Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• MIC ranges of 6.25–25 μg/mL. Keywords: 1JC,H; alkanoylimidazoles; anteiso; Kocuria; nocarimidazole; Introduction The phylum Actinobacteria contains bacterial genera most prolific as producers of novel natural products with high structural diversity, unique modes of action, and potent bioactivities

• medium at 30 °C for five days, was extracted with 1-butanol, and the extract was subjected to chromatographic purification, yielding two new alkanoylimidazoles, nocarimidazole C (1) and D (2), along with three known congeners, nocarimidazole A (3) and B (4) as well as bulbimidazole A (5, Figure 1

• ). Nocarimidazole C (1) was obtained as a pale yellow amorphous solid. The molecular formula was determined as C12H21N3O based on a protonated molecular ion [M + H]+ at m/z 224.1763 (Δ = +0.6 mmu). The four degrees of unsaturation, calculated from the molecular formula, and the UV absorption band around 296 nm