New insight into the essential oil from Calocedrus rupestris wood: Chemical composition, in vitro and in silico biological activities

This study investigated the chemical composition and the in vitro and in silico activities of the essential oil (EO) from Calocedrus rupestris wood. The EO was analyzed by GC-MS, while antimicrobial activity was assessed against Staphylococcus aureus, Escherichia coli, and Candida albicans using microdilution assays. Anti-inflammatory potential was evaluated through inhibition of LPS-induced nitric oxide (NO) production in RAW 264.7 cells. Molecular docking was performed to examine interactions of the main EO constituents with MurE (S. aureus), MurA (E. coli), ARO1 (C. albicans), and iNOS. The EO yield was 1.08% (dry wt.) and contained 10 identified constituents, predominantly methyl thujate (46.07%), methyl myrtenate (17.91%), cadalene (10.41%), and α-terpineol (10.0%). The EO exhibited strong antifungal activity against C. albicans (MIC = MFC = 0.1%) and moderate antibacterial activity against S. aureus (MIC = MBC = 0.4%) and E. coli (MIC = MBC = 0.8%). It also inhibited NO production (IC = 25.08 µg/mL) without causing cell toxicity. Docking results supported these findings: cadalene showed strong affinity for ARO1, methyl thujate and α-terpineol for MurE, while weaker antibacterial effects correlated with lower affinity at MurA; methyl myrtenate displayed high affinity for iNOS. In conclusion, the EO of C. rupestris demonstrated notable antimicrobial and anti-inflammatory activities, with methyl thujate, methyl myrtenate, cadalene, and α-terpineol identified as the principal active constituents.