Seasonal Influence on the Bioactive Profile of Essential Oil from Azorean Cryptomeria japonica Foliage: In Vitro and...

Driven by the growing demand for quality assurance within the essential oil (EO) industry, this study builds upon prior seasonal chemical and anticholinergic characterizations of Azorean Cryptomeria japonica foliage (Az-CJF) EO by presently evaluating the seasonal variations in its antibacterial, antioxidant, and anti-inflammatory activities. Autumn (Aut-EO) and spring (Spr-EO) samples exhibited a uniform, targeted antibacterial profile exclusively against Gram-positive bacteria, with a MIC of 5.0 mg/mL for Micrococcus luteus and ≥10.0 mg/mL for Bacillus licheniformis, B. subtilis, and Staphylococcus aureus. Antioxidant capacities also remained seasonally consistent within each of the three individual assays, namely the DPPH, ABTS, and β-carotene bleaching assays (EC₅₀ ≤ 10.5, ≤ 6.0, and ≤0.3 mg/mL, respectively), suggesting a stable potential for lipid peroxidation inhibition. In addition, both EOs protected against bovine serum albumin denaturation (84-98%) with no statistically significant differences, generally outperforming diclofenac sodium (70-87%). Notably, anti-inflammatory activity via COX pathways proved to be seasonally dependent: Spr-EO inhibited COX-1 and COX-2 more significantly than Aut-EO, with both EOs showing COX-1 selectivity (IC₅₀ of 284 vs. 560 µg/mL). Although less potent than diclofenac sodium (COX IC₅₀ < 0.2 µg/mL), the superior activity of Spr-EO was supported by molecular docking, suggesting this enhanced effect is driven by higher contents of kaur-16-ene and oxygenated sesquiterpenes (such as α- and β-eudesmol). These bioactivities provide baseline parameters for batch standardization. By merging stable core properties with seasonal anti-inflammatory profiles, Az-CJF EO shows promise as a natural multi-target-directed ligand (MTDL) for therapeutic applications within a circular bioeconomy.