Tropolone-Bearing Sesquiterpenes from Juniperus chinensis: Structures, Photochemistry and Bioactivity

The tropolone-bearing sesquiterpenes juniperone A (1) and norjuniperone A (2) were isolated from the folk medicinal plant Juniperus chinensis, and their structures were determined by a combination of spectroscopic and crystallographic methods. Photojuniperones A1 (3) and A2 (4), bearing bicyclo[3,2,0]heptadienones derived from tropolone, were photochemically produced and structurally identified by spectroscopic methods. Predicted by the machine learning-based assay, 1 significantly inhibited the action of tyrosinase. The new compounds also inhibited lipid accumulation and enhanced the extracellular glycerol excretion.

Automated summary

Through a combination of spectroscopic and crystallographic methods, natural compounds with different chemical structures were isolated from Juniperus chinensis, with novel compounds being photochemically produced. One of the compounds significantly inhibited the activity of tyrosinase as predicted by a machine learning-based assay, while also displaying characteristics of inhibiting lipid accumulation and enhancing extracellular glycerol excretion.