Discovery of an undescribed pyrazine and five known alkaloids from the myxobacterium Corallococcus silvisoli sp. nov. GDMCC 1.1387

Objective This study aims to study the chemical compositions from Corallococcus silvisoli sp. nov. GDMCC 1.1387 and explore their antibacterial activity and ABTS radical scavenging capacity. Methods The ethyl acetate extract of Corallococcus silvisoli sp. nov. was purified by column chromatography including ODS, Sephadex LH-20, and semi-preparative HPLC. Their structures were determined by spectroscopic analysis, theoretical electronic circular dichroism (ECD) calculation, and comparison with the reported literature. Results A previously undescribed pyrazine designated corapyrazine ( 1 ), along with five known alkaloids ( 2 ‒ 6 ), was isolated and identified from the first comprehensive chemical investigation of the myxobacterium Corallococcus silvisoli sp. nov. Compound 1 is the first naturally occurring dibenzylpyrazine featuring a hydroxyl functional group at the C-7 position. In biological assays, compounds 5 and 6 exhibited moderate antibacterial activity against Xanthomonas campestris pv. campestris with EC 50 values of 62.12 ± 0.25 and 14.90 ± 0.97 μg/mL, respectively. Additionally, compounds 2 ‒ 4 demonstrated potent ABTS free radical scavenging activity with EC 50 values ranging from 11.41 to 18.61 μM, comparable to that of ascorbic acid with a value of 18.07 μM. Conclusion This study expands the chemical diversity of the rare myxobacterium of the genus Corallococcus and provides promising molecules for the development of potent biocontrol agents and antioxidants.