Bulbimidazoles A–C, Antimicrobial and Cytotoxic Alkanoyl Imidazoles from a Marine Gammaproteobacterium Microbulbifer Species

• Published in: Journal of natural products (Washington, D.C.) Vol. 83; no. 4; pp. 1295 - 1299
• Main Authors: Karim, Md. Rokon Ul, Harunari, Enjuro, Oku, Naoya, Akasaka, Kazuaki, Igarashi, Yasuhiro
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society and American Society of Pharmacognosy 24.04.2020; Amer Chemical Soc
• Subjects: Alteromonadaceae - chemistry; Alteromonadaceae - isolation & purification; Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antineoplastic Agents - chemistry; Antineoplastic Agents - isolation & purification; Antineoplastic Agents - pharmacology; Chemistry, Medicinal; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Gammaproteobacteria - isolation & purification; Gammaproteobacteria - metabolism; Imidazoles - chemistry; Life Sciences & Biomedicine; Microbial Sensitivity Tests; Molecular Structure; Pharmacology & Pharmacy; Plant Sciences; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - metabolism; Science & Technology; BACTERIUM; ORIGIN; SP NOV; BIOSYNTHESIS; FATTY-ACID; ISOLEUCINE
• ISSN: 0163-3864; 1520-6025
• DOI: 10.1021/acs.jnatprod.0c00082

Three new alkanoyl imidazoles, designated bulbimidazoles A–C (1–3), were found from the culture extract of the gammaproteobacterium Microbulbifer sp. DC3-6 isolated from a stony coral of the genus Tubastraea. The absolute configuration of the anteiso-methyl substitution in 1 was established to be a mixture of (R)- and (S)-configurations in a ratio of 9:91 by applying the Ohrui–Akasaka method. Compounds 1–3 displayed unique broad-spectrum antimicrobial activity against Gram-positive and -negative bacteria and fungi with MICs ranging from 0.78 to 12.5 μg/mL. They also exhibited cytotoxicity toward P388 murine leukemia cells with IC50 in the micromolar range.