with streptozotocin
Li-Yan Zeng, Yang Liu, Jiakun Han, Jinhong Chen, Shuwen Liu, Baomin Xi Org Biomol Chem. 2022 Jul 6;20(26):5230-5233. doi: 10.1039/d2ob00578f.
The clinically used DNA-alkylating drug streptozotocin (STZ) was investigated using a simple work-up as an O-methylating agent to transform various carboxylic acids, sulfonic acids and phosphorous acids into corresponding methyl esters, and did so with yields of up to 97% in 4 h at room temperature. Good substrate tolerance was observed, and benefited from the mild conditions and compatibility of the reaction with water.
2. Acridinium Ester Chemiluminescence: Methyl Substitution on the Acridine Moiety
Manabu Nakazono, Shinkoh Nanbu, Takeyuki Akita, Kenji Hamase J Oleo Sci. 2021;70(11):1677-1684. doi: 10.5650/jos.ess21186.
Methyl groups were introduced on the acridine moiety in chemiluminescent acridinium esters that have electron-withdrawing groups (trifluoromethyl, cyano, nitro, ethoxycarbonyl) at the 4-position on the phenyl ester. The introduction of methyl groups at the 2-, 2,7-, and 2,3,6,7-positions on the acridine moiety shifted the optimal pH that gave relatively strong chemiluminescence intensity from neutral conditions to alkaline conditions. 4-(Ethoxycarbonyl)phenyl 2,3,6,7,10-pentamethyl-10λ4-acridine-9-carboxylate, trifluoromethanesulfonate salt showed long-lasting chemiluminescence under alkaline conditions. Acridinium esters to determine hydrogen peroxide concentration at pH 7-10 were newly developed.
3. Binding of indomethacin methyl ester to cyclooxygenase-2. A computational study
Menyhárt-Botond Sárosi J Mol Model. 2018 Jun 5;24(7):150. doi: 10.1007/s00894-018-3686-8.
Inhibitors selective towards the second isoform of prostaglandin synthase (cyclooxygenase, COX-2) are promising nonsteroidal anti-inflammatory drugs and antitumor medications. Methylation of the carboxylate group in the relatively nonselective COX inhibitor indomethacin confers significant COX-2 selectivity. Several other modifications converting indomethacin into a COX-2 selective inhibitor have been reported. Earlier experimental and computational studies on neutral indomethacin derivatives suggest that the methyl ester derivative likely binds to COX-2 with a similar binding mode as that observed for the parent indomethacin. However, docking studies followed by molecular dynamics simulations revealed two possible binding modes in COX-2 for indomethacin methyl ester, which differs from the experimental binding mode found for indomethacin. Both alternative binding modes might explain the observed COX-2 selectivity of indomethacin methyl ester. Graphical abstract Binding of indomethacin methyl ester to cyclooxygenase-2.
