Isolation and evaluation of virucidal activities of flavanone glycosides and rosmarinic acid derivatives from Dracocephalum spp. against feline calicivirus

Feline calicivirus is one of the surrogate viruses of human norovirus. This study aimed to identify virucidal compounds, chemical constituents of plants from the genus Dracocephalum, which are rich in flavonoids and phenylpropanoid oligomers. Four undescribed compounds, including a flavanone glucoside, two stilbenoid glycosides, and a phenylpropanoid amide glycoside, as well as 17 known compounds, were isolated from the Mongolian plants Dracocephalum fruticulosum Stephan ex Willd., and D. nutans L. belonging to the family Lamiaceae. The structures of the compounds were determined based on NMR, MS, and electronic CD spectroscopic data. In addition to these 21 compounds, 15 previously reported compounds from D. foetidum Bunge in C.F. von Ledebour were included, and a total of 36 compounds were evaluated for their virucidal activities against feline calicivirus. Some of the flavanone glycosides and phenylpropanoid oligomers showed virucidal activities, and their structural features are discussed. The findings suggest that isosakuranetin glycosides and phenylpropanoid oligomers may have the potential for norovirus inactivation.

Monoterpene glycosides, phenylpropanoids, and acacetin glycosides from Dracocephalum foetidum

Chemical investigation of the acetone extract from the aerial parts of the Mongolian medicinal plant Dracocephalum foetidum resulted in the isolation of three limonene glycosides, a caffeic acid trimer, four rosmarinic acid glucosides, and five acacetin acyl glycosides, together with 13 known natural products. The chemical structures of all of the compounds were determined by spectroscopic analyses. Among these compounds three showed hyaluronidase inhibitory activity. In addition, one other compound showed stronger 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity than the positive control Trolox, whereas three other compounds demonstrated a similar activity to that of Trolox.