Variations in Essential Oil Biological Activities of Female Cones at Different Developmental Stages from Azorean Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae)

Abstract

In the Azores Archipelago, Cryptomeria japonica is, currently, the most cultivated forestry tree for timber production, landscaping, and gardening, generating large amounts of foliage waste that is used for local essential oils (EOs) production. However, the existing literature on the biological potential of EOs from different C. japonica foliage parts, such as female cones (FC), remains limited. Thus, in the present study, EOs extracted by hydrodistillation from Azorean C. japonica immature and mature FC (IFC and MFC), as well as some major EO components, were screened for their: (i) antioxidant capacity, evaluated by DPPH free-radical-scavenging activity (FRSA) and β-carotene-linoleic acid bleaching activity (BCBA), (ii) antimicrobial activities, assessed by the disc diffusion method against eight bacteria and one fungus, and (iii) toxicity against Artemia salina. Among both FC EO samples, the IFC EO exhibited the best DPPH–FRSA, BCBA, and growth inhibitory activity against Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, and Penicillium italicum, as well as a slightly increased toxic potential, due to their differential compositions, as assessed by GC–MS analysis. Thus, the FC’s maturation process decreased their EOs’ bioactivities. In conclusion, this finding could help in determining the optimal developmental stage for enhancing the antioxidant and antimicrobial compounds content in FC EOs. In turn, this contributes to increasing the commercial potential of C. japonica’s EO industry.

Chemical Compositions and In Vitro Antioxidant Activities of the Essential Oils of Sawdust and Resin-Rich Bark from Azorean Cryptomeria japonica (Cupressaceae)

“…However, when compared with the other plant parts of C. japonica , namely immature female cones (IFC), both EO samples in this study exhibited less scavenging activity in the DPPH assay, with EC 50 values of 1.1–1.3 mg/mL vs. 0.67 ± 0.24 mg/mL for IFC. These results may be associated with the content of γ-eudesmol and nezukol, which are both higher in the IFC samples [ 19 ].…”

“…Helium was used as the carrier gas at a linear velocity of 36.3 cm/s. The mass spectra were recorded over the 40–400 atomic mass units (amu) range at 0.3 scans per second, with an ionization energy of 70 eV and the ion source temperature at 260 °C [ 19 ]. The identification of the EO components was assigned by matching (i) their recorded mass spectra with the standard mass spectra from several libraries (a lab-made library and FFNSC4.0, NIST11, and Wiley10 libraries) and (ii) their retention indices (RI), calculated according to ISO 7609 [ 32 ], relative to a homologous series of n -alkanes (C 7 –C 33 ).…”

“…The FRSA of the EOs, at different concentrations (0.024–25 mg/mL), and gallic acid (positive control) was determined following the procedure reported by Chen et al [ 33 ], with slight modifications [ 19 ]. In brief, 0.1 mL of each EO or gallic acid was allowed to react with 0.1 mL of DPPH solution (0.08 mg/mL in methanol) in the well of a 96-well plate.…”

“…Cryptomeria japonica is, currently, the most important commercial forestry tree in the Azores, representing 60% of the total wood-producing forest area [ 19 ]. Therefore, the logging of Azorean C. japonica produces significant quantities of biomass residues (e.g., foliage, cones, and bark), which are often left unattended, representing an environmental problem.…”

“…Nevertheless, C. japonica foliage is by far the plant organ most studied and used by Azorean wood producers to obtain EOs, with several applications, such as in the fragrance industry and aromatherapy. As part of our continuing strategy of the valorization of Azorean CJBR, thus contributing to increasing the local circular economy, we recently reported that EOs obtained via hydrodistillation (HD) processes from various aerial plant parts (leaves, foliage, female cones, and male cones) exhibit multi-bioactivities, such as natural biocides [ 29 ] and antioxidants [ 19 ]. However, studies on the chemical composition and biological activities of EOs of sawdust and bark from C. japonica remain limited.…”