Sesquiterpene acids from Shellac and their bioactivities evaluation.

Seven sesquiterpenes, including four α-cedrene types (Shellolic acid A-C, Laccishellolic acid), two R-curcumene types (Shellolic acid D-E) and Shellolic acid F were isolated from Shellac, of which six were unknown. Their structures were elucidated by HR-ESI-MS, UV, IR, 1D and 2D NMR methods. The absolute configurations were confirmed via the Mosher's method, circular dichroism (CD) and optical rotation analyses. A plausible biogenetic relationship for 1-6 is proposed. Cytotoxic and anti-bacterial activities of the isolates were evaluated. To the best of our knowledge, none compounds showed any cytotoxic activity, which is well consistent with that Shellac used as nontoxic material in pharmaceutical formulations and food additives. However, compound 1 exhibited inhibitory activity against Bacillus subtilis with the MIC value of 0.1 mg/mL.