Isolation and Structure Identification of Cyclic Dipeptides from Cordyceps militaris

Abstract Background Cordyceps militaris (Cordycipitaceae) is a parasitic fungus that infects insects or larvae hosts and has been widely used to boost energy and enhance the immune system. A well-known nucleoside from C. militaris , cordycepin (3′-deoxyadenosine), has been reported to exhibit anti-inflammatory, anti-microbial, and anti-oxidant activities. Methods In this study, nine compounds were isolated from C. militaris using chromatographic purification techniques, and their structures were elucidated using spectroscopic analyses, including UV and NMR. Results Four tryptophan-containing cyclic dipeptides ( 1 – 4 ) were isolated from this species for the first time along with five known compounds, and the separation techniques for diketopiperazines were explained. The skeleton of the compounds 1 – 4 is reported for the first time from this species. Conclusion By expanding the chemical profile of C. militaris , our results may open new avenues for investigating its various biological potentials. Graphical abstract